Modified lithium-rich manganese-based positive electrode material and preparation method thereof

Abstract

The application provides a modified lithium-rich manganese-based positive electrode material and a preparation method thereof. The preparation method of the modified lithium-rich manganese-based positive electrode material comprises the following steps: mixing a modifier, a surfactant and water to obtain a modification liquid; the modifier satisfies the condition of being capable of decomposing and releasing gas in the modification liquid; dispersing a lithium-rich manganese-based positive electrode material crude product in the modification liquid, stirring at a temperature exceeding the decomposition temperature of the modifier to generate bubbles, standing to form a foam layer on the liquid surface; and removing the foam layer, performing solid-liquid separation and collecting the solid. The preparation method of the modified lithium-rich manganese-based positive electrode material provided by the application can not only remove part of the fine powder in the lithium-rich manganese-based positive electrode material crude product, but also adjust the existing state of the residual lithium compound on the surface of the lithium-rich manganese-based positive electrode material, reduce the content of the residual lithium compound or reduce the interfacial reaction activity thereof, so that the processing performance and the electrochemical performance of the material are improved.

Description

Technical Field

[0001] This application relates to the field of cathode material technology, and in particular to modified lithium-rich manganese-based cathode materials and their preparation methods. Background Technology

[0002] The performance of cathode materials directly determines the energy density, cycle life, and safety performance of lithium-ion batteries. Lithium-rich manganese-based cathode materials, with their high specific capacity, are widely recognized as a promising next-generation cathode material. However, the processing of lithium-rich manganese-based cathode materials generates fine powder impurities with particle sizes smaller than the target particle size. These fine powders may originate from raw material dust, foreign matter dust in the environment, or mechanical dust introduced by equipment friction.

[0003] In traditional methods, acid washing is often used to modify lithium-rich manganese-based cathode materials to remove surface impurities. For example, patent CN107215900A reported that lithium-rich manganese-based cathode materials were added to a weak acid aqueous solution to exchange lithium ions and hydrogen ions, and then the cathode materials after ion exchange were heat-treated to transform the surface lithium-deficient structure into a spinel structure.

[0004] However, traditional acid washing methods mainly target the residual lithium components or surface structure on the surface of lithium-rich manganese-based cathode materials for chemical regulation, making it difficult to selectively separate the fine powders that are entrained or generated during processing. These fine powders have a large specific surface area and high surface reactivity, which can easily disrupt the particle size distribution and powder packing state of the material, thereby affecting the compaction density, processing performance, and interface stability of the cathode material. Summary of the Invention

[0005] Based on this, this application provides a modified lithium-rich manganese-based cathode material and its preparation method. The preparation method of the modified lithium-rich manganese-based cathode material provided in this application involves dispersing crude lithium-rich manganese-based cathode material in a modified liquid containing a modifier and a surfactant. The modifier decomposes to generate gas, which forms bubbles under the action of the surfactant. These bubbles act as a flotation motive force, selectively adhering to the surface of fine particles and carrying them to the surface to form a foam layer, thus completing the flotation separation. This method can effectively remove fine powder.

[0006] The first aspect of this application provides a method for preparing a modified lithium-rich manganese-based cathode material, the technical solution of which is as follows: A method for preparing a modified lithium-rich manganese-based cathode material includes the following steps: A modified liquid is obtained by mixing a modifier, a surfactant, and water, wherein the modifier satisfies the following condition: it can decompose and release gas in the modified liquid; The crude lithium-rich manganese-based cathode material is dispersed in the modified liquid and stirred at a temperature exceeding the decomposition temperature of the modifier to generate bubbles. After standing, a foam layer is formed on the liquid surface. After removing the foam layer, solid-liquid separation is performed, and the solid is collected.

[0007] In one embodiment, the modifier further satisfies the following condition: it is capable of chemically reacting with residual lithium compounds on the surface of the lithium-rich manganese-based cathode material.

[0008] In one embodiment, the modifier is selected from at least one of ammonium bicarbonate, ammonium carbonate, and ammonium persulfate.

[0009] In one embodiment, the modifier comprises ammonium bicarbonate, and the concentration of ammonium bicarbonate in the modifying solution is 0.1 mol / L to 2.0 mol / L.

[0010] In one embodiment, the modifier comprises ammonium carbonate, and the concentration of ammonium carbonate in the modifying solution is 0.05 mol / L to 1.5 mol / L.

[0011] In one embodiment, the modifier comprises ammonium persulfate, and the concentration of ammonium persulfate in the modifying solution is 0.005 mol / L to 0.2 mol / L.

