Recycling method of waste secondary battery

Abstract

The invention relates to the technical field of waste secondary battery recovery, in particular to a waste secondary battery recovery treatment method, and aims to solve the problems of complex process, high cost, low recovery rate and purity of different materials, poor separation precision and the like in the waste secondary battery recovery treatment method in the related technology. And the resource effective utilization of the waste secondary battery can be conveniently realized. The invention relates to a waste secondary battery recovery processing method, which comprises: disassembling and crushing a waste secondary battery, and sorting out a mixed material of positive and negative pole pieces; performing color sorting on the positive plate and the negative plate in the mixed material; grinding and crushing the positive plate in a first grinding mode to dissociate the positive active material and the positive current collector, and reselecting the dissociated material; and grinding and crushing the negative electrode plate in a second grinding mode to dissociate the negative electrode active material and the negative electrode current collector, and carrying out flotation on the dissociated material.

Description

Technical Field

[0001] The present application relates to the technical field of waste secondary battery recycling, and in particular to a waste secondary battery recycling method. Background Art

[0002] At present, waste secondary batteries have not been properly handled, and most of them are idle or landfilled in landfills. Waste secondary batteries usually contain a large amount of metal elements and toxic and harmful substances, such as lithium, copper, aluminum, iron and other metal elements and harmful substances such as electrolytes. If they are not recycled, it will cause a large amount of resource waste and cause environmental pollution.

[0003] The recycling of used secondary batteries is currently a hot topic of concern, and is mainly achieved through gravity separation, color separation, magnetic separation, air separation and screening. However, the current recycling process of used secondary batteries has problems such as complex process, high cost, low recovery rate and purity of different materials, and poor separation accuracy, which is not conducive to the effective utilization of used secondary batteries as resources. Summary of the invention

[0004] Based on this, some embodiments of the present application provide a method for recycling and processing waste secondary batteries to solve the problems of complex process, high cost, low recovery rate and purity of different materials, poor separation accuracy, etc. in the recycling and processing methods of waste secondary batteries in related technologies, so as to facilitate the effective resource utilization of waste secondary batteries.

[0005] In a first aspect, a method for recycling waste secondary batteries is provided, comprising:

[0006] Dismantle and crush the waste secondary batteries in a protective atmosphere or vacuum environment;

[0007] Through wind separation and magnetic separation, the mixed materials of positive and negative electrode sheets are sorted out from the broken battery fragments;

[0008] Separate the positive and negative electrode sheets in the mixed material by color sorting;

[0009] Grinding and crushing the separated positive electrode sheet by a first grinding method, so that the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet are dissociated;

[0010] Reselecting the dissociated positive electrode active material and positive electrode current collector by using density difference to obtain positive electrode active material and positive electrode current collector;

[0011] Grinding and crushing the separated negative electrode sheet by a second grinding method, so that the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet are dissociated;

[0012] The dissociated negative electrode active material and negative electrode current collector are floated by utilizing the hydrophilic and hydrophobic differences to obtain the negative electrode active material and the negative electrode current collector.

[0013] By first color-sorting the positive and negative electrode sheets, and then using gravity to sort the positive electrode collector and the positive electrode active material, and using flotation to sort the negative electrode collector and the negative electrode active material, the color difference between the positive and negative electrode sheets themselves can be used to quickly separate the positive and negative electrode sheets, and then the property differences of the current collectors and active materials contained in the positive and negative electrode sheets can be used to separate the respective current collectors and active materials, thereby improving the sorting efficiency. When the positive electrode current collector and the positive electrode active material are separated by gravity separation, the first grinding method is used to grind and crush the separated positive electrode sheet, which can promote the dissociation of the positive electrode active material and the positive electrode current collector in the positive electrode sheet, and can increase the density difference between the positive electrode active material and the positive electrode current collector, thereby improving the precision and efficiency of gravity separation; when the negative electrode current collector and the negative electrode active material are separated by flotation separation, the second grinding method is used to grind and crush the separated negative electrode sheet, which can promote the dissociation of the negative electrode active material and the negative electrode current collector in the negative electrode sheet, and can increase the hydrophobicity difference between the negative electrode active material and the negative electrode current collector, thereby improving the precision and efficiency of flotation separation. The problems of complex process, high cost, low recovery rate and purity of different materials, and poor separation accuracy existing in the related art are solved.

[0014] Optionally, the recycling method satisfies at least one of the following conditions:

[0015] (1) The protective atmosphere is an inert gas atmosphere; the inert gas in the inert gas atmosphere may include nitrogen, argon or helium, etc.;

[0016] (2) The diameters of the positive electrode sheet and the negative electrode sheet in the mixed material are independently 1 cm to 4 cm;

[0017] (3) The positive electrode sheet and the negative electrode sheet in the mixed material are in sheet form, and the single-side area of ​​the positive electrode sheet and the negative electrode sheet are independently 1 cm²~4.5 cm².

[0018] The positive electrode sheet and the negative electrode sheet in the mixed material may be regular or irregular sheets, and the diameter of the positive electrode sheet and the negative electrode sheet here may be represented by the maximum size passing through the center of the positive electrode sheet and the negative electrode sheet.

[0019] The single-sided area of ​​the positive electrode sheet and the negative electrode sheet in the mixed material refers to the area of ​​any one side of each sheet located on one side in the thickness direction, which can be used to characterize the size of the positive electrode sheet and the negative electrode sheet in the mixed material.

[0020] The positive electrode sheet and the negative electrode sheet have larger sizes, which can improve the color sorting efficiency and color sorting accuracy.

[0021] Optionally, before the separated positive electrode sheet is ground and crushed by the first grinding method so that the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet are dissociated, the recycling method further includes:

[0022] Adding an organic solvent to the separated positive electrode sheet to prepare a first slurry;

[0023] The separated positive electrode sheet is ground and pulverized by a first grinding method so that the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet are dissociated, including:

[0024] Performing a first ball milling process on the first slurry to dissociate the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet;

[0025] The dissociated positive electrode active material and positive electrode current collector are reselected by using density difference to obtain positive electrode active material and positive electrode current collector, including:

[0026] The dissociated positive electrode active material and positive electrode current collector are sorted by utilizing the density difference between the dissociated positive electrode active material and positive electrode current collector and the centrifugal force to obtain the positive electrode active material and the positive electrode current collector.

[0027] In this embodiment, an organic solvent is added to the separated positive electrode sheet to prepare a first slurry, and a first ball milling treatment is performed. On the one hand, the organic solvent can be used to dissolve the organic binder in the positive electrode sheet, thereby removing the organic binder and reducing the residual organic binder in the subsequent separation material, thereby improving the separation accuracy and purity of the positive electrode active material and the positive electrode collector; on the other hand, the positive electrode active material and the positive electrode collector in the positive electrode sheet can be quickly dissociated, and the particle size of the positive electrode active material and the positive electrode collector can be reduced, and the density difference between the positive electrode active material and the positive electrode collector can be increased, thereby improving the accuracy and efficiency of gravity separation; on the other hand, after the first slurry is prepared, it is convenient to directly centrifuge the dissociated positive electrode active material and the positive electrode collector in the organic solvent, thereby achieving gravity separation of the positive electrode active material and the positive electrode collector.

