CN116022859A - Method for preparing positive electrode material and positive electrode material - Google Patents
Method for preparing positive electrode material and positive electrode material Download PDFInfo
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- CN116022859A CN116022859A CN202111250645.7A CN202111250645A CN116022859A CN 116022859 A CN116022859 A CN 116022859A CN 202111250645 A CN202111250645 A CN 202111250645A CN 116022859 A CN116022859 A CN 116022859A
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Abstract
The present disclosure relates to a method of preparing a positive electrode material and a positive electrode material, the method comprising: mixing a manganese-containing precursor with a lithium source, and calcining in an oxygen-containing atmosphere to obtain a layered lithium-rich manganese-based anode material matrix; washing the layered lithium-rich manganese-based positive electrode material matrix to obtain a washed layered lithium-rich manganese-based positive electrode material matrix; and mixing the washed layered lithium-rich manganese-based positive electrode material matrix with an aluminum source, and then carrying out secondary calcination in an oxygen-containing atmosphere to obtain the positive electrode material. According to the method, a large amount of aluminum elements can be uniformly introduced into the internal crystal structure of the layered lithium-rich manganese-based positive electrode material by adopting a step-by-step calcination process, so that the structural stability of the positive electrode material can be remarkably improved, and the problem that the discharge median voltage of the positive electrode material is fast in decay in a cyclic process is effectively solved, so that the positive electrode material prepared by the method is slow in decay of the discharge median voltage and has good cyclic performance and multiplying power performance.
Description
Technical Field
The disclosure relates to the technical field of lithium ion batteries, in particular to a method for preparing a positive electrode material and the positive electrode material.
Background
With the rapid development of new energy automobiles, the demand for high-energy density lithium ion batteries in the field is increasing. The positive electrode material is a key factor for determining the energy density of the lithium ion battery, and the positive electrode material of the lithium ion battery which is commercially applied at present mainly comprises lithium manganate, lithium iron phosphate, ternary materials and the like, but the materials have the defect of low specific capacity.
Layered lithium-rich manganese-based positive electrode material xLi 2 MnO 3 ·(1-x)LiMO 2 (M=at least one of Mn, ni and Co) has high discharge specific capacity>250 mAh/g), high energy density, low raw material cost, environmental protection, high safety and the like, and is one of important candidate cathode materials for developing high-energy-density (300 Wh/kg), low-cost and high-safety lithium ion batteries. However, the layered lithium-rich manganese-based positive electrode material also has the defects of poor circularity, poor ploidy, rapid discharge median voltage decay and the like, and especially the problem of discharge median voltage decay in the circulation process severely restricts the application of the layered lithium-rich manganese-based positive electrode material in commercialization.
The internal crystal structure of the layered lithium-rich manganese-based positive electrode material can be improved by introducing the Al element into the layered lithium-rich manganese-based positive electrode material, so that the problem of serious discharge median voltage attenuation of the layered lithium-rich manganese-based positive electrode material is solved, however, in the related art, the amount of the Al element introduced into the layered lithium-rich manganese-based positive electrode material is still small, and the discharge median voltage attenuation resisting effect is not obvious enough.
Disclosure of Invention
The purpose of the present disclosure is to solve the problems in the prior art that the amount of Al element introduced into a layered lithium-rich manganese-based positive electrode material is small and the effect of reducing the median voltage of discharge resistance is not obvious enough, and provide a method for preparing the positive electrode material and the positive electrode material.
In order to achieve the above object, the present disclosure provides a method of preparing a positive electrode material, the method comprising:
mixing a manganese-containing precursor with a lithium source, and calcining in an oxygen-containing atmosphere to obtain a layered lithium-rich manganese-based anode material matrix;
washing the layered lithium-rich manganese-based positive electrode material matrix to obtain a washed layered lithium-rich manganese-based positive electrode material matrix;
and mixing the washed layered lithium-rich manganese-based positive electrode material matrix with an aluminum source, and then carrying out secondary calcination in an oxygen-containing atmosphere to obtain the positive electrode material.
Optionally, when the layered lithium-rich manganese-based positive electrode material matrix is obtained by calcination, the calcination comprises low-temperature presintering and high-temperature sintering; wherein, the liquid crystal display device comprises a liquid crystal display device,
the low-temperature presintering conditions comprise: the temperature rising rate is 1-5 ℃/min, the presintering temperature is 400-550 ℃, and the presintering time is 3-5 h;
the conditions of the high-temperature sintering include: the temperature rising rate is 1-3 ℃/min, the sintering temperature is 800-900 ℃ and the sintering time is 10-15 h.
