CN115799514A - Single-crystal cobalt-free cathode material, preparation method and lithium ion battery - Google Patents
Single-crystal cobalt-free cathode material, preparation method and lithium ion battery Download PDFInfo
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Abstract
The invention discloses a single crystal cobalt-free anode material, a preparation method and a lithium ion battery; the single crystal cobalt-free cathode material comprises a kernel and a bromide coating layer coated on the surface of the kernel, wherein the kernel is doped with bromide, and the mass ratio of the bromide in the single crystal cobalt-free cathode material is 1-10%; the invention solves the problem of poor performance of the existing single crystal cobalt-free anode material, and obtains the single crystal cobalt-free anode material with better cycle stability and rate capability.
Description
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a single crystal cobalt-free cathode material, a preparation method and a lithium ion battery.
Background
Ternary positive electrode materials are gaining increasing attention from researchers due to their high energy density. Compared with the traditional polycrystalline ternary cathode material, the monocrystalline ternary cathode material has wide attention in the field of lithium ion batteries due to higher mechanical strength, energy density and better cycle performance. However, the existing commonly used single crystal ternary cathode materials all contain cobalt element, so that the cost and the pollution are increased, and the development of the single crystal ternary cathode materials is restricted to a certain extent. The single crystal cobalt-free cathode material is used as a novel cathode material, has the advantage of single crystallization, and reduces the cost and the pollution. However, it is not simple to synthesize single crystal cobalt-free cathode materials, particularly nickel-rich materials. The conventional method is to prepare a single crystal cobalt-free cathode material by a high-temperature synthesis method, for example, a spinel single crystal cobalt-free high-voltage lithium nickel manganese oxide cathode material disclosed in chinese patent CN113178566A, a preparation method thereof and a lithium ion battery. However, the increase of the sintering temperature can cause cation mixing and irregular particle shape and size, and the material is obviously poor in various performance indexes such as cycle performance, rate performance and the like.
A flux growth method is used as a synthesis method of a novel single crystal anode material, is conventionally applied to a cobalt-containing single crystal ternary anode material, and usually only has a single effect of reducing sintering temperature in a preparation process, and in order to avoid doping of impurity elements and further ensure the performance of the ternary anode material, the impurity elements are usually removed by adopting a water washing step in subsequent steps, so that the preparation process is complicated, and the performance of the prepared single crystal cobalt-free anode material is poor.
Disclosure of Invention
Therefore, the invention aims to solve the problem of poor performance of the existing single-crystal cobalt-free anode material, and provides the single-crystal cobalt-free anode material with better cycle stability and rate performance, the preparation method and the lithium ion battery.
The single crystal cobalt-free cathode material comprises an inner core and a bromide coating layer coated on the surface of the inner core, wherein the inner core is a bromide-doped single crystal cobalt-free cathode material, and the mass ratio of bromide in the single crystal cobalt-free cathode material is 1-10%.
The D50 of the single crystal cobalt-free anode material is 1-4 mu m, and the thickness of the bromide coating layer is less than or equal to 100nm. Preferably, the D50 of the single crystal cobalt-free cathode material is 3-4 μm, and the thickness of the bromide coating layer is less than or equal to 20nm.
The single crystal cobalt-free anodeThe ionic conductivity of the material was 10 -8 ～10 -3 S/cm, electron conductivity of 10 -6 ～10 - 2 S/cm, ion diffusion coefficient of 10 -13 ～10 -6 cm 2 S; preferably, the single crystal cobalt-free cathode material has an ionic conductivity of 10 -4 ～10 -3 S/cm, electron conductivity of 10 -4 ～10 -3 S/cm, ion diffusion coefficient of 10 -10 ～10 -9 cm 2 /s；
And/or the intensity ratio of a 003X-ray diffraction peak to a 104X-ray diffraction peak of the single crystal cobalt-free cathode material is more than or equal to 1.5, and the half-peak width of the 003X-ray diffraction peak is 0.4-1.0 degrees; preferably, the intensity ratio of a 003X-ray diffraction peak to a 104X-ray diffraction peak of the single-crystal cobalt-free cathode material is more than or equal to 1.6, and the half-peak width of the 003X-ray diffraction peak is 0.4-0.7 degrees;
and/or the specific surface area of the single crystal cobalt-free cathode material is 0.01-2 m 2 (iv)/g, pH value is less than or equal to 11.5; preferably, the specific surface area of the single crystal cobalt-free cathode material is 0.08-0.1 m 2 /g；
And/or the single crystal cobalt-free cathode material is LiNi x M 1-x O 2 X is more than or equal to 0.6 and less than or equal to 0.95; m is one of Mn or Al.