[0028] Optionally, the recycling method satisfies at least one of the following conditions:

[0029] (1) The organic solvent includes at least one of N-methylpyrrolidone, dimethylacetamide, ethylene glycol and propylene glycol;

[0030] (2) The solid content of the first slurry is 20 wt% to 30 wt%;

[0031] (3) After grinding and crushing, the particle size of the material in the first slurry is 0.01 mm ~ 2 mm;

[0032] (4) The centrifugal force is 300G~500G.

[0033] After grinding and crushing, the particle size of the material in the first slurry is 0.01mm~2mm, which means that the particle size of the material in the first slurry is unevenly distributed, basically normally distributed, with a minimum particle size of 0.01mm and a maximum particle size of 2mm.

[0034] The centrifugal force is 300 G ~500G, where G represents the acceleration due to gravity and is the unit of centrifugal force.

[0035] Optionally, before the separated negative electrode sheet is ground and crushed by the second grinding method so that the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet are dissociated, the recycling method further includes:

[0036] In an air atmosphere, the separated negative electrode sheets are baked to remove the organic binder in the separated negative electrode sheets; and

[0037] Adding cold water to the negative electrode sheet from which the organic binder has been removed to prepare a second slurry; wherein the temperature of the cold water is less than or equal to 10° C.;

[0038] The separated negative electrode sheet is ground and pulverized by a second grinding method so that the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet are dissociated, including:

[0039] The second slurry is subjected to a second ball milling treatment to dissociate the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet, and the second slurry is heated by using the heat generated by the second ball milling treatment to allow air in the second slurry to be adsorbed on the surface of the negative electrode active material to form nanobubbles;

[0040] The dissociated negative electrode active material and negative electrode current collector are floated by utilizing the hydrophilic and hydrophobic differences to obtain the negative electrode active material and the negative electrode current collector, including:

[0041] Under the flotation effect of the nanobubbles, the dissociated negative electrode active material and negative electrode current collector are floated to obtain the negative electrode active material and the negative electrode current collector.

[0042] Among them, the presence of organic binder will affect the adhesion efficiency of nanobubbles on the surface of negative electrode active materials. At the same time, the organic binder will also adhere to the surface of negative electrode active materials and negative electrode current collectors and affect the hydrophilic and hydrophobic properties of the two. Therefore, before the second grinding treatment, the organic binder in the separated negative electrode sheets is removed by first calcining in an air atmosphere. This can reduce the adhesion of organic binder to the surface of negative electrode active materials and negative electrode current collectors and affect the hydrophilic and hydrophobic properties of the two and the adhesion efficiency of nanobubbles on the surface of negative electrode active materials, thereby improving flotation efficiency and accuracy.

[0043] At the same time, compared with other methods such as organic solvent dissolution used in related technologies to remove organic binders in negative electrode sheets, the organic solvent in the negative electrode sheet can be decomposed and removed by roasting, which can reduce resource waste, is simple and efficient, and will not introduce new impurities, which can improve subsequent separation effects.

[0044] Then, by adding cold water to the negative electrode sheet from which the organic binder has been removed, a second slurry is prepared. On the one hand, the cold water can be used to adjust the slurry of the negative electrode sheet from which the organic binder has been removed, and the second ball milling treatment can promote the rapid dissociation of the negative electrode active material and the negative electrode current collector of the negative electrode sheet, while reducing the particle size of the negative electrode active material and the negative electrode current collector, and improving the hydrophilic and hydrophobic difference between the negative electrode active material and the negative electrode current collector, thereby improving the accuracy and efficiency of flotation separation; on the other hand, compared with the water at room temperature such as water at 25°C used in the related art, the cold water can also generate heat during the second ball milling process, thereby heating the second slurry, and then the temperature difference before and after the second slurry is ground can be used to increase the local supersaturation of air in the second slurry, so that the air gathers and adsorbs on the surface of the negative electrode active material in the form of bubbles, and nanobubbles are formed on the surface of the negative electrode active material. With the help of the bridging effect of the nanobubbles, the apparent diameter of the negative electrode active material can be further increased, thereby increasing the collision and adhesion probability of the negative electrode active material and the bubbles, and then the sorting efficiency and sorting accuracy of the negative electrode active material can be further improved.

[0045] In this process, under the flotation effect of nanobubbles, the reagent consumption in the flotation process can be reduced to improve the dispersion efficiency and sorting accuracy, thereby reducing costs. At the same time, the embodiment of the present application uses the heat generated by the second ball milling process to heat the second slurry, and the temperature difference causes the air to be locally supersaturated, thereby forming nanobubbles, without the need to add additional heating steps and equipment, and without the need to fill the second slurry with additional gas, which can achieve effective resource utilization of energy and materials, reduce unnecessary energy and material losses, reduce costs, and improve efficiency.

[0046] Optionally, the recycling method satisfies at least one of the following conditions:

[0047] (1) The calcination temperature is 400℃~600℃ and the calcination time is 1 h~3h;

[0048] (2) The temperature of cold water is 5℃~10℃;

[0049] (3) The solid content of the second slurry is 15wt%~25wt%;

[0050] (4) After grinding and crushing, the particle size of the material in the second slurry is 0.01 mm ~ 2 mm.

[0051] After grinding and crushing, the particle size of the material in the second slurry is 0.01 mm ~ 2 mm, which has the same explanation as the particle size of the material in the first slurry after grinding and crushing, and also means that after grinding and crushing, the minimum particle size of the material in the second slurry can reach 0.01 mm and the maximum particle size can reach 2 mm.

[0052] Optionally, under the flotation effect of nanobubbles, the dissociated negative electrode active material and negative electrode current collector are floated, including:

[0053] adding a flotation frother and a collector to the second slurry, and flotating the dissociated negative electrode active material and the negative electrode current collector in the presence of the flotation frother and the collector;

[0054] Among them, relative to the negative electrode sheet from which the organic binder is removed, the added amount of the flotation frother is 50 g / t ~100 g / t; relative to the negative electrode sheet from which the organic binder is removed, the added amount of the collector is 100 g / t ~300 g / t.

[0055] Among them, the amount of flotation frother added relative to the negative electrode sheet from which the organic binder has been removed is 50 g / t ~100 g / t, which means that the amount of flotation frother added is 50 g ~100 g per ton of the negative electrode sheet from which the organic binder has been removed. The amount of collector added relative to the negative electrode sheet from which the organic binder has been removed is 100 g / t ~300 g / t, which means that the amount of collector added is 100 g ~300 g per ton of the negative electrode sheet from which the organic binder has been removed.

[0056] By adding a small amount of flotation frother and collector, the flotation efficiency and accuracy can be improved.

