Lithium-rich manganese-based precursor material, preparation method therefor and use thereof

Abstract

A lithium-rich manganese-based precursor material, a preparation method therefor and a use thereof. The preparation method comprises the following steps: adding a nickel-cobalt-manganese mixed sulfate solution, a precipitant solution and a complexing agent solution in parallel flows, performing a coprecipitation reaction under a protective atmosphere, and aging in an aging agent solution after the reaction, to obtain a lithium-rich manganese-based precursor material; the aging agent solution comprises a carbonate and an organic solvent. In the aging process of the lithium-rich manganese-based precursor material, the carbonate and the organic solution are used together as an aging medium, and the removal rate of sodium and sulfur impurities is high.

Description

A lithium-rich manganese-based precursor material and its preparation method and use Technical Field

[0001] The present application relates to the field of lithium-ion battery technology, for example, a lithium-rich manganese-based precursor material and its preparation method and use. Background Art

[0002] Due to their unique crystal structure and elemental composition, lithium-rich manganese-based cathode materials exhibit distinct transition metal redox and anion redox mechanisms, resulting in extremely high theoretical specific capacity and a high voltage platform. Their energy density is far higher than that of ternary cathode materials and lithium iron phosphate. Furthermore, lithium-rich manganese-based materials greatly reduce the use of expensive Co and Ni, significantly reducing material costs. Lithium-rich manganese-based materials are considered one of the most promising next-generation lithium-ion battery cathode materials and have broad market prospects.

[0003] At present, the mainstream industrial preparation method for layered oxide cathode materials, including lithium-rich manganese-based materials, is the co-precipitation method. In addition to indicators such as particle size, crystal quality, primary particles, specific surface area and tap density, the impurity content of the precursor material also strongly affects the capacity release, cycle performance and safety of the battery, and requires special attention. In the co-precipitation process of the ternary high nickel precursor, the transition metal ions (Ni 2+ 、Co 2+ 、Mn 2+ or Al 3+ ) and hydroxide (OH - ) undergoes precipitation reaction to obtain secondary spherical particles formed by the accumulation of primary particles. The sodium ions (Na + ) and sulfate ions (SO4 2-) will be adsorbed on the surface of the particles or embedded in the crystal lattice, and the sodium sulfur impurity content exceeds the standard, resulting in reduced cycle performance and safety. Common methods for reducing the sodium sulfur content of ternary precursors mainly include the following methods: CN103342395A controls the sulfur content from the precipitation reaction stage and the post-processing stage. In the synthesis reaction stage, the stirring speed, precipitation pH and other processes and the fluid mechanics of the slurry are controlled to reduce the production of basic nickel sulfate in principle; in the post-processing stage, LiOH is used as an aging agent to remove sulfate ions adsorbed on the surface of the precipitate and to utilize the principle that basic nickel sulfate is unstable in a strong alkaline solution to convert it into a hydroxide precipitate to remove sulfur. CN113683130A provides a channel for the removal of impurity ions during the washing process by constructing radial cracks from the inside to the outside of the ternary precursor; CN112582605A realizes the continuous preparation of a low-sulfur-content ternary precursor through a multi-stage series connection of a reactor-concentrator-washing kettle-regulating kettle. The above documents cannot combine the advantages of high-efficiency impurity removal, simple process, easy operation, cheap equipment, small amount of washing wastewater generated, and high reliability, and the impurity removal effect, especially the effect of removing sodium and sulfur impurities, is average.

[0004] Therefore, how to effectively remove sodium-sulfur impurities in lithium-rich manganese-based precursor materials under the sulfate raw material system is a technical problem that needs to be solved urgently.

[0005] Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] The present application provides a lithium-rich manganese-based precursor material, its preparation method, and its use. During the aging process of the lithium-rich manganese-based precursor material, the present application uses carbonate and organic solution as aging media, resulting in a high sodium and sulfur impurity removal rate. The process is simple, easy to operate, generates little washing wastewater, and has high reliability. This allows for the controllable preparation of a lithium-rich manganese-based precursor with low sodium and sulfur impurities, improves the structural stability of the subsequent positive electrode material, and enhances electrochemical performance.

