High-performance regenerated ternary material and preparation method thereof

Abstract

The application relates to the technical field of ternary materials, in particular to a high-performance regenerated ternary material and a preparation method thereof. The preparation method comprises the following steps: carrying out pretreatment on waste ternary positive electrode active material to form ternary positive electrode powder with high surface carbon acidification; mixing a lithium source and a long-chain carbon alcohol to form starch-based lithium; mixing and treating the starch-based lithium and the ternary positive electrode powder with high surface carbon acidification to form pre-lithiated ternary positive electrode powder, wherein the long-chain carbon alcohol is selected from alcohols with a carbon number greater than 5; and mixing and sintering the pre-lithiated ternary positive electrode powder and a fluxing agent. The preparation method can greatly improve the performance of the waste ternary regenerated material, and improve the discharge gram capacity and capacity retention rate of the waste ternary regenerated material.

Description

Technical Field

[0001] This invention relates to the field of ternary materials technology, and more specifically, to a high-performance recycled ternary material and its preparation method. Background Technology

[0002] my country is a major producer and consumer of batteries, with civilian batteries being the most widely used type. The amount of discarded batteries each year is enormous, posing a serious threat to environmental safety and wasting resources. Therefore, recycling of discarded batteries is necessary. For example, after safe discharge treatment, discarded ternary lithium batteries are disassembled and decased under a protective gas atmosphere to obtain ternary cathode active material. This material is then soaked in potassium hydroxide solution and washed with deionized water to obtain cathode active material free of electrolyte components. The treated ternary cathode active material is then placed in a supercritical fluid extraction device to obtain the extracted product. However, the performance improvement of this extracted product is not significant, and further improvements to the preparation method of recycled ternary cathode material are needed to enhance its performance.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a high-performance recycled ternary material and its preparation method. The preparation method provided in this invention can greatly improve the performance of recycled ternary materials, enhancing their discharge capacity and capacity retention.

[0005] The implementation method of this invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a high-performance recycled ternary material, comprising:

[0007] Waste ternary cathode active materials are pretreated to form ternary cathode powder with highly carbonated surface;

[0008] A lithium source and a long-chain carbon alcohol are mixed to form starch-based lithium; the starch-based lithium is mixed with the ternary cathode powder with a highly carbonized surface to form a pre-lithiated ternary cathode powder, wherein the long-chain carbon alcohol is selected from alcohols with more than 5 carbon atoms;

[0009] The pre-lithiated ternary cathode powder and flux are mixed and sintered.

[0010] In an optional embodiment, the long-chain alcohol is a monohydric alcohol; more preferably, it is a monohydric terminal hydroxyl alcohol.

[0011] Preferably, the structural formula of the long-chain carbon alcohol is as follows: 1-C n H (2n+1) OH, where n≥5; the most preferred is n-octanol.

[0012] In an optional embodiment, the lithium source is selected from lithium hydroxide.

[0013] In an optional implementation, 1-5g of lithium source corresponds to 100ml of the long-chain alcohol.

[0014] In an optional embodiment, the method includes: mixing and stirring the starch-based lithium with the surface-highly carbonized ternary cathode powder, and then filtering and drying to form the pre-lithiated ternary cathode powder.

[0015] In an optional embodiment, the flux is selected from one or more combinations of lithium niobate, lithium phosphate, strontium nitrate, strontium oxide, strontium hydroxide, and barium nitrate, with lithium niobate being the most preferred.

[0016] In an optional embodiment, the amount of flux used is 500-5000 ppm.

[0017] In an optional implementation, sintering includes negative pressure high-temperature sintering;

[0018] Preferably, the sintering conditions include: a pressure of -100 MPa to -300 MPa, a temperature of 700-900 °C, and a time of 2-6 hours.

[0019] In an optional embodiment, the pretreatment includes: stirring the waste ternary cathode active material in a supersaturated carbon dioxide aqueous solution and then air-drying it;

[0020] Preferably, the pretreatment is supercritical extraction;

[0021] Preferably, the extraction pressure is 15-30 MPa; the extraction temperature is 30-60℃; the extraction time is 1-2 h; and the extraction gas is carbon dioxide.

[0022] Secondly, the present invention provides a high-performance recycled ternary material, which is prepared by the preparation method of high-performance recycled ternary material described in any of the foregoing embodiments.