[0057] Optionally, the positive electrode sheets and the negative electrode sheets in the mixed material are separated by color sorting, including:

[0058] Multi-stage color sorting is used to separate the positive and negative electrodes multiple times;

[0059] Among them, the spectral resolution of the next level of color sorting is higher than the spectral resolution of the previous level of color sorting. Spectral resolution is a parameter used to describe the ability of AI visual color sorters to distinguish wavelengths, and can be used to measure the color resolution ability of AI visual color sorters for different materials. The higher the spectral separation rate, the stronger its color resolution ability, and the more accurately it can detect the colors of different materials, thereby improving the color sorting accuracy. By gradually improving the spectral resolution, the color sorting accuracy can be improved.

[0060] Optionally, before separating the mixed material of positive and negative electrode sheets from the crushed battery fragments by air separation and magnetic separation, the recycling method further comprises:

[0061] The electrolyte in the mixed material is volatilized by heat treatment, and the volatilized material is collected and purified.

[0062] By volatilizing the electrolyte in the mixed material through heat treatment, the adhesion of positive and negative electrodes can be reduced in the subsequent color sorting process, thereby improving the sorting accuracy. At the same time, by collecting and purifying the volatilized materials, waste gas emissions can be reduced, and the electrolyte volatilization and overflow into the air during the subsequent air separation and magnetic separation processes can be avoided to cause pollution.

[0063] Optionally, the temperature of the heat treatment is 100° C. to 200° C. At this temperature, the electrolyte can be prevented from exploding at a higher temperature, and the electrolyte can be completely volatilized to reduce electrolyte residue.

[0064] Optionally, the collection and purification treatment includes: performing dust removal, alkaline washing and activated carbon adsorption treatment on the volatilized materials in sequence. During the volatilization of the electrolyte, the electrolyte will carry the battery black powder dust generated during the heat treatment process. The battery black powder dust can be removed by dust removal to reduce the emission of battery black powder dust. Then, after alkaline washing, the fluoride ions in the electrolyte can be precipitated in a solid form such as CaF2 to reduce the emission of fluoride ions. Finally, through activated carbon adsorption treatment, the volatile harmful gases in the electrolyte can be adsorbed and removed, thereby reducing waste gas emissions.

[0065] Compared with the related art, this application has at least the following beneficial technical effects:

[0066] By first color-sorting the positive and negative electrode sheets, and then using gravity to sort the positive electrode collector and the positive electrode active material, and using flotation to sort the negative electrode collector and the negative electrode active material, the color difference between the positive and negative electrode sheets themselves can be used to quickly separate the positive and negative electrode sheets, and then the property differences of the current collectors and active materials contained in the positive and negative electrode sheets can be used to separate the respective current collectors and active materials, thereby improving the sorting efficiency. When the positive electrode current collector and the positive electrode active material are separated by gravity separation, the first grinding method is used to grind and crush the separated positive electrode sheet, which can promote the dissociation of the positive electrode active material and the positive electrode current collector in the positive electrode sheet, and can increase the density difference between the positive electrode active material and the positive electrode current collector, thereby improving the precision and efficiency of gravity separation; when the negative electrode current collector and the negative electrode active material are separated by flotation separation, the second grinding method is used to grind and crush the separated negative electrode sheet, which can promote the dissociation of the negative electrode active material and the negative electrode current collector in the negative electrode sheet, and can increase the hydrophobicity difference between the negative electrode active material and the negative electrode current collector, thereby improving the precision and efficiency of flotation separation. The problems of complex process, high cost, low recovery rate and purity of different materials, and poor separation accuracy existing in the related art are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 A schematic diagram of a process for recycling and treating waste secondary batteries provided in an embodiment of the present application;

[0068] Figure 2 This is a flow chart of the resource recycling method for waste lithium-ion batteries provided in Example 1 of the present application. DETAILED DESCRIPTION

[0069] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0070] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0071] The present application will be further described in detail below in conjunction with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly understood.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0073] In the present application, "at least one" refers to any one, any two, or any two or more of the listed items.

[0074] In the present application, the terms "combination thereof", "any combination thereof", "any combination thereof" and the like include all suitable combinations of any two or more of the listed items.

[0075] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0076] In the present application, reference to a numerical range includes both endpoints of the numerical range unless otherwise specified.

[0077] In this application, when it comes to percentage concentration, unless otherwise specified, it refers to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of the component.

[0078] In this application, when it comes to temperature parameters, unless otherwise specified, both constant temperature treatment and treatment within a certain temperature range are permitted. The constant temperature treatment allows the temperature to fluctuate within the precision range controlled by the instrument.

[0079] In view of the problems existing in the related technologies such as complex process, high cost, low recovery rate and purity of different materials, poor precision, etc., the specific implementation methods of this application are described as follows:

[0080] Some embodiments of the present application provide a method for recycling waste lithium-ion batteries, such as Figure 1 As shown, the recycling method includes:

[0081] S11. Dismantle and crush the waste secondary batteries in a protective atmosphere or vacuum environment;

[0082] The waste secondary battery can be any rechargeable battery having a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.

[0083] Here, taking the waste secondary battery as a lithium-ion battery as an example, the positive electrode sheet of the lithium-ion battery includes a positive electrode active material, a positive electrode current collector and an organic binder, and the negative electrode sheet includes a negative electrode active material, a negative electrode current collector and an organic binder. Among them, the positive electrode active material is coated on the positive electrode current collector through the organic binder contained in the positive electrode sheet, and the negative electrode active material is coated on the negative electrode current collector through the organic binder contained in the negative electrode sheet. The positive electrode active material may include at least one of lithium manganese oxide, lithium nickel cobalt aluminum oxide and lithium cobalt oxide, and the negative electrode active material may include carbon materials such as graphite. The positive electrode sheet, the negative electrode sheet and the diaphragm are superimposed together through a pressing process to prevent the positive electrode sheet and the negative electrode sheet from short-circuiting. In addition, the lithium-ion battery also includes positive and negative electrode leads, terminal posts and battery casings.

[0084] The above disassembly process may include: disassembling and cutting the waste secondary battery into larger pieces. For example, the shell of the waste secondary battery may be disassembled to expose the internal battery cell components, and then the shell and the battery cell components may be cut into larger pieces by mechanical cutting or hydraulic shearing to facilitate subsequent crushing.

[0085] The above-mentioned crushing can be carried out by a shear crusher, and the positive electrode sheet, the negative electrode sheet, the separator, the terminal post, the battery shell, etc. can be crushed into battery fragments.

[0086] In some embodiments, the protective atmosphere may be an inert gas atmosphere.

[0087] S12, separating the mixed material of positive and negative electrode sheets from the crushed battery fragments by air separation and magnetic separation;

[0088] Among them, the diaphragm, positive electrode sheet, negative electrode sheet, iron parts and plastic shell in the broken battery fragments can be separated by air separation and magnetic separation, so that the mixed material of positive and negative electrode sheets can be sorted out.

[0089] S13, separating the positive electrode sheet and the negative electrode sheet in the mixed material by color sorting;

[0090] Color sorting refers to the use of AI visual color sorters to separate the positive and negative current collectors according to their different colors. The colors of different materials are determined by their absorption and reflection of specific wavelengths of light. Materials of different colors have differences in reflection and absorption of certain specific wavelengths of light. The AI ​​visual color sorter can detect these differences, thereby detecting the colors of different materials and separating them.