[0008] In a first aspect, the present application provides a method for preparing a lithium-rich manganese-based precursor material, the preparation method comprising the following steps:

[0009] Adding a nickel-cobalt-manganese mixed sulfate solution, a precipitant solution, and a complexing agent solution in parallel, performing a coprecipitation reaction under a protective atmosphere, and aging the mixture in an aging agent solution after the reaction to obtain the lithium-rich manganese-based precursor material;

[0010] Wherein, the aging agent solution includes carbonate and organic solvent.

[0011] The preparation method provided in this application uses carbonate and organic solution as aging medium in the aging process of lithium-rich manganese-based precursor materials, and the exchange capacity of inorganic anions is CO3 2- >SO4 2- At the same time, the addition of organic solvents helps to open the precursor interlayer, allowing more CO3 to enter the interlayer 2- , thereby improving the replacement of SO4 2- efficiency, and in the subsequent sintering process of preparing the positive electrode material, the CO3 2- It can be decomposed into CO2 without introducing new impurities, thereby effectively reducing the content of sodium and sulfur impurities in the precursor material. The process is simple, easy to operate, produces little washing wastewater, and has high reliability. It can achieve controllable preparation of lithium-rich manganese-based precursors with low sodium and sulfur impurities, improve the structural stability of subsequent positive electrode materials, and enhance electrochemical performance.

[0012] In this application, if no organic solvent is added to the aging agent solution, that is, a pure carbonate aqueous solution system, it is impossible to remove SO4 efficiently. 2- Impurities, and if the hydroxide system reacts with organic solvents, it is also impossible to remove SO4 with high efficiency and high reliability. 2- Impurities, that is, the carbonate and organic solvent in the aging agent solution in this application work synergistically, and neither is indispensable.

[0013] In one embodiment, the co-current addition further includes a reducing agent solution.

[0014] In the present application, the addition of a reducing agent combined with a protective atmosphere reduces the oxidation of divalent manganese ions, thereby reducing the adsorption and embedding of sulfate groups.

[0015] In one embodiment, the concentration of the reducing agent solution is 0.05 to 0.1 mol / L, for example, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L.

[0016] In one embodiment, the reducing agent includes any one of sodium sulfite, sodium thiosulfate, citric acid or hydrogen sulfide, or a combination of at least two thereof.

[0017] In one embodiment, the concentration of the nickel-cobalt-manganese mixed sulfate solution is 1 to 2.5 mol / L, for example, 1 mol / L, 1.5 mol / L, 2 mol / L or 2.5 mol / L.

[0018] In one embodiment, the concentration of the precipitant solution is 5 to 10 mol / L, for example, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L or 10 mol / L.

[0019] In one embodiment, the precipitating agent comprises sodium hydroxide and / or potassium hydroxide.

[0020] In one embodiment, the concentration of the complexing agent solution is 0.1-0.3 mol / L, such as 0.1 mol / L, 0.2 mol / L or 0.3 mol / L.

[0021] In one embodiment, the complexing agent comprises disodium EDTA.

[0022] In the present application, a reducing complexing agent is selected, which can also reduce the oxidation of divalent manganese ions.

[0023] In one embodiment, the reaction temperature of the coprecipitation reaction is 40-60°C, such as 40°C, 50°C or 60°C.

[0024] In one embodiment, the stirring rate of the coprecipitation reaction is 300-400 rpm, such as 300 rpm, 350 rpm or 400 rpm.

[0025] In one embodiment, the pH value of the coprecipitation reaction is 8-10, such as 8, 8.5, 9, 9.5 or 10.

[0026] In one embodiment, the aging temperature is 60-80°C, such as 60°C, 65°C, 70°C, 75°C or 80°C.

[0027] In one embodiment, the concentration of the carbonate solution in the aging agent solution is 0.1 to 0.5 mol / L, such as 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L.