Optionally, the washing treatment comprises:
mixing the layered lithium-rich manganese-based positive electrode material matrix with a washing solution, washing the layered lithium-rich manganese-based positive electrode material matrix under a stirring condition, and performing suction filtration and drying after washing to obtain a washed layered lithium-rich manganese-based positive electrode material matrix; wherein, the liquid crystal display device comprises a liquid crystal display device,
the washing liquid is used in an amount of 10-20 parts by weight relative to 1 part by weight of the layered lithium-rich manganese-based positive electrode material matrix; the washing conditions included: stirring speed is 100-1000 rpm, washing temperature is 20-100 ℃, and washing time is 30-180 min; the drying conditions include: the drying temperature is 100-150 ℃ and the drying time is 2-8 h.
Optionally, when the positive electrode material is obtained by secondary calcination, the conditions of the secondary calcination include: the temperature rising rate is 3-10 ℃/min, the calcining temperature is 600-900 ℃ and the calcining time is 6-15 h;
preferably, the temperature rising rate is 4-8 ℃/min, the calcining temperature is 700-800 ℃ and the calcining time is 8-14 h.
Optionally, the manganese-containing precursor comprises a nickel cobalt manganese ternary precursor comprising Mn a Co b Ni c (OH) 2 And/or Mn a Co b Ni c CO 3 Wherein a is more than or equal to 0.5 and less than or equal to 1, b is more than or equal to 0.25, c is more than or equal to 0 and less than or equal to 0.25, and a+b+c=1.
Optionally, the lithium source comprises lithium carbonate and/or lithium hydroxide; the usage amount of the nickel-cobalt-manganese ternary precursor and the lithium source based on the element molar amount satisfies the following relation: li/(Ni+Co+Mn) = (1.0 to 1.5): 1, preferably (1.1 to 1.4): 1.
Optionally, the aluminum source comprises at least one of aluminum oxide, aluminum hydroxide, aluminum nitrate, or pseudo-boehmite; the use amounts of the washed layered lithium-rich manganese-based positive electrode material matrix and the aluminum source satisfy the following relationship based on the element molar amount: al/(Ni+Co+Mn+Al) = (0.01 to 0.1): 1, preferably (0.03 to 0.05): 1.
The disclosure also provides a positive electrode material, which comprises a layered lithium-rich manganese-based positive electrode material matrix and aluminum uniformly distributed in the layered lithium-rich manganese-based positive electrode material matrix, wherein the loading amount of the aluminum is not less than 2 wt%, preferably not less than 3 wt%, based on the total weight of the positive electrode material.
Optionally, the chemical formula of the positive electrode material is Li 1.2+x [(Mn a Co b Ni c ) 1-d Al d ] 0.8-x O 2 Wherein, -0.2 < x is less than or equal to 0.3,0.5 is less than or equal to a is less than or equal to 1,0 < b is less than or equal to 0.25,0 < c is less than or equal to 0.25,0.01, d is less than or equal to 0.1, and a+b+c=1;
preferably, x is more than or equal to 0.005 and less than or equal to 0.015,0.5 and less than or equal to a is more than or equal to 0.8,0.1 and less than or equal to b is more than or equal to 0.2,0.1 and less than or equal to c is more than or equal to 0.2,0.03 and less than or equal to d is more than or equal to 0.05.
Optionally, the positive electrode material is spherical particles, the particle size is 5-20 mu m, and the particle size D50 is 8-12 mu m.
The disclosure also provides a positive electrode plate of a lithium ion battery, which contains the positive electrode material prepared by the method or the positive electrode material prepared by the method.
The disclosure also provides a lithium ion battery having the positive electrode plate.
Through the technical scheme, a large amount of aluminum elements can be uniformly introduced into the internal crystal structure of the layered lithium-rich manganese-based positive electrode material by adopting the step-by-step calcination process, so that the structural stability of the positive electrode material can be remarkably improved, and the problem that the discharge median voltage of the positive electrode material decays rapidly in the circulating process is effectively solved. Therefore, the positive electrode material prepared by the method disclosed by the invention has slower discharge median voltage attenuation and better cycle performance and rate performance.
Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate the disclosure and together with the description serve to explain, but do not limit the disclosure. In the drawings:
FIG. 1 is a graph of electron microscope scan results for a nickel cobalt manganese ternary precursor material in example 1 of the present disclosure;
fig. 2 is a graph showing XRD analysis results of the positive electrode material S1 prepared in example 1 of the present disclosure and the positive electrode material D1 prepared in comparative example 1;
FIG. 3 is a graph showing the electron microscope scan results of the positive electrode material S1 prepared in example 1 of the present disclosure and the positive electrode material D1 prepared in comparative example 1;
FIG. 4 is a graph showing the result of EPAM analysis of the positive electrode material S1 prepared in example 1 of the present disclosure;
FIG. 5 is a graph showing the cycle performance of the positive electrode material S1 prepared in example 1 of the present disclosure and the positive electrode material D1 prepared in comparative example 1 at a rate of 0.2C;
FIG. 6 is a graph showing the comparison of the rate performance of the positive electrode material S1 prepared in example 1 of the present disclosure and the positive electrode material D1 prepared in comparative example 1 at a rate of 0.1 to 3C;
fig. 7 is a graph showing the discharge median voltage decay at 0.2C rate of the positive electrode material S1 prepared in example 1 of the present disclosure and the positive electrode material D1 prepared in comparative example 1.