[0091] For example, in some embodiments of the present application, one surface of the positive electrode sheet is covered with positive electrode active material, and the other surface presents the color of the positive electrode collector, such as silver-white; one surface of the negative electrode sheet is covered with negative electrode active material, and the other surface presents the color of the negative electrode collector, such as yellow. The reflectivity of the silvery-white positive electrode collector to light of different wavelengths is different from the reflectivity of the yellow negative electrode collector to light of different wavelengths. Therefore, the AI ​​visual color sorter can sort materials of different colors according to the reflection of light within these wavelength ranges, thereby separating positive and negative electrode sheets from each other.

[0092] S14, grinding and crushing the separated positive electrode sheet by a first grinding method, so that the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet are dissociated;

[0093] By grinding and pulverizing the separated positive electrode sheets in the first grinding method, the dissociation of the positive electrode active material and the positive electrode current collector can be accelerated, and the positive electrode active material and the positive electrode current collector can be further broken up to increase the density difference between the positive electrode active material and the positive electrode current collector during subsequent reselection.

[0094] S15, reselecting the dissociated positive electrode active material and positive electrode current collector by using density difference to obtain a positive electrode active material and a positive electrode current collector;

[0095] Among them, by utilizing the characteristics that the density of the positive electrode active material is relatively large and the density of the positive electrode current collector is relatively small, the positive electrode active material and the positive electrode current collector can be obtained by reselection using the density difference.

[0096] S16, grinding and crushing the separated negative electrode sheet by a second grinding method, so that the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet are dissociated;

[0097] Grinding and crushing the separated negative electrode sheets by the second grinding method can accelerate the dissociation of the negative electrode active material and the negative electrode current collector, and can further break up the negative electrode active material and the negative electrode current collector, thereby improving the hydrophilic and hydrophobic difference between the negative electrode active material and the negative electrode current collector during subsequent flotation.

[0098] S17, flotation separation is performed on the dissociated negative electrode active material and negative electrode current collector by utilizing the hydrophilic and hydrophobic differences to obtain the negative electrode active material and the negative electrode current collector.

[0099] In the recycling method of waste secondary batteries provided in the embodiment of the present application, by first color-sorting the positive and negative electrodes, and then using gravity to sort the positive current collector and the positive active material, and using flotation to sort the negative current collector and the negative active material, the positive and negative electrodes can be quickly separated by using the color difference between the positive and negative electrodes, and then the property difference between the current collector and the active material contained in the positive and negative electrodes can be used to separate the current collector and the active material, respectively, so as to improve the sorting efficiency. When using gravity to sort the positive current collector and the positive active material, using

[0100] The first grinding method grinds and crushes the separated positive electrode sheet, which can promote the dissociation of the positive electrode active material and the positive electrode collector in the positive electrode sheet, and can increase the density difference between the positive electrode active material and the positive electrode collector, thereby improving the accuracy and efficiency of gravity separation; while when flotation is used to separate the negative electrode collector and the negative electrode active material, the second grinding method is used to grind and crush the separated negative electrode sheet, which can promote the dissociation of the negative electrode active material and the negative electrode collector in the negative electrode sheet, and can increase the hydrophobicity difference between the negative electrode active material and the negative electrode collector, thereby improving the accuracy and efficiency of flotation separation. This solves the problems of complex process, high cost, low recovery rate and purity of different materials, and poor separation accuracy in related technologies.

[0101] In some embodiments, in the above S11, the protective atmosphere may be an inert gas atmosphere, and the inert gas in the inert gas atmosphere may include nitrogen, argon, helium, etc.

[0102] There is no specific limitation on the size of the positive electrode sheet and the negative electrode sheet in the mixed material in S12, as long as the two can be separated by color sorting.

[0103] In some embodiments, in S12, the diameters of the positive electrode sheet and the negative electrode sheet in the mixed material are independently 1 cm to 4 cm.

[0104] The positive electrode sheet and the negative electrode sheet here can be of regular shape or irregular shape. Regardless of whether the positive electrode sheet and the negative electrode sheet are of regular shape or irregular shape, the positive electrode sheet and the negative electrode sheet can both be sheets with a certain shape, and the sheet diameter of the positive electrode sheet and the negative electrode sheet can be expressed by the maximum dimension passing through the center of the positive electrode sheet and the negative electrode sheet.

[0105] In these embodiments, the positive electrode sheet and the negative electrode sheet have larger sizes to facilitate color sorting and separation.

[0106] In some embodiments, the positive electrode sheet and the negative electrode sheet may be rectangular, and the lengths of two mutually perpendicular sides of the rectangle are independently 1 cm to 3 cm.

[0107] In some embodiments, in S12, the positive electrode sheet and the negative electrode sheet in the mixed material are in sheet shape, and the single-side area of ​​the positive electrode sheet and the negative electrode sheet are independently 1 cm²~4.5 cm².

[0108] The single-sided area of ​​the positive electrode sheet and the negative electrode sheet in the mixed material refers to the area of ​​any one side of each sheet located on one side in the thickness direction, which can be used to characterize the size of the positive electrode sheet and the negative electrode sheet in the mixed material.

[0109] In these embodiments, the positive electrode sheets and the negative electrode sheets in the mixed material have larger sizes, which are convenient for color sorting and separation.

[0110] In some embodiments, S13, separating the positive electrode sheet and the negative electrode sheet in the mixed material by color sorting, comprises:

[0111] Multi-level color sorting is used to separate the positive electrode sheets and the negative electrode sheets multiple times; wherein the spectral resolution of the next level of color sorting is higher than the spectral resolution of the previous level of color sorting.

[0112] Spectral resolution is a parameter used to describe the ability of AI visual color sorters to distinguish wavelengths, and can be used to measure the color resolution ability of AI visual color sorters for different materials. The higher the spectral separation rate, the stronger its color resolution ability, and the more accurately it can detect the colors of different materials, thereby improving color sorting accuracy.

[0113] In these embodiments, the color sorting accuracy can be improved by gradually improving the spectral resolution.

[0114] In some embodiments, before S14, the separated positive electrode sheet is ground and crushed by a first grinding method so that the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet are dissociated, the recycling method further includes:

[0115] Adding an organic solvent to the separated positive electrode sheet to prepare a first slurry;

[0116] S14, grinding and crushing the separated positive electrode sheet by a first grinding method, so that the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet are dissociated, including:

[0117] Performing a first ball milling process on the first slurry to dissociate the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet;

[0118] S15, reselecting the dissociated positive electrode active material and positive electrode current collector by using density difference to obtain positive electrode active material and positive electrode current collector, including:

[0119] The dissociated positive electrode active material and positive electrode current collector are sorted by utilizing the density difference between the dissociated positive electrode active material and positive electrode current collector and the centrifugal force to obtain the positive electrode active material and the positive electrode current collector.