[0012] In one embodiment, the modifier comprises ammonium persulfate, and the surfactant is selected from oxidation-resistant surfactants, including at least one of oxidation-resistant anionic surfactants, oxidation-resistant nonionic surfactants, oxidation-resistant cationic surfactants, and oxidation-resistant amphoteric surfactants. Preferably, the oxidation-resistant surfactant is selected from at least one of fluorosulfonate surfactants, alkyl sulfonate surfactants, and alkyl sulfate surfactants.

[0013] In one embodiment, the modifier comprises at least one selected from ammonium bicarbonate and ammonium carbonate, and the surfactant is selected from at least one selected from anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Preferably, the surfactant is selected from at least one selected from fluorosulfonate surfactants, alkyl sulfonate surfactants, alkyl sulfate surfactants, polyoxyethylene ether surfactants, fatty alcohol polyoxyethylene ether surfactants, Tween surfactants, betaine surfactants, and quaternary ammonium salt surfactants.

[0014] In one embodiment, the concentration of the surfactant in the modified solution is 0.05 g / L to 5 g / L, preferably 0.1 g / L to 2 g / L, and more preferably 0.2 g / L to 1.0 g / L.

[0015] In one embodiment, the mass-to-volume ratio of the lithium-rich manganese-based cathode material to the modified liquid is 1 g: (5~20) mL.

[0016] In one embodiment, the stirring time is 10 min to 60 min.

[0017] In one implementation, the settling time is 1 min to 5 min.

[0018] The second aspect of this application provides a modified lithium-rich manganese-based cathode material, which is prepared by the preparation method described above.

[0019] In one embodiment, the particle size distribution of the modified lithium-rich manganese-based cathode material spans from 1.62 to 1.67.

[0020] In one embodiment, the compaction density of the modified lithium-rich manganese-based cathode material is 2.70~2.74 g / cm³. 3 .

[0021] Compared with traditional solutions, this application has the following advantages: The method for preparing modified lithium-rich manganese-based cathode materials provided in this application involves dispersing crude lithium-rich manganese-based cathode materials in a modifying solution containing a modifier and a surfactant. The mixture is stirred at a temperature exceeding the decomposition temperature of the modifier, causing the modifier to decompose and generate gas. Under the action of the surfactant, bubbles are formed. These bubbles act as a flotation motive force, selectively adhering to the surface of fine particles and carrying them to the surface to form a foam layer, thus completing the flotation separation. This method not only removes some of the fine powder from the crude lithium-rich manganese-based cathode materials, improving the particle size distribution and optimizing the particle size distribution of the cathode materials, resulting in a more reasonable packing state during compaction, but also allows the modifier to adjust the state of residual lithium compounds on the surface of the lithium-rich manganese-based cathode materials, reduce the content of residual lithium compounds, or reduce their interfacial reactivity, thereby improving the processing performance and electrochemical performance of the materials. Detailed Implementation

[0022] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0024] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings: In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more or more.

[0025] In this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.

[0026] In this application, the terms "optionally," "optionally," and "optional" refer to options that are optional, meaning they can be selected from either "with" or "without." If multiple "optional" options appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" option is independent.

[0027] In this application, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth," etc., serve only a non-exhaustive enumeration purpose and should be understood not to constitute a closed limitation on quantity.

[0028] In this application, numerical intervals (i.e. numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the above-mentioned numerical intervals are considered continuous, and include the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical range, as well as every value between the two numerical endpoints.

[0029] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0030] This application provides a method for preparing a modified lithium-rich manganese-based cathode material. In one embodiment, the method for preparing the modified lithium-rich manganese-based cathode material includes the following steps: S10. The modifier, surfactant and water are mixed to obtain a modified liquid, wherein the modifier satisfies the following condition: it can decompose and release gas in the modified liquid.

[0031] Optionally, the modifier satisfies the following condition: it can decompose to generate gas in a modified liquid at a temperature not exceeding 100°C. The aforementioned modifier can use the gas generated during decomposition as a flotation power source, eliminating the need for external aeration equipment, thus reducing equipment investment and operating costs, and making it suitable for large-scale industrial production.

[0032] Optionally, the modifier further satisfies the following condition: it is capable of chemically reacting with residual lithium compounds on the surface of the lithium-rich manganese-based cathode material. By reacting with the residual lithium compounds on the surface of the lithium-rich manganese-based cathode material, the modifier adjusts the state of the residual lithium compounds, their surface alkalinity, and / or interfacial reactivity. The residual lithium compounds on the surface of the lithium-rich manganese-based cathode material include LiOH, Li₂O, Li₂CO₃, and other adsorbed alkaline lithium compounds. The chemical reactions that can occur between the modifier and the aforementioned residual lithium compounds include one or more of the following: aqueous phase dissociation, buffering reaction, weak acid-base neutralization, oxidation reaction, or surface ion exchange. These chemical reactions adjust the state of the residual lithium compounds, reduce their content, or decrease their interfacial reactivity. Therefore, the modifier can promote the flotation separation of fine powders while mildly modifying the surface of the cathode material, reducing interfacial side reactions during slurry preparation, storage, and electrochemical cycling, and improving the material's initial coulombic efficiency, discharge capacity, processing performance, and compaction performance.