[0023] The present invention has the following beneficial effects: The embodiments of the present invention utilize pretreatment to form carbonation on the surface of ternary cathode materials, combined with subsequent pre-lithiation and flux coating technologies, to achieve a synergistic effect and greatly improve the performance of waste ternary recycled materials. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram illustrating the principle of the preparation method of high-performance recycled ternary materials provided in the embodiments of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0027] This invention provides a method for preparing high-performance recycled ternary materials, and the preparation principle diagram is shown below. Figure 1 The specific preparation process is as follows:

[0028] S1, Pre-processing;

[0029] The waste ternary cathode active material stripped from the electrode sheet is pretreated to obtain ternary cathode powder with highly carbonated surface.

[0030] The method for obtaining waste ternary cathode active material by peeling off waste electrode sheets can refer to the steps or methods in the prior art, and will not be described in detail in the embodiments of the present invention.

[0031] Specifically, the pretreatment includes: stirring the waste ternary cathode active material in a supersaturated carbon dioxide aqueous solution and then air-drying it; using a supersaturated carbon dioxide aqueous solution for pretreatment can not only remove impurities from the waste ternary material powder and remove residual F from the surface, but also... - (Electrolyte), Al element (aluminum foil), and at the same time, supersaturated carbon dioxide bubbles can form a dense lithium carbonate layer on the surface of the ternary cathode material, which is beneficial to subsequent operation and improves the performance of the ternary cathode material.

[0032] Specifically, in this embodiment of the invention, supercritical extraction is used to achieve pretreatment. Supercritical extraction is only an example of this embodiment of the invention. Other methods can also be used, as long as the waste ternary positive electrode active material is stirred in a supersaturated carbon dioxide aqueous solution.

[0033] Specifically, the extraction pressure is 15-30 MPa; the extraction temperature is 30-60℃; the extraction time is 1-2 h; and the extraction gas is carbon dioxide.

[0034] S2, forming pre-lithiated ternary cathode powder;

[0035] A lithium source and a long-chain carbon alcohol are mixed to form starch-based lithium, and the starch-based lithium is mixed with the highly carbonized ternary cathode powder to form a pre-lithiated ternary cathode powder.

[0036] The formed starch-based lithium can be adsorbed onto the surface of waste ternary materials through van der Waals forces between the lithium carbonate layer and the starch base. Compared with directly adding lithium source, this process has a higher utilization rate of lithium source, shortens the diffusion path of lithium into the material surface and interior, and reduces the reaction time between lithium source and material during sintering.

[0037] Specifically, a lithium source and a long-chain carbon alcohol are mixed and dissolved to form a starch-based lithium solution, which is then mixed with a ternary cathode powder with a highly carbonized surface and stirred at room temperature for 2-4 hours. The mixture is then filtered and dried to obtain a pre-lithiated ternary cathode powder.

[0038] The long-chain alcohols are selected from alcohols with more than 5 carbon atoms. If the number of carbon atoms in the long-chain alcohols is too low, such as methanol, ethanol and butanol, they cannot form starch-like long-chain groups, and they cannot effectively form van der Waals forces to adhere to the surface of the ternary material matrix and cooperate with the subsequent flux, thus failing to effectively improve the performance of the recycled ternary material.

[0039] Specifically, the long-chain alcohol is a monohydric alcohol; more preferably, it is a monohydric terminal hydroxyl alcohol; for example, 1-C n H (2n+1) OH, where n≥5; preferably 5≤n≤10, for example, including but not limited to n-octanol. The lithium source is selected from lithium hydroxide. 1-5g of lithium source corresponds to 100ml of the long-chain carbon alcohol. The above conditions are beneficial for the formation of van der Waals forces, which in turn is beneficial for improving the performance of the recycled ternary material.

[0040] S3, sintering;

[0041] The pre-lithiated ternary cathode powder and flux are mixed and sintered. Specifically, the pre-lithiated ternary cathode powder and flux are dry-mixed, then sintered under negative pressure at high temperature, and cooled to obtain the desired recycled ternary material.

[0042] In this embodiment of the invention, flux coating and high-temperature sintering are performed after pre-lithiation. The sintering time is shorter under the effect of pre-lithiation, which significantly reduces energy consumption in industry. In addition, low-cost additives and processes are used in the process, which is green and environmentally friendly and has universal applicability.

[0043] The amount of flux used is 500-5000 ppm, for example, any value between 500 ppm, 1000 ppm, 2000 ppm, 3000 ppm, 4000 ppm and 5000 ppm.