Detailed Description
Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.
A first aspect of the present disclosure provides a method of preparing a positive electrode material, the method comprising: mixing a manganese-containing precursor with a lithium source, and calcining in an oxygen-containing atmosphere to obtain a layered lithium-rich manganese-based anode material matrix; washing the layered lithium-rich manganese-based positive electrode material matrix to obtain a washed layered lithium-rich manganese-based positive electrode material matrix; and mixing the washed layered lithium-rich manganese-based positive electrode material matrix with an aluminum source, and then carrying out secondary calcination in an oxygen-containing atmosphere to obtain the positive electrode material.
The aluminum element is introduced into the layered lithium-rich manganese-based positive electrode material, so that on one hand, the bond energy of Al-O is larger, and the structural stability of the positive electrode material can be obviously improved, thereby improving various electrochemical properties and thermal stability of the positive electrode material, and on the other hand, the aluminum element is Al 3+ Can reduce the positive electrode material in Li + Volume change in the process of de-intercalation effectively inhibits the appearance and the expansion of microcracks in the secondary particles.
In the related art, when aluminum element is introduced into a layered lithium-rich manganese-based positive electrode material, typically after a manganese-containing precursor, a lithium source and an aluminum source are blended and then sintered at a high temperature, the inventors of the present disclosure found that since Al and Li easily react under high temperature and oxygen-containing conditions, liAlO is generated 2 This results in less aluminum element being incorporated into the layered lithium-rich manganese-based cathode material。
In the method, a layered lithium-rich manganese-based positive electrode material matrix is obtained by adopting a step-by-step calcination process, excessive Li is washed and washed, and then the washed layered lithium-rich manganese-based positive electrode material matrix and an aluminum source are subjected to secondary calcination to obtain the positive electrode material, wherein the method does not cause Li and Al to react in an oxygen-containing atmosphere, and LiAlO is avoided 2 The generation of the lithium-rich manganese-based anode material does not destroy the microscopic morphology of the layered lithium-rich manganese-based anode material matrix, so that aluminum elements are uniformly distributed in the layered lithium-rich manganese-based anode material, the structural stability of the anode material can be remarkably improved, and the problem that the discharge median voltage of the anode material decays rapidly in the circulation process is effectively solved. Therefore, the positive electrode material prepared by the method disclosed by the invention has slower discharge median voltage attenuation, higher discharge specific capacity, better cycle performance and rate capability.
In addition, the method disclosed by the invention has the advantages of simple and feasible process steps, convenience in operation, lower cost and controllable process, and is suitable for large-scale industrial production.
According to the present disclosure, when the layered lithium-rich manganese-based positive electrode material matrix is obtained by calcination, the conditions of the calcination may vary within a certain range, for example, the calcination may include low-temperature pre-sintering and high-temperature sintering; wherein, the low-temperature presintering condition may include: the temperature rising rate is 1-5 ℃/min, the presintering temperature is 400-550 ℃, and the presintering time is 3-5 h; the conditions of the high temperature sintering may include: the temperature rising rate is 1-3 ℃/min, the sintering temperature is 800-900 ℃ and the sintering time is 10-15 h.
In the present disclosure, specifically, the manganese-containing precursor and the lithium source may be uniformly mixed by a ball milling method, and the ball milling conditions may be changed within a certain range, for example, the rotational speed of the ball milling may be 150 to 250rpm, and the ball milling time may be 0.5 to 3 hours. When the mixture of the manganese-containing precursor and the lithium source is calcined, the gas in the oxygen-containing atmosphere may be air and/or oxygen.
According to the present disclosure, the washing process may include: mixing the layered lithium-rich manganese-based positive electrode material matrix with a washing solution, washing the layered lithium-rich manganese-based positive electrode material matrix under a stirring condition, and performing suction filtration and drying after washing to obtain a washed layered lithium-rich manganese-based positive electrode material matrix; wherein, relative to 1 part by weight of the layered lithium-rich manganese-based positive electrode material matrix, the dosage of the washing liquid can be 10 to 20 parts by weight; the washing conditions may include: stirring speed is 100-1000 rpm, washing temperature is 20-100 ℃, and washing time is 30-180 min; the conditions for drying may include: the drying temperature is 100-150 ℃ and the drying time is 2-8 h.
In the present disclosure, in particular, the washing liquid may be selected within a certain range, for example, the washing liquid may be deionized water.
