Method for directly repairing failed lithium nickel cobalt manganese oxide cathode material by carbon reduction and application

Abstract

The application discloses a method and application for directly repairing failed lithium nickel cobalt manganese oxide positive materials through carbon reduction, and belongs to the technical field of lithium ion batteries. The preparation method provided by the application comprises the following steps: (1) mixing a mixture containing failed lithium nickel cobalt manganese oxide, a lithium source and a carbon source to form a uniform mixture; (2) placing the mixture in an inert gas atmosphere and heating to obtain a precursor; and (3) continuing to place the precursor in an air atmosphere and heating to obtain a perfect lithium nickel cobalt manganese oxide positive material after the repair is completed. The preparation method provided by the application is simple, and the repaired lithium nickel cobalt manganese oxide has good high-pressure cycle performance and excellent rate performance.

Description

Technical Field

[0001] This application relates to a method and application for directly repairing failed lithium nickel cobalt manganese oxide cathode materials through carbon reduction, which belongs to the field of lithium-ion batteries. Background Technology

[0002] Currently, the contradiction between rapidly growing energy demand and limited fossil fuel reserves is becoming increasingly prominent. In this context, energy storage has been elevated to a crucial strategic position because it can compensate for the discontinuity and instability of renewable energy sources such as solar and wind power. Consequently, the production scale of lithium-ion batteries, as the most mainstream electrochemical energy storage technology, has seen significant growth in recent years. Considering the limited cycle life of lithium-ion batteries, it is foreseeable that the retirement of lithium-ion batteries will increase rapidly in the coming years. On the one hand, these waste lithium-ion batteries contain large amounts of heavy metals and organic solvents, which, if not properly disposed of, will cause serious environmental pollution. On the other hand, recycling the high-value components from waste lithium-ion batteries may bring economic benefits. Therefore, the recycling and reuse of waste lithium-ion batteries is gradually becoming a key link in the entire lithium-ion battery industry chain.

[0003] Given that cathode materials account for the highest cost (approximately 25%-35%) in lithium-ion batteries, and that heavy metals are primarily found in the cathode, the regeneration of the cathode through degradation is considered the most valuable step in LIBS recycling. Currently available cathode materials mainly include lithium nickel cobalt manganese oxide (NCM), lithium cobalt oxide (LCO), and lithium iron phosphate (LFP). Among these, lithium nickel cobalt manganese oxide is widely used in various power batteries due to its balance between cost and capacity.

[0004] However, traditional hydrometallurgical or pyrometallurgical methods for recovering lithium nickel cobalt manganese oxide (NCO) not only generate severe pollution and have relatively high energy consumption, but also contain relatively low-value nickel and manganese elements, making the costs disproportionate to the expenses incurred in the pyrometallurgical or hydrometallurgical processes. Therefore, there is an urgent need to find a method that is low in energy consumption, low in pollution, highly efficient, and has good recovery results for recovering spent NCO cathodes. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a method for directly repairing failed lithium nickel cobalt manganese oxide cathode materials via carbon reduction. This method directly repairs failed lithium nickel cobalt manganese oxide cathode materials through a simple preparation method, using carbon reduction to provide the repair impetus. This reduces repair time while forming a high-voltage resistant layer in situ on the surface, improving the high-voltage electrochemical performance of the repaired material, thereby promoting its commercial development.

[0006] According to one aspect of this application, a method for directly repairing lithium nickel cobalt manganese oxide cathode materials by carbon reduction is provided, comprising the following steps:

[0007] The spent lithium nickel cobalt manganese oxide, lithium source, and carbon source are mixed and subjected to heat treatment I under an inactive gas atmosphere, followed by heat treatment II under an oxidizing atmosphere to obtain the lithium nickel cobalt manganese oxide cathode material.

[0008] The lithium source is selected from at least one of lithium sulfate, lithium carbonate, lithium hydroxide, lithium nitrate, lithium chloride, lithium fluoride, and lithium bromide;

[0009] The carbon source is selected from at least one of graphite, carbon black, graphene, activated carbon, and carbon nanotubes;

[0010] The degraded nickel cobalt manganese oxide lithium is selected from at least one of degraded NCM111, degraded NCM523, degraded NCM433, degraded NCM622, degraded NCM811 and degraded NCM900.

[0011] The molar ratio of the failed lithium nickel cobalt manganese oxide to the lithium source is 10:1 to 10;

[0012] The mass ratio of the failed lithium nickel cobalt manganese oxide to the carbon source is 92-98:1-4;

[0013] The molar amount of failed lithium nickel cobalt manganese oxide is expressed as the molar amount of lithium nickel manganese oxide.

