Method for separating positive electrode active material and current collector of waste lithium ion battery

Abstract

The invention discloses a method for separating a positive electrode active material and a current collector of a waste lithium ion battery, and belongs to the technical field of recycling of the waste lithium ion battery. The method comprises the following steps: discharging and disassembling the waste lithium ion battery pack, and mechanically crushing to obtain a positive electrode current collector loaded with an active material; and activating the positive current collector loaded with the active material by adopting an aqueous solution containing an activating agent, adjusting the pH value of the system to be acidic, adding a positive separating agent to form an interface layer with the positive current collector, stripping, filtering, sorting and drying to obtain the positive current collector and the positive active material. The wettability of the positive electrode active material is improved by adopting the activating agent, so that hydrogen ions and the positive electrode separating agent can enter the aluminum foil layer to form a new interface layer, and the positive electrode active material is stripped. The method is high in separation efficiency, simple and convenient to operate and free of damage to the positive electrode active material.

Description

Technical Field

[0001] The present invention relates to a method for separating the positive electrode active material from the current collector of waste lithium-ion batteries, and belongs to the technical field of comprehensive utilization of solid waste resources. Background Art

[0002] With the continuous development of new energy vehicles and related industries, the production and usage of lithium-ion batteries have been increasing year by year. However, the cycle service life of ordinary lithium-ion batteries is 5 - 8 years. Under the premise of such a large usage scale, a large number of waste lithium-ion batteries will inevitably be generated in the future. These waste lithium-ion batteries contain a large amount of heavy metals and organic substances. If they are not properly treated or recycled, once the harmful substances in the batteries leak, they will not only cause serious harm to the ecological environment and biological safety, but also waste a large amount of valuable metal resources. Currently, the recycling methods of waste lithium-ion batteries are mainly divided into pyrometallurgy, hydrometallurgy, and direct repair. During the hydrometallurgy and direct repair processes, it is often necessary to separate the positive electrode active material from the current collector aluminum foil to prevent aluminum impurities from polluting the solution or material. However, the positive electrode active material and the current collector aluminum foil are tightly bonded through a polyvinylidene fluoride (PVDF) polymer binder, and PVDF has characteristics such as stable chemical properties, strong thermal stability, and excellent mechanical properties, resulting in the separation of the positive electrode active material from the current collector becoming a challenging task.

[0003] Currently, the methods for separating the positive electrode active material from the aluminum foil mainly include mechanical crushing, ultrasonic separation, high-temperature pyrolysis, molten salt method, alkali solution dissolution of aluminum foil, organic reagent separation, etc. However, in practical applications, mechanical crushing and ultrasonic separation have problems such as difficult complete removal of aluminum foil fragments; high-temperature pyrolysis and molten salt method not only have high energy consumption, but also generate gases that cause greater environmental pollution; alkali solution method and organic reagents have problems such as difficult treatment of waste liquid, low efficiency, and weak economic benefits. Therefore, how to achieve low-cost, pollution-free, and efficient separation of the positive electrode active material from the current collector during the pretreatment of current waste batteries is crucial for the recycling of waste lithium-ion batteries. Summary of the Invention

[0004] Aiming at the problems of incomplete separation, poor applicability, and poor economy of the positive electrode active material from the current collector during the recycling of current waste lithium-ion batteries, the purpose of the present invention is to provide a method for separating the positive electrode active material from the current collector of waste lithium-ion batteries. This method uses an activator to increase the wettability of the positive electrode active material to facilitate the entry of hydrogen ions and the positive electrode separator into the aluminum foil layer (i.e., the positive electrode current collector) to form a new interface layer, thereby realizing the peeling of the positive electrode active material. This method has high separation efficiency, is easy to operate, and will not damage the positive electrode active material.

[0005] In order to achieve the above technical objectives, the present invention provides a method for separating the cathode active material and the current collector of waste lithium-ion batteries. The method is to mechanically crush the waste lithium-ion battery pack after discharging and disassembling to obtain a cathode current collector loaded with the active material; after the cathode current collector loaded with the active material is activated with an aqueous solution containing an activator, the pH of the system is adjusted to acidic, and then a cathode separator is added to form an interface layer with the cathode current collector for peeling. After filtration, sorting, and drying, the cathode current collector and the cathode active material are obtained.

