Application of poly 2-acrylamide-2-methylpropanesulfonic acid in removing residual lithium on surface of high-nickel NCM ternary material

Abstract

The application provides application of poly-2-acrylamide-2-methylpropanesulfonic acid in removal of residual lithium on the surface of high-nickel NCM ternary material, and relates to the technical field of surface treatment of high-nickel NCM ternary material.The application is aimed at the problem that the existing method of removing lithium carbonate on the surface of NCM material by high-temperature calcination or high-concentration ethanol immersion cleaning has an adverse effect on the structure and performance of high-nickel NCM ternary material, and proposes to use a cleaning agent with poly-2-acrylamide-2-methylpropanesulfonic acid as a main component to clean residual lithium on the high-nickel NCM ternary material, which is verified to be able to effectively avoid the damage of the existing high-temperature calcination and high-concentration ethanol immersion cleaning treatment to the high-nickel NCM ternary material, and significantly improve the electrochemical performance of the high-nickel NCM ternary material.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology for high-nickel NCM ternary materials, and in particular to the application of poly-2-acrylamide-2-methylpropanesulfonic acid in removing residual lithium from the surface of high-nickel NCM ternary materials. Background Technology

[0002] With the rapid development of electric vehicles, portable electronic devices, and energy storage systems, lithium-ion battery technology has been widely used and developed rapidly over the past few decades. As a new generation of cathode materials for lithium-ion batteries, high-nickel NCM (nickel-cobalt-manganese oxide) ternary materials have attracted widespread attention due to their high energy density and low cost. However, during the synthesis and use of high-nickel NCM ternary materials, the residual lithium content on their surface increases. This residual lithium readily reacts with water and carbon dioxide to form byproducts such as lithium carbonate (Li₂CO₃). These byproducts not only affect the battery's cycle performance and rate performance but may also pose safety hazards.

[0003] Traditional techniques typically employ high-temperature calcination or organic washing to remove lithium carbonate from the surface of NCM materials. High-temperature calcination involves heating the NCM material at high temperatures, causing the surface lithium carbonate to decompose into carbon dioxide and lithium oxide, thus removing residual lithium. Organic washing involves immersing the NCM material in high-concentration ethanol, dissolving the surface lithium carbonate and removing residual lithium. However, these methods suffer from problems such as operational complexity, high energy consumption, and environmental pollution. Furthermore, the process of removing lithium carbonate may adversely affect the material's structure and properties.

[0004] Therefore, it is particularly important to research and develop a new treatment method that is efficient, environmentally friendly, and does not damage the material itself.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an acid detergent and treatment method for removing residual lithium from the surface of high-nickel NCM ternary materials. After treatment with the acid detergent and method of this application, the damage to high-nickel NCM ternary materials caused by existing high-temperature calcination and organic water washing treatments can be effectively avoided, while significantly improving the electrochemical performance of the materials.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] The present invention relates to the application of poly-2-acrylamide-2-methylpropanesulfonic acid in removing residual lithium from the surface of high-nickel NCM ternary materials.

[0009] Furthermore, the nickel content in the high-nickel NCM ternary material is greater than 80%.

[0010] Furthermore, the residual lithium on the surface of the high-nickel NCM ternary material is lithium carbonate formed on the surface of the high-nickel NCM ternary material during synthesis and use.

[0011] The present invention provides an acid washing solution for removing residual lithium from the surface of high-nickel NCM ternary materials, characterized in that the acid washing solution is mainly prepared by dissolving poly-2-acrylamide-2-methylpropanesulfonic acid in a solvent.

[0012] Furthermore, the solvent includes any one of phosphoric acid, boric acid, and N-methylpyrrolidone;

[0013] Furthermore, the concentration of poly-2-acrylamide-2-methylpropanesulfonic acid in the acid washing solution is 0.5 to 1.5 wt%.

[0014] This invention provides a method for treating residual lithium on the surface of a high-nickel NCM ternary material, characterized in that the treatment method includes:

[0015] The above-mentioned acid washing solution was mixed with the high-nickel NCM ternary material to be treated and stirred. Then, the mixture was filtered and the filtered product was dried to complete the treatment.

[0016] Furthermore, the mass ratio of the acid washing solution to the high-nickel NCM ternary material to be treated during the process is 1:(50-200).

[0017] Furthermore, the stirring speed is 600-1200 rpm, and the stirring time is 0.5-2 hours.