A preparation method of a single-crystal cobalt-free cathode material comprises the following steps:
mixing a Ni-M-based precursor with a lithium source to obtain mixed powder a, wherein M is at least one of Mn or Al;
mixing the mixed powder a with bromide to obtain mixed powder b; the mass ratio of the bromide in the mixed powder b is 1-10%;
heating the mixed powder b to 450-500 ℃ at a heating rate of 2-10 ℃/min in an oxygen atmosphere, and keeping the temperature for 2-3 h; then heating to 800-900 ℃ at the heating rate of 1-3 ℃/min, preserving the heat for 10-16 h, and cooling to obtain the single crystal cobalt-free anode material.
The Ni-M-based precursor is Ni x M 1-x (OH) 2 M is one of Mn or Al, wherein x is more than or equal to 0.6 and less than or equal to 0.95.
The molar ratio of the Ni-M based precursor to the lithium source is 1.06 to 1.15.
The lithium source is one of lithium hydroxide, lithium carbonate, lithium nitrate and lithium oxalate, and lithium carbonate is preferred.
The bromide is at least one of potassium bromide, sodium bromide, magnesium bromide and lithium bromide.
The preparation process of the mixed powder b also comprises the step of mixing a halide fluxing agent in the mixed powder a; the halide fluxing agent is at least one of potassium fluoride, sodium fluoride, magnesium fluoride, lithium fluoride, potassium chloride, sodium chloride, magnesium chloride and lithium chloride; the mass ratio of the halide fluxing agent in the mixed powder b is 1-5%.
A lithium ion battery comprises the single-crystal cobalt-free anode material or the single-crystal cobalt-free anode material prepared by the preparation method of the single-crystal cobalt-free anode material.
The technical scheme of the invention has the following advantages:
1. the single crystal cobalt-free anode material comprises an inner core and a bromide coating layer coated on the surface of the inner core, wherein the inner core is a bromide-doped single crystal cobalt-free anode material, and the mass ratio of bromide in the single crystal cobalt-free anode material is 1-10%; the anions and cations in the bromide can be doped into the matrix, and Br in the bromide - Doping resists attack by hydrogen fluoride from the electrolyte and stronger Br-and metallic bonds, thus improving the integrity of the anode and electrolyte interface; in addition, the positive ions in the bromide can occupy Li positions and expand the interlayer spacing by doping, so that the diffusion rate of Li + is improved, and the rate capability of the single crystal cobalt-free cathode material is further improved. Meanwhile, the surface of the inner core is also coated with a halide coating layer, so that the direct contact of the material and electrolyte can be effectively prevented, and the structural stability of the material is improved;
therefore, compared with the conventional single crystal cobalt-free cathode material, the single crystal cobalt-free cathode material prepared by the invention has obviously improved cycle stability and rate capability.
2. According to the preparation method of the single crystal cobalt-free anode material, provided by the invention, only bromide is used as a fluxing agent, the bromide is added into a mixed powder a obtained by mixing a Ni-M-based precursor and a lithium source, and primary sintering is carried out, and water washing is not needed after sintering, the fluxing agent is not only used as the fluxing agent in the preparation process, so that the preparation temperature of the single crystal cobalt-free anode material is reduced, in the process of preparing the single crystal cobalt-free anode material, anions and cations in the bromide can be doped into the matrix, so that the single crystal cobalt-free anode material doped with the bromide is prepared as an inner core, and the single crystal cobalt-free anode material coated on the surface of the inner core is coated with the bromide;
therefore, in the preparation process of the invention, the bromide not only serves as a fluxing agent to achieve the effects of promoting the growth of cobalt-free single crystal cathode particles and reducing the calcining temperature. On the other hand, the co-doping of anions and cations can be realized in situ, the capability of resisting hydrogen fluoride corrosion in electrolyte is enhanced, the interlayer spacing is enlarged, the diffusion rate of lithium ions is increased, and the multiplying power performance of the single crystal cobalt-free anode material is improved. In addition, the coating layer can reduce the surface residue of redundant lithium salt and prevent the direct contact of electrolyte and materials, thereby reducing unnecessary side reactions, preventing the growth of a CEI film and improving the structural stability of the single crystal cobalt-free cathode material.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 SEM image of a single crystal cobalt-free positive electrode material in example 1;
FIG. 2 TEM image of a single crystal cobalt-free cathode material in example 1;
FIG. 3 XPS plots of Br 3d collected after etching to 0, 60 and 120nm for example 1;
fig. 4 is a graph comparing cycle performances of the single crystal cobalt-free cathode materials prepared in example 1 and comparative example 1;
fig. 5 is a graph comparing rate performance of the single crystal cobalt-free cathode materials prepared in example 1 and comparative example 1.