[0006] The key to the technical solution of the present invention lies in the synergistic effect of the activator and the cathode separator to promote the separation of the cathode active material and the cathode current collector (aluminum foil). Specifically, the activator used in the present invention can perform hydrophilic modification on the surface of the cathode active material, improve the wettability of the cathode active material, and enhance the penetration effect. After activation treatment, hydrogen ions in the solution and the cathode separator can quickly penetrate through the cathode active material and then contact the aluminum foil. By adjusting the pH of the system to acidic, on the one hand, it can prevent the occurrence of side reactions, and on the other hand, hydrogen ions in the acidic aqueous solution and hydrogen ions partially hydrolyzed and ionized from the cathode separator can jointly penetrate to the contact surface between the cathode active material and the aluminum foil, and produce a micro-corrosion effect on the aluminum foil surface. This not only helps to reduce the usage amount of the cathode separator but also improves the micro-corrosion efficiency. After the aluminum foil is micro-corroded by hydrogen ions, the exposed aluminum can combine with the anions in the cathode separator to form a new interface layer, significantly destroying the binding force between the cathode active material and the cathode current collector, so that they can be easily peeled off.

[0007] As a preferred solution, the activator is at least one of polyethylene glycol, glycerol, sodium dodecyl sulfate, sodium butylnaphthalene sulfonate, polyethylene oxide, Tween 80, and sodium dioctyl sulfosuccinate. Further preferably, it is polyethylene glycol, sodium dodecyl sulfate, and Tween 80. The activator selected in the present invention has hydrophilic groups such as hydroxyl groups, ether bonds, sulfate ions, or sulfonate ions. When it contacts the surface of the cathode active material, it can perform hydrophilic modification on the surface of the cathode active material, thereby significantly improving the wettability of the cathode active material and facilitating the subsequent penetration of hydrogen ions and the cathode separator.

[0008] As a preferred solution, the positive electrode separator is at least one of potassium persulfate, disodium hydrogen phosphate, potassium dihydrogen phosphate, potassium bicarbonate, manganese dihydrogen phosphate, ammonium dihydrogen phosphate, iron dihydrogen phosphate, ammonium persulfate and sodium persulfate. The positive electrode separator selected in the present invention is prone to hydrolysis in an aqueous solution to generate hydrogen ions, and the hydrogen ions preferentially react with the aluminum foil at the boundary region of the aluminum foil current collector (i.e., the cross-section at the edge of the electrode sheet) to cause micro-corrosion. The anions in the separator, such as sulfate, hydrogen phosphate, dihydrogen phosphate, bicarbonate or persulfate, quickly combine with the aluminum ions formed by the micro-corrosion of the hydrogen ions to form a new interface layer, weakening the binding ability between the aluminum foil and the positive electrode active material, resulting in the gradual delamination of the active material layer at the edge of the electrode sheet from the aluminum foil. The hydrogen ions will continue to extend inward along the interlayer gap at the edge of the electrode sheet and react with the new aluminum layer, and finally diffuse to the central region of the electrode sheet to achieve the complete separation of the aluminum foil. Further preferably, it is disodium hydrogen phosphate, potassium dihydrogen phosphate, potassium bicarbonate, manganese dihydrogen phosphate, ammonium dihydrogen phosphate, iron dihydrogen phosphate.

[0009] As a preferred solution, during the activation treatment process, the solid-liquid ratio of the positive electrode current collector and the aqueous solution containing the activator is 100-500 g / L; in some embodiments of the present invention, the optional solid-liquid ratios are 100, 200, 300, 400 or 500 g / L. The concentration of the activator in the aqueous solution containing the activator is 0.1-1 mol / L, and the optional activator concentrations are 0.1, 0.3, 0.5, 0.7 or 1.0 mol / L. Increasing the solid-liquid ratio in the reaction system of the present invention will result in a decrease in the liquid phase volume, thereby weakening the hydrophilic effect on the surface of the positive electrode sheet, making it difficult for hydrogen ions to effectively penetrate to the aluminum foil interface, resulting in a slow boundary corrosion reaction. If the solid-liquid ratio is too small, the amount of activator used will increase, resulting in too high a cost and not significantly improving the wetting effect on the positive electrode sheet.

[0010] As a preferred solution, the conditions for the activation treatment are: the time is 10-60 min, and the temperature is 20-60 °C. In some embodiments of the present invention, the optional activation times are 10, 20, 30, 45 or 60 min; the optional activation temperatures are 20, 30, 40, 50 or 60 °C.