[0120] In these embodiments, an organic solvent is added to the separated positive electrode sheet to prepare a first slurry, and a first ball milling treatment is performed. On the one hand, the organic solvent can be used to dissolve the organic binder in the positive electrode sheet, thereby removing the organic binder and reducing the residual organic binder in the subsequent separation material, thereby improving the separation accuracy and purity of the positive electrode active material and the positive electrode collector; on the other hand, the positive electrode active material and the positive electrode collector in the positive electrode sheet can be rapidly dissociated, and the particle size of the positive electrode active material and the positive electrode collector can be reduced, and the density difference between the positive electrode active material and the positive electrode collector can be increased, thereby improving the accuracy and efficiency of gravity separation; on the other hand, after the first slurry is prepared, it is convenient to directly centrifuge the dissociated positive electrode active material and the positive electrode collector in the organic solvent, thereby achieving gravity separation of the positive electrode active material and the positive electrode collector.

[0121] In some embodiments, the organic solvent may include at least one of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), ethylene glycol, and propylene glycol.

[0122] In these embodiments, the use of these organic solvents can better dissolve the organic binder in the positive electrode sheet, facilitate the gravity separation of the positive electrode active material and the positive electrode current collector, and improve the accuracy of gravity separation.

[0123] In some embodiments, the solid content of the first slurry is 20 wt% to 30 wt%.

[0124] In some embodiments, after grinding and crushing, the particle size of the material in the first slurry is 0.01 mm to 2 mm. Wherein, after grinding and crushing, the particle size of the material in the first slurry is 0.01 mm to 2 mm, which means that the particle size of the material in the first slurry is unevenly distributed, basically normally distributed, with a minimum particle size of 0.01 mm and a maximum particle size of 2 mm.

[0125] In these embodiments, after grinding and pulverizing, the material in the first slurry has a moderate particle size, which is convenient for increasing the density difference between the positive electrode current collector and the positive electrode active material, thereby facilitating separation of the positive electrode current collector and the positive electrode active material by gravity separation.

[0126] In some embodiments, the reselection can be carried out in a centrifugal device, such as a Nelson centrifuge, a jig, a chute or a shaking table, and the centrifugal force is 300G~500G, so as to obtain the light components of the positive electrode current collector and the heavy components of the positive electrode active material.

[0127] Among them, in 300 G ~500G, G represents gravitational acceleration, which is the unit of centrifugal force.

[0128] In some embodiments, before S16, the separated negative electrode sheet is ground and crushed by a second grinding method so that the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet are dissociated, the recycling method further includes:

[0129] In an air atmosphere, the separated negative electrode sheets are baked to remove the organic binder in the separated negative electrode sheets; and

[0130] Adding cold water to the negative electrode sheet from which the organic binder has been removed to prepare a second slurry; wherein the temperature of the cold water is less than or equal to 10° C.;

[0131] S16, grinding and crushing the separated negative electrode sheet by a second grinding method, so that the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet are dissociated, including:

[0132] The second slurry is subjected to a second ball milling treatment to dissociate the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet, and the second slurry is heated by using the heat generated by the second ball milling treatment to allow air in the second slurry to be adsorbed on the surface of the negative electrode active material to form nanobubbles;

[0133] S17, flotation of the dissociated negative electrode active material and negative electrode current collector using hydrophilic and hydrophobic differences to obtain the negative electrode active material and negative electrode current collector, including:

[0134] Under the flotation effect of the nanobubbles, the dissociated negative electrode active material and negative electrode current collector are floated to obtain the negative electrode active material and the negative electrode current collector.

[0135] Among them, the presence of organic binder will affect the adhesion efficiency of nanobubbles on the surface of negative electrode active materials. At the same time, the organic binder will also adhere to the surface of negative electrode active materials and negative electrode current collectors and affect the hydrophilic and hydrophobic properties of the two. Therefore, before the second grinding treatment, the organic binder in the separated negative electrode sheets is removed by first calcining in an air atmosphere. This can reduce the adhesion of organic binder to the surface of negative electrode active materials and negative electrode current collectors and affect the hydrophilic and hydrophobic properties of the two and the adhesion efficiency of nanobubbles on the surface of negative electrode active materials, thereby improving flotation efficiency and accuracy.

[0136] At the same time, compared with other methods such as organic solvent dissolution used in related technologies to remove organic binders in negative electrode sheets, the organic solvent in the negative electrode sheet can be decomposed and removed by roasting, which can reduce resource waste, is simple and efficient, and will not introduce new impurities, which can improve subsequent separation effects.

[0137] Then, by adding cold water to the negative electrode sheet from which the organic binder has been removed, a second slurry is prepared. On the one hand, the cold water can be used to adjust the slurry of the negative electrode sheet from which the organic binder has been removed, and the second ball milling treatment can promote the rapid dissociation of the negative electrode active material and the negative electrode current collector of the negative electrode sheet, while reducing the particle size of the negative electrode active material and the negative electrode current collector, and improving the hydrophilic and hydrophobic difference between the negative electrode active material and the negative electrode current collector, thereby improving the accuracy and efficiency of flotation separation; on the other hand, compared with the water at room temperature such as water at 25°C used in the related art, the cold water can also generate heat during the second ball milling process, thereby heating the second slurry, and then the temperature difference before and after the second slurry is ground can be used to increase the local supersaturation of air in the second slurry, so that the air gathers and adsorbs on the surface of the negative electrode active material in the form of bubbles, and nanobubbles are formed on the surface of the negative electrode active material. With the help of the bridging effect of the nanobubbles, the apparent diameter of the negative electrode active material can be further increased, thereby increasing the collision and adhesion probability of the negative electrode active material and the bubbles, and then the sorting efficiency and sorting accuracy of the negative electrode active material can be further improved.

[0138] In this process, under the flotation effect of nanobubbles, the reagent consumption in the flotation process can be reduced to improve the dispersion efficiency and sorting accuracy, thereby reducing costs. At the same time, the embodiment of the present application uses the heat generated by the second ball milling process to heat the second slurry, and the temperature difference causes the air to be locally supersaturated, thereby forming nanobubbles, without the need to add additional heating steps and equipment, and without the need to fill the second slurry with additional gas, which can achieve effective resource utilization of energy and materials, reduce unnecessary energy and material losses, reduce costs, and improve efficiency.

[0139] In some embodiments, the calcination temperature is 400° C. to 600° C., and the calcination time is 1 h to 3 h.

[0140] In some embodiments, the temperature of the cold water is 5°C to 10°C.

[0141] In some embodiments, the solid content of the second slurry may be 15 wt % to 25 wt %.

[0142] In some embodiments, after the grinding and crushing, the particle size of the material in the second slurry is 0.01 mm ~ 2 mm.

[0143] After grinding and crushing, the particle size of the material in the second slurry is 0.01 mm ~ 2 mm, which has the same explanation as the particle size of the material in the first slurry after the first ball milling treatment, and also means that after the second ball milling treatment, the minimum particle size of the material in the second slurry can reach 0.01 mm and the maximum particle size can reach 2 mm.

[0144] In these embodiments, after grinding and pulverizing, the material in the second slurry has a moderate particle size, which is convenient for improving the hydrophobicity and air flotation difference between the negative electrode collector and the negative electrode active material, thereby facilitating the separation of the negative electrode collector and the negative electrode active material by flotation.

