Method for separating positive electrode active material and substrate of lithium battery

Abstract

The invention discloses a method for separating a lithium battery positive electrode active material from a substrate, which comprises the following steps: S1, carrying out leaching treatment on a waste lithium battery positive plate by using a decomposable organic acid to obtain a mixture of positive electrode powder and aluminum foil; s2, washing and filtering the mixture obtained in the step S1 to obtain a filtrate and a cleaned mixture; s3, the cleaned mixture obtained in the step S2 is dried, and the dried mixture is obtained; and S4, mechanically screening the dried material obtained in the step S3, so that the positive electrode powder is completely separated from the aluminum foil, and then classifying and recycling the positive electrode powder and the aluminum foil. The method can quickly and efficiently realize separation of the positive electrode powder and the aluminum foil, does not change the molecular structure of the positive electrode material in the positive electrode powder, and reduces the material loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste lithium battery recycling and treatment, and in particular relates to a method for separating a lithium battery positive electrode active material and a substrate. Background Art

[0002] With the global development of electrification, new energy sources are experiencing explosive growth worldwide. The resulting waste lithium batteries contain a large amount of precious metals and toxic substances. Failure to properly dispose of waste lithium batteries will not only result in a waste of resources but also cause serious environmental pollution. Lithium battery cathodes contain a variety of high-value metals and are the most valuable component in lithium batteries. Clean, efficient, and high-quality separation and recovery of the active materials in waste lithium battery cathodes from the substrate is a key component in the recycling of waste lithium-ion power batteries.

[0003] Patent CN 219168518 U uses a plate crushing method to process positive electrode sheets. Patents CN 112599877 B, CN 114473769 A, and CN 215541461 U use mechanical grinding to separate active material from aluminum foil. Patent CN 116216674 A uses acid leaching to separate materials from positive electrode sheets, and patent CN 115863813 A uses high-temperature plasma technology to recover positive electrode materials for lithium iron manganese phosphate batteries. Patents CN 114639887 A, CN 110767956 A, and CN 116177516 A use organic solvent immersion to separate the material from the current collector. However, mechanical stripping methods struggle to completely separate the materials, making subsequent impurity removal difficult. High-temperature heat treatment consumes a lot of energy and generates a large amount of waste gas. Acid leaching and alkaline leaching also present complex processes, low recovery rates, and difficult wastewater disposal. Some organic solvents are toxic and expensive, resulting in high costs. Summary of the Invention

[0004] Technical problems to be solved: In response to the above technical problems, the present invention provides a method for separating lithium battery positive electrode active materials from a substrate, which can effectively solve the problems existing in the recycling process of the above lithium battery positive electrode sheets, such as incomplete separation, low recovery rate, high impurities, poor grade, serious pollution, and high processing costs.

[0005] Technical solution: A method for separating a lithium battery positive electrode active material from a substrate, comprising the following steps: S1. Leaching waste lithium battery positive electrode sheets with a decomposable organic acid to obtain a mixture of positive electrode powder and aluminum foil; S2. Washing and filtering the mixture obtained in step S1 to obtain a filtrate and a washed mixture; S3, drying the cleaned mixture obtained in step S2 to obtain a dried mixture; S4. Mechanically screen the dried material obtained in step S3 to completely separate the positive electrode powder from the aluminum foil, and then classify and recycle them.

[0006] Preferably, the organic acid is one or more of citric acid, formic acid, acetic acid, and aspartic acid.

[0007] Preferably, the temperature of the leaching treatment in step S1 is 50-80° C., and the concentration of the organic acid is 0.1 mol / L-1 mol / L.

[0008] Preferably, in step S1, bubbling or ultrasonic vibration is used to promote the separation of the positive electrode active material and the aluminum foil during the leaching treatment. The bubbling input pressure is 0.6-1.0 MPa, the ultrasonic vibration power is 2 KW-5 KW, and the ultrasonic vibration frequency is 28 KHz or 40 KHz.

[0009] Preferably, the equipment used for washing in step S2 is a cylindrical screen or a spray cleaning equipment, and the filtrate is returned to the leaching treatment step for recycling.

[0010] Preferably, the mechanical screening equipment in step S4 is a linear screen, a vibrating circular screen or an air separator.