[0044] The flux is selected from one or more combinations of lithium niobate, lithium phosphate, strontium nitrate, strontium oxide, strontium hydroxide, and barium nitrate, with lithium niobate being the most preferred.

[0045] Specifically, the sintering conditions include: a pressure of -100 MPa to -300 MPa, a temperature of 700-900℃, and a time of 2-6 hours.

[0046] Secondly, the present invention provides a high-performance recycled ternary material, which is prepared by the preparation method of high-performance recycled ternary material described in any of the foregoing embodiments.

[0047] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0048] Example 1

[0049] This invention provides a method for preparing high-performance recycled ternary materials, comprising:

[0050] S1: Place the waste ternary cathode active material stripped from the electrode sheet into a supercritical extraction device, set the extraction pressure to 20 MPa, the extraction temperature to 50°C and the extraction time to 1 h, and obtain the ternary cathode powder with highly carbonated surface.

[0051] S2: Dissolve lithium hydroxide monohydrate in n-octanol at a ratio of 1g / 100mL to prepare a starch-based lithium solution; then, based on the ICP test of the ternary powder obtained in S1, obtain the Li / (Ni+Co+Mn) value of the waste ternary powder, and add the ternary powder obtained in S1 to the solution according to the weight of the additional lithium required for this design value of 1.05. After stirring at room temperature for 4 hours, filter and dry under vacuum at 75℃ to obtain the pre-lithiated ternary cathode powder.

[0052] S3: The powder obtained in S2 is mixed with 2000ppm lithium niobate in a high-speed mixer at 800r / min for 10min, sintered at 800℃ for 4h at -150Mpa, and then cooled to obtain the recycled ternary material.

[0053] Example 2-3

[0054] Examples 2-3 of this invention provide a method for preparing high-performance recycled ternary materials. The preparation method is basically the same as the preparation method provided in Example 1, except that some conditions are different.

[0055] Example 2: The long-chain alcohol is n-pentanol, and 2g of lithium hydroxide corresponds to 100ml of n-pentanol; the flux is lithium phosphate, and the amount of lithium phosphate used is 3500ppm.

[0056] Example 3: The long-chain alcohol is n-heptanol, and 5g of lithium hydroxide corresponds to 100ml of n-pentanol; the flux is strontium hydroxide, and the amount of strontium hydroxide used is 1500ppm.

[0057] Comparative Example 1: The cathode material provided in this comparative example is the waste ternary cathode active material peeled off from the electrode sheet obtained in Example 1.

[0058] Comparative Example 2: The preparation method of the cathode material provided in this comparative example is as follows:

[0059] The waste ternary cathode active material stripped from the electrode sheet was subjected to ICP testing to obtain the Li / (Ni+Co+Mn) value of the waste ternary powder. After mixing with lithium hydroxide, which requires an additional lithium replenishment amount of 1.05 as designed, the mixture was sintered at low pressure and high temperature to form a ternary cathode material. The sintering conditions included -150 MPa, 800 °C, and 10 h.

[0060] Comparative Example 3: The preparation method of the cathode material provided in this comparative example is as follows:

[0061] The waste ternary cathode active material stripped from the electrode sheet and 2000ppm lithium niobate were stirred in a high-speed mixer at 800r / min for 10min, sintered at 800℃ for 4h at -150Mpa, and then cooled to obtain the recycled ternary material.

[0062] Comparative Example 4: The preparation method of the cathode material provided in this comparative example is as follows:

[0063] The pre-lithiated ternary cathode powder prepared in Example 1 was sintered at 800°C for 4 hours at -150 MPa, and the recycled ternary material was obtained after cooling. That is, no flux was added.

[0064] Comparative Example 5: The preparation method of the cathode material provided in this comparative example is as follows:

[0065] Lithium hydroxide monohydrate was dissolved in ethanol at a ratio of 1 g / 100 mL to prepare an ethanol solution of lithium hydroxide; then, the surface-high carbonated ternary cathode powder of Example 1 S1 was added to obtain pre-lithiated ternary cathode powder; and the conditions and steps of Example 1 S3 were used to form a recycled ternary material.

[0066] Experimental Example

[0067] The ternary cathode materials of Examples 1-2 and Comparative Examples 1-5 were tested to determine their discharge specific capacity (4.45V, 0.5C, mAh / g) and capacity retention rate (%) after 100 cycles.