In accordance with the present disclosure, when the secondary calcination is performed to obtain the positive electrode material, the conditions of the secondary calcination may vary within a certain range, for example, the conditions of the secondary calcination may include: the temperature rising rate is 3-10 ℃/min, the calcining temperature is 600-900 ℃ and the calcining time is 6-15 h; preferably, the temperature rising rate is 4-8 ℃/min, the calcining temperature is 700-800 ℃ and the calcining time is 8-14 h.
In the present disclosure, specifically, the washed layered lithium-rich manganese-based positive electrode material substrate may be uniformly mixed with the aluminum source by a ball milling method, and the ball milling conditions may be changed within a certain range, for example, the rotational speed of the ball milling may be 150 to 250rpm, and the ball milling time may be 0.5 to 3 hours. When the mixture of the washed layered lithium-rich manganese-based positive electrode material matrix and the aluminum source is subjected to secondary calcination, the gas in the oxygen-containing atmosphere may be air and/or oxygen.
The manganese-containing precursor may be selected within a range, for example, the manganese-containing precursor may include a nickel cobalt manganese ternary precursor that may include Mn in accordance with the present disclosure a Co b Ni c (OH) 2 And/or Mn a Co b Ni c CO 3 Wherein a is more than or equal to 0.5 and less than or equal to 1, b is more than or equal to 0.25, c is more than or equal to 0 and less than or equal to 0.25, and a+b+c=1.
According to the present disclosure, the lithium source may be selected within a range, for example, the lithium source may include lithium carbonate and/or lithium hydroxide; the usage amount of the nickel-cobalt-manganese ternary precursor and the lithium source based on the element molar amount satisfies the following relation: li/(Ni+Co+Mn) = (1.0 to 1.5): 1, preferably (1.1 to 1.4): 1.
According to the present disclosure, the aluminum source may be selected within a range, for example, the aluminum source may include at least one of alumina, aluminum hydroxide, aluminum nitrate, or pseudo-boehmite; the use amounts of the washed layered lithium-rich manganese-based positive electrode material matrix and the aluminum source satisfy the following relationship based on the element molar amount: al/(Ni+Co+Mn+Al) = (0.01 to 0.1): 1, preferably (0.03 to 0.05): 1.
A second aspect of the present disclosure provides a positive electrode material comprising a layered lithium-rich manganese-based positive electrode material matrix and aluminum uniformly distributed in the layered lithium-rich manganese-based positive electrode material matrix, wherein the loading amount of aluminum is not less than 2 wt% based on the total weight of the positive electrode material; preferably, the aluminum loading is not less than 3 wt.%.
In the positive electrode material provided by the disclosure, aluminum element deeply permeates into the internal crystal structure of the layered lithium-rich manganese-based positive electrode material matrix, and aluminum element is uniformly distributed, so that the positive electrode material has the advantages of good internal structure stability, slower discharge median voltage attenuation, higher discharge specific capacity, better cycle performance and rate capability.
According to the present disclosure, the positive electrode material may have a chemical formula of Li 1.2+x [(Mn a Co b Ni c ) 1-d Al d ] 0.8-x O 2 Wherein, -0.2 < x is less than or equal to 0.3,0.5 is less than or equal to a is less than or equal to 1,0 < b is less than or equal to 0.25,0 < c is less than or equal to 0.25,0.01, d is less than or equal to 0.1, and a+b+c=1; preferably, x is more than or equal to 0.005 and less than or equal to 0.015,0.5 and less than or equal to a is more than or equal to 0.8,0.1 and less than or equal to b is more than or equal to 0.2,0.1 and less than or equal to c is more than or equal to 0.2,0.03 and less than or equal to d is more than or equal to 0.05.
According to the present disclosure, the positive electrode material may be spherical particles, and the particle diameter may be 5 to 20 μm, and the particle diameter D50 and 8 to 12 μm.
A third aspect of the present disclosure provides a positive electrode sheet of a lithium ion battery, where the positive electrode sheet contains the positive electrode material prepared by any one of the methods described above or the positive electrode material described above.
A fourth aspect of the present disclosure provides a lithium ion battery having the positive electrode tab described above.
The present disclosure is further illustrated by the following examples, but the present disclosure is not limited thereby. The materials, reagents, instruments and equipment involved in the embodiments of the present disclosure, unless otherwise specified, are all available commercially.
The analysis methods involved in the embodiments of the present disclosure are as follows:
XRD analysis: performing crystal structure analysis on the powder sample by using an X-ray powder diffractometer of U.S. Thermo Fisher Thermo ESCALAB; the sample preparation method comprises the following steps: taking a certain amount of powder sample, placing the powder sample in a groove of a ground glass sheet, and flattening the powder sample by a flat plate; test parameters: the Cu target K alpha light source is adopted, the wavelength lambda=0.154 nm, the scanning speed is 5 degrees/min, the step size is 0.04 degrees, and the test power of the equipment is 200kW.
