Method for recycling high-purity graphite from negative electrode of waste lithium battery by using fine washing agent

Abstract

The invention relates to a method for recycling high-purity graphite from a negative electrode of a waste lithium battery by using a fine washing agent. The method comprises the following steps: preliminarily disassembling the waste lithium battery negative electrode to separate out a negative electrode plate; crushing and screening the negative plate by adopting a machine crusher, and collecting screened fine powder; carrying out heat treatment to remove the binder and other organic matters; stirring and soaking the graphite powder subjected to heat treatment, inorganic acid, sodium carbonate and a fine washing agent; filtering, washing a filter cake with deionized water, and drying to obtain high-purity graphite; the fine cleaning agent is prepared by the following steps: continuously irradiating acrylamide-beta-cyclodextrin, tetramercapto porphyrin, 1-butylene-2, 3, 4-tricarboxylic acid, dimethyl sulfoxide and a photoinitiator at room temperature for 30-80 minutes by keeping ultraviolet light of 365 nm and 10 mW / cm < 2 >, and distilling to remove dimethyl sulfoxide. The fixed carbon content of the recovered graphite can reach 99.98%.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling of the negative electrodes of waste lithium batteries, and in particular to a method for recycling high-purity graphite from the negative electrodes of waste lithium batteries using a refining agent. Background Art

[0002] The popularization of new energy vehicles is an important strategic choice to promote green development and ensure energy security, and is also a key measure for the automotive industry to achieve carbon emission reduction. As the core driving force of new energy vehicles, the clean treatment and efficient utilization of lithium-ion power batteries after retirement are directly related to whether the electric vehicle industry can achieve green and sustainable development.

[0003] In the composition of lithium-ion batteries, graphite is widely used in the preparation of negative electrode materials for lithium-ion batteries due to its significant advantages such as high reversible capacity and good cycle stability. Therefore, high attention should be paid to the recycling treatment and resource recycling of graphite negative electrode materials.

[0004] Currently, there are already some related patented technologies for recycling the negative electrodes of waste lithium batteries:

[0005] Chinese Patent CN117699793A: This patent belongs to the technical field of resource recycling, and relates to a method for recycling graphite negative electrodes, a nitrogen-doped graphite filler, and a method for treating wastewater. The specific recycling method is as follows: First, grind the waste graphite negative electrode material, then soak it in an acidic solution, and perform operations such as stirring, filtering, and washing; then mix the washed waste graphite negative electrode material with a nitrogen-doped solution containing calcium chloride and polyacrylamide and carrier particles, and then stir and granulate to obtain graphite particles mixed with a nitrogen source; finally, sinter the graphite particles anaerobically at a temperature of 900-1100°C for 1-3 hours to obtain a nitrogen-doped graphite filler.

[0006] Chinese Patent CN118486939A: Provides a carbon-coated graphite material and its preparation method using the negative electrode material and separator in waste batteries as raw materials. The steps of this method are as follows: First, obtain the graphite negative electrode sheet and separator in waste batteries; then sequentially perform water washing, acid washing, centrifugal water washing, drying, and pre-calcination on the graphite negative electrode sheet, and then screen it to obtain graphite black powder with a particle size D50 of 5-18 μm; wash, dry, and airflow crush the separator to obtain separator powder with a particle size D50 of 2-4 μm; finally, mix the graphite black powder and separator powder, place it in an inert atmosphere for carbonization treatment, and then perform operations such as dispersion and depolymerization, screening, and demagnetization to obtain a carbon-coated graphite material with a particle size D50 of 7-20 μm.

[0007] Chinese Patent CN118198570B: Belonging to the technical field of battery material recycling, a high-rate regenerated graphite anode material, its preparation method and application are provided. The preparation steps are as follows: First, discharge the used lithium-ion battery to below 2V, disassemble the used graphite anode sheet, clean and dry it with dimethyl carbonate, and then separate the waste graphite from the copper foil by knocking to obtain the graphite to be recycled; then calcine the graphite to be recycled at medium and high temperatures to obtain purified graphite; then mix the purified graphite, modified phenolic resin, non-ionic surfactant and ethanol, stir magnetically for 3-5h, filter and dry until all the ethanol volatilizes to obtain a solid; finally, carbonize the solid in a nitrogen atmosphere at 1000°C for 9-10h to obtain the high-rate regenerated graphite anode material.

[0008] However, in the above patent and the existing related technologies, when recycling the anode of used lithium batteries, there are generally problems of relatively high metal impurity content and relatively low fixed carbon content. Summary of the Invention

[0009] To solve the above problems, the present invention provides a method for recycling high-purity graphite from the anode of used lithium batteries using a refining agent, and its operation steps are as follows:

[0010] S1 Pretreatment by manual disassembly device: Use a general-purpose battery disassembly tool to preliminarily disassemble the used lithium battery and separate the anode sheet;

[0011] S2 Machine crushing: Use a machine crusher model XYZ-123 to crush the anode sheet into particles with a particle size less than 2 cm;

[0012] S3 Screening: Remove large particles and impurities through a screening device model ABC-456, and collect the fine powder passing through the sieve;

[0013] S4 Heat treatment: Conduct heat treatment in a heat treatment furnace model DEF-789 to remove the binder and other organic substances;

[0014] S5 Acid leaching: Add 17-22 parts of the heat-treated graphite powder to the soaking container, and then add 100-200 parts of inorganic acid, 1-5 parts of sodium carbonate, and 0.05-0.5 parts of refining agent, stir and soak;

[0015] S6 Filtration and washing: Perform solid-liquid separation, and wash the filter cake with deionized water until the pH value of the washed water is close to neutral;

[0016] S7 Drying: Heat up and dry to constant weight to obtain high-purity graphite.