[0011] As a preferred solution, the range of the pH is 1.5-3.5. In some embodiments of the present invention, the optional stable pH values are 1.5, 2, 3 or 3.5.

[0012] As a preferred solution, the mass ratio of the positive electrode separator to the positive electrode current collector loaded with the active material ranges from 1:(5 - 20), and the optional mass ratio ranges are 1:5, 1:10, 1:15, and 1:20. If the mass ratio is too small, the content of the separator will decrease, the hydrogen ion concentration will be insufficient, and the boundary corrosion reaction will be difficult to continuously expand, making it impossible to achieve complete stripping. If the mass ratio is too large, the dosage of the reagent will be large and the cost will be too high, and the hydrogen ion concentration in the stripping system will be too high, which will cause irreversible damage to the positive electrode active material.

[0013] As a preferred solution, the stripping is promoted by mechanical stirring, and the stirring speed is 100 - 800 r / min; the stripping time is 5 - 45 min, and the separation temperature is 20 - 60 °C. In some embodiments of the present invention, the optional separation times are 5, 15, 25, 35, or 45 min; the optional separation temperatures are 20, 30, 40, 50, or 60 °C; the optional stirring speeds are 100, 250, 400, 650, or 800 r / min.

[0014] As a preferred solution, the types of the used lithium-ion battery packs are at least one of ternary nickel cobalt manganese batteries, lithium iron phosphate batteries, lithium cobalt oxide batteries, lithium manganese oxide batteries, lithium nickel oxide batteries, and ternary nickel cobalt aluminum batteries. The area of the positive electrode current collector obtained by crushing in the present invention is (1 cm × 1 cm) - (5 cm × 5 cm). In the embodiments of the present invention, the optional crushing areas are 1 cm × 1 cm, 3 cm × 3 cm, or 5 cm × 5 cm.

[0015] As a preferred solution, the mesh number of the sieve used for filtration is 50 - 200 meshes. In some embodiments of the present invention, the optional mesh numbers are 50, 100, 150, and 200 meshes.

[0016] As a preferred solution, the drying temperature of the solid after solid-liquid separation is 80 - 120 °C. In some embodiments of the present invention, the optional drying temperatures are 80, 90, 100, 110, and 120 °C.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) This separation method provides a new idea for stripping the positive electrode active material from the current collector. The present invention avoids directly damaging PVDF with stable chemical properties and strong thermal stability, but uses a positive electrode separator and hydrogen ions in the solution for micro-corrosion to form a new interface layer between the positive electrode active material and the aluminum foil, thereby achieving easy stripping of the positive electrode active material and the current collector. This separation has high efficiency, large separation output, and low reagent consumption.

[0019] (2) The activator and the positive electrode separator used in the present invention have a synergistic effect to promote the separation of the positive electrode active material from the positive electrode current collector (aluminum foil). The activator has the ability to improve the wettability of the surface of the positive electrode active material and enhance the penetration effect. After activation treatment, hydrogen ions in the solution and the positive electrode separator can quickly penetrate through the positive electrode active material and then contact the aluminum foil to form a new interfacial layer.

[0020] (3) The separation method has a simple process, is easy to operate industrially, has strong applicability, and can still exhibit high separation ability when facing positive electrode sheets with different active substances.

[0021] (4) The separation process of the present invention will not damage the positive electrode active material and is easy for subsequent recycling.

[0022] (5) The separation method is economical and environmentally friendly and can meet industrial requirements. Description of the Drawings

[0023] Figure 1 It is a process flow chart of separating the positive electrode active material and the current collector of waste lithium-ion batteries according to the present invention.

[0024] Figure 2 It is a diagram showing the situation of the aluminum foil and the positive electrode active material before and after separation in Example 3, where Figure 2 (a) is the positive electrode sheet before peeling, Figure 2 (b) is the aluminum foil after peeling.

[0025] Figure 3 It is a SEM micrograph of the positive electrode active material and the aluminum foil after separation in Example 3, where Figure 3 (a) is the positive electrode sheet before peeling, Figure 3 (b) and Figure 3 (c) are the aluminum foil and the positive electrode active material after peeling, respectively.

[0026] Figure 4 It is an XRD pattern of the positive electrode active material after separation and recovery in Example 8. Detailed Embodiments

[0027] The following further illustrates the present invention in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by those skilled in the art without creative efforts still fall within the protection scope of the present invention.

[0028] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through the market or can be prepared by existing methods.