SEM analysis: and (3) observing the morphology of the sample by adopting a FEI Quanta 200FEG scanning electron microscope.
EPMA analysis: the internal element distribution of the sample was analyzed using a JXA-8230 electron probe micro-zone analyzer of Japan.
Example 1
The positive electrode material S1 was prepared as follows:
(1) A nickel cobalt manganese ternary precursor material (Mn 0.54 Co 0.13 Ni 0.13 (CO 3 ) 0.8 ) Mixing with lithium carbonate according to Li: placing the molar ratio of M=1.3 (lithium excess is 5%, M=Ni+Mn+Co) in a ball milling tank for ball milling, fully and uniformly mixing, transferring into a box type furnace filled with air, heating to 500 ℃ at a heating rate of 2 ℃/min for presintering for 5 hours, heating to 850 ℃ at a heating rate of 1 ℃/min, preserving heat for 15 hours, cooling along with the furnace, crushing and sieving to obtain a layered lithium-rich manganese-based positive electrode material matrix;
(2) Mixing the layered lithium-rich manganese-based positive electrode material matrix obtained in the step (1) with deionized water in a ratio of 1:10, vigorously stirring for 1h at 80 ℃ and 500rpm, and then carrying out suction filtration and drying to obtain a washed layered lithium-rich manganese-based positive electrode material matrix;
(3) Mixing the layered lithium-rich manganese-based positive electrode material matrix washed in the step (2) with nano Al 2 O 3 Ball-milling and mixing for 1h in a planetary ball mill at a rotating speed of 200rmp according to the proportion of Al/(Ni+Co+Mn+Al) =0.03, transferring into a box-type furnace, heating to 850 ℃ at a heating rate of 5 ℃/min, preserving heat for 8h, cooling along with the furnace, crushing and sieving to obtain the anode material S1.
Example 2
The positive electrode material S2 was prepared as follows:
(1) A nickel cobalt manganese ternary precursor material (Mn 0.54 Co 0.13 Ni 0.13 (CO 3 ) 0.8 ) Mixing with lithium carbonate according to Li: placing the molar ratio of M=1.3 (lithium excess is 5%, M=Ni+Mn+Co) in a ball milling tank for ball milling, fully and uniformly mixing, transferring into a box furnace filled with air, heating to 500 ℃ at a heating rate of 2 ℃/min for presintering for 5 hours, heating to 820 ℃ at a heating rate of 1 ℃/min, preserving heat for 12 hours, cooling along with the furnace, crushing and sieving to obtain a layered lithium-rich manganese-based positive electrode material matrix;
(2) Mixing the layered lithium-rich manganese-based positive electrode material matrix obtained in the step (1) with deionized water in a ratio of 1:10, vigorously stirring for 1h at 50 ℃ and 800rpm, and then carrying out suction filtration and drying to obtain a washed layered lithium-rich manganese-based positive electrode material matrix;
(3) Mixing the layered lithium-rich manganese-based positive electrode material matrix washed in the step (2) with nano Al 2 O 3 Ball-milling and mixing for 1h in a planetary ball mill at a rotating speed of 200rmp according to the proportion of Al/(Ni+Co+Mn+Al) =0.05, transferring into a box-type furnace, heating to 850 ℃ at a heating rate of 10 ℃/min, preserving heat for 10h, cooling along with the furnace, crushing and sieving to obtain the anode material S2.
Example 3
The positive electrode material S3 was prepared as follows:
(1) A nickel cobalt manganese ternary precursor material (Mn 0.54 Co 0.13 Ni 0.13 (CO 3 ) 0.8 ) Mixing with lithium carbonate according to Li: molar ratio of m=1.3 (lithium excess 5%, m=ni+mn+co) Placing the materials in a ball milling tank for ball milling, fully and uniformly mixing, transferring the materials into a box furnace filled with air, heating to 500 ℃ at a heating rate of 2 ℃/min for presintering for 5 hours, heating to 850 ℃ at a heating rate of 1 ℃/min, preserving heat for 10 hours, cooling along with the furnace, crushing and sieving to obtain a layered lithium-rich manganese-based anode material matrix;
(2) Mixing the layered lithium-rich manganese-based positive electrode material matrix obtained in the step (1) with deionized water in a ratio of 1:20, vigorously stirring for 1h at 60 ℃ and 600rpm, and then carrying out suction filtration and drying to obtain a washed layered lithium-rich manganese-based positive electrode material matrix;
(3) Mixing the layered lithium-rich manganese-based positive electrode material matrix washed in the step (2) with nano Al (OH) 3 Ball-milling and mixing for 1h in a planetary ball mill at a rotating speed of 250rmp according to the proportion of Al/(Ni+Co+Mn+Al) =0.03, transferring into a box-type furnace, heating to 850 ℃ at a heating rate of 5 ℃/min, preserving heat for 8h, cooling along with the furnace, crushing and sieving to obtain the anode material S3.