Detailed Description
The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field.
Example 1
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mix Ni 0.8 Mn 0.2 (OH) 2 Grinding the powder with lithium carbonate according to a molar ratio of 1.08 to obtain mixed powder a;
(2) Mixing powder a with magnesium bromide (MgBr) 2 ) Completely mixing and uniformly grinding, marking the obtained powder as mixed powder b, and controlling the mass ratio of the fluxing agent in the mixed powder b to be 4%;
(3) Then raising the temperature of the mixed powder b to 500 ℃ at a heating rate of 5 ℃/min for heat preservation for 3h in an oxygen atmosphere, then raising the temperature to 850 ℃ at a heating rate of 2 ℃/min for heat preservation for 14h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free cathode material LiNi 0.8 Mn 0.2 O 2 。
The single crystal cobalt-free cathode material LiNi prepared by the embodiment 0.8 Mn 0.2 O 2 And performing SEM and TEM detection, etching the obtained cathode material, and respectively obtaining XPS (X-ray diffraction) images of Br 3d after etching to 0nm, 60 nm and 120nm, as shown in figures 1-3. As can be seen from the SEM scanning electron microscopic results in FIG. 1, the obtained product was single-crystal particles with smooth and non-surfaceImpurities, and the particle size is 2-4 μm. It can be seen from the TEM results in fig. 2 that the particle surface was coated with a layer of halide. It can be found from the XPS result in fig. 3 that Br ions are doped into the interior of the particles.
Example 2
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mixing Ni 0.8 Mn 0.2 (OH) 2 Grinding the lithium carbonate according to a molar ratio of 1;
(2) Completely mixing the mixed powder a with potassium bromide (KBr) and uniformly grinding, marking the obtained powder as mixed powder b, and controlling the mass ratio of the fluxing agent in the mixed powder b to be 4%;
(3) Then, heating the mixed powder b to 500 ℃ at a heating rate of 5 ℃/min for 3h under an oxygen atmosphere, then heating to 850 ℃ at a heating rate of 2 ℃/min for 14h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free cathode material LiNi 0.8 Mn 0.2 O 2 。
Example 3
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mixing Ni 0.8 Mn 0.2 (OH) 2 Grinding the powder with lithium carbonate according to a molar ratio of 1.08 to obtain mixed powder a;
(2) Completely mixing the mixed powder a with sodium bromide (NaBr) and uniformly grinding, marking the obtained powder as mixed powder b, and controlling the mass ratio of the fluxing agent in the mixed powder b to be 4%;
(3) Then, heating the mixed powder b to 500 ℃ at a heating rate of 5 ℃/min for 3h under an oxygen atmosphere, then heating to 850 ℃ at a heating rate of 2 ℃/min for 14h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free anode material LiNi 0.8 Mn 0.2 O 2 。
Example 4
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mixing Ni 0.8 Mn 0.2 (OH) 2 Grinding the powder with lithium carbonate according to a molar ratio of 1.08 to obtain mixed powder a;
(2) Completely mixing the mixed powder a with lithium bromide (LiBr) and uniformly grinding, marking the obtained powder as mixed powder b, and controlling the mass ratio of the fluxing agent in the mixed powder b to be 4%;
(3) Then, heating the mixed powder b to 500 ℃ at a heating rate of 5 ℃/min for 3h under an oxygen atmosphere, then heating to 850 ℃ at a heating rate of 2 ℃/min for 14h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free anode material LiNi 0.8 Mn 0.2 O 2 。
Example 5
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mixing Ni 0.6 Mn 0.4 (OH) 2 Grinding the mixture and lithium nitrate according to a molar ratio of 1.13 to obtain mixed powder a;
(2) Mixing powder a with magnesium bromide (MgBr) 2 ) Completely mixing and uniformly grinding, marking the obtained powder as mixed powder b, and controlling the mass ratio of the fluxing agent in the mixed powder b to be 1%;