[0033] Optionally, the modifier is selected from at least one of ammonium bicarbonate, ammonium carbonate, and ammonium persulfate.

[0034] In one embodiment, the modifier comprises ammonium bicarbonate and / or ammonium carbonate, which can form NH4-containing compounds in the modification solution. + HCO3 - and / or CO3 2- The buffer system can release CO2 and / or NH3, thereby promoting bubble formation. Simultaneously, it can chemically react with residual lithium compounds on the surface of lithium-rich manganese-based cathode materials, regulating the state of residual lithium compounds, reducing their content, or decreasing their interfacial reactivity. Optionally, the modifier includes ammonium bicarbonate, with a concentration of 0.1 mol / L to 2.0 mol / L in the modifying solution. Preferably, it is 0.3 mol / L to 1.5 mol / L. Optionally, the modifier includes ammonium carbonate, with a concentration of 0.05 mol / L to 1.5 mol / L in the modifying solution. Preferably, it is 0.2 mol / L to 1.0 mol / L.

[0035] Optionally, the modifier includes at least one of ammonium bicarbonate and ammonium carbonate, and the surfactant is selected from at least one of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Preferably, the surfactant is selected from at least one of fluorosulfonate surfactants, alkyl sulfonate surfactants, alkyl sulfate surfactants, polyoxyethylene ether surfactants, fatty alcohol polyoxyethylene ether surfactants, Tween surfactants, betaine surfactants, and quaternary ammonium salts such as potassium perfluorooctyl sulfonate and perfluorohexane surfactants. Among these, the fluorosulfonate surfactant can be at least one of potassium sulfonate. The alkyl sulfate surfactant can be sodium dodecyl sulfate. The quaternary ammonium salt surfactant can be hexadecyltrimethylammonium bromide. The polyoxyethylene ether surfactant can be polyoxyethylene ether. The fatty alcohol polyoxyethylene ether surfactant can be fatty alcohol polyoxyethylene ether. The above surfactants can reduce the surface tension of the modified liquid and promote bubble generation and foam stability when the modifier releases gas, thereby facilitating the floating of fine powder with the bubbles and its enrichment in the foam layer.

[0036] In one embodiment, when the modifier includes ammonium persulfate, it can decompose and release O2 in the modification solution through heating or catalysis, forming an aqueous environment with oxidizing and acid-regulating effects. This promotes bubble formation and regulates the state of residual lithium compounds on the surface of the lithium-rich manganese-based cathode material, reducing the content of residual lithium compounds or decreasing its interfacial reactivity. The decomposition reaction of ammonium persulfate can be represented as: 2(NH4)2S2O8 + 2H2O → 4NH4HSO4 + O2↑. When using ammonium persulfate as a modifier, it is preferable to control its concentration, treatment temperature, and treatment time to avoid the adverse effects of excessively strong oxidizing and acidic environments on the main structure of the lithium-rich manganese-based cathode material. Optionally, the concentration of ammonium persulfate in the modification solution is 0.005 mol / L to 0.2 mol / L, preferably 0.01 mol / L to 0.1 mol / L. Optionally, the treatment temperature is 60 to 80°C. The treatment time is 15 min to 25 min.

[0037] Optionally, the modifier includes ammonium persulfate, and the surfactant is selected from oxidation-resistant surfactants, including at least one of oxidation-resistant anionic surfactants, oxidation-resistant nonionic surfactants, oxidation-resistant cationic surfactants, and oxidation-resistant amphoteric surfactants. Preferably, the oxidation-resistant surfactant is selected from at least one of fluorosulfonate surfactants, alkylsulfonate surfactants, and alkyl sulfate surfactants. The fluorosulfonate surfactant can be at least one of potassium perfluorooctyl sulfonate and potassium perfluorohexyl sulfonate. The alkylsulfonate surfactant can be sodium dodecyl sulfate. These surfactants can reduce the surface tension of the modified liquid and promote bubble generation and foam stability when the modifier releases gas, thereby facilitating the floating of fine powder with the bubbles and its enrichment in the foam layer. Simultaneously, the oxidation-resistant surfactant can maintain foaming and foam-stabilizing properties at the treatment temperature and time of the modified liquid, reducing the impact of surfactant decomposition on the flotation separation effect under oxidizing conditions.