[0145] In some embodiments, the dissociated negative electrode active material and negative electrode current collector are floated under the flotation effect of nanobubbles, including:

[0146] adding a flotation frother and a collector to the second slurry, and flotating the dissociated negative electrode active material and the negative electrode current collector in the presence of the flotation frother and the collector;

[0147] Among them, relative to the negative electrode sheet from which the organic binder is removed, the added amount of the flotation frother is 50 g / t ~100 g / t; relative to the negative electrode sheet from which the organic binder is removed, the added amount of the collector is 100 g / t ~300 g / t.

[0148] Among them, the amount of flotation frother added relative to the negative electrode sheet from which the organic binder has been removed is 50 g / t ~100 g / t, which means that the amount of flotation frother added is 50 g ~100 g per ton of the negative electrode sheet from which the organic binder has been removed. The amount of collector added relative to the negative electrode sheet from which the organic binder has been removed is 100 g / t ~300 g / t, which means that the amount of collector added is 100 g ~300 g per ton of the negative electrode sheet from which the organic binder has been removed.

[0149] In these embodiments, the flotation efficiency and accuracy can be improved by adding a small amount of flotation frother and collector.

[0150] In some embodiments, before separating the mixed material of positive and negative electrode sheets from the crushed battery fragments by air separation and magnetic separation, the recycling method may further include:

[0151] The electrolyte in the mixed material is volatilized by heat treatment, and the volatilized material is collected and purified.

[0152] In these embodiments, the electrolyte in the mixed material is volatilized by heat treatment, which can reduce the adhesion of positive and negative electrode sheets in the subsequent color sorting process and improve the sorting accuracy. At the same time, by collecting and purifying the volatilized materials, the exhaust gas emission can be reduced, and the electrolyte volatilization overflowing into the air and causing pollution in the subsequent air separation and magnetic separation process can be avoided.

[0153] In some embodiments, the temperature of the heat treatment may be 100°C to 200°C.

[0154] In these embodiments, at this temperature, the electrolyte can be prevented from exploding at a higher temperature, and the electrolyte can be completely volatilized to reduce electrolyte residue.

[0155] In some embodiments, the collection and purification process includes: sequentially performing dust removal, alkaline washing and activated carbon adsorption treatment on the volatilized materials.

[0156] In these embodiments, during the volatilization of the electrolyte, the electrolyte will carry over the battery black powder dust generated during the heat treatment process. The battery black powder dust can be removed by dust removal to reduce the emission of battery black powder dust. Then, through alkaline washing treatment, the fluoride ions in the electrolyte can be precipitated in a solid form such as CaF2 to reduce fluoride ion emissions. Finally, through activated carbon adsorption treatment, the volatile harmful gases in the electrolyte can be adsorbed and removed, thereby reducing exhaust gas emissions.

[0157] The above introduces the specific implementation methods of the present application. In order to objectively illustrate the technical effects produced by the present application, the following examples and comparative examples will be used for description.

[0158] In the following examples and comparative examples, all raw materials can be purchased in commercial form, and in order to maintain the reliability of the experiment, the raw materials used in the following examples and comparative examples have the same physical and chemical parameters or are processed in the same way.

[0159] Example 1

[0160] Example 1 provides a method for recycling waste lithium-ion batteries. Figure 2 As shown, the steps of the method are as follows:

[0161] (1) Dismantle the waste lithium-ion batteries under a nitrogen atmosphere, shear and crush the materials to separate and crush the lithium battery separator, positive and negative electrode sheets, terminal posts, and shell. The crushed materials are rectangular fragments with a length and width of 2 cm, and the temperature of the crushed products is ≤45°C.

[0162] (2) The crushed materials are subjected to a high temperature of 150°C to promote the volatilization and decomposition of the electrolyte. The volatilized electrolyte is then processed through rapid cooling, dust removal, water washing and alkaline washing in sequence before meeting the discharge standards.

[0163] (3) After high-temperature treatment, the materials are separated by air separation and magnetic separation equipment to separate the diaphragm, iron parts, plastic shells, positive and negative pole pieces, etc. The purity of the separated iron parts, plastic shells, etc. after water washing and spray purification is greater than 99%, and the content of pole powder is less than 0.1%.

[0164] (4) The collected positive and negative electrode sheets are sorted twice with increasing resolution using a high-precision color sorter equipped with an optical detection system, an AI visual system, and an intelligent resolution algorithm to obtain positive and negative electrode sheets. The recovery rate of positive electrode sheets is 99.80%, and the recovery rate of negative electrode sheets is 99.76%.

[0165] (5) The positive electrode sheets obtained by color sorting are mixed with an organic solvent (a mixed solvent of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) and ethylene glycol (the mass percentages of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) and ethylene glycol satisfy: the mass percentage of N-methylpyrrolidone (NMP) in the mixed solvent is 35%, the mass percentage of dimethylacetamide (DMAc) in the mixed solvent is 30%, and the mass percentage of ethylene glycol in the mixed solvent is 35%)) to make a slurry with a solid content of 30 wt% and ball milling is performed to promote the dissociation of the active material and the current collector. The particle size of the material after ball milling is 0.01 mm~2 mm.

[0166] (6) After ball milling, the positive electrode slurry is passed through a plate and frame filter press for solid-liquid separation, and the filtrate (organic solvent) is returned to the ball mill for recycling. The filter residue (positive electrode powder) is re-separated by a Nelson centrifuge. The yields of aluminum powder and positive electrode active materials are 95.37% and 93.58%, respectively, and the purities are 92.93% and 95.26%, respectively.

[0167] (7) The negative electrode sheets obtained by color sorting were calcined at 500℃ for 2h in air atmosphere to promote the decomposition of organic binder. After calcination, the negative electrode sheets were mixed with 5℃ cold water to adjust the mass concentration of the slurry to 25%. The electrode sheets were crushed into 0.01mm~2mm powder by ball milling to achieve efficient stripping, shedding and dissociation of the negative electrode active material and the current collector. At the same time, the heat released during the ball milling process caused the slurry temperature to rise to 50℃. The change in slurry temperature caused the change in air solubility in the slurry, resulting in local gas supersaturation, and then forming nanobubbles on the hydrophobic surface of graphite.

[0168] (8) To the slurry obtained in step (7), 100 g / t methyl isobutyl carbinol (MIBC) was added as a foaming agent, and 200 g / t kerosene was added as a collector. The slurry after ball milling was subjected to flotation separation to obtain a hydrophobic product with a negative electrode active material and a single metallic copper with a yield of 95.65% and 93.89%, respectively, and a purity of 94.88% and 95.83%, respectively.

[0169] Example 2

[0170] The method for recycling waste lithium-ion batteries in Example 2 is basically the same as the method for recycling waste lithium-ion batteries in Example 1, except that:

[0171] After step (2) is removed and color separation is performed in step (4), the recovery rate of the positive electrode sheets is 87.62%, and the recovery rate of the negative electrode sheets is 89.33%.