[0028] In one embodiment, the volume concentration of the organic solvent in the aging agent solution is 1 to 4 vol%, for example, 1 vol%, 1.25 vol%, 1.5 vol%, 1.75 vol%, 2 vol%, 2.25 vol%, 2.5 vol%, 2.75 vol%, 3 vol%, 3.25 vol%, 3.5 vol%, 3.75 vol% or 4 vol%, etc.

[0029] In this application, if the volume concentration of the organic solvent is too small, it will not be able to fully contact with the precursor particles, weakening the SO4 2- However, if the volume concentration is too high, the organic solvent will be adsorbed on the surface of the precursor particles, resulting in impurity contamination.

[0030] In one embodiment, the organic solvent includes any one or a combination of at least two of ethylene glycol, acetone, 1,2-propylenediamine, hexamethylenediamine, glycerol or N-acyl glutamate diester, and 1,2-propylenediamine and / or N-acyl glutamate diester can be selected.

[0031] In one embodiment, the aging is followed by washing.

[0032] In one embodiment, the temperature of the washing medium is 60-100°C, such as 60°C, 70°C, 80°C, 90°C or 100°C.

[0033] In the present application, washing is performed at a hot washing temperature, which is beneficial to promoting the exchange of impurity ions, enhancing the washing effect, reducing the amount of washing waste liquid, and saving production costs.

[0034] In one embodiment, the washing liquid comprises an alkaline solution.

[0035] In one embodiment, the concentration of the washing solution is 0.2 to 0.6 mol / L, for example, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L or 0.6 mol / L.

[0036] In one embodiment, the preparation method comprises the following steps:

[0037] Adding a nickel-cobalt-manganese mixed sulfate solution, a precipitant solution, a complexing agent solution, and a reducing agent solution in parallel, performing a coprecipitation reaction under a protective atmosphere, aging the mixture in an aging agent solution at an aging temperature of 60 to 80° C., and washing the mixture at 60 to 100° C. to obtain the lithium-rich manganese-based precursor material;

[0038] The aging agent solution includes carbonate and an organic solvent, the concentration of the carbonate solution in the aging agent solution is 0.1 to 0.5 mol / L, the volume concentration of the organic solvent is 1 to 4 vol%, and the organic solvent includes any one or a combination of at least two of ethylene glycol, acetone, 1,2-propylenediamine, hexamethylenediamine, glycerol or N-acyl glutamate diester.

[0039] In a second aspect, the present application provides a lithium-rich manganese-based precursor material, which is prepared by the preparation method described in the first aspect.

[0040] In a third aspect, the present application provides a positive electrode material, which is obtained by mixing and sintering the lithium-rich manganese-based precursor material as described in the second aspect with a lithium source.

[0041] In a fourth aspect, the present application further provides a lithium-ion battery, which includes the positive electrode material as described in the third aspect.

[0042] Compared with the related art, this application has the following beneficial effects:

[0043] The preparation method provided in this application uses carbonate and organic solution as aging medium in the aging process of lithium-rich manganese-based precursor materials, and the exchange capacity of inorganic anions is CO3 2- >SO4 2- At the same time, the addition of organic solvents helps to open the precursor interlayer, allowing more CO3 to enter the interlayer 2- , thereby improving the replacement of SO4 2- efficiency, and in the subsequent sintering process of preparing the positive electrode material, the CO3 2- It can be decomposed into CO2 without introducing new impurities, thereby effectively reducing the content of sodium and sulfur impurities in the precursor material. The process is simple, easy to operate, produces little washing wastewater, and has high reliability. It can achieve controllable preparation of lithium-rich manganese-based precursors with low sodium and sulfur impurities, improve the structural stability of subsequent positive electrode materials, and enhance electrochemical performance.

[0044] Still other aspects will become apparent upon reading and understanding the detailed description. DETAILED DESCRIPTION

[0045] The technical solution of the present application is further illustrated below by specific examples. Those skilled in the art should understand that the examples are only for facilitating understanding of the present application and should not be regarded as specific limitations of the present application.

