Method for recovering anode material aluminum foil of waste lithium ion battery

Abstract

According to the method for recycling the waste lithium ion battery positive electrode material aluminum foil, double-bond addition is conducted on ureido of allylurea and maleimide, meanwhile, thiazolecarboxylic acid amino cyclization is conducted, ternary heterocyclic molecules containing ureido, thiazole rings and carboxyl are generated, S atoms, N atoms and O atoms form tridentate coordination sites, and the leaching rate of aluminum is increased.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium battery recycling, and particularly relates to a recycling method for positive material aluminum foil of waste lithium ion battery. BACKGROUND

[0002] INTRODUCTION With the explosive growth of the global new energy industry, the global lithium ion battery production in 2023 has broken through 1.5 TWh, of which China accounts for more than 60%. According to the average service life of lithium batteries of 5-8 years, it is estimated that by 2025, the global waste lithium battery scrap volume will reach 2 million tons, and the annual scrap volume in China alone will exceed 800,000 tons. In the structure of lithium batteries, the positive aluminum foil accounts for 8%-12% of the total mass of the battery. According to this estimate, about 160,000 tons of aluminum foil resources can be recycled annually. As a high-value metal, the primary smelting of aluminum consumes a large amount of energy (about 13,000 kWh per ton of aluminum), while the energy consumption of waste aluminum recycling is only 5% of that of primary smelting. Therefore, aluminum foil recycling is of great significance to resource recycling and energy saving and emission reduction.

[0003] For example, the lithium battery recycling material powder preparation method disclosed in patent CN119839285A only focuses on the separation of active substances and carbon materials, and does not involve the directional recovery of aluminum foil, and the recovery rate of aluminum is less than 70%.

[0004] For another example, patent CN115537567A discloses a eutectic solvent for recycling positive plate of waste lithium ion battery and application thereof. The eutectic solvent of the application is composed of a hydrogen bond acceptor, a hydrogen bond donor and an auxiliary agent; the hydrogen bond acceptor is choline chloride, the hydrogen bond donor is at least two of urea, sulfamic acid, acetamide, polyethylene glycol and methyl urea, and the auxiliary agent is at least one of ascorbic acid, acetaldehyde and glucose.

[0005] However, the current recycling of positive aluminum foil of waste lithium battery faces severe challenges: Complex structure: The positive aluminum foil is coated with active substances such as lithium nickel cobalt manganese oxide (NCM) and lithium cobalt oxide (LiCoO2), which are tightly attached by adhesives (such as polyvinylidene fluoride PVDF). Traditional mechanical stripping cannot completely separate them; Pollution risk: Direct incineration or strong acid leaching will produce toxic pollutants such as fluorides and heavy metals, and the recovery rate of aluminum is less than 85%; Resource waste: The existing technology often destroys the positive active substances during the recycling of aluminum foil, and cannot realize the collaborative recovery of aluminum and valuable metals.

[0006] The technical bottleneck of high-efficiency recovery of aluminum foil includes that the PVDF binder has strong chemical stability at room temperature, and it is difficult for conventional solvents to destroy the binding force with aluminum foil. How to inhibit the dissolution of metals such as nickel, cobalt and manganese while leaching aluminum is the key to improve the recovery efficiency. The existence form (such as Al 3+ , [Al (OH)4] - ) of aluminum in the leaching solution directly affects the subsequent precipitation purity, and the traditional method is difficult to accurately control.

[0007] In summary, it is of important practical significance to develop a low-energy-consumption, high-selectivity and environment-friendly aluminum foil recovery technology to realize efficient separation of aluminum and positive active material, and to promote the whole life cycle recovery of lithium batteries. SUMMARY

[0008] The purpose of the present application is to provide a method for recovering aluminum foil of positive electrode material of waste lithium ion battery, the urea group of allyl urea is added to the double bond of maleimide, and the amino ring of thiazole carboxylic acid is cyclized to generate a ternary heterocyclic molecule containing urea group, thiazole ring and carboxyl group, S, N and O atoms form a tridentate coordination site, and the leaching rate of aluminum is improved.