[0029] Example 1

[0030] (1) Mechanically crush the recycled ternary nickel-cobalt-manganese cathode sheet to obtain a cathode sheet with an area of 1 cm × 1 cm.

[0031] (2) Add the ternary nickel-cobalt-manganese cathode sheet to an aqueous solution of polyethylene glycol with an activator concentration of 0.1 mol / L according to a solid-liquid ratio of 100 g / L for activation. The activation temperature is 20 °C and the activation time is 10 min.

[0032] (3) After the activation is completed, adjust the pH of the solution to 1.5, and add potassium persulfate to the solution. The mass ratio of potassium persulfate to the ternary nickel-cobalt-manganese cathode sheet is 1:5. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 100 r / min, a temperature of 20 °C, and a separation time of 5 min.

[0033] (4) Screen the obtained mixture through a 50-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 80 °C, sort out the separated aluminum foil, and obtain a black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent and a positive electrode separator for recycling.

[0034] Comparative Example 1

[0035] (1) Mechanically crush the recycled ternary nickel-cobalt-manganese cathode sheet to obtain a cathode sheet with an area of 1 cm × 1 cm.

[0036] (2) Add the ternary nickel-cobalt-manganese cathode sheet to an aqueous solution of polyethylene glycol with an activator concentration of 0.1 mol / L according to a solid-liquid ratio of 100 g / L for activation. The activation temperature is 20 °C and the activation time is 10 min.

[0037] (3) After the activation is completed, do not add a positive electrode separator to the solution. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 100 r / min, a temperature of 20 °C, and a separation time of 5 min.

[0038] (4) Screen the obtained mixture through a 50-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 80 °C, sort out the separated aluminum foil, and obtain a black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent for recycling.

[0039] Example 2

[0040] (1) Mechanically crush the recycled lithium cobalt oxide cathode sheet to obtain a cathode sheet with an area of 3 cm × 3 cm.

[0041] (2) Add the lithium cobalt oxide positive electrode sheet into an aqueous solution of glycerol with an activator concentration of 0.3 mol / L and polyethylene glycol with a concentration of 0.1 mol / L according to a solid-liquid ratio of 200 g / L for activation. The activation temperature is 30 °C and the activation time is 20 min.

[0042] (3) After the activation is completed, adjust the pH of the solution to 2, and add disodium hydrogen phosphate to the solution. The mass ratio of disodium hydrogen phosphate to the lithium cobalt oxide positive electrode sheet is 1:10. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 250 r / min, a separation temperature of 30 °C, and a separation time of 15 min.

[0043] (4) Screen the obtained mixture through a 100-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 90 °C, sort out the separated aluminum foil, and obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an activator and a positive electrode separator for recycling.

[0044] Example 3

[0045] (1) Mechanically crush the recycled lithium manganese oxide positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0046] (2) Add the lithium manganese oxide positive electrode sheet into an aqueous solution of sodium dodecyl sulfate with an activator concentration of 0.3 mol / L according to a solid-liquid ratio of 200 g / L for activation. The activation temperature is 40 °C and the activation time is 30 min.

[0047] (3) After the activation is completed, adjust the pH of the solution to 2, and add potassium bicarbonate to the solution. The mass ratio of potassium bicarbonate to the lithium manganese oxide positive electrode sheet is 1:15. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 400 r / min, a separation temperature of 30 °C, and a separation time of 15 min.

[0048] (4) Screen the obtained mixture through a 150-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 100 °C, sort out the separated aluminum foil, and obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an activator and a positive electrode separator for recycling.

[0049] Comparative Example 2

[0050] (1) Mechanically crush the recycled lithium manganese oxide positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0051] (2) Add the lithium manganese oxide positive electrode sheet into an aqueous solution of sodium dodecyl sulfate with an activator concentration of 0.3 mol / L according to a solid-liquid ratio of 200 g / L for activation. The activation temperature is 40 °C and the activation time is 30 min.

[0052] (3) After the activation is completed, no positive electrode separator is added to the solution. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 400 r / min, a separation temperature of 30 °C, and a separation time of 15 min.

[0053] (4) Screen the obtained mixture through a 150-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 100 °C, sort out the separated aluminum foil to obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent and a positive electrode separator for recycling.