[0046] Example 1

[0047] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material, and the preparation method is as follows:

[0048] Step 1: 2 mol / L ternary sulfate solution with a metal molar ratio of Ni:Co:Mn = 0.3:0.2:0.5, 8 mol / L NaOH solution, 0.3 mol / L complexing agent disodium ethylenediaminetetraacetic acid solution, 0.1 mol / L reducing agent sodium thiosulfate solution and nitrogen were simultaneously injected into a 200 L continuously stirred reactor. The reaction temperature was maintained at 60°C, the pH was 8.8, and the stirring rate was 400 rpm. The reaction was stopped after the target particle size was reached.

[0049] Step 2: After the reaction slurry was allowed to stand, the supernatant was removed and the slurry was aged in a mixed solution of Na2CO3 (concentration of 0.4 mol / L) / ethylene glycol (2.0 vol.%) at 70°C for 8 hours;

[0050] Step 3: After centrifugation using a tripod centrifuge, the product is washed with a 0.3 mol / L NaOH solution and pure water in sequence. The temperature of the washing medium is 80° C. After drying, a lithium-rich manganese-based precursor with low sodium and sulfur impurities is obtained.

[0051] Example 2

[0052] A method for preparing a lithium-rich manganese-based precursor material is provided, and the preparation method is as follows:

[0053] Step 1: 1 mol / L ternary sulfate solution with a metal molar ratio of Ni:Co:Mn = 0.3:0.2:0.5, 5 mol / L NaOH solution, 0.1 mol / L complexing agent disodium ethylenediaminetetraacetic acid solution, 0.1 mol / L reducing agent sodium thiosulfate solution, and nitrogen were simultaneously injected into a 200 L continuously stirred reactor. The reaction temperature was maintained at 60°C, the pH was 9, and the stirring rate was 400 rpm. The reaction was stopped when the target particle size was reached.

[0054] Step 2: After the reaction slurry was allowed to stand, the supernatant was removed and the slurry was aged in a mixed solution of Na2CO3 (concentration of 0.1 mol / L) / acetone (1 vol.%) at 80°C for 9 hours;

[0055] Step 3: After centrifugation using a tripod centrifuge, the product is washed with a 0.3 mol / L NaOH solution and pure water in sequence. The temperature of the washing medium is 80° C. After drying, a lithium-rich manganese-based precursor with low sodium and sulfur impurities is obtained.

[0056] Example 3

[0057] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material, and the preparation method is as follows:

[0058] Step 1: 2 mol / L ternary sulfate solution with a metal molar ratio of Ni:Co:Mn = 0.2:0.2:0.6, 8 mol / L NaOH solution, 0.3 mol / L complexing agent disodium ethylenediaminetetraacetic acid solution, 0.1 mol / L reducing agent sodium thiosulfate solution and nitrogen were simultaneously injected into a 200 L continuously stirred reactor. The reaction temperature was maintained at 60°C, the pH was 8.8, and the stirring rate was 400 rpm. The reaction was stopped after the target particle size was reached.

[0059] Step 2: After the reaction slurry was allowed to stand, the supernatant was removed and the slurry was aged in a mixed solution of Na2CO3 (concentration of 0.4 mol / L) / ethylene glycol (4.0 vol.%) at 60°C for 8 hours;

[0060] Step 3: After centrifugation using a tripod centrifuge, the product is washed with a 0.3 mol / L NaOH solution and pure water in sequence. The temperature of the washing medium is 80° C. After drying, a lithium-rich manganese-based precursor with low sodium and sulfur impurities is obtained.

[0061] Example 4

[0062] The difference between this embodiment and embodiment 1 is that the volume concentration of the organic solvent in step 2 of this embodiment is 5 vol%.

[0063] The rest of the preparation methods and parameters were the same as those in Example 1.

[0064] Example 5

[0065] The difference between this embodiment and embodiment 1 is that the volume concentration of the organic solvent in step 2 of this embodiment is 0.5 vol%.

[0066] The rest of the preparation methods and parameters were the same as those in Example 1.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 1 is that the organic solvent in step 2 of this embodiment is N-acyl glutamate diester.

[0069] The rest of the preparation methods and parameters were the same as those in Example 1.