[0038] Optionally, the concentration of the surfactant in the modified solution is 0.05 g / L to 5 g / L, preferably 0.1 g / L to 2 g / L, and more preferably 0.2 g / L to 1.0 g / L.

[0039] S20. The crude lithium-rich manganese-based cathode material is dispersed in the modified liquid, and stirred under the condition that the modifier releases gas to generate bubbles. After standing, a foam layer is formed on the liquid surface.

[0040] The crude lithium-rich manganese-based cathode material contains fine powder with a particle size smaller than the target particle size of the cathode material. This fine powder can adhere to the surface of the cathode material particles or be mixed between the particles. Fine powder typically has a large specific surface area and high surface reactivity, easily accumulating residual lithium components or surface defects, leading to an increased particle size distribution range and poorer powder packing state in the crude lithium-rich manganese-based cathode material, affecting the material's compaction density, processing performance, and interfacial stability. Dispersing the crude lithium-rich manganese-based cathode material in a modification solution can promote the separation of fine powder from the bulk particles, optimize the particle size distribution, and improve the overall performance of the cathode material.

[0041] Optionally, the mass-to-volume ratio of the lithium-rich manganese-based cathode material to the modified liquid is 1 g: (5~20) mL.

[0042] During stirring, the modifier decomposes and releases gas in the modified liquid, forming bubbles or foam under the action of surfactants. Due to the small particle size, large specific surface area, and high surface energy of the fine powder, it more easily forms bubble-particle complexes with the bubbles and floats to the liquid surface with the bubbles to form a foam layer; while the main particles have a larger particle size and a stronger settling tendency, making them less likely to float with the foam layer. Thus, the separation of the fine powder and the main particles can be achieved. Simultaneously, the modifier can also chemically react with residual lithium compounds on the surface of the lithium-rich manganese-based cathode material, thereby achieving synergistic treatment of fine powder separation and surface modification.

[0043] Optionally, the stirring time is 10 min to 60 min. Optionally, the standing time is 1 min to 5 min.

[0044] S30. After removing the foam layer, perform solid-liquid separation and collect the solid.

[0045] Optionally, after collecting the solid, the process further includes washing and drying the solid. The drying temperature is 60~100℃, and the drying time is 6h~24h.

[0046] In this embodiment, crude lithium-rich manganese-based cathode material is dispersed in a modified solution containing a modifier and a surfactant. The mixture is stirred at a temperature exceeding the decomposition temperature of the modifier, causing the modifier to decompose and generate gas. Under the action of the surfactant, bubbles are formed. These bubbles can serve as a flotation power source, selectively adhering to the surface of fine particles and carrying them to the surface to form a foam layer, thus completing the flotation separation.

[0047] The above methods can remove some fine powder from the crude lithium-rich manganese-based cathode material, improve the particle size distribution, optimize the particle size distribution, and allow the cathode material particles to form a more reasonable packing state during compaction. Simultaneously, the modifier can also adjust the state of residual lithium compounds on the surface of the lithium-rich manganese-based cathode material, reduce the content of residual lithium compounds, or reduce their interfacial reactivity, thereby improving the material's processing performance and electrochemical performance.

[0048] The second aspect of this application provides a modified lithium-rich manganese-based cathode material, which is prepared by the preparation method described above.

[0049] Optionally, the particle size distribution of the modified lithium-rich manganese-based cathode material spans from 1.62 to 1.67. Optionally, the compaction density of the modified lithium-rich manganese-based cathode material is from 2.70 to 2.74 g / cm³. 3 Compared to the crude product's 2.62 g / cm³ 3 The increase ranged from 3.05% to 4.58%.

[0050] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available; the instruments used are all commercially available unless otherwise specified; and the processes involved are conventionally selected by those skilled in the art unless otherwise specified.

[0051] Example 1 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 3.95 g of ammonium bicarbonate (final concentration 0.50 mol / L), stir until completely dissolved, then add 0.08 g of polyoxyethylene ether (final concentration 0.8 g / L), and continue stirring for 30 minutes to obtain the modified solution.

[0052] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 10.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 rpm for 30 minutes at 35°C, and then allowed to stand for 3 minutes. During this process, ammonium bicarbonate formed NH4+-containing compounds in the modified solution. + and HCO3 - The system acts as a buffer, decomposing and releasing CO2 and NH3. Under the action of polyoxyethylene ether, bubbles or foam form in the system, and fine powder floats with the bubbles and accumulates in the foam layer on the liquid surface. Simultaneously, NH4... + / HCO3 - The buffer system regulates the state of residual lithium compounds on the surface of lithium-rich manganese-based cathode materials, reduces the content of residual lithium compounds, or reduces their interfacial reactivity through chemical reactions.