[0018] Furthermore, the filtration is vacuum filtration, the temperature of the vacuum filtration is 20-25°C, and the pressure of the vacuum filtration is -0.06 to -0.10 MPa.

[0019] Furthermore, the drying temperature is 80–120°C, and the drying time is 1–4 hours.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention relates to the application of poly-2-acrylamide-2-methylpropanesulfonic acid in removing residual lithium from the surface of high-nickel NCM ternary materials. Addressing the problems of existing methods that use high-temperature calcination or high-concentration organic ethanol immersion to remove lithium carbonate from the surface of NCM materials, which adversely affect the structure and properties of high-nickel NCM ternary materials, this application creatively proposes using poly-2-acrylamide-2-methylpropanesulfonic acid as the main component of a cleaning agent to clean residual lithium from high-nickel NCM ternary materials. Verification has shown that this method effectively avoids the damage to high-nickel NCM ternary materials caused by existing high-temperature calcination and organic water washing treatments, while significantly improving the electrochemical performance of the material.

[0022] The acid washing solution provided by the present invention has poly-2-acrylamide-2-methylpropanesulfonic acid as its main solute component. The acid washing solution can effectively remove the lithium carbonate content on the surface of high-nickel NCM ternary materials and improve the electrochemical performance of high-nickel NCM ternary materials.

[0023] The present invention provides a method for treating residual lithium on the surface of high-nickel NCM ternary materials. This method involves first mixing the aforementioned acid washing solution with the high-nickel NCM ternary material to be treated, then stirring, followed by filtration, and finally drying the filtered product to obtain the treated high-nickel NCM ternary material. This method has the advantages of being environmentally friendly and easy to operate. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 The discharge specific capacity diagrams for the third cycle of Examples 1-3, the base group, and the bare group provided in Experiment 1 of the present invention. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] According to one aspect of the present invention, poly-2-acrylamide-2-methylpropanesulfonic acid is used in the removal of residual lithium from the surface of high-nickel NCM ternary materials.

[0028] This invention relates to the application of poly-2-acrylamide-2-methylpropanesulfonic acid in removing residual lithium from the surface of high-nickel NCM ternary materials. Addressing the problems of existing methods that use high-temperature calcination or high-concentration organic ethanol immersion to remove lithium carbonate from the surface of NCM materials, which adversely affect the structure and properties of high-nickel NCM ternary materials, this application creatively proposes using poly-2-acrylamide-2-methylpropanesulfonic acid as the main component of the cleaning agent to clean residual lithium from high-nickel NCM ternary materials. Verification has shown that this method effectively avoids the damage to high-nickel NCM ternary materials caused by existing high-temperature calcination and organic water washing treatments, while significantly improving the electrochemical performance of the material.

[0029] It should be noted that, through research, this application has found that although polyacrylamide-2-methylpropanesulfonic acid (PAMPS) is a strong acid, due to its specific molecular structure and the processing method of this application, damage to the material can be reduced during the removal of residual lithium from the surface of high-nickel NCM ternary materials.

[0030] In a preferred embodiment of the present invention, the nickel content in the high-nickel NCM ternary material is greater than 80%.

[0031] In a preferred embodiment of the present invention, the residual lithium on the surface of the high-nickel NCM ternary material is lithium carbonate formed on the surface of the high-nickel NCM ternary material during synthesis and use.

[0032] According to one aspect of the present invention, an acid washing solution for removing residual lithium from the surface of high-nickel NCM ternary materials is provided, the acid washing solution being mainly prepared by dissolving poly-2-acrylamide-2-methylpropanesulfonic acid in a solvent.

[0033] The acid washing solution provided by the present invention has poly-2-acrylamide-2-methylpropanesulfonic acid as its main solute component. The acid washing solution can effectively remove residual lithium (lithium carbonate) from the surface of high-nickel NCM ternary materials.

[0034] In a preferred embodiment of the present invention, the solvent includes any one of phosphoric acid, boric acid, and N-methylpyrrolidone;

[0035] In the preferred embodiment described above, the concentration of poly-2-acrylamide-2-methylpropanesulfonic acid in the acid washing solution is 0.5 to 1.5 wt%.

[0036] In a preferred embodiment, the concentration of poly-2-acrylamide-2-methylpropanesulfonic acid in the above-mentioned acid washing solution is 0.5 to 1.5 wt%. Too high a concentration will lead to structural degradation of the high-nickel NCM ternary material, while too low a concentration will result in poor lithium carbonate removal.