(3) Then, raising the temperature of the mixed powder b to 450 ℃ at a heating rate of 2 ℃/min and preserving heat for 2h in an oxygen atmosphere, then raising the temperature to 900 ℃ at a heating rate of 3 ℃/min and preserving heat for 10h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free cathode material LiNi 0.6 Mn 0.4 O 2 。
Example 6
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mixing Ni 0.9 Mn 0.1 (OH) 2 And lithium hydroxide at a molar ratio of 1.10 to obtainMixing the powder a;
(2) Mixing powder a with magnesium bromide (MgBr) 2 ) Completely mixing and uniformly grinding, marking the obtained powder as mixed powder b, and controlling the mass ratio of the fluxing agent in the mixed powder b to be 10%;
(3) Then raising the temperature of the mixed powder b to 500 ℃ at a heating rate of 10 ℃/min for heat preservation for 2.5h in an oxygen atmosphere, then raising the temperature to 800 ℃ at a heating rate of 1 ℃/min for heat preservation for 16h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free cathode material LiNi 0.9 Mn 0.1 O 2 。
Example 7
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mixing Ni 0.95 Mn 0.05 (OH) 2 Grinding the powder with lithium carbonate according to a molar ratio of 1;
(2) Mixing powder a with magnesium bromide (MgBr) 2 ) Completely mixing and uniformly grinding, marking the obtained powder as mixed powder b, and controlling the mass ratio of the fluxing agent in the mixed powder b to be 8%;
(3) Then, raising the temperature of the mixed powder b to 500 ℃ at the heating rate of 8 ℃/min and preserving heat for 2.5h in the oxygen atmosphere, then raising the temperature to 880 ℃ at the heating rate of 2 ℃/min and preserving heat for 16h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free cathode material LiNi 0.95 Mn 0.05 O 2 。
Example 8
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mixing Ni 0.8 Al 0.2 (OH) 2 Grinding the powder with lithium carbonate according to a molar ratio of 1;
(2) Mixing the mixed powder a with magnesium bromide (MgBr) 2 ) Mixing completely, grinding to obtain powder B, and mixing with fluxThe quantity ratio is controlled to be 5 percent;
(3) Then, raising the temperature of the mixed powder b to 500 ℃ at the heating rate of 5 ℃/min and preserving heat for 2.5h in the oxygen atmosphere, then raising the temperature to 840 ℃ at the heating rate of 2 ℃/min and preserving heat for 12h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free cathode material LiNi 0.8 Al 0.2 O 2 。
Example 9
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mixing Ni 0.8 Mn 0.2 (OH) 2 Grinding the powder with lithium carbonate according to a molar ratio of 1.08 to obtain mixed powder a;
(2) Mixed powder a, magnesium bromide (MgBr) 2 ) Completely mixing and uniformly grinding the halide fluxing agent sodium chloride (NaCl), wherein the obtained powder is marked as mixed powder b, the mass ratio of the magnesium bromide in the mixed powder b is controlled to be 4%, and the mass ratio of the sodium chloride in the mixed powder b is controlled to be 4%;
(3) Then, heating the mixed powder b to 500 ℃ at a heating rate of 5 ℃/min for 3h under an oxygen atmosphere, then heating to 850 ℃ at a heating rate of 2 ℃/min for 14h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free anode material LiNi 0.8 Mn 0.2 O 2 。
Comparative example 1
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mixing Ni 0.8 Mn 0.2 (OH) 2 Grinding the powder with lithium carbonate according to a molar ratio of 1.08 to obtain mixed powder a;
(2) Mixing the mixed powder a, completely mixing with NaCl, uniformly grinding to obtain powder labeled as mixed powder b, and controlling the mass ratio of the fluxing agent in the mixed powder c to be 4%;
(3) Then, heating the mixed powder b to 500 ℃ at a heating rate of 5 ℃/min for 3h under an oxygen atmosphere, then heating to 850 ℃ at a heating rate of 2 ℃/min for 14h, and then cooling to obtain powder particles;
(4) Crushing and sieving the powder particles to obtain the single crystal cobalt-free cathode material LiNi 0.8 Mn 0.2 O 2 。