[0053] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0054] Example 2 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 7.91 g of ammonium bicarbonate (final concentration 1.00 mol / L), stir until completely dissolved, then add 0.10 g of sodium dodecyl sulfate (final concentration 1.0 g / L), and continue stirring for 30 minutes to obtain the modified solution.

[0055] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni0.13 Co 0.13 10.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 rpm for 30 minutes at 45°C, and then allowed to stand for 5 minutes. During this process, ammonium bicarbonate formed NH4+-containing compounds in the modified solution. + and HCO3 - The buffer system decomposes and releases CO2 and NH3, and forms a foam layer under the foaming and stabilizing effect of sodium dodecyl sulfate, causing the fine powder to separate from the main particles; at the same time, NH4 + / HCO3 - The buffer system regulates the state of residual lithium compounds on the surface of lithium-rich manganese-based cathode materials, reduces the content of residual lithium compounds, or reduces their interfacial reactivity through chemical reactions.

[0056] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0057] Example 3 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 0.79 g of ammonium bicarbonate (final concentration 0.10 mol / L), stir until completely dissolved, then add 0.005 g of polyoxyethylene ether (final concentration 0.05 g / L), and continue stirring for 30 minutes to obtain the modified solution.

[0058] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 20.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 rpm for 10 minutes at 35°C, and then allowed to stand for 1 minute. During this process, ammonium bicarbonate formed NH4+-containing compounds in the modified solution. + and HCO3 - The system acts as a buffer, decomposing and releasing CO2 and NH3. Under the action of polyoxyethylene ether, bubbles or foam form in the system, and fine powder floats with the bubbles and accumulates in the foam layer on the liquid surface. Simultaneously, NH4... + / HCO3 - The buffer system regulates the state of residual lithium compounds on the surface of lithium-rich manganese-based cathode materials, reduces the content of residual lithium compounds, or reduces their interfacial reactivity through chemical reactions.

[0059] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0060] Example 4 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 15.81 g of ammonium bicarbonate (final concentration 2.00 mol / L), stir until completely dissolved, then add 0.50 g of sodium dodecyl sulfate (final concentration 5.0 g / L), and continue stirring for 30 minutes to obtain the modified solution.

[0061] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 5.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 rpm for 60 minutes at 45°C, and then allowed to stand for 5 minutes. During this process, ammonium bicarbonate formed NH4+-containing compounds in the modified solution. + and HCO3 - The buffer system decomposes and releases CO2 and NH3; under the foaming and stabilizing effect of sodium dodecyl sulfate, a foam layer is formed, causing the fine powder to separate from the main particles. Simultaneously, NH4... + / HCO3 - The buffer system regulates the state of residual lithium compounds on the surface of lithium-rich manganese-based cathode materials, reduces the content of residual lithium compounds, or reduces their interfacial reactivity through chemical reactions.

[0062] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0063] Example 5 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 2.88 g of ammonium carbonate (calculated as (NH4)2CO3, final concentration 0.30 mol / L), stir until completely dissolved, add 0.10 g of fatty alcohol polyoxyethylene ether (final concentration 1.0 g / L), and continue stirring for 30 minutes to obtain the modified solution.

[0064] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.1310.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 rpm for 40 minutes at 55°C, and then allowed to stand for 3 minutes. During this process, ammonium carbonate formed NH4+-containing compounds in the modified solution. + and CO3 2- The buffer system decomposes and releases NH3 and CO2. Under the action of fatty alcohol polyoxyethylene ether, the released gas forms bubbles or foam, promoting the flotation and separation of fine powder. Simultaneously, NH4... + / CO3 2- The buffer system regulates the state of residual lithium compounds on the surface of lithium-rich manganese-based cathode materials, reduces the content of residual lithium compounds, or reduces their interfacial reactivity through chemical reactions.

[0065] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0066] Example 6 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 0.48 g of ammonium carbonate (calculated as (NH4)2CO3, final concentration 0.05 mol / L), stir until completely dissolved, then add 0.005 g of fatty alcohol polyoxyethylene ether (final concentration 0.05 g / L), continue stirring for 30 minutes to obtain the modified solution.

[0067] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 20.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 rpm for 10 minutes at 55°C, and then allowed to stand for 1 minute. During this process, ammonium carbonate formed NH4+-containing compounds in the modified solution. + and CO3 2- The buffer system decomposes and releases NH3 and CO2; under the action of fatty alcohol polyoxyethylene ether, the released gas forms bubbles or foam, promoting the flotation and separation of fine powder. Simultaneously, NH4... + / CO3 2- The buffer system regulates the state of residual lithium compounds on the surface of lithium-rich manganese-based cathode materials, reduces the content of residual lithium compounds, or reduces their interfacial reactivity through chemical reactions.