[0070] Example 7

[0071] The difference between this embodiment and embodiment 4 is that the volume concentration of the organic solvent in step 2 of this embodiment is 4 vol%.

[0072] The remaining preparation methods and parameters were consistent with those in Example 4.

[0073] Example 8

[0074] The difference between this embodiment and embodiment 4 is that the volume concentration of the organic solvent in step 2 of this embodiment is 5 vol%.

[0075] The remaining preparation methods and parameters were consistent with those in Example 4.

[0076] Comparative Example 1

[0077] The difference between this comparative example and Example 1 is that the aging agent solution in step 2 of this comparative example does not contain an organic solvent, that is, it is a pure sodium carbonate aqueous solution.

[0078] The rest of the preparation methods and parameters were the same as those in Example 1.

[0079] Comparative Example 2

[0080] The difference between this comparative example and Example 1 is that the sodium carbonate solution in the aging agent solution in step 2 of this comparative example is replaced by sodium hydroxide solution.

[0081] The rest of the preparation methods and parameters were the same as those in Example 1.

[0082] Comparative Example 3

[0083] The difference between this comparative example and Example 1 is that in step 1 of this comparative example, no reducing agent sodium thiosulfate solution is added; the aging agent solution in step 2 is only sodium hydroxide solution, and aging is performed at room temperature; and the washing medium temperature in step 3 is 50°C.

[0084] The lithium-rich manganese-based precursors provided in Examples 1-8 and Comparative Examples 1-3 were tested for the final sodium-sulfur impurity content. The test results are shown in Table 1.

[0085] Table 1

[0086] From the data results of Examples 1, 4 and 5, 6 and 7 and 8, it can be seen that if the volume concentration of the organic solvent in the aging agent solution is too small, it will not be able to fully contact with the precursor particles, thus weakening the SO4 2- The removal effect is poor, but the volume concentration is too high. On the one hand, the removal effect cannot be improved, which increases the cost. On the other hand, it will cause the organic solvent to be adsorbed on the surface of the precursor particles, resulting in new impurity contamination.

[0087] From the data results of Example 1 and Example 6, it can be seen that the organic solvent selected from N-acyl glutamate diester has a more excellent impurity removal effect.

[0088] From the data results of Example 1, Example 6 and Comparative Examples 1-2, it can be seen that in the aging agent solution, the carbonate and the organic solvent must work synergistically to achieve the controllable preparation of the lithium-rich manganese-based precursor with low sodium and sulfur impurities.

[0089] From the data results of Example 1 and Comparative Example 3, it can be seen that compared with the conventional preparation process, the sodium sulfur removal effect of the present application is very obvious.

[0090] In summary, the preparation method provided by this application, in the aging process of the lithium-rich manganese-based precursor material, carbonate and organic solution work together as aging media, and the exchange capacity of inorganic anions CO3 2- >SO4 2- At the same time, the addition of organic solvents helps to open the precursor interlayer, allowing more CO3 to enter the interlayer 2- , thereby improving the replacement of SO4 2- efficiency, and in the subsequent sintering process of preparing the positive electrode material, the CO3 2-It can be decomposed into CO2 without introducing new impurities, thereby effectively reducing the content of sodium and sulfur impurities in the precursor material. The process is simple, easy to operate, produces little washing wastewater, and has high reliability. It can achieve controllable preparation of lithium-rich manganese-based precursors with low sodium and sulfur impurities, improve the structural stability of subsequent positive electrode materials, and enhance electrochemical performance.

[0091] The applicant declares that the above is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Technical personnel in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technical personnel in the relevant technical field within the technical scope disclosed in this application fall within the protection scope and disclosure scope of this application.

Claims

1. A method for preparing a lithium-rich manganese-based precursor material, comprising the following steps: Adding a nickel-cobalt-manganese mixed sulfate solution, a precipitant solution and a complexing agent solution in parallel, performing a coprecipitation reaction under a protective atmosphere, and aging the mixture in an aging agent solution after the reaction to obtain the lithium-rich manganese-based precursor material; Wherein, the aging agent solution comprises carbonate and an organic solvent.