[0037] According to one aspect of the present invention, a method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0038] The above-mentioned acid washing solution was mixed with the high-nickel NCM ternary material to be treated and stirred. Then, the mixture was filtered and the filtered product was dried to complete the treatment.

[0039] The present invention provides a method for treating residual lithium on the surface of high-nickel NCM ternary materials. This method involves first mixing the aforementioned acid washing solution with the high-nickel NCM ternary material to be treated, then stirring, followed by filtration, and finally drying the filtered product to obtain the treated high-nickel NCM ternary material. This method has the advantages of being environmentally friendly and easy to operate.

[0040] In a preferred embodiment of the present invention, the mass ratio of the acid washing solution to the high-nickel NCM ternary material to be treated during the treatment process is 1:(50-200).

[0041] In a preferred embodiment of the present invention, the stirring speed is 600-1200 rpm and the stirring time is 0.5-2 h.

[0042] In a preferred embodiment of the present invention, the filtration is vacuum filtration, the temperature of the vacuum filtration is 20-25°C, and the pressure of the vacuum filtration is -0.06 to -0.10 MPa.

[0043] In a preferred embodiment of the present invention, the drying temperature is 80-120°C and the drying time is 1-4 hours.

[0044] Preferably, the method for treating residual lithium on the surface of the high-nickel NCM ternary material includes:

[0045] S1: First, 2-acrylamide-2-methylpropanesulfonic acid (AMPS) monomer is mixed and stirred with N-methylpyrrolidone (NMP) solvent, and then azobisisobutyronitrile (AIBN) initiator is added to induce monomer polymerization to prepare poly-2-acrylamide-2-methylpropanesulfonic acid (PAMPS).

[0046] S2: Mix poly(2-acrylamide-2-methylpropanesulfonic acid) (PAMPS) and N-methylpyrrolidone (NMP) to prepare acid detergents with different mass fractions;

[0047] S3: Mix the acid detergent with the nickel-cobalt-manganese ternary material (NCM) with an aging time of 7 days;

[0048] S4: Filter and dry the mixture to obtain the acid-washed product.

[0049] The technical solution of the present invention will be further described below with reference to the embodiments.

[0050] Note: In the following examples and comparative examples, "high-nickel NCM ternary material with an aging time of 7 days" refers to high-nickel NCM ternary material exposed to humid and hot air for 7 days, with its surface covered with lithium carbonate. The following examples and comparative examples all use the same batch of high-nickel NCM ternary material with an aging time of 7 days, and their raw materials, specifications, performance parameters, and aging time and degree are all at the same level.

[0051] Example 1

[0052] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0053] (1) Preparation of acid detergent: Take 1g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and add it to 5mL of N-methylpyrrolidone (NMP) solvent. Seal with sealant and ultrasonically stir for 10min. Then add 0.02g of azobisisobutyronitrile (AIBN) and place at 60℃ for 24h to allow the monomer to polymerize and obtain poly-2-acrylamido-2-methylpropanesulfonic acid (PAMPPS) solution. Mix with N-methylpyrrolidone (NMP) to prepare an acid detergent with a mass fraction of 0.5wt%.

[0054] (2) Pickling step: NCM aged for 7 days is mixed with 0.5wt% of pickling agent and stirred at 1000rpm for 2h. Then, vacuum filtration is performed. The filtered product is placed in a vacuum oven at 100℃ and dried for 2h to obtain the final acid-treated product.

[0055] Example 2

[0056] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0057] (1) Preparation of acid detergent: Take 1g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and add it to 5mL of N-methylpyrrolidone (NMP) solvent. Seal with sealant and ultrasonically stir for 10min. Then add 0.02g of azobisisobutyronitrile (AIBN) and place at 60℃ for 24h to allow the monomer to polymerize and obtain 2-acrylamido-2-methylpropanesulfonic acid (PAMPPS) solution. Mix with N-methylpyrrolidone (NMP) to prepare an acid detergent with a mass fraction of 1.0wt%.

[0058] (2) Pickling step: NCM aged for 7 days is mixed with 1.0wt% of acid detergent and stirred at 1000rpm for 2h. Then, vacuum filtration is performed. The filtered product is placed in a vacuum oven at 100℃ and dried for 2h to obtain the final acid-treated product.