Example 4
The positive electrode material S4 was prepared as follows:
(1) A nickel cobalt manganese ternary precursor material (Mn 0.54 Co 0.13 Ni 0.13 (CO 3 ) 0.8 ) Mixing with lithium carbonate according to Li: placing the molar ratio of M=1.3 (lithium excess is 5%, M=Ni+Mn+Co) in a ball milling tank for ball milling, fully and uniformly mixing, transferring into a box type furnace filled with air, heating to 500 ℃ at a heating rate of 2 ℃/min for presintering for 5 hours, heating to 850 ℃ at a heating rate of 1 ℃/min, preserving heat for 12 hours, cooling along with the furnace, crushing and sieving to obtain a layered lithium-rich manganese-based positive electrode material matrix;
(2) Mixing the layered lithium-rich manganese-based positive electrode material matrix obtained in the step (1) with deionized water in a ratio of 1:20, vigorously stirring for 1h at 80 ℃ and 500rpm, and then carrying out suction filtration and drying to obtain a washed layered lithium-rich manganese-based positive electrode material matrix;
(3) And (3) ball-milling and mixing the layered lithium-rich manganese-based positive electrode material substrate washed in the step (2) and pseudo-boehmite according to the proportion of Al/(Ni+Co+Mn+Al) =0.03 in a planetary ball mill at the rotating speed of 200rmp for 1h, transferring into a box-type furnace, heating to 850 ℃ at the heating rate of 10 ℃/min, preserving heat for 10h, cooling along with the furnace, crushing and sieving to obtain the positive electrode material S4.
Comparative example 1
The positive electrode material D1 was prepared as follows:
a nickel cobalt manganese ternary precursor material (Mn 0.54 Co 0.13 Ni 0.13 (CO 3 ) 0.8 ) Lithium carbonate and nano Al 2 O 3 Placing the materials into a ball milling tank for ball milling (molar ratio Li: M=1.3, M=Ni+Mn+Co, molar ratio Al/(Ni+Co+Mn+Al) =0.03), fully and uniformly mixing, transferring the materials into a box-type furnace filled with air, heating to 500 ℃ at a heating rate of 2 ℃/min for presintering for 5 hours, heating to 850 ℃ at a heating rate of 1 ℃/min for 12 hours, cooling along with the furnace, crushing and sieving to obtain the anode material D1.
Comparative example 2
The positive electrode material D2 was prepared as follows:
a nickel cobalt manganese ternary precursor material (Mn 0.54 Co 0.13 Ni 0.13 (CO 3 ) 0.8 ) Lithium carbonate and nano Al 2 O 3 Placing the materials into a ball milling tank for ball milling (molar ratio Li: M=1.3, M=Ni+Mn+Co, molar ratio Al/(Ni+Co+Mn+Al) =0.05), fully and uniformly mixing, transferring the materials into a box-type furnace filled with air, heating to 500 ℃ at a heating rate of 2 ℃/min for presintering for 5 hours, heating to 850 ℃ at a heating rate of 1 ℃/min for 15 hours, cooling along with the furnace, crushing and sieving to obtain the anode material D2.
Comparative example 3
The positive electrode material D3 was prepared as follows:
a nickel cobalt manganese ternary precursor material (Mn 0.54 Co 0.13 Ni 0.13 (CO 3 ) 0.8 ) Lithium carbonate and nano Al (OH) 3 Ball milling in a ball milling tank (molar ratio Li: M=1.3, M=Ni+Mn+Co, molar ratio Al/(Ni+Co+Mn+Al) =0.03), mixing, transferring to a box furnace filled with air, heating to 500 deg.C at 2 deg.C/min for presintering for 5 hr, heating to 850 deg.C at 1 deg.C/min, and maintaining the temperatureAnd (5) cooling along with a furnace for 10 hours, crushing and sieving to obtain the anode material D3.
Comparative example 4
The positive electrode material D4 was prepared as follows:
a nickel cobalt manganese ternary precursor material (Mn 0.54 Co 0.13 Ni 0.13 (CO 3 ) 0.8 ) Putting the mixture and lithium carbonate into a ball milling tank for ball milling (molar ratio Li: m=1.3, m=ni+mn+co), and after fully and uniformly mixing, transferring into a box furnace filled with air, heating to 500 ℃ at a heating rate of 2 ℃/min for presintering for 5 hours, heating to 850 ℃ at a heating rate of 1 ℃/min, preserving heat for 15 hours, cooling along with the furnace, crushing, and sieving to obtain the anode material D4.
Test example 1
(1) The nickel-cobalt-manganese ternary precursor material in example 1 was subjected to electron microscopy, and the scanning result is shown in fig. 1, and as can be seen from fig. 1, the nickel-cobalt-manganese ternary precursor material has a good spherical morphology, a median particle diameter D50 of about 10 μm, and a uniform particle size.