[0014] The molar amount of the lithium source is expressed in terms of the molar amount of lithium element.

[0015] The mixing process is selected from at least one of grinding, ball milling, high-energy ball milling, vibration mixing, sieving mixing, and stirring mixing;

[0016] The mixing time is 5 to 60 minutes.

[0017] The inactive gas atmosphere is selected from at least one of nitrogen atmosphere, carbon dioxide atmosphere, and inert gas atmosphere.

[0018] The temperature of the heat treatment I is 200–600°C;

[0019] Optionally, the temperature of the heat treatment I is independently selected from any value of 200°C, 300°C, 400°C, 500°C, 600°C, or a range between any two.

[0020] The heat treatment I lasts for 0.5 to 3 hours.

[0021] Optionally, the duration of the heat treatment I is independently selected from any value among 0.5h, 1h, 1.5h, 2h, 2.5h, and 3h, or a range between any two.

[0022] The oxidizing atmosphere is selected from air and / or oxygen atmosphere.

[0023] The temperature of the heat treatment II is 750–900°C;

[0024] Optionally, the temperature of the heat treatment II is independently selected from any value of 750°C, 800°C, 850°C, 900°C, or a range between any two.

[0025] The duration of the heat treatment II is 2 to 6 hours.

[0026] Optionally, the duration of the heat treatment II is independently selected from any value of 2h, 3h, 4h, 5h, 6h, or a range between any two.

[0027] According to another aspect of this application, a lithium nickel cobalt manganese oxide cathode material obtained by the above method is provided.

[0028] According to another aspect of this application, an application of the above-mentioned lithium nickel cobalt manganese oxide cathode material is provided for use in lithium-ion batteries.

[0029] The beneficial effects that this application can produce include:

[0030] (1) This application reduces the high-temperature repair time of failed lithium nickel cobalt manganese oxide by adjusting the lithium source, carbon source and type, and improves the high-voltage electrochemical performance of the repaired lithium nickel cobalt manganese oxide, thereby obtaining a lithium nickel cobalt manganese oxide cathode material with excellent electrochemical performance.

[0031] (2) This application uses a solid-phase direct repair method, which provides the repair driving force through carbon reduction. While reducing the repair time, it forms a high-voltage resistant layer in situ on the surface, which can improve the electrochemical performance of the cathode material and reduce the material production cost. At the same time, the preparation method provided by this application is simple, the raw material composition is simple, and it is easy to produce in large quantities. The repaired lithium nickel cobalt manganese oxide has good crystallinity, high working potential, excellent cycle performance and rate performance. Attached Figure Description

[0032] Figure 1 This is a scanning electron microscope image of the repaired lithium nickel cobalt manganese oxide prepared in Example 1 of this application;

[0033] Figure 2 This is a rate performance diagram of the repaired lithium nickel cobalt manganese oxide half-cell prepared in Example 1 of this application;

[0034] Figure 3 This is a graph showing the cycling performance of the carbon-repaired lithium nickel cobalt manganese oxide half-cell prepared in Example 1 of this application at a current density of 2C. Detailed Implementation

[0035] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0036] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0037] Unless otherwise specified, the analytical methods in the embodiments all adopt conventional instrument or equipment settings and conventional analytical methods.

[0038] The following examples and experimental cases used scanning electron microscopy (SEM, JSM-7900F) to analyze the morphology of the samples; X-ray diffraction (XRD, SmartLab) to analyze the composition of the samples; and a LAND CT3001A battery system (Wuhan Landian Electronics Co., Ltd.) to test the electrochemical performance. Room temperature in the following examples refers to "25°C".

[0039] Example 1

[0040] The molar ratios of lithium, nickel, cobalt, and manganese in the degraded lithium nickel cobalt manganese oxide used were 0.712:0.36:0.33:0.31. The molar ratio of lithium nickel manganese oxide to lithium in the degraded lithium nickel cobalt manganese oxide and lithium source was 1:0.676, and the mass ratio of degraded lithium nickel cobalt manganese oxide to carbon source was 92:4. 0.2346 g of degraded lithium nickel cobalt manganese oxide, 0.0703 g of lithium hydroxide, and 0.0132 g of graphite were manually ground and mixed for 15 min. Then, the sample was heat-treated under an argon atmosphere using a segmented heating method. First, it was heated to 400℃ and held for 1 h. Then, the atmosphere was switched to oxygen and the sample was heated to 850℃ and held for 4 h. The final product was the repaired lithium nickel cobalt manganese oxide.