[0059] Example 3

[0060] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0061] (1) Preparation of acid detergent: 1g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was added to 5mL of N-methylpyrrolidone (NMP) solvent and sealed with sealant. The mixture was ultrasonically stirred for 10min, and then 0.02g of azobisisobutyronitrile (AIBN) was added. The mixture was placed at 60℃ for 24h to allow the monomer to polymerize and obtain a 2-acrylamido-2-methylpropanesulfonic acid (PAMPPS) solution. This solution was then mixed with N-methylpyrrolidone (NMP) to prepare acid detergents with different mass fractions of 1.5wt%.

[0062] (2) Pickling step: NCM aged for 7 days is mixed with 1.5wt% of acid detergent and stirred at 1000rpm for 2h. Then, vacuum filtration is performed. The filtered product is placed in a vacuum oven at 100℃ and dried for 2h to obtain the final acid-treated product.

[0063] Example 4

[0064] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0065] (1) Preparation of acid detergent: Take 1g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and add it to 5mL of N-methylpyrrolidone (NMP) solvent. Seal with sealant and ultrasonically stir for 10min. Then add 0.02g of azobisisobutyronitrile (AIBN) and place at 60℃ for 24h to allow the monomer to polymerize and obtain 2-acrylamido-2-methylpropanesulfonic acid (PAMPPS) solution. Mix with N-methylpyrrolidone (NMP) to prepare an acid detergent with a mass fraction of 2.0wt%.

[0066] (2) Pickling step: NCM aged for 7 days is mixed with 2.0wt% of acid detergent and stirred at 1000rpm for 2h. Then, vacuum filtration is performed. The filtered product is placed in a vacuum oven at 100℃ and dried for 2h to obtain the final acid-treated product.

[0067] The difference between this embodiment and Embodiment 1 is that the acid washing treatment is performed using an acid detergent with a mass fraction of 2.0 wt%.

[0068] Example 5

[0069] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0070] (1) Preparation of acid detergent: Take 1g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and add it to 5mL of N-methylpyrrolidone (NMP) solvent. Seal with sealant and ultrasonically stir for 10min. Then add 0.02g of azobisisobutyronitrile (AIBN) and place at 60℃ for 24h to allow the monomer to polymerize and obtain 2-acrylamido-2-methylpropanesulfonic acid (PAMPPS) solution. Mix with N-methylpyrrolidone (NMP) to prepare an acid detergent with a mass fraction of 0.3wt%.

[0071] (2) Pickling step: NCM aged for 7 days is mixed with 0.3wt% of pickling agent and stirred at 1000rpm for 2h. Then, vacuum filtration is performed. The filtered product is placed in a vacuum oven at 100℃ and dried for 2h to obtain the final acid-treated product.

[0072] The difference between this embodiment and Embodiment 1 is that the acid washing treatment is performed using an acid detergent with a mass fraction of 0.3 wt%.

[0073] Example 6

[0074] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0075] (1) Preparation of acid detergent: Same as in Example 1.

[0076] (2) Pickling step: NCM aged for 7 days is mixed with 0.5wt% of acid detergent and stirred at 1000rpm for 2h. Then, vacuum filtration is performed, and the filtered product is placed in a vacuum oven at 120℃ and dried for 2h to obtain the final acid-treated product.

[0077] Comparative Example 1

[0078] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0079] Pickling step: NCM aged for 7 days is mixed with 0.5 wt% polyacrylic acid detergent and stirred at 1000 rpm for 2 hours. Then, vacuum filtration is performed, and the filtered product is placed in a vacuum oven at 100°C and dried for 2 hours to obtain the final acid-treated product.

[0080] The difference between this comparative example and Example 1 is that polyacrylic acid was used instead of poly-2-acrylamide-2-methylpropanesulfonic acid (PAMPPS) to prepare the acid detergent.

[0081] Comparative Example 2

[0082] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0083] Pickling step: NCM aged for 7 days is mixed with 0.5 wt% poly-2-acrylamide-2-methylpropanesulfonic acid (PAMPPS) pickling agent and stirred at 1000 rpm for 2 hours. Then, the mixture is evaporated and crystallized. The product is then placed in a vacuum oven at 100°C and dried for 2 hours to obtain the final acid-treated product.

[0084] Comparative Example 3

[0085] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0086] The NCM aged for 7 days was calcined at 800°C for 3 hours in an O2 atmosphere to obtain the final high-temperature calcined product.

[0087] Comparative Example 4

[0088] A method for treating residual lithium on the surface of a high-nickel NCM ternary material, the method comprising:

[0089] NCM aged for 7 days was mixed with 2.0 wt% glycolic acid detergent and stirred at 1000 rpm for 2 hours. Then, the mixture was evaporated and crystallized. The product was then dried in a vacuum oven at 100°C for 2 hours to obtain the final acid-treated product.