(2) XRD analysis was performed on the positive electrode material S1 prepared in example 1 and the positive electrode material D1 prepared in comparative example 1, respectively, and the analysis results are shown in FIG. 2. As can be seen from FIG. 2, the positive electrode materials S1 and D1 have the same structure and belong to alpha-NaFeO 2 The hexagonal system of the structure has narrower half-width, high peak intensity and good crystallinity.
(3) The positive electrode material S1 prepared in the example 1 and the positive electrode material D1 prepared in the comparative example 1 are subjected to electron microscope scanning respectively, the scanning results are shown in fig. 3, and as can be seen from fig. 3, the positive electrode materials S1 and D1 basically keep the spherical morphology of the nickel-cobalt-manganese ternary precursor material and have uniform particle sizes; however, compared with the cathode material D1, the surface of the cathode material S1 has no obvious agglomeration phenomenon, which means that the aluminum element is already in the internal crystal structure of the layered lithium-rich manganese-based cathode material matrix and does not react with lithium to generate LiAlO 2 。
(4) The positive electrode material S1 prepared in example 1 was subjected to EPAM analysis, and the analysis results are shown in fig. 4, and it can be seen from fig. 4 that in the positive electrode material S1, aluminum element has deeply penetrated into the internal crystal structure of the layered lithium-rich manganese-based positive electrode material matrix, and the distribution of aluminum element is uniform.
Test example 2
The positive electrode materials S1-S4 and D1-D4 are respectively utilized to prepare lithium ion batteries S1-S4 and D1-D4, and the preparation method is as follows:
preparing a pole piece: adding a positive electrode material, acetylene black and polyvinylidene fluoride (PVDF) into N-methyl pyrrolidone (NMP) according to the mass ratio of 8:1:1, uniformly mixing, coating on an aluminum foil, drying at 110 ℃ for 1h, rolling the dried pole piece, cutting into a positive electrode piece with the diameter of 12mm by a sheet punching machine, and vacuum drying at 110 ℃ for 12h in a vacuum oven to obtain the positive electrode piece;
assembling a battery: liPF with metal Li sheet as negative plate and 1mol/L 6 The EC-DEC-EMC solution (volume ratio is 1:1:1) is used as electrolyte, a single-layer polyethylene film (Celgard 2300) is used as a diaphragm, and the CR2032 button half cell is assembled in a glove box filled with argon.
Electrochemical tests are respectively carried out on lithium ion batteries s 1-s 4 and d 1-d 4, and the test method is as follows:
electrochemical performance test was performed using a wuhan blue electrical system, wherein the charge-discharge current density of 1C was 250mA/g and the test temperature was 25 ℃. Performing charge and discharge test on each assembled button cell at 2.0-4.6V and 0.1C, and evaluating the first discharge specific capacity and the first coulomb efficiency of each positive electrode material; circulating each assembled button cell for 50 times under 2.0-4.6V and 0.2C, and evaluating the circulation performance and voltage attenuation condition of the positive electrode material; and (3) carrying out charge and discharge tests on each assembled button cell under 2.0-4.6V, 0.1C, 0.2C, 0.5C, 1C, 2C and 3C, and evaluating the multiplying power performance of the positive electrode material. The test results are shown in FIGS. 5 to 7 and Table 1.
Wherein, fig. 5 is a graph comparing the cycle performance of the positive electrode material S1 prepared in example 1 and the cycle performance of the positive electrode material D1 prepared in comparative example 1 at a 0.2C rate, and as can be seen from fig. 1, the capacity retention rate of the positive electrode material S1 after being cycled for 50 times at the 0.2C rate is much higher than that of the positive electrode material D1; FIG. 6 is a graph showing the comparison of the rate performance of the positive electrode material S1 prepared in example 1 and the positive electrode material D1 prepared in comparative example 1 at a rate of 0.1-3C, and as can be seen from FIG. 6, the rate performance of the positive electrode material S1 is significantly higher than that of the positive electrode material D1; fig. 7 is a graph showing the discharge median voltage decay of the positive electrode material S1 prepared in example 1 and the positive electrode material D1 prepared in comparative example 1 at a rate of 0.2C, and it can be seen from fig. 7 that the discharge median voltage decay of the positive electrode material S1 is significantly lower than that of the positive electrode material D1.
TABLE 1
As can be seen from table 1, the positive electrode material of the present disclosure has slower discharge median voltage decay, higher specific discharge capacity, better cycle performance and rate capability.
The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.
In addition, the specific features described in the foregoing embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present disclosure does not further describe various possible combinations.
Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.