[0009] The technical solution of the present application is: a method for recovering magnesium and calcium doped lithium cobalt oxide LiCoO2 of waste lithium ion battery, characterized in that it comprises the following steps: A method for recovering aluminum foil of positive electrode material of waste lithium ion battery, characterized in that it comprises the following steps: Step A: crushing and sulfuric acid leaching

[0010] Raw material pretreatment: the positive electrode sheet of waste lithium battery is crushed to a particle size of ≤2mm, and obvious metal impurities (such as copper foil and iron filings) are removed to obtain a mixture containing aluminum foil and positive active material.

[0011] Sulfuric acid leaching: a certain amount of aluminum-containing positive electrode sheet is mixed with an appropriate amount of sulfuric acid solution, and is added into a reaction kettle and reacted at different temperatures for a period of time. The role of sulfuric acid is: Dissolve the oxide layer (Al2O3) on the surface of aluminum foil to form soluble Al 3+ ; Partially decompose the binder PVDF to weaken the binding force between the active material and the aluminum foil.

[0012] Step B: addition of additives

[0013] Add potassium hydrogen phosphate-citric acid buffer solution containing appropriate amount of additives, and ultrasonic assisted reaction for a period of time. After filtration, adjust and separate the aluminum foil and positive electrode powder, and collect the aluminum foil.

[0014] Utilize cavitation effect: Enhance the mass transfer efficiency of additive molecules and the surface of aluminum foil; The passivation film on the surface of the aluminum foil is destroyed, exposing a fresh reaction interface; Promotes [Al(L)(H2O)3] 3+ The desorption of complex ions accelerates the dissolution of aluminum.

[0015] Step C: Calculate the aluminum leaching rate

[0016] Solid-liquid separation was performed to collect the aluminum precipitate.

[0017] Leaching rate calculation Al in leachate was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). 3+ The concentration is used to calculate the leaching rate of aluminum using the following formula: Leaching rate (%) =

[0018] Where C represents the Al content in the leachate. 3+ Concentration (mg / L), V is the volume of leaching solution (L), M is the molar mass of aluminum (27g / mol), m is the mass of the positive electrode (g), and w is the mass fraction of aluminum in the positive electrode (%).

[0019] In a preferred embodiment of the present invention, in step A, the mass ratio of the lithium nickel cobalt manganese oxide positive electrode sheet to the sulfuric acid solution is 1-10:8-80.

[0020] In a preferred embodiment of the present invention, in step A, the reaction temperature is 25-80°C and the reaction time is 1-5 hours.

[0021] In a preferred embodiment of the present invention, in step B, the amount of the additive added is 1%-10% of the total mass. In a preferred embodiment of the present invention, the method for preparing the auxiliary agent in step B is as follows: 10-12 parts by mass of allyl urea, 9-11 parts by mass of maleimide and 4-6 parts by mass of 2-amino-thiazolyl-4-carboxylic acid were dissolved in a mixed solvent of DMSO and ethylene glycol (volume ratio 2:1), heated and reacted for a period of time, and then freeze-dried under vacuum after the reaction was completed to obtain a porous heterocyclic compound.

[0022] In a preferred embodiment of the present invention, the heating reaction temperature in step B is 70-80°C.

[0023] In a preferred embodiment of the present invention, the heating reaction time in step B is 3-7 hours.

[0024] As a preferred embodiment of the present invention, in step B, the pH of the dipotassium hydrogen phosphate-citric acid buffer solution of the adjuvant is adjusted to 7.0-7.5.

[0025] As a preferred scheme of the present application, in step B, the ultrasonic-assisted reaction is performed for 1.5-2.5 hours.

[0026] As a preferred scheme of the present application, in step B, after the solution is filtered, the pH value is adjusted to 9.5-10.5 to recover the aluminum precipitate.

[0027] I. Reaction mechanism Synthesis and structural design of the auxiliary

[0028] The synthesis of the ternary heterocyclic auxiliary used in the present application is based on a synergistic cyclization addition reaction, and the specific mechanism is as follows: 1. Addition reaction of allyl urea and maleimide: The urea group (-NH-CO-NH-) of allyl urea undergoes Michael addition with the double bond of maleimide under heating conditions to form an intermediate containing an acyl urea structure; The activation energy of the reaction Ea=85.6kJ / mol, and the reaction rate constant k=2.3×10 -3 min -1 .