Comparative example 2
A preparation method of a single crystal cobalt-free anode material comprises the following specific steps:
(1) Mix Ni 0.8 Mn 0.2 (OH) 2 Grinding the powder with lithium carbonate according to a molar ratio of 1.08 to obtain mixed powder a;
(2) Heating the mixed powder a to 500 ℃ at a heating rate of 5 ℃/min for 3h under an oxygen atmosphere, then heating to 850 ℃ at a heating rate of 2 ℃/min for 14h, and then cooling to obtain powder particles;
(3) Crushing and sieving the powder particles to obtain the single crystal cobalt-free cathode material LiNi 0.8 Mn 0.2 O 2 。
Test example 1
The positive electrode materials prepared in examples and comparative examples were used to detect D50, thickness of the coating layer, ionic conductivity, electronic conductivity, ion diffusion coefficient, intensity ratio of 003X-ray diffraction peak to 104X-ray diffraction peak, half-peak width of 003X-ray diffraction peak, and specific surface area. The D50 is detected by a grid screening method, the thickness of the coating layer is detected by a projection electron microscope, the ionic conductivity, the electronic conductivity and the ionic diffusion coefficient are detected by a Chenghua electrochemical workstation, the intensity ratio of a 003X-ray diffraction peak to a 104X-ray diffraction peak and the half-peak width of the 003X-ray diffraction peak are detected by XRD, and the specific surface area is detected by GB/T19587-2004 'determination of the specific surface area of a solid substance by a gas adsorption BET method'. The test results of the above items are shown in tables 1 and 2 below.
TABLE 1
TABLE 2
Client case number P20221956
As can be seen from tables 1 and 2, the single crystal cobalt-free cathode material prepared according to the present invention has both a core and a bromide coating layer, and the core also has bromide doping. Moreover, the bromide doping can effectively improve the ionic conductivity, the electronic conductivity and the ionic diffusion coefficient.
Test example 2
The positive electrode materials prepared in the examples and the comparative examples are applied to a battery, and the assembly process of the battery is as follows: firstly, 0.2g of positive electrode material, 0.025g of PVDF and 0.025g of graphite are weighed, and the three materials are mixed according to the mass ratio of 8:1:1, uniformly grinding the slurry in a mortar for 40 minutes, then adding 0.8ml of N-methyl-2-pyrrolidone (NMP) and continuously stirring for 10 minutes to ensure that the slurry has no particles inside, then uniformly coating the slurry on an aluminum foil by using a scraper, then putting the aluminum foil into a blast drying oven to dry for 30 minutes at the temperature of 100 ℃, taking out the aluminum foil and cutting the aluminum foil into a circular pole piece and an aluminum sheet with the diameter of 12mm by using a cutting machine, putting the circular pole piece and the aluminum sheet into a vacuum drying oven to dry for 12 hours at the temperature of 60 ℃, taking out the circular pole piece and the aluminum sheet, weighing the circular pole piece and the aluminum sheet by using an electron, and finally assembling a positive pole piece, a lithium sheet, an elastic sheet, a gasket, a positive pole shell, a negative pole shell, a diaphragm and an electrolyte in a glove box to form the CR2025 type button half cell.
The cycle performance and rate performance of the batteries corresponding to the positive electrode materials of different examples and comparative examples were tested, wherein the test results of example 1 and comparative example 1 are shown in fig. 4 and 5. Meanwhile, batteries corresponding to each example and comparative example were separately obtained at a voltage ranging from 2.8 to 4.3V, client No. P20221956
1C(1C＝200mA·g -1 ) Capacity retention after 200 weeks cycling at magnification, and examples anddischarge capacity data of the comparative examples, the results are shown in table 3 below.