[0041] Example 2

[0042] A method for preparing a repaired lithium nickel cobalt manganese oxide cathode material is described in Example 1, except that the lithium source is lithium carbonate.

[0043] Example 3

[0044] A method for preparing a repaired lithium nickel cobalt manganese oxide cathode material is described in Example 1, except that the lithium source is lithium nitrate.

[0045] Example 4

[0046] A method for preparing a repaired lithium nickel cobalt manganese oxide cathode material is described in Example 1, except that the carbon source is carbon black.

[0047] Example 5

[0048] A method for preparing a repaired lithium nickel cobalt manganese oxide cathode material is described in Example 1, except that the carbon source is graphene.

[0049] Experimental Example 1

[0050] Taking Example 1 as an example, the repaired lithium nickel cobalt manganese oxide prepared therefrom was subjected to SEM analysis, XRD analysis, and electrochemical performance testing:

[0051] SEM analysis results are as follows: Figure 1 As shown. (Through) Figure 1 The scanning electron microscope (SEM) images show that the prepared repaired lithium nickel cobalt manganese oxide has a distinct granular structure.

[0052] The repaired lithium nickel cobalt manganese oxide prepared in Example 1 was used as the positive electrode of a lithium-ion battery, forming a half-cell with a lithium metal negative electrode. The electrochemical performance of the prepared repaired lithium nickel cobalt manganese oxide positive electrode material was tested. The results are as follows: Figure 2 and Figure 3 As shown. (Through) Figure 3 Rate testing shows that the electrode material can provide reversible capacities of 181.10, 173.34, 165.44, 155.06, 147.31, and 135.65 mAh·g at 0.2, 0.5, 1, 2, 3, and 5C in the voltage range of 3-4.6V. -1 .pass Figure 3 Cyclic testing shows that, at a current density of 2C, the prepared repaired lithium nickel cobalt manganese oxide electrode still retains a capacity of 138.9 mAh·g after 100 cycles. -1 It has a capacity retention rate of 91.8% and exhibits excellent cycle stability.

[0053] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for directly repairing lithium nickel cobalt manganese oxide cathode materials via carbon reduction, characterized in that, Includes the following steps: The spent lithium nickel cobalt manganese oxide, lithium source, and carbon source are mixed and subjected to heat treatment I under an inactive gas atmosphere, followed by heat treatment II under an oxidizing atmosphere to obtain the lithium nickel cobalt manganese oxide cathode material.

2. The method according to claim 1, characterized in that, The lithium source is selected from at least one of lithium sulfate, lithium carbonate, lithium hydroxide, lithium nitrate, lithium chloride, lithium fluoride, and lithium bromide; The carbon source is selected from at least one of graphite, carbon black, graphene, activated carbon, and carbon nanotubes; The degraded nickel cobalt manganese oxide lithium is selected from at least one of degraded NCM111, degraded NCM523, degraded NCM433, degraded NCM622, degraded NCM811 and degraded NCM900.

3. The method according to claim 1, characterized in that, The molar ratio of the failed lithium nickel cobalt manganese oxide to the lithium source is 10:1 to 10; The mass ratio of the failed lithium nickel cobalt manganese oxide to the carbon source is 92-98:1-4; The molar amount of failed lithium nickel cobalt manganese oxide is expressed as the molar amount of lithium nickel manganese oxide. The molar amount of the lithium source is expressed in terms of the molar amount of lithium element.

4. The method according to claim 1, characterized in that, The mixing process is selected from at least one of grinding, ball milling, high-energy ball milling, vibration mixing, sieving mixing, and stirring mixing; The mixing time is 5 to 60 minutes.

5. The method according to claim 1, characterized in that, The inactive gas atmosphere is selected from at least one of nitrogen atmosphere, carbon dioxide atmosphere, and inert gas atmosphere.

6. The method according to claim 1, characterized in that, The temperature of the heat treatment I is 200–600°C; The heat treatment I lasts for 0.5 to 3 hours.

7. The method according to claim 1, characterized in that, The oxidizing atmosphere is selected from air and / or oxygen atmosphere.

8. The method according to claim 1, characterized in that, The temperature of the heat treatment II is 750–900°C; The duration of the heat treatment II is 2 to 6 hours.

9. A lithium nickel cobalt manganese oxide cathode material obtained by the method according to any one of claims 1 to 8.

10. An application of the lithium nickel cobalt manganese oxide cathode material according to claim 9, characterized in that, Used in lithium-ion batteries.

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