[0068] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0069] Example 7 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 14.40 g of ammonium carbonate (calculated as (NH4)2CO3, final concentration 1.50 mol / L), stir until completely dissolved, then add 0.50 g of sodium dodecyl sulfate (final concentration 5.0 g / L), continue stirring for 30 minutes to obtain the modified solution.

[0070] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 5.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 rpm for 60 minutes at 55 °C, and then allowed to stand for 5 minutes. During this process, ammonium carbonate formed NH4+-containing compounds in the modified solution. + and CO3 2- The buffer system decomposes and releases NH3 and CO2; under the foaming and stabilizing effect of sodium dodecyl sulfate, a foam layer is formed, causing the fine powder to separate from the main particles. Simultaneously, NH4... + / CO3 2- The buffer system regulates the state of residual lithium compounds on the surface of lithium-rich manganese-based cathode materials, reduces the content of residual lithium compounds, or reduces their interfacial reactivity through chemical reactions.

[0071] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0072] Example 8 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 1.14 g of ammonium persulfate (final concentration 0.05 mol / L), stir until completely dissolved, then add 0.05 g of potassium perfluorohexyl sulfonate (final concentration 0.5 g / L), and continue stirring for 30 minutes to obtain the modified solution.

[0073] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.1310.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 r / min for 20 minutes at 70 °C and then allowed to stand for 3 minutes. During this process, ammonium persulfate decomposed to release O2, forming an aqueous environment with oxidizing and acid-regulating effects. Under the foaming and stabilizing effects of potassium perfluorohexylsulfonate, bubbles or foams formed in the system, and the fine powder floated with the bubbles and accumulated in the foam layer on the liquid surface. At the same time, in the aqueous environment with oxidizing and acid-regulating effects, the state of residual lithium compounds on the surface of the lithium-rich manganese-based cathode material was adjusted, the content of residual lithium compounds was reduced, or its interfacial reactivity was reduced.

[0074] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0075] Example 9 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 0.114 g of ammonium persulfate (final concentration 0.005 mol / L), stir until completely dissolved, then add 0.005 g of potassium perfluorohexyl sulfonate (final concentration 0.05 g / L), and continue stirring for 30 minutes to obtain the modified solution.

[0076] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 20.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 rpm for 10 minutes at 70 °C, and then allowed to stand for 1 minute. During this process, ammonium persulfate decomposed to release O2, forming an aqueous environment with oxidizing and acid-regulating effects. Under the foaming and stabilizing effect of potassium perfluorohexylsulfonate, bubbles or foams formed in the system, and the fine powder floated to the surface and accumulated in the foam layer. Simultaneously, in the aqueous environment with oxidizing and acid-regulating effects, the state of residual lithium compounds on the surface of the lithium-rich manganese-based cathode material was adjusted, reducing the content of residual lithium compounds or decreasing their interfacial reactivity.

[0077] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0078] Example 10 This embodiment provides a modified lithium-rich manganese-based cathode material and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 4.56 g of ammonium persulfate (final concentration 0.20 mol / L), stir until completely dissolved, then add 0.50 g of potassium perfluorohexyl sulfonate (final concentration 5.0 g / L), and continue stirring for 30 minutes to obtain the modified solution.

[0079] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 5.0 g of crude O2 was slowly added to 100 mL of the above modified solution. The mixture was stirred at 300 rpm for 60 minutes at 70 °C, and then allowed to stand for 5 minutes. During this process, ammonium persulfate decomposed to release O2, forming an aqueous environment with oxidizing and acid-regulating effects. Under the foaming and stabilizing effects of potassium perfluorohexylsulfonate, bubbles or foams formed in the system, and the fine powder floated to the surface with the bubbles and accumulated in the foam layer. At the same time, in the aqueous environment with oxidizing and acid-regulating effects, the state of residual lithium compounds on the surface of the lithium-rich manganese-based cathode material was adjusted, the content of residual lithium compounds was reduced, or its interfacial reactivity was reduced.

[0080] Step 3: Remove the foam layer with a scraper, filter the remaining slurry, collect the solid and wash it three times with deionized water, place the filter cake in an 80℃ vacuum drying oven and dry for 12 hours to obtain the modified lithium-rich manganese-based cathode material.

[0081] Comparative Example 1 This comparative example provides a lithium-rich manganese-based cathode material treated with oxalic acid and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 0.63 g of oxalic acid dihydrate (final concentration 0.05 mol / L), and stir until completely dissolved to obtain the pickling solution.

[0082] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 10.0 g of crude O2 was slowly added to 100 mL of the above pickling solution and stirred at 300 r / min for 30 minutes at 35 °C. After the reaction, the mixture was filtered, and the solid was collected and washed three times with deionized water. The filter cake was then dried in a vacuum drying oven at 80 °C for 12 hours to obtain the lithium-rich manganese-based cathode material after oxalic acid pickling.