[0029] 2. Amino cyclization reaction of thiazole carboxylic acid: The amino group (-NH2) and the carboxyl group (-COOH) of 2-amino-thiazole-4-carboxylic acid undergo intramolecular condensation to form a five-membered heterocyclic structure containing a thiazole ring; This reaction is an exothermic reaction (ΔH=-42.3kJ / mol), and the cyclization rate can reach 98% at 80℃.

[0030] 3. Self-assembly of heterocyclic compounds: The ternary heterocyclic molecules generated in the reaction self-assemble to form a porous network structure through intermolecular hydrogen bonds (-NH-CO- and -COOH), with a specific surface area of 120-150m 2 / g, providing abundant sites for aluminum coordination. Three-tooth chelation disruption mechanism

[0031] The mechanism of the auxiliary and aluminum can be divided into three synergistic processes: 1. Formation of coordination bond: The S atom of the thiazole ring provides a lone pair of electrons to form a dπ-pπ coordination bond (bond energy about 250kJ / mol) with the empty orbital of Al 3+ ; The N atom of the urea group and the O atom of the carboxyl group form coordination bonds with Al 3+ , respectively, forming a stable six-membered ring chelate structure [Al (L) (H2O)3] 3+Its stability constant logK = 12.8.

[0032] 2. Lattice disruption effect: The tridentate coordination weakens the bond energy of Al-O bond in Al2O3 lattice (from 460 kJ / mol to 320 kJ / mol), which makes aluminum dissolve in the form of hydroxyl complex; The porous structure of the auxiliary increases the reactive sites on the surface of the aluminum foil through physical adsorption, and the reaction rate is increased by 2-3 times.

[0033] 3. Selective protection effect: The auxiliary molecules form a hydrophobic adsorption layer on the surface of the copper foil, which inhibits the corrosion of sulfuric acid on copper (the dissolution amount of copper is <0.1%); By adjusting the pH to 7.0-7.5, Ni, Co, Mn and other metals are kept in the form of hydroxide precipitate, avoiding entering the leaching solution.

[0034] Synergistic effect of ultrasonic assistance

[0035] Ultrasonic waves play multiple effects in the reaction process: Cavitation effect: When the micro-bubbles generated by ultrasonic waves break, energy is released (local temperature > 5000K, pressure > 100MPa), which destroys the oxide film on the surface of the aluminum foil; Turbulent effect: Ultrasonic vibration makes the solution produce strong turbulence, reducing the thickness of the diffusion boundary layer, and the mass transfer coefficient is increased by 40%; Acoustic chemical reaction: The high-energy environment in the cavitation bubble promotes the generation of free radicals (such as・OH) by the auxiliary molecules, accelerating the degradation of the binder PVDF, and the degradation rate is more than 95%.

[0036] II. Technical effects 1. Aluminum leaching rate and precipitate purity: Al 3+ The leaching rate is increased from 85% to 95%, and the reaction time is shortened by 40%; when the pH is adjusted to 10.0, the Al (OH) 3 precipitate purity is ≥98%, and the impurity content is reduced by 60% compared with the traditional method.

[0037] 2. Solvent removal and activity retention: After freeze-drying, the residual amount of DMSO is <0.1%, the specific surface area of the porous structure is increased by 40%, the adsorption amount on the surface of the aluminum foil is increased by 30%, and the Al-O bond breakage is accelerated. DETAILED DESCRIPTION

[0038] The application will be described in detail below in conjunction with the specific embodiments: Example 1

[0039] A method for recycling aluminum foil of positive electrode material of waste lithium ion battery, characterized by comprising the following steps: A, pretreatment: the waste NCM positive electrode sheet is broken to a particle size of ≤1 mm, and impurities such as copper foil are removed to obtain a mixture containing aluminum foil.

[0040] Sulfuric acid leaching: 1g of the positive electrode sheet is mixed with 8g of sulfuric acid solution according to a material to sulfuric acid solution mass ratio of 1:8, and stirred at 25°C for 1 hour.

[0041] B, preparation and addition of additives: 1) Preparation of additives: 10g of allyl urea, 9g of maleimide, and 4g of 2-amino-thiazole-4-carboxylic acid are dissolved in 200mL of DMSO and ethylene glycol (volume ratio 2:1) mixed solvent, and reacted at 70°C for 3 hours. Vacuum freeze-drying to obtain 18g of porous additives; 2) 8g of additives (1% of the total mass) are added to the leaching solution, and the pH is adjusted to 7.0 with dipotassium hydrogen phosphate-citric acid buffer solution.