[0172] Example 3

[0173] The method for recycling waste lithium-ion batteries in Example 3 is basically the same as the method for recycling waste lithium-ion batteries in Example 1, except that:

[0174] In step (1), the crushed material is rectangular fragments with a length and width of 0.5 cm. After color sorting and separation in step (4), the recovery rate of the positive electrode sheet is 95.05%, and the recovery rate of the negative electrode sheet is 97.19%.

[0175] Example 4

[0176] The method for recycling waste lithium-ion batteries in Example 4 is basically the same as the method for recycling waste lithium-ion batteries in Example 1, except that:

[0177] In step (5), the positive electrode sheet obtained by color sorting is mixed with an organic solvent (a mixed solvent of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) and ethylene glycol (the mass percentages of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) and ethylene glycol satisfy: the mass percentage of N-methylpyrrolidone (NMP) in the mixed solvent is 40%, the mass percentage of dimethylacetamide (DMAc) in the mixed solvent is 40%, and the mass percentage of ethylene glycol in the mixed solvent is 20%)) to prepare a slurry with a solid content of 20wt% and ball milling is performed to promote the dissociation of the active material and the current collector. The particle size of the material after ball milling is 0.01mm~2mm. After gravity separation, the yields of aluminum powder and positive electrode active material are 97.21% and 94.03%, respectively, and the purities are 94.71% and 95.89%, respectively.

[0178] It can be seen that compared with Example 1, the gravity separation accuracy of Example 4 is improved to a certain extent.

[0179] Example 5

[0180] The method for recycling waste lithium-ion batteries in Example 5 is basically the same as the method for recycling waste lithium-ion batteries in Example 1, except that:

[0181] In step (5), the positive electrode sheet obtained by color sorting is mixed with an organic solvent (a mixed solvent of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) and ethylene glycol (the mass percentages of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) and ethylene glycol satisfy: the mass percentage of N-methylpyrrolidone (NMP) in the mixed solvent is 35%, the mass percentage of dimethylacetamide (DMAc) in the mixed solvent is 30%, and the mass percentage of ethylene glycol in the mixed solvent is 35%)) to prepare a slurry with a solid content of 35wt% for ball milling to promote the dissociation of the active material and the current collector. The particle size of the material after ball milling is 0.01mm~2mm. After gravity separation, the yields of aluminum powder and positive electrode active material are 90.76% and 89.23%, respectively, and the purities are 90.64% and 91.19%, respectively.

[0182] Example 6

[0183] The method for recycling waste lithium-ion batteries in Example 6 is basically the same as the method for recycling waste lithium-ion batteries in Example 1, except that:

[0184] In step (5), the positive electrode sheets obtained by color sorting are mixed with an organic solvent N-methylpyrrolidone (NMP) to prepare a slurry with a solid content of 30 wt% and then ball milled to promote the dissociation of the active material and the current collector. The particle size of the material after ball milling is 0.01 mm~2 mm. After gravity separation, the yields of aluminum powder and positive electrode active material are 85.76% and 83.23%, respectively, and the purities are 85.64% and 87.19%, respectively.

[0185] Example 7

[0186] The method for recycling waste lithium-ion batteries in Example 7 is basically the same as the method for recycling waste lithium-ion batteries in Example 1, except that:

[0187] In step (5), the positive electrode sheets obtained by color sorting are mixed with water to form a slurry with a solid content of 30 wt % and ball milled to obtain aluminum powder and positive electrode active material with a yield of 80.67% and 75.92% respectively, and a purity of 79.15% and 81.83% respectively.

[0188] Example 8

[0189] The method for recycling waste lithium-ion batteries in Example 8 is basically the same as the method for recycling waste lithium-ion batteries in Example 1, except that:

[0190] In step (5), the positive electrode sheet obtained by color sorting is mixed with an organic solvent (a mixed solvent of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) and ethylene glycol (the mass percentages of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) and ethylene glycol satisfy: the mass percentage of N-methylpyrrolidone (NMP) in the mixed solvent is 35%, the mass percentage of dimethylacetamide (DMAc) in the mixed solvent is 30%, and the mass percentage of ethylene glycol in the mixed solvent is 35%)) to prepare a slurry with a solid content of 30 wt% and ball milling is performed to promote the dissociation of the active material and the current collector. The particle size of the material after ball milling is 1 mm to 5 mm. After gravity separation, the yields of aluminum powder and positive electrode active material are 87.16% and 87.77%, respectively, and the purities are 84.98% and 86.64%, respectively.

[0191] Example 9

[0192] The method for recycling waste lithium-ion batteries in Example 9 is basically the same as the method for recycling waste lithium-ion batteries in Example 1, except that:

[0193] In step (7), the negative electrode sheet is calcined at 500°C for 2h in an air atmosphere to promote the decomposition of the organic binder. After calcination, the negative electrode sheet is mixed with 5°C cold water to adjust the mass concentration of the slurry to 20%, and the electrode sheet is crushed into 0.01mm~2mm powder by ball milling to achieve efficient peeling and dissociation of the active material and the current collector. At the same time, the heat released during the ball milling process causes the slurry temperature to rise to 50°C. The change in slurry temperature causes the change in air solubility in the slurry, resulting in local gas supersaturation, and then forming nanobubbles on the hydrophobic surface of the graphite.

[0194] In step (8), the frother used for flotation separation is 50 g / t methyl isobutyl carbinol (MIBC), and the collector is 200 g / t kerosene. The yields of the hydrophobic product negative electrode active material and metallic copper are 92.19% and 95.28%, respectively, and the purities are 93.36% and 93.07%, respectively.

[0195] It can be seen that compared with Example 1, the yield and purity of the negative electrode active material of Example 9 are both reduced to a small extent, the yield of metallic copper is increased, and the purity is reduced to a small extent.

[0196] Example 10

[0197] The method for recycling waste lithium-ion batteries in Example 10 is basically the same as the method for recycling waste lithium-ion batteries in Example 1, except that:

[0198] In step (7), the calcined negative electrode sheet is mixed with 25° C. room temperature water to a slurry with a mass concentration of 25%, and ball milled. The hydrophobic product negative electrode active material and metallic copper are obtained by flotation with a yield of 87.75% and 88.79%, and a purity of 90.97% and 89.06%, respectively.

[0199] It can be seen that the use of low-temperature water slurrying in Example 1 can effectively improve the yield and purity of the negative electrode active material and the metallic copper.

[0200] Comparative Example 1

[0201] The resource recycling method of waste lithium-ion batteries in Comparative Example 1 is as follows:

[0202] (1) Dismantle the waste lithium-ion batteries in a nitrogen atmosphere, shear and crush the materials, and separate and crush the lithium battery separator, positive and negative electrode sheets, terminal posts, and shell. The crushed materials are fine-grained battery powder with a particle size of 0.5 mm. The temperature of the crushed materials is ≤45°C;

[0203] (2) After high-temperature treatment, the materials are separated by air separation and magnetic separation equipment to separate the diaphragm, iron parts, plastic shells, positive and negative pole pieces, etc. The purity of the separated iron parts, plastic shells, etc. after water washing and spray purification is greater than 99%, and the content of pole powder is less than 0.1%.