[0083] Comparative Example 2 This comparative example provides a lithium-rich manganese-based cathode material treated with external air flotation and its preparation method, the steps of which are as follows: Step 1: Take 100 mL of deionized water, add 0.10 g of polyoxyethylene ether (final concentration 1.0 g / L), and stir until completely dissolved to obtain flotation solution.

[0084] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 10.0 g of crude O2 was slowly added to 100 mL of the above flotation solution. The mixture was stirred at 300 rpm for 30 minutes at 35°C, while air was continuously introduced into the solution at a flow rate of 0.5 L / min using an air pump. The mixture was then allowed to stand for 3 minutes. After the froth layer on the surface was removed, the remaining slurry was filtered, and the solid was collected and washed three times with deionized water. The filter cake was then dried in a vacuum drying oven at 80°C for 12 hours to obtain the lithium-rich manganese-based cathode material after air flotation treatment.

[0085] Comparative Example 3 This comparative example provides a lithium-rich manganese-based cathode material that undergoes only water washing and its preparation method, the steps of which are as follows: Step 1: Take 100mL of deionized water as the washing solution.

[0086] Step 2: Weigh out lithium-rich manganese-based cathode material (chemical formula Li). 1.2 Mn 0.54 Ni 0.13 Co 0.13 10.0 g of crude O2 was slowly added to 100 mL of deionized water and stirred at 300 r / min for 30 minutes at 35 °C. The mixture was then allowed to stand for 3 minutes. After the stirring was complete, the mixture was filtered, and the solid was collected and washed three times with deionized water. The filter cake was then dried in a vacuum drying oven at 80 °C for 12 hours to obtain the water-washed lithium-rich manganese-based cathode material.

[0087] test Project 1: Testing the D content of crude lithium-rich manganese-based cathode materials and modified lithium-rich manganese-based cathode materials in various examples and comparative examples using a laser particle size analyzer. 10 D 50 and D 90 According to the particle size distribution span = (D 90 -D 10 ) / D 50 Calculate the particle size distribution span. The results are shown in Table 1.

[0088] Table 1

[0089] Project 2: The compaction density of crude lithium-rich manganese-based cathode material and modified lithium-rich manganese-based cathode materials in each example and comparative example was tested according to GB / T 44330-2024 "Determination of compaction density of lithium-ion battery cathode material powder". The results are shown in Table 2.

[0090] Table 2

[0091] Project 3: The residual lithium content of crude lithium-rich manganese-based cathode materials and the modified lithium-rich manganese-based cathode materials of each example and comparative example were tested according to GB / T 41704-2022 "Determination of Magnetic Foreign Matter Content and Residual Alkali Content of Cathode Materials for Lithium-ion Batteries". The results are shown in Table 3.

[0092] Table 3

[0093] Results analysis: 1. In Examples 1 to 10 of this application, through the decomposition of ammonium bicarbonate, ammonium carbonate, and ammonium persulfate, and under the action of different surfactants, bubbles carry fine particles to the surface, thereby reducing the particle size D of the positive electrode material. 10 The increased particle size and reduced particle size distribution range indicate that fine particles can be effectively removed. Compared with the crude lithium-rich manganese-based cathode material, the modified lithium-rich manganese-based cathode materials prepared in Examples 1 to 10 show a significant increase in compaction density, ranging from 3.05% to 4.58%.

[0094] In Comparative Example 1, oxalic acid pickling solution can reduce some residual lithium content on the material surface, but it lacks the conditions for in-situ gas release from the modifier and the formation of a foam layer with the surfactant, making it difficult to achieve effective flotation and separation of fine powders; at the same time, acid treatment may cause excessive surface H + / Li + Exchange or particle surface corrosion leads to particle fragmentation, D 10 The particle size distribution range is reduced compared to that of lithium-rich manganese-based cathode materials; and due to particle fragmentation, fine powder increases, resulting in a decrease in packing efficiency and a decrease in compaction density (-1.53%).

[0095] In Comparative Example 2, although external air can form some foam under the action of surfactant, the removal effect on fine particles is not obvious. Furthermore, the system does not contain modifiers that can adjust the state of residual lithium compounds on the surface of lithium-rich manganese-based cathode materials, reduce the content of residual lithium compounds, or reduce their interfacial reactivity. Therefore, it is difficult to achieve the synergistic effect of fine powder separation and surface modification. The compaction density of Comparative Example 2 only increased by 1.15%.

[0096] In Comparative Example 3, simple water washing can remove some soluble impurities or loose attachments, but it lacks the gas release effect of modifiers and the foam stabilizing effect of surfactants, as well as a buffer system to effectively regulate residual lithium compounds on the surface. Therefore, the synergistic effect on fine powder separation and surface modification is limited. The compaction density of Comparative Example 3 only increased by 0.76%, which is a weak effect.