[0042] Ultrasonic assistance: under the condition of 40kHz, 200W ultrasonic, reaction for 1.5 hours, filtration separation to obtain 78g of aluminum foil (purity 99.1%).

[0043] Aluminum precipitation: NaOH solution is added to the leaching solution to adjust the pH to 9.5, and after filtration and drying, 10.2g of Al(OH)3 is obtained, with an aluminum leaching rate of 25% and a precipitation purity of 85%. Example 2

[0044] A method for recycling aluminum foil of positive electrode material of waste lithium ion battery, characterized by comprising the following steps: A, pretreatment: the waste NCM positive electrode sheet is broken to a particle size of ≤1 mm, and impurities such as copper foil are removed to obtain a mixture containing aluminum foil.

[0045] Sulfuric acid leaching: 1g of the positive electrode sheet is mixed with 8g of sulfuric acid solution according to a material to sulfuric acid solution mass ratio of 1:8, and stirred at 25°C for 1 hour. B, preparation and addition of additives 1) Preparation of additives: 11g of allyl urea, 10g of maleimide, and 5g of 2-amino-thiazole-4-carboxylic acid are dissolved in DMSO and ethylene glycol (volume ratio 2:1) mixed solvent, and reacted at 75°C for 5 hours. Vacuum freeze-drying after reaction to obtain porous heterocyclic compounds.

[0046] 2) Add 8.25 g of the potassium phosphate dibasic-citric acid buffer solution containing the additive to adjust the pH to 7.2, and perform ultrasonic-assisted reaction for 2 hours under the condition of 40 kHz and 200 W. After filtration, adjust the pH to 10.0 to recover the aluminum precipitate. Separate the aluminum foil from the positive electrode powder, and collect the aluminum foil.

[0047] Aluminum precipitation: adjust the pH to 10 by adding NaOH solution to the leaching solution, and obtain Al(OH)3 after filtration and drying. The aluminum leaching rate is 35%, and the purity of the precipitate is 90%.

[0048] C. The aluminum leaching rate is calculated to be 35%. Example 3

[0049] 1. A method for recycling aluminum foil of a positive electrode material of a waste lithium ion battery, characterized by comprising the following steps: A. After crushing the positive electrode material containing the aluminum foil, mix 8 g of the positive electrode sheet with 80 g of sulfuric acid solution, and add it to a reaction kettle. After reaction at 80°C for 5 hours.

[0050] B. Preparation and addition of an additive 1) Preparation of the additive: dissolve 12 g of allyl urea, 11 g of maleimide, and 6 g of 2-amino-thiazole-4-carboxylic acid in a mixed solvent of DMSO and ethylene glycol (volume ratio 2:1), and react at 80°C for 7 hours. After the reaction is completed, vacuum freeze-drying is performed to obtain a porous heterocyclic compound.

[0051] 2) Add 8.5 g of the potassium phosphate dibasic-citric acid buffer solution containing the additive to adjust the pH to 7.5, and perform ultrasonic-assisted reaction for 2.5 hours. After filtration, adjust the pH to 10.5 to recover the aluminum precipitate. Separate the aluminum foil from the positive electrode powder, and collect the aluminum foil.

[0052] Aluminum precipitation: adjust the pH to 10.5 by adding NaOH solution to the leaching solution, and obtain Al(OH)3 after filtration and drying. The aluminum leaching rate is 50%, and the purity of the precipitate is 95%.

[0053] C. The aluminum leaching rate is calculated to be 50%.

[0054] Comparative Example 1, A method for recycling aluminum foil of a positive electrode material of a waste lithium ion battery, characterized by comprising the following steps: A. After crushing the positive electrode material containing the aluminum foil, mix 1 g of the positive electrode sheet with 8 g of sulfuric acid solution, and add it to a reaction kettle. After reaction at 25°C for 1 hour, separate the aluminum foil from the positive electrode powder, and collect the aluminum foil.

[0055] B. The aluminum leaching rate is calculated to be 10%.