[0204] (3) The organic binder in the battery powder is first removed by calcination at a temperature of 500°C for 2 hours.

[0205] (4) obtaining fine-grained positive and negative electrode active material mixed powder and coarse-grained copper foil and aluminum foil mixed material by crushing and screening;

[0206] (5) The coarse-grained copper foil and aluminum foil mixture after screening is separated by color sorting by a high-precision color sorter;

[0207] (6) The screened mixed powders of positive and negative electrode active materials were prepared into a slurry with a mass percentage concentration of 20%, and separated by an aerated agitated flotation machine with a foaming agent of 100 g / t methyl isobutyl carbinol (MIBC) and a collector of 300 g / t kerosene to obtain a hydrophilic product negative electrode active material and a hydrophobic positive electrode active material.

[0208] The yields of copper and aluminum metals obtained by color sorting were 80.71% and 82.98% respectively, and the purities were 84.39% and 75.96% respectively. The yields of hydrophilic positive active materials and hydrophobic negative active materials obtained by flotation were 82.75% and 83.79% respectively, and the purities were 84.97% and 80.06% respectively.

[0209] It can be seen that compared with Comparative Example 1, Examples 1 to 6 and Examples 8 to 10 of the present application can effectively improve the sorting accuracy and improve the recovery rate and purity of each material.

[0210] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0211] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A method for recycling waste secondary batteries, characterized in that: include: Dismantle and crush the waste secondary batteries in a protective atmosphere or vacuum environment; Through wind separation and magnetic separation, the mixed materials of positive and negative electrode sheets are sorted out from the broken battery fragments; Separating the positive electrode sheet and the negative electrode sheet in the mixed material by color sorting; Grinding and crushing the separated positive electrode sheet by a first grinding method, so that the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet are dissociated; Reselecting the dissociated positive electrode active material and the positive electrode current collector by using density difference to obtain the positive electrode active material and the positive electrode current collector; Grinding and crushing the separated negative electrode sheet by a second grinding method, so that the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet are dissociated; The dissociated negative electrode active material and the negative electrode current collector are floated by utilizing the hydrophilic and hydrophobic differences to obtain the negative electrode active material and the negative electrode current collector.

2. The recycling method according to claim 1, characterized in that: The recycling method meets at least one of the following conditions: (1) The protective atmosphere is an inert gas atmosphere; (2) The diameters of the positive electrode sheet and the negative electrode sheet in the mixed material are independently 1 cm to 4 cm; (3) The positive electrode sheet and the negative electrode sheet in the mixed material are in sheet form, and the single-side area of ​​the positive electrode sheet and the negative electrode sheet is independently 1 cm²~4.5 cm².

3. The recycling method according to claim 1, characterized in that: Before the separated positive electrode sheet is ground and pulverized by the first grinding method so that the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet are dissociated, the recycling method further comprises: Adding an organic solvent to the separated positive electrode sheet to prepare a first slurry; Grinding and crushing the separated positive electrode sheet by a first grinding method so that the positive electrode active material and the positive electrode current collector contained in the positive electrode sheet are dissociated, including: Performing a first ball milling treatment on the first slurry so as to dissociate the positive electrode active material contained in the positive electrode sheet and the positive electrode current collector; The method of reselecting the dissociated positive electrode active material and the positive electrode current collector by using density difference to obtain the positive electrode active material and the positive electrode current collector comprises: Separating the dissociated positive electrode active material and the positive electrode current collector by using the density difference between the dissociated positive electrode active material and the positive electrode current collector and the centrifugal force to obtain the positive electrode active material and the positive electrode current collector; Optionally, the recycling method satisfies at least one of the following conditions: (1) The organic solvent comprises: at least one of N-methylpyrrolidone, dimethylacetamide, ethylene glycol and propylene glycol; (2) The solid content of the first slurry is 20 wt% to 30 wt%; (3) After grinding and crushing, the particle size of the material in the first slurry is 0.01 mm to 2 mm; (4) The centrifugal force is 300G~500G.

4. The recycling method according to claim 1, characterized in that: Before the separated negative electrode sheet is ground and pulverized by the second grinding method so that the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet are dissociated, the recycling method further comprises: In an air atmosphere, baking the separated negative electrode sheet to remove the organic binder in the separated negative electrode sheet; and Adding cold water to the negative electrode sheet from which the organic binder has been removed to prepare a second slurry; wherein the temperature of the cold water is less than or equal to 10° C.; Grinding and crushing the separated negative electrode sheet by a second grinding method so that the negative electrode active material and the negative electrode current collector contained in the negative electrode sheet are dissociated, including: Performing a second ball milling treatment on the second slurry to dissociate the negative electrode active material contained in the negative electrode sheet and the negative electrode current collector, and heating the second slurry using the heat generated by the second ball milling treatment so that air in the second slurry is adsorbed on the surface of the negative electrode active material to form nanobubbles; The dissociated negative electrode active material and the negative electrode current collector are subjected to floatation by utilizing the hydrophilic and hydrophobic differences to obtain the negative electrode active material and the negative electrode current collector, comprising: Under the flotation effect of the nanobubbles, the dissociated negative electrode active material and the negative electrode current collector are floated to obtain the negative electrode active material and the negative electrode current collector.

5. The recycling method according to claim 4, characterized in that: The recycling method meets at least one of the following conditions: (1) The calcination temperature is 400°C to 600°C and the calcination time is 1 h to 3 h; (2) The temperature of the cold water is 5°C to 10°C; (3) The solid content of the second slurry is 15wt% to 25wt%; (4) After grinding and crushing, the particle size of the material in the second slurry is 0.01 mm to 2 mm.

6. The recycling method according to claim 4, characterized in that: Under the flotation effect of the nanobubbles, the dissociated negative electrode active material and the negative electrode current collector are floated, including: adding a flotation frother and a collector to the second slurry, and flotating the dissociated negative electrode active material and the negative electrode current collector in the presence of the flotation frother and the collector; Wherein, relative to the negative electrode sheet from which the organic binder is removed, the added amount of the flotation frother is 50 g / t to 100 g / t; relative to the negative electrode sheet from which the organic binder is removed, the added amount of the collector is 100 g / t to 300 g / t.

7. The recycling method according to any one of claims 1 to 6, characterized in that: Separating the positive electrode sheet and the negative electrode sheet in the mixed material by color sorting includes: The positive electrode sheet and the negative electrode sheet are separated multiple times by multi-stage color sorting; Among them, the spectral resolution of the next level of color sorting is higher than the spectral resolution of the previous level of color sorting.

8. The recycling method according to any one of claims 1 to 6, characterized in that: Before separating the mixed material of positive and negative electrode sheets from the crushed battery fragments by air separation and magnetic separation, the recycling method further comprises: The electrolyte in the mixed material is volatilized by heat treatment, and the volatilized material is collected and purified.

9. The recycling method according to claim 8, characterized in that: The temperature of the heat treatment is 100°C to 200°C.

10. The recycling method according to claim 8, characterized in that: The collection and purification process includes: performing dust removal, alkali washing and activated carbon adsorption on the volatilized materials in sequence.

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