[0054] Example 4

[0055] (1) Mechanically crush the recycled lithium iron phosphate positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0056] (2) Add the lithium iron phosphate positive electrode sheet to an aqueous solution of Tween 80 with an activator concentration of 0.5 mol / L according to a solid-liquid ratio of 300 g / L for activation. The activation temperature is 40 °C and the activation time is 30 min.

[0057] (3) After the activation is completed, adjust the pH of the solution to 3, add manganese dihydrogen phosphate to the solution, and the mass ratio of manganese dihydrogen phosphate to the lithium manganese oxide positive electrode sheet is 1:5. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 400 r / min, a separation temperature of 40 °C, and a separation time of 15 min.

[0058] (4) Screen the obtained mixture through a 100-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 110 °C, sort out the separated aluminum foil to obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent and a positive electrode separator for recycling.

[0059] Example 5

[0060] (1) Mechanically crush the recycled lithium iron phosphate positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0061] (2) Add the lithium iron phosphate positive electrode sheet to an aqueous solution of Tween 80 with an activator concentration of 0.5 mol / L according to a solid-liquid ratio of 300 g / L for activation. The activation temperature is 40 °C and the activation time is 30 min.

[0062] (3) After the activation is completed, adjust the pH of the solution to 3, add manganese dihydrogen phosphate to the solution, and the mass ratio of manganese dihydrogen phosphate to the lithium manganese oxide positive electrode sheet is 1:10. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 400 r / min, a separation temperature of 40 °C, and a separation time of 15 min.

[0063] (4) Screen the obtained mixture through a 100-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 110 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent and a positive electrode separator for recycling.

[0064] Example 6

[0065] (1) Mechanically crush the recycled lithium iron phosphate positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0066] (2) Add the lithium iron phosphate positive electrode sheet to an aqueous solution of Tween 80 with an activator concentration of 0.5 mol / L according to a solid-liquid ratio of 300 g / L for activation. The activation temperature is 40 °C, and the activation time is 30 min.

[0067] (3) After the activation is completed, adjust the pH of the solution to 3, and add manganese dihydrogen phosphate to the solution. The mass ratio of manganese dihydrogen phosphate to the lithium manganese oxide positive electrode sheet is 1:20. Separate the positive electrode active material and the aluminum foil under the conditions of a stirring speed of 400 r / min, a separation temperature of 40 °C, and a separation time of 15 min.

[0068] (4) Screen the obtained mixture through a 100-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 110 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent and a positive electrode separator for recycling.

[0069] Example 7

[0070] (1) Mechanically crush the recycled lithium nickelate positive electrode sheet to obtain a positive electrode sheet with an area of 5 cm × 5 cm.

[0071] (2) Add the lithium nickelate positive electrode sheet to an aqueous solution of polyethylene oxide with an activator concentration of 0.5 mol / L according to a solid-liquid ratio of 300 g / L for activation. The activation temperature is 50 °C, and the activation time is 45 min.

[0072] (3) After the activation is completed, adjust the pH of the solution to 3, and add ammonium dihydrogen phosphate to the solution. The mass ratio of ammonium dihydrogen phosphate to the lithium nickelate positive electrode sheet is 1:10. Separate the positive electrode active material and the aluminum foil under the conditions of a stirring speed of 650 r / min, a separation temperature of 50 °C, and a separation time of 25 min.

[0073] (4) Screen the obtained mixture through a 100-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 120 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. In the filtrate obtained after solid-liquid separation, add an active agent and a positive electrode separator in sequence for recycling.

[0074] Example 8

[0075] (1) Mechanically crush the recycled ternary nickel-cobalt-manganese positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0076] (2) Add the ternary nickel-cobalt-manganese positive electrode sheet to an aqueous solution of sodium butylnaphthalenesulfonate with an activator concentration of 0.7 mol / L according to a solid-liquid ratio of 400 g / L for activation. The activation temperature is 60 °C, and the activation time is 60 min.

[0077] (3) After the activation is completed, adjust the pH of the solution to 3.5, and add iron dihydrogen phosphate to the solution. The mass ratio of iron dihydrogen phosphate to the lithium nickelate positive electrode sheet is 1:10. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 800 r / min, a separation temperature of 60 °C, and a separation time of 35 min.

[0078] (4) Screen the obtained mixture through a 150-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 100 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. In the filtrate obtained after solid-liquid separation, add an active agent and a positive electrode separator in sequence for recycling.