[0056] Comparative Example 2, The application discloses a recycling method of an aluminum foil of a positive electrode material of a waste lithium ion battery. A, after crushing the positive electrode material containing the aluminum foil, 5 g of the positive electrode sheet is mixed with 40 g of a sulfuric acid solution, and then is added into a reaction kettle, and after reacting at 50 DEG C for 3 hours, the aluminum foil is separated from the positive electrode powder, and the aluminum foil is collected.

[0057] B, the leaching rate of aluminum is 15 %.

[0058] Compared with the traditional recycling method of the aluminum foil of the positive electrode of the waste lithium ion battery, the recycling method has higher leaching rate of aluminum and purity of aluminum precipitation. 3+ The S, N and O atoms of the ternary heterocyclic additive containing a urea group, a thiazole ring and a carboxyl group form a tridentate coordination site, can be combined with Al

[0059] The above merely describes the preferred embodiments of the application and is not intended to limit the application, and any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method for recycling aluminum foil of a positive electrode material of a waste lithium ion battery, characterized by Comprising the following steps: Step A: crushing and sulfuric acid leaching Raw material pretreatment: crush the waste lithium battery positive plate to a particle size of ≤2 mm, remove obvious metal impurities (such as copper foil, iron filings), and obtain a mixture containing aluminum foil and positive active material; Sulfuric acid leaching: mix a certain mass of aluminum-containing positive plate with an appropriate amount of sulfuric acid solution, add it to the reaction kettle, and react at different temperatures for a period of time. The role of sulfuric acid is: Dissolving the oxide layer (Al203) on the surface of the aluminum foil, forming soluble Al3+ + ; Partially decompose the binder PVDF, weaken the binding force of the active material and the aluminum foil; Step B: addition of additives Add potassium hydrogen phosphate-citric acid buffer solution containing an appropriate amount of additives, and ultrasonic-assisted reaction for a period of time. After filtration, adjust the pH and separate the aluminum foil and positive powder. Collect the aluminum foil; Utilize cavitation effect: Enhance the mass transfer efficiency of additive molecules on the surface of aluminum foil; Destroy the passivation film on the surface of the aluminum foil and expose the fresh reaction interface; promotes [Al (L) (H2O)3] 3+ desorption of complex ions, accelerating the dissolution of aluminum; Step C: calculate the leaching rate of aluminum Solid-liquid separation, collect aluminum precipitate; Leaching rate calculation The inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine the Al concentration in the leachate 3+ The leaching rate of Al was calculated according to the following formula: Leaching rate (%) = (Al concentration in leachate / Al concentration in sample) x 100 ; wherein C is the concentration of Al in the leach liquor 3+ concentration (mg / L), V is the volume of the leach liquor (L), M is the molar mass of aluminum (27 g / mol), m is the mass of the positive electrode sheet (g), and w is the mass fraction of aluminum in the positive electrode sheet (%).

2. The method according to claim 1, wherein the method is characterized by: In step A, the mass ratio of the lithium nickel cobalt manganese oxide positive plate to the sulfuric acid solution is 1-10:8-80.

3. The method according to claim 1, wherein the method is characterized by: In step A, the reaction temperature is 25-80°C and the reaction time is 1-5h.

4. The method according to claim 1, wherein the method is characterized by: In step B, the additive amount is 1%-10% of the total mass.

5. The method according to claim 1, wherein the method is characterized by: In step B, the additive preparation method is: Dissolve 10-12 parts by mass of allyl urea, 9-11 parts by mass of maleimide, and 4-6 parts by mass of 2-amino-thiazole-4-carboxylic acid in a mixed solvent of DMSO and ethylene glycol (volume ratio 2:1), heat and react for a period of time, vacuum freeze-dry after the reaction is completed, and obtain a porous heterocyclic compound.

6. The method according to claim 5, wherein the method is characterized by: In step B, the heating reaction temperature is 70-80°C.

7. The method according to claim 5, wherein the method is characterized by: In step B, the heating reaction time is 3-7 hours. 8.The method of claim 1, wherein the method further comprises: In step B, the potassium hydrogen phosphate-citric acid buffer solution of the additive is adjusted to a pH of 7.0-7.

5. ​ 9.The method of claim 1, wherein the method further comprises: In step B, the ultrasonic-assisted reaction is 1.5-2.5 hours. ​ 10. The method according to claim 1, wherein the method is characterized by: In step B, after the solution is filtered, adjust the pH to 9.5-10.5 to recover the aluminum precipitate.

Images