2. The method for preparing the lithium-rich manganese-based precursor material according to claim 1, wherein: The co-current addition also includes a reducing agent solution.

3. The method for preparing the lithium-rich manganese-based precursor material according to claim 2, wherein: The concentration of the reducing agent solution is 0.05-0.1 mol / L.

4. The method for preparing a lithium-rich manganese-based precursor material according to claim 2 or 3, wherein: The reducing agent includes any one of sodium sulfite, sodium thiosulfate, citric acid or hydrogen sulfide, or a combination of at least two thereof.

5. The method for preparing the lithium-rich manganese-based precursor material according to any one of claims 1 to 4, wherein: The concentration of the nickel-cobalt-manganese mixed sulfate solution is 1-2.5 mol / L.

6. The method for preparing a lithium-rich manganese-based precursor material according to any one of claims 1 to 5, wherein: The concentration of the precipitant solution is 5 to 10 mol / L; Optionally, the precipitating agent comprises sodium hydroxide and / or potassium hydroxide; Optionally, the concentration of the complexing agent solution is 0.1 to 0.3 mol / L; Optionally, the complexing agent comprises disodium ethylenediaminetetraacetate.

7. The method for preparing a lithium-rich manganese-based precursor material according to any one of claims 1 to 6, wherein: The reaction temperature of the coprecipitation reaction is 40 to 60°C; Optionally, the stirring rate of the coprecipitation reaction is 300-400 rpm; Optionally, the pH value of the coprecipitation reaction is 8-10.

8. The method for preparing a lithium-rich manganese-based precursor material according to any one of claims 1 to 7, wherein: The aging temperature is 60-80°C.

9. The method for preparing a lithium-rich manganese-based precursor material according to any one of claims 1 to 8, wherein: The concentration of the carbonate solution in the aging agent solution is 0.1-0.5 mol / L; Optionally, in the aging agent solution, the volume concentration of the organic solvent is 1 to 4 vol%.

10. The method for preparing a lithium-rich manganese-based precursor material according to any one of claims 1 to 9, wherein: The organic solvent includes any one of ethylene glycol, acetone, 1,2-propylenediamine, hexamethylenediamine, glycerol or N-acyl glutamic acid diester or a combination of at least two thereof, and 1,2-propylenediamine and / or N-acyl glutamic acid diester may be selected.

11. The method for preparing a lithium-rich manganese-based precursor material according to any one of claims 1 to 10, wherein: After the aging, washing is performed; Optionally, the temperature of the washing medium is 60-100°C; Optionally, the washing liquid of the washing comprises alkali solution; Optionally, the concentration of the washing solution is 0.2-0.6 mol / L.

12. The method for preparing the lithium-rich manganese-based precursor material according to any one of claims 1 to 11, comprising the following steps: Adding a nickel-cobalt-manganese mixed sulfate solution, a precipitant solution, a complexing agent solution and a reducing agent solution in parallel, performing a coprecipitation reaction under a protective atmosphere, aging in an aging agent solution at an aging temperature of 60 to 80° C. after the reaction, and washing at 60 to 100° C. to obtain the lithium-rich manganese-based precursor material; The aging agent solution comprises carbonate and an organic solvent, the concentration of the carbonate solution in the aging agent solution is 0.1 to 0.5 mol / L, the volume concentration of the organic solvent is 1 to 4 vol%, and the organic solvent comprises any one of ethylene glycol, acetone, 1,2-propylenediamine, hexamethylenediamine, glycerol or N-acyl glutamate diester or a combination of at least two thereof.

13. A lithium-rich manganese-based precursor material, wherein: The lithium-rich manganese-based precursor material is prepared by the preparation method according to any one of claims 1 to 12.

14. A positive electrode material, wherein: The positive electrode material is obtained by mixing and sintering the lithium-rich manganese-based precursor material as claimed in claim 13 and a lithium source.

15. A lithium ion battery, wherein: The lithium-ion battery comprises the positive electrode material as claimed in claim 14.

Images