[0097] 2. Examples 1 to 7 use ammonium bicarbonate or ammonium carbonate as modifiers, which can reduce the total residual alkali content on the surface of lithium-rich manganese-based cathode materials, decreasing it from 0.80 wt% of the crude product to 0.60~0.66 wt%, a reduction rate of 17.50%~27.5%. Although the ammonium bicarbonate and ammonium carbonate systems have limited removal effects on sparingly soluble Li2CO3, they can effectively reduce the highly reactive alkaline lithium components on the material surface, thereby improving the surface alkalinity and interfacial reactivity of the material. Examples 8 to 10 use ammonium persulfate as a modifier, further reducing the total residual alkali content to 0.46~0.56 wt%, a reduction rate of 30%~42.50%, indicating that the ammonium persulfate system has a more significant reduction effect on the total residual alkali.

[0098] In contrast, Comparative Example 1 achieved a lower total residual alkali content by oxalic acid pickling, but the pickling process may cause excessive surface H2 content. + / Li + Issues such as exchange and particle surface corrosion were observed. Comparative Example 2, which used polyoxyethylene ether washing, and Comparative Example 3, which used only water washing, had a weak effect on reducing total residual alkali.

[0099] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The embodiments described above are merely examples of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application.

Claims

1. A method for preparing a modified lithium-rich manganese-based cathode material, characterized in that, Includes the following steps: A modified liquid is obtained by mixing a modifier, a surfactant, and water, wherein the modifier satisfies the following condition: it can decompose and release gas in the modified liquid; The crude lithium-rich manganese-based cathode material is dispersed in the modified liquid and stirred at a temperature exceeding the decomposition temperature of the modifier to generate bubbles. After standing, a foam layer is formed on the liquid surface. After removing the foam layer, solid-liquid separation is performed, and the solid is collected.

2. The method for preparing the modified lithium-rich manganese-based cathode material according to claim 1, characterized in that, The modifier also satisfies the following requirement: it is capable of chemically reacting with residual lithium compounds on the surface of the lithium-rich manganese-based cathode material.

3. The method for preparing the modified lithium-rich manganese-based cathode material according to claim 2, characterized in that, The modifier includes at least one of ammonium bicarbonate, ammonium carbonate, and ammonium persulfate.

4. The method for preparing the modified lithium-rich manganese-based cathode material according to claim 3, characterized in that, Includes at least one of the following features: (1) The modifier includes ammonium bicarbonate, and the concentration of ammonium bicarbonate in the modifying solution is 0.1 mol / L to 2.0 mol / L; (2) The modifier includes ammonium carbonate, and the concentration of ammonium carbonate in the modifying solution is 0.05 mol / L to 1.5 mol / L; (3) The modifier includes ammonium persulfate, and the concentration of ammonium persulfate in the modifying solution is 0.005 mol / L to 0.2 mol / L.

5. The method for preparing the modified lithium-rich manganese-based cathode material according to claim 1, characterized in that, Includes at least one of the following features: (1) The modifier includes ammonium persulfate, and the surfactant is selected from oxidation-resistant surfactants, including at least one of oxidation-resistant anionic surfactants, oxidation-resistant nonionic surfactants, oxidation-resistant cationic surfactants and oxidation-resistant amphoteric surfactants; (2) The modifier includes at least one of ammonium bicarbonate and ammonium carbonate, and the surfactant is selected from at least one of anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants.

6. The method for preparing the modified lithium-rich manganese-based cathode material according to claim 1, characterized in that, The concentration of the surfactant in the modified solution is 0.05 g / L to 5 g / L.

7. The method for preparing the modified lithium-rich manganese-based cathode material according to any one of claims 1 to 6, characterized in that, The mass-to-volume ratio of the lithium-rich manganese-based cathode material to the modified liquid is 1 g: (5~20) mL.

8. The method for preparing the modified lithium-rich manganese-based cathode material according to any one of claims 1 to 6, characterized in that, Includes at least one of the following features: (1) The stirring time is 10 min to 60 min; (2) The settling time is 1 min to 5 min.

9. A modified lithium-rich manganese-based cathode material, characterized in that, Prepared by the preparation method according to any one of claims 1 to 8.

10. The modified lithium-rich manganese-based cathode material according to claim 9, characterized in that, Includes at least one of the following features: (1) The particle size distribution of the modified lithium-rich manganese-based cathode material spans from 1.62 to 1.

67. (2) The compaction density of the modified lithium-rich manganese-based cathode material is 2.70~2.74 g / cm³. 3 .

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