[0079] Example 9

[0080] (1) Mechanically crush the recycled ternary nickel-cobalt-manganese positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0081] (2) Add the ternary nickel-cobalt-manganese positive electrode sheet to an aqueous solution of sodium butylnaphthalenesulfonate with an activator concentration of 0.7 mol / L according to a solid-liquid ratio of 200 g / L for activation. The activation temperature is 60 °C, and the activation time is 60 min.

[0082] (3) After the activation is completed, adjust the pH of the solution to 3.5, and add iron dihydrogen phosphate to the solution. The mass ratio of iron dihydrogen phosphate to the lithium nickelate positive electrode sheet is 1:10. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 800 r / min, a separation temperature of 60 °C, and a separation time of 35 min.

[0083] (4) Screen the obtained mixture through a 150-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 100 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is supplemented with an active agent and a positive electrode separator in sequence for recycling.

[0084] Example 10

[0085] (1) Mechanically crush the recycled ternary nickel-cobalt-manganese positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0086] (2) Add the ternary nickel-cobalt-manganese positive electrode sheet to an aqueous solution of sodium butylnaphthalenesulfonate with an activator concentration of 0.7 mol / L according to a solid-liquid ratio of 100 g / L for activation. The activation temperature is 60 °C, and the activation time is 60 min.

[0087] (3) After the activation is completed, adjust the pH of the solution to 3.5, and add iron dihydrogen phosphate to the solution. The mass ratio of iron dihydrogen phosphate to the lithium nickelate positive electrode sheet is 1:10. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 800 r / min, a separation temperature of 60 °C, and a separation time of 35 min.

[0088] (4) Screen the obtained mixture through a 150-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 100 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is supplemented with an active agent and a positive electrode separator in sequence for recycling.

[0089] Example 11

[0090] (1) Mechanically crush the recycled lithium cobaltate positive electrode sheet to obtain a positive electrode sheet with an area of 1 cm × 1 cm.

[0091] (2) Add the lithium cobaltate positive electrode sheet to an aqueous solution of sodium dioctyl sulfosuccinate with an activator concentration of 1 mol / L according to a solid-liquid ratio of 500 g / L for activation. The activation temperature is 30 °C, and the activation time is 45 min.

[0092] (3) After the activation is completed, adjust the pH of the solution to 2, and add ammonium persulfate to the solution. The mass ratio of ammonium persulfate to the lithium cobaltate positive electrode sheet is 1:10. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 400 r / min, a separation temperature of 40 °C, and a separation time of 45 min.

[0093] (4) Screen the obtained mixture through a 100-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 100 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent and a positive electrode separating agent for recycling.

[0094] Example 12

[0095] (1) Mechanically crush the recycled ternary nickel-cobalt-aluminum positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0096] (2) Add the ternary nickel-cobalt-aluminum positive electrode sheet to an aqueous solution of glycerol with an activator concentration of 0.3 mol / L according to a solid-liquid ratio of 500 g / L for activation. The activation temperature is 40 °C and the activation time is 20 min.

[0097] (3) After the activation is completed, adjust the pH of the solution to 1.5, and add sodium persulfate to the solution. The mass ratio of sodium persulfate to the ternary nickel-cobalt-aluminum positive electrode sheet is 1:10. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 650 r / min, a separation temperature of 30 °C, and a separation time of 25 min.

[0098] (4) Screen the obtained mixture through a 100-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 80 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent and a positive electrode separating agent for recycling.

[0099] Example 13

[0100] (1) Mechanically crush the recycled lithium iron phosphate positive electrode sheet to obtain a positive electrode sheet with an area of 1 cm × 1 cm.

[0101] (2) Add the lithium iron phosphate positive electrode sheet to an aqueous solution of polyethylene glycol with an activator concentration of 0.5 mol / L according to a solid-liquid ratio of 300 g / L for activation. The activation temperature is 30 °C and the activation time is 10 min.

[0102] (3) After the activation is completed, adjust the pH of the solution to 2, and add potassium dihydrogen phosphate to the solution. The mass ratio of potassium dihydrogen phosphate to the lithium iron phosphate positive electrode sheet is 1:15. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 400 r / min, a separation temperature of 50 °C, and a separation time of 45 min.

[0103] (4) Screen the obtained mixture through a 100-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 100 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent and a positive electrode separating agent for recycling.

[0104] Example 14

[0105] (1) Mechanically crush the recycled lithium cobalt oxide positive electrode sheet to obtain a positive electrode sheet with an area of 3 cm × 3 cm.