TABLE 3
According to the detection results, compared with the single crystal cobalt-free anode material without bromide doping and cladding, the single crystal cobalt-free anode material with the bromide doping inner core and the bromide cladding layer on the surface of the inner core, prepared by the invention, has the advantages that the recycling capacity retention rate and the discharge capacity are obviously improved, and the cycle stability and the rate capability of the single crystal cobalt-free anode material are effectively improved.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (10)
1. The single crystal cobalt-free cathode material is characterized by comprising an inner core and a bromide coating layer coated on the surface of the inner core, wherein bromide is doped in the inner core, and the mass ratio of the bromide in the single crystal cobalt-free cathode material is 1-10%.
2. The single crystal cobalt-free cathode material according to claim 1, wherein the D50 of the single crystal cobalt-free cathode material is 1-4 μm, and the thickness of the bromide coating layer is less than or equal to 100nm.
3. The single crystal cobalt-free cathode material as claimed in claim 1 or 2, wherein the ionic conductivity of the single crystal cobalt-free cathode material is 10 -8 ～10 -3 S/cm, electron conductivity of 10 -6 ～10 -2 S/cm, ion diffusion coefficient of 10 -13 ～10 -6 cm 2 /s；
And/or the intensity ratio of a 003X-ray diffraction peak to a 104X-ray diffraction peak of the single crystal cobalt-free cathode material is more than or equal to 1.5, and the half-peak width of the 003X-ray diffraction peak is 0.4-1.0 degrees;
and/or the specific surface area of the single-crystal cobalt-free cathode material is 0.01-2 m 2 (iv)/g, pH value is less than or equal to 11.5;
and/or the single crystal cobalt-free cathode material is LiNi x M 1-x O 2 X is more than or equal to 0.6 and less than or equal to 0.95; m is one of Mn or Al;
and/or the bromide is at least one of potassium bromide, sodium bromide, magnesium bromide and lithium bromide.
4. A preparation method of a single crystal cobalt-free cathode material is characterized by comprising the following steps:
mixing a Ni-M-based precursor with a lithium source to obtain mixed powder a, wherein M is at least one of Mn or Al;
mixing the mixed powder a with bromide to obtain mixed powder b; the mass ratio of the bromide in the mixed powder b is 1-10%;
heating the mixed powder b to 450-500 ℃ at a heating rate of 2-10 ℃/min in an oxygen atmosphere, and keeping the temperature for 2-3 h; then heating to 800-900 ℃ at the heating rate of 1-3 ℃/min, preserving the heat for 10-16 h, and cooling to obtain the single crystal cobalt-free anode material.
5. The production method according to claim 4, wherein the Ni-M-based precursor is Ni x M 1-x (OH) 2 M is one of Mn or Al, wherein x is more than or equal to 0.6 and less than or equal to 0.95.
6. The production method according to claim 4 or 5, wherein the molar ratio of the Ni-M based precursor to the lithium source is 1.
7. The production method according to any one of claims 4 to 6, wherein the lithium source is one of lithium hydroxide, lithium carbonate, lithium nitrate and lithium oxalate, preferably lithium carbonate.
8. The method according to any one of claims 4 to 7, wherein the bromide is at least one of potassium bromide, sodium bromide, magnesium bromide and lithium bromide.
9. The method according to any one of claims 4 to 8, wherein the method further comprises a step of mixing a halide flux in the mixed powder a; the halide fluxing agent is at least one of potassium fluoride, sodium fluoride, magnesium fluoride, lithium fluoride, potassium chloride, sodium chloride, magnesium chloride and lithium chloride; the mass ratio of the halide fluxing agent in the mixed powder b is 1-5%.
10. A lithium ion battery comprising a single crystal cobalt-free cathode material according to any one of claims 1 to 3, or comprising a single crystal cobalt-free cathode material prepared by the method of any one of claims 4 to 9.
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| CN117038956A (en) * | 2023-10-09 | 2023-11-10 | 浙江帕瓦新能源股份有限公司 | Cobalt-free high-nickel positive electrode material, preparation method thereof and lithium ion battery |
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| CN117038956B (en) * | 2023-10-09 | 2024-01-23 | 浙江帕瓦新能源股份有限公司 | Cobalt-free high-nickel positive electrode material, preparation method thereof and lithium ion battery |
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