[0011] Beneficial effects: In the method of the present invention, the degradable organic solvent reacts with the adhesion interface between the positive electrode powder and the aluminum foil during the leaching process. Combined with the auxiliary effect of bubbling or ultrasonic vibration, the positive electrode powder and the aluminum foil can be separated quickly and efficiently without changing the molecular structure of the positive electrode material in the positive electrode powder, thereby reducing material loss. The organic solvents used in the present invention are all decomposable organic solvents, which are easy to obtain, widely available, low in price, small in amount, low in overall composition, and easy to decompose, environmentally friendly, and less polluting; The mechanical equipment used in the separation process are all general equipment, widely available and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a process flow chart of a method for separating a positive electrode active material and a substrate of a lithium battery according to the present invention; Figure 2 This is a photo of the positive electrode sheet of the lithium iron phosphate battery of Example 1 of the present invention before separation; Figure 3 This is a photo of the positive electrode sheet of the lithium iron phosphate battery after separation in Example 1 of the present invention; Figure 4 This is a photo of the positive electrode sheet of the lithium iron phosphate battery after separation in Example 2 of the present invention; Figure 5 This is a photo of the positive electrode sheet of the lithium iron phosphate battery after separation in Example 3 of the present invention. DETAILED DESCRIPTION

[0013] The present invention is described in detail below in conjunction with specific embodiments: like Figure 1 As shown, a method for separating a positive electrode active material of a lithium battery from a substrate comprises the following steps: S1. Leaching waste lithium battery positive electrode sheets with a decomposable organic solvent to obtain a mixture of positive electrode powder and aluminum foil; S2. Washing and filtering the mixture obtained in step S1 to obtain a filtrate and a washed mixture; S3, drying the cleaned mixture obtained in step S2 to obtain a dried mixture; S4. Mechanically screen the dried material obtained in step S3 to completely separate the positive electrode powder from the aluminum foil, and then classify and recycle them. Example 1

[0014] Photos of lithium iron phosphate battery positive electrode before separation Figure 2 As shown, 200g of waste lithium iron phosphate battery positive electrode sheets were leached with 1L of 0.1mol / L citric acid solution at a leaching temperature of 60°C, a leaching time of 15min, and a bubbling pressure of 0.6Mpa. After the leaching was completed, a leachate and a mixture were obtained; the mixture was washed twice with distilled water and filtered, and the filtrate was returned to the leaching treatment step; the washed mixture was dried at 200°C-220°C for 10min to obtain a dried positive electrode powder and aluminum foil mixture, which was vibrated and sieved on a linear sieve to obtain clean, high-grade positive electrode powder and bright aluminum foil, as shown in FIG. Figure 3 shown. Example 2

[0015] 200g of waste lithium iron phosphate battery positive electrode sheets were leached with 1L of 0.1mol / L formic acid solution at 80°C, 10min, and 0.6MPa bubbling pressure. After leaching, a leachate and a mixture were obtained. The mixture was washed twice with distilled water and filtered, and the filtrate was returned to the leaching step. The washed mixture was dried at 200-220°C for 10min to obtain a dried positive electrode powder and aluminum foil mixture. After vibrating and screening on a linear sieve, clean, high-grade positive electrode powder and bright aluminum foil were obtained. Figure 4 shown. Example 3

[0016] 400g of waste lithium iron phosphate battery positive electrode sheets were leached with 1L of 0.2mol / L citric acid solution at 60°C, 20min, and 0.6MPa of bubbling pressure. After leaching, a leachate and a mixture were obtained. The mixture was washed twice with distilled water and filtered, and the filtrate was returned to the leaching step. The washed mixture was dried at 200-220°C for 10min to obtain a dried positive electrode powder and aluminum foil mixture. After vibrating and screening on a linear sieve, clean, high-grade positive electrode powder and bright aluminum foil were obtained. Figure 5 shown.

[0017] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for separating a positive electrode active material of a lithium battery from a substrate, characterized in that: The following steps are involved: S1. Leaching waste lithium battery positive electrode sheets with a decomposable organic acid to obtain a mixture of positive electrode powder and aluminum foil; S2. Washing and filtering the mixture obtained in step S1 to obtain a filtrate and a washed mixture; S3, drying the cleaned mixture obtained in step S2 to obtain a dried mixture; S4. Mechanically screen the dried material obtained in step S3 to completely separate the positive electrode powder from the aluminum foil, and then classify and recycle them.

2. The method for separating a positive electrode active material of a lithium battery from a substrate according to claim 1, wherein: The organic acid is one or more of citric acid, formic acid, acetic acid and aspartic acid.

3. The method for separating a positive electrode active material and a substrate of a lithium battery according to claim 1, wherein: The temperature of the leaching treatment in step S1 is 50-80° C., and the concentration of the organic acid is 0.1 mol / L-1 mol / L.

4. The method for separating a positive electrode active material and a substrate of a lithium battery according to claim 1, wherein: In step S1, bubbling or ultrasonic vibration is used to promote the separation of the positive electrode active material and the aluminum foil during the leaching treatment. The bubbling input pressure is 0.6-1.0 MPa, the ultrasonic vibration power is 2 KW-5 KW, and the ultrasonic vibration frequency is 28 KHz or 40 KHz.

5. The method for separating a positive electrode active material and a substrate of a lithium battery according to claim 1, wherein: The equipment used for washing in step S2 is a cylindrical screen or a spray cleaning device, and the filtrate is returned to the leaching treatment step for recycling.

6. The method for separating a positive electrode active material and a substrate of a lithium battery according to claim 1, wherein: The mechanical screening equipment in step S4 is a linear screen, a vibrating circular screen or an air separator.

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