[0090] Experimental Example 1

[0091] To demonstrate that the acid detergent of this application can effectively remove residual lithium from the surface of high-nickel NCM ternary materials aged for 7 days, the specific capacity and coulombic efficiency of the high-nickel NCM ternary materials treated in Examples 1-6 and Comparative Examples 1-4 were tested in the third discharge cycle. The specific results are as follows:

[0092]

[0093]

[0094] Figure 1 The discharge specific capacity of the third cycle of Examples 1-3, the base group, and the bare group provided for this test case.

[0095] Note: Figure 1 The base group (control group) consists of high-nickel NCM ternary materials aged for 7 days without any treatment; the bare group refers to high-nickel NCM ternary materials aged for 7 days, that is, high-nickel NCM ternary materials exposed to humid and hot air for 7 days, with their surface covered with lithium carbonate.

[0096] As can be seen from the above, the high-nickel cathode materials obtained after treatment in Examples 1 to 3 of this application show improved third-cycle discharge specific capacity and coulombic efficiency compared to the untreated control group, indicating that the high-nickel cathode materials have a good lithium carbonate removal effect on the surface.

[0097] Compared with Examples 1-3, in Examples 4 and 5, pickling solutions with a poly(2-acrylamide-2-methylpropanesulfonic acid) concentration higher than 1.5 wt% resulted in structural degradation of the high-nickel NCM ternary material, while pickling solutions with a poly(2-acrylamide-2-methylpropanesulfonic acid) concentration lower than 0.5 wt% were ineffective in removing lithium carbonate. In Example 6, compared with Examples 1-3, the implementation method of Examples 1-3 with a vacuum filtration temperature of 100°C showed better results than the implementation method of Example 6 with a vacuum filtration temperature of 120°C.

[0098] Compared to Examples 1-3, Comparative Example 1 showed better removal of lithium carbonate using poly(2-acrylamide-2-methylpropanesulfonic acid) (PAMPPS), which was superior to polyacrylic acid. In Comparative Example 2, vacuum filtration was more effective than evaporation crystallization than in Examples 1-3. Comparing Comparative Examples 3 and 4 with Examples 1-3, the processing methods of Examples 1-3 of this application effectively avoid the damage to high-nickel NCM ternary materials caused by existing high-temperature calcination and high-concentration ethanol immersion cleaning treatments, while significantly improving the electrochemical performance of the high-nickel NCM ternary materials.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Application of poly-2-acrylamide-2-methylpropanesulfonic acid in removing residual lithium from the surface of high-nickel NCM ternary materials; in, The residual lithium on the surface of the high-nickel NCM ternary material is lithium carbonate formed on the surface of the high-nickel NCM ternary material during synthesis and use.

2. The application according to claim 1, characterized in that, The nickel content in the high-nickel NCM ternary material is greater than 80%.

3. An acid washing solution for removing residual lithium from the surface of high-nickel NCM ternary materials, characterized in that, The acid washing solution is mainly prepared by dissolving poly-2-acrylamide-2-methylpropanesulfonic acid in a solvent; The residual lithium on the surface of the high-nickel NCM ternary material is lithium carbonate formed on the surface of the high-nickel NCM ternary material during synthesis and use.

4. The acid washing solution according to claim 3, characterized in that, The solvent includes phosphoric acid, boric acid, N Any one of methylpyrrolidone; The concentration of poly-2-acrylamide-2-methylpropanesulfonic acid in the acid washing solution is 0.5~1.5 wt%.

5. A method for treating residual lithium on the surface of a high-nickel NCM ternary material, characterized in that, The processing method includes: The acid washing solution described in claim 3 or 4 is mixed with the high-nickel NCM ternary material to be treated and stirred, then filtered, and the filtered product is dried to complete the treatment.

6. The processing method according to claim 5, characterized in that, During the treatment process, the mass ratio of the acid washing solution to the high-nickel NCM ternary material to be treated is 1:(50~200).

7. The processing method according to claim 5, characterized in that, The stirring speed is 600~1200 rpm, and the stirring time is 0.5~2 h.

8. The processing method according to claim 5, characterized in that, The filtration is a vacuum filtration, the temperature of which is 20~25℃ and the pressure of which is -0.06~-0.10 MPa.

9. The processing method according to claim 5, characterized in that, The drying temperature is 80~120℃, and the drying time is 1~4 h.

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