Claims (12)
1. A method of preparing a positive electrode material, the method comprising:
mixing a manganese-containing precursor with a lithium source, and calcining in an oxygen-containing atmosphere to obtain a layered lithium-rich manganese-based anode material matrix;
washing the layered lithium-rich manganese-based positive electrode material matrix to obtain a washed layered lithium-rich manganese-based positive electrode material matrix;
and mixing the washed layered lithium-rich manganese-based positive electrode material matrix with an aluminum source, and then carrying out secondary calcination in an oxygen-containing atmosphere to obtain the positive electrode material.
2. The method according to claim 1, wherein the calcination comprises low temperature pre-sintering and high temperature sintering when the layered lithium-rich manganese-based positive electrode material matrix is obtained by calcination; wherein, the liquid crystal display device comprises a liquid crystal display device,
the low-temperature presintering conditions comprise: the temperature rising rate is 1-5 ℃/min, the presintering temperature is 400-550 ℃, and the presintering time is 3-5 h;
the conditions of the high-temperature sintering include: the temperature rising rate is 1-3 ℃/min, the sintering temperature is 800-900 ℃ and the sintering time is 10-15 h.
3. The method of claim 1, wherein the washing process comprises:
mixing the layered lithium-rich manganese-based positive electrode material matrix with a washing solution, washing the layered lithium-rich manganese-based positive electrode material matrix under a stirring condition, and performing suction filtration and drying after washing to obtain a washed layered lithium-rich manganese-based positive electrode material matrix; wherein, the liquid crystal display device comprises a liquid crystal display device,
the washing liquid is used in an amount of 10-20 parts by weight relative to 1 part by weight of the layered lithium-rich manganese-based positive electrode material matrix; the washing conditions included: stirring speed is 100-1000 rpm, washing temperature is 20-100 ℃, and washing time is 30-180 min; the drying conditions include: the drying temperature is 100-150 ℃ and the drying time is 2-8 h.
4. The method according to claim 1, wherein when the positive electrode material is obtained by secondary calcination, the conditions of the secondary calcination include: the temperature rising rate is 3-10 ℃/min, the calcining temperature is 600-900 ℃ and the calcining time is 6-15 h;
preferably, the temperature rising rate is 4-8 ℃/min, the calcining temperature is 700-800 ℃ and the calcining time is 8-14 h.
5. The method of any one of claims 1-4, wherein the manganese-containing precursor comprises a nickel cobalt manganese ternary precursor comprising Mn a Co b Ni c (OH) 2 And/or Mn a Co b Ni c CO 3 Wherein a is more than or equal to 0.5 and less than or equal to 1, b is more than or equal to 0.25, c is more than or equal to 0 and less than or equal to 0.25, and a+b+c=1.
6. The method of claim 5, wherein the lithium source comprises lithium carbonate and/or lithium hydroxide; the usage amount of the nickel-cobalt-manganese ternary precursor and the lithium source based on the element molar amount satisfies the following relation: li/(Ni+Co+Mn) = (1.0 to 1.5): 1, preferably (1.1 to 1.4): 1.
7. The method of claim 6, wherein the aluminum source comprises at least one of aluminum oxide, aluminum hydroxide, aluminum nitrate, or pseudo-boehmite; the use amounts of the washed layered lithium-rich manganese-based positive electrode material matrix and the aluminum source satisfy the following relationship based on the element molar amount: al/(Ni+Co+Mn+Al) = (0.01 to 0.1): 1, preferably (0.03 to 0.05): 1.
8. The positive electrode material is characterized by comprising a layered lithium-rich manganese-based positive electrode material matrix and aluminum uniformly distributed in the layered lithium-rich manganese-based positive electrode material matrix, wherein the aluminum loading is not less than 2 weight percent, preferably not less than 3 weight percent, based on the total weight of the positive electrode material.
9. The positive electrode material according to claim 8, wherein the positive electrode material has a chemical formula of Li 1.2+x [(Mn a Co b Ni c ) 1-d Al d ] 0.8-x O 2 Wherein, -0.2 < x is less than or equal to 0.3,0.5 is less than or equal to a is less than or equal to 1,0 < b is less than or equal to 0.25,0 < c is less than or equal to 0.25,0.01, d is less than or equal to 0.1, and a+b+c=1;
preferably, x is more than or equal to 0.005 and less than or equal to 0.015,0.5 and less than or equal to a is more than or equal to 0.8,0.1 and less than or equal to b is more than or equal to 0.2,0.1 and less than or equal to c is more than or equal to 0.2,0.03 and less than or equal to d is more than or equal to 0.05.
10. The positive electrode material according to claim 8, wherein the positive electrode material is spherical particles having a particle diameter of 5 to 20 μm and a particle diameter D50 of 8 to 12 μm.
11. A positive electrode sheet of a lithium ion battery, wherein the positive electrode sheet comprises the positive electrode material prepared by the method of any one of claims 1 to 7 or the positive electrode material of any one of claims 8 to 10.
12. A lithium ion battery having the positive electrode sheet of claim 11.
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