[0068] The testing method was as follows: The obtained recycled ternary material, carbon black, and polyvinylidene fluoride (PVDF) were mixed uniformly at a mass ratio of 94:3:3. N-methyl-2-pyrrolidone (NMP) was added, and the mixture was ground into a uniform slurry. This slurry was then coated onto aluminum foil and placed in a vacuum drying oven at 120℃ for 12 hours to form the positive electrode of a button cell. A lithium metal sheet was used as the negative electrode, and 1M lithium hexafluorophosphate was used as the electrolyte to form a CR2025 button cell. The specific capacity of the button cell at 0.5C and the capacity retention after 100 cycles at 45℃ were obtained by exporting data from the LANDdt testing software. The results are shown in Table 1.

[0069] Table 1 Test Results

[0070]

[0071]

[0072] As shown in Table 1 above, the waste ternary material powder in Comparative Example 1 has low discharge capacity and poor cycle performance. In Comparative Example 2, conventional long-term high-temperature lithium-added sintering only slightly improves its electrical performance and cannot effectively improve it. In Comparative Examples 3-4, the steps of the present invention are broken down. Although Comparative Example 4 can significantly improve the electrical performance compared to the other comparative examples, it is far less effective than that of Examples 1-3. In Comparative Example 5, replacing S2 with a low-carbon chain alcohol (ethanol) in the present invention results in poor improvement. The above data comparison shows that the steps described in the present invention have an effective synergistic effect on improving the electrical performance of waste ternary material powder, which can significantly improve the electrical performance of recycled waste ternary materials. Moreover, the raw material cost is low, the high-temperature sintering time is short, and it has universality and high efficiency.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance recycled ternary material, characterized in that, include: Waste ternary cathode active materials are pretreated to form ternary cathode powder with highly carbonated surface; A lithium source and a long-chain carbon alcohol are mixed to form starch-based lithium; the starch-based lithium is mixed with the ternary cathode powder with a highly carbonized surface to form a pre-lithiated ternary cathode powder, wherein the long-chain carbon alcohol is selected from alcohols with more than 5 carbon atoms; The pre-lithiated ternary cathode powder and flux are mixed and sintered. The pretreatment is as follows: the waste ternary cathode active material is stirred in a supersaturated carbon dioxide aqueous solution and then air-dried; Alternatively, the pretreatment can be supercritical extraction, wherein the extraction pressure is 15-30 MPa, the extraction temperature is 30-60℃, the extraction time is 1-2 h, and the extraction gas is carbon dioxide.

2. The method for preparing high-performance recycled ternary materials according to claim 1, characterized in that, The long-chain alcohol is a monohydric alcohol.

3. The method for preparing high-performance recycled ternary materials according to claim 1, characterized in that, The long-chain carbon alcohol is a monohydroxy alcohol.

4. The method for preparing high-performance recycled ternary materials according to claim 1, characterized in that, The structural formula of the long-chain alcohol is shown below: 1-C n H (2n+1) OH, where n≥5.

5. The method for preparing high-performance recycled ternary materials according to claim 1, characterized in that, The long-chain alcohol is n-octanol.

6. The method for preparing high-performance recycled ternary materials according to claim 1, characterized in that, The lithium source is selected from lithium hydroxide.

7. The method for preparing high-performance recycled ternary materials according to claim 1, characterized in that, 1-5g of lithium source corresponds to 100mL of the long-chain alcohol.

8. The method for preparing high-performance recycled ternary materials according to any one of claims 1-7, characterized in that, include: The starch-based lithium is mixed and stirred with the highly carbonized ternary cathode powder, and then filtered and dried to form the pre-lithiated ternary cathode powder.

9. The method for preparing high-performance recycled ternary materials according to claim 1, characterized in that, The flux is selected from one or more combinations of lithium niobate, lithium phosphate, strontium nitrate, strontium oxide, strontium hydroxide, and barium nitrate.

10. The method for preparing high-performance recycled ternary materials according to claim 1, characterized in that, The flux lithium niobate.

11. The method for preparing high-performance recycled ternary materials according to claim 1 or 9, characterized in that, The amount of flux used is 500-5000 ppm.

12. The method for preparing high-performance recycled ternary materials according to claim 1 or 9, characterized in that, Sintering includes negative pressure high-temperature sintering.

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