[0106] (2) Add the lithium cobalt oxide positive electrode sheet to an aqueous solution of sodium butylnaphthalene sulfonate with an activator concentration of 0.5 mol / L according to a solid-liquid ratio of 300 g / L for activation. The activation temperature is 30 °C, and the activation time is 10 min.

[0107] (3) After the activation is completed, adjust the pH of the solution to 2, and add manganese dihydrogen phosphate to the solution. The mass ratio of manganese dihydrogen phosphate to the lithium iron phosphate positive electrode sheet is 1:10. Separate the positive electrode active material from the aluminum foil under the conditions of a stirring speed of 400 r / min, a separation temperature of 40 °C, and a separation time of 25 min.

[0108] (4) Screen the obtained mixture through a 50-mesh sieve to obtain a solid part and a filtrate. Dry the solid part at a temperature of 100 °C, and after sorting out the separated aluminum foil, obtain the black positive electrode active material. The filtrate obtained after solid-liquid separation is successively supplemented with an active agent and a positive electrode separating agent for recycling.

[0109] Comparative Example 3

[0110] The difference between this comparative example and Example 1 is only that the pH in step (3) is 3.8, and the other conditions and steps are the same.

[0111] Table 1 Materials separated and separation efficiency in each example

[0112]

[0113]

[0114] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for separating the positive electrode active material and the current collector of waste lithium-ion batteries, characterized in that: The waste lithium-ion battery pack is discharged and disassembled, and then mechanically crushed to obtain a positive current collector loaded with active materials. After the positive current collector loaded with active materials is activated with an aqueous solution containing an activator, the pH of the system is adjusted to acidic, and then a positive separator is added to form an interfacial layer with the positive current collector for peeling. After filtration, sorting, and drying, the positive current collector and the positive active materials are obtained.

2. The method for separating the cathode active material and the current collector of waste lithium-ion batteries according to claim 1, wherein: The activator is at least one of polyethylene glycol, glycerol, sodium dodecyl sulfate, sodium butylnaphthalene sulfonate, polyethylene oxide, Tween 80, and sodium dioctyl sulfosuccinate.

3. A method for separating the cathode active material and the current collector of a waste lithium-ion battery according to claim 1 or 2, characterized in that: The positive separator is at least one of potassium persulfate, disodium hydrogen phosphate, potassium dihydrogen phosphate, potassium bicarbonate, manganese dihydrogen phosphate, ammonium dihydrogen phosphate, ferrous dihydrogen phosphate, ammonium persulfate, and sodium persulfate.

4. A method for separating the positive electrode active material and the current collector of a waste lithium-ion battery according to claim 3, characterized in that: During the activation process, the solid-liquid ratio of the positive current collector to the aqueous solution containing the activator is 100-500 g / L; the concentration of the activator in the aqueous solution containing the activator is 0.1-1 mol / L.

5. A method for separating the cathode active material and the current collector of a waste lithium-ion battery according to claim 4, characterized in that: The conditions for the activation treatment are: the time is 10-60 min, and the temperature is 20-60 °C.

6. A method for separating the positive electrode active material and the current collector of waste lithium-ion batteries according to claim 1 or 5, characterized in that: The range of the pH is 1.5-3.

5.

7. A method for separating the cathode active material and the current collector of waste lithium-ion batteries according to claim 1, characterized in that: The range of the mass ratio of the positive separator to the positive current collector loaded with active materials is 1:(5-20).

8. A method for separating the positive electrode active material and the current collector of waste lithium ion batteries according to claim 7, characterized in that: The peeling is promoted by mechanical stirring, and the stirring speed is 100-800 r / min; the peeling time is 5-45 min, and the separation temperature is 20-60 °C.

9. A method for separating the cathode active material and the current collector of waste lithium-ion batteries according to claim 1, 2, 4, 5, 7 or 8, characterized in that: The types of the waste lithium-ion battery packs are at least one of ternary nickel cobalt manganese batteries, lithium iron phosphate batteries, lithium cobalt oxide batteries, lithium manganese oxide batteries, lithium nickel oxide batteries, and ternary nickel cobalt aluminum batteries.

10. A method for separating the positive electrode active material and the current collector of a waste lithium-ion battery according to claim 9, characterized in that: The mesh number of the sieve used for filtration is 50-200 meshes, the drying temperature is 80-120 °C, and the filtrate after solid-liquid separation can be recycled by adding an activator and a positive separator.

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