[0017] The heat treatment temperature in S4 is 300-400°C, and the time is 30-50 min.

[0018] The inorganic acid described above is one of phosphoric acid, sulfuric acid, nitric acid, and hydrochloric acid.

[0019] The soaking temperature of S5 is 70 - 90 °C, and the time is 100 - 150 min.

[0020] The stirring rate of S5 is 100 - 300 rpm.

[0021] The drying temperature of S7 is 50 - 120 °C.

[0022] The preparation method of the fine cleaning agent is as follows:

[0023] By mass fraction, add 10 - 20 parts of acrylamido-β-cyclodextrin (CAS No. 131991 - 70 - 3), 50 - 100 parts of tetramercapto porphyrin, 2 - 6 parts of 1-butene-2,3,4-tricarboxylic acid (CAS No.: 26326 - 05 - 6), 1000 - 1200 parts of dimethyl sulfoxide, and 0.05 - 0.5 parts of photoinitiator. Under room temperature conditions, keep ultraviolet light at 365 nm and 10 mW / cm 2 Continuously irradiate for reaction for 30 - 80 minutes, and distill off dimethyl sulfoxide to obtain the fine cleaning agent.

[0024] Reaction mechanism

[0025] Under ultraviolet light initiation, the double bond in acrylamido-β-cyclodextrin undergoes a thiol click chemical reaction with the thiol group in tetramercapto porphyrin; the thiol group is excited by ultraviolet light to generate free radicals, which then attack the double bond to form a cross-linked structure, and finally a polymer material containing porphyrin and cyclodextrin is obtained.

[0026] Under ultraviolet light irradiation, the carbon-carbon double bond in 1-butene-2,3,4-tricarboxylic acid undergoes a thiol click chemical reaction with the thiol group in tetramercapto porphyrin; the thiol free radical attacks the double bond to form a new carbon-sulfur bond, and a complex polymer structure containing multiple carboxyl groups and porphyrin is generated through multiple addition reactions.

[0027] Technical effects

[0028] A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using the fine cleaning agent of the present invention has the following remarkable effects compared with the prior art:

[0029] 1. The present invention uses porphyrin, tricarboxylic acid, and phosphoric acid to synergistically purify graphite. Porphyrin and tricarboxylic acid first form stable complexes with metal ions, and then phosphoric acid dissolves metal impurities to purify graphite. This process includes steps such as complexation, dissolution, and separation, ensuring efficient impurity removal and purification.

[0030] 2. The present invention not only improves the purity of graphite but also reduces environmental pollution. This technology has broad application prospects in the industry, can promote the development of the battery recycling industry, and achieve the effective utilization of resources. Detailed implementation mode

[0031] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in combination with preferred embodiments, details the specific implementation mode, structure, characteristics and their effects of the present invention as follows.

[0032] Determination of fixed carbon content: Detection is carried out with reference to GB / T24533 - 2019.

[0033] Example 1

[0034] A method for recycling high - purity graphite from the negative electrode of waste lithium batteries using a refining agent, the operation steps of which are as follows:

[0035] S1 Pretreatment of manual disassembly device: Use a general - type battery disassembly tool to preliminarily disassemble the waste lithium battery and separate the negative electrode sheet.

[0036] S2 Machine crushing: Use a machine crusher with the model XYZ - 123 to crush the negative electrode sheet into particles with a particle size less than 2 cm.

[0037] S3 Screening: Pass through a screening device with the model ABC - 456 to remove large particles and impurities, and collect the fine powder passing through the sieve mesh.

[0038] S4 Heat treatment: Conduct heat treatment in a heat treatment furnace with the model DEF - 789 to remove the binder and other organic substances.

[0039] S5 Acid leaching: Add 17 g of heat - treated graphite powder to the soaking container, and then continue to add 100 g of inorganic acid, 1 g of sodium carbonate, and 0.05 g of refining agent, stir and soak.

[0040] S6 Filtration and washing: Conduct solid - liquid separation, and wash the filter cake with deionized water until the pH value of the washed - out water is close to neutral.

[0041] S7 Drying: Heat up and dry to constant weight to obtain high - purity graphite.

[0042] The heat treatment temperature in S4 is 300 °C and the time is 30 min.

[0043] The inorganic acid is phosphoric acid.

[0044] The soaking temperature in S5 is 70 °C and the time is 100 min.

[0045] The stirring rate in S5 is 100 rpm.

[0046] The drying temperature of the S7 is 50 °C.

[0047] The preparation method of the fine cleaning agent is as follows:

[0048] 10 g of acrylamido-β-cyclodextrin (CAS No. 131991-70-3), 50 g of tetramercapto porphyrin, 2 g of 1-butene-2,3,4-tricarboxylic acid (CAS No.: 26326-05-6), 1000 g of dimethyl sulfoxide, and 0.05 g of photoinitiator are kept under ultraviolet light at 365 nm and 10 mW / cm 2 Irradiate continuously for 30 minutes, and distill off dimethyl sulfoxide to obtain the fine cleaning agent.

[0049] Example 2

[0050] A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a fine cleaning agent, and its operation steps are as follows:

[0051] S1 Pretreatment by manual disassembly device: Use a general-purpose battery disassembly tool to preliminarily disassemble the waste lithium battery and separate the negative electrode sheet;

[0052] S2 Machine crushing: Use a machine crusher with the model XYZ-123 to crush the negative electrode sheet into particles with a particle size less than 2 cm;

[0053] S3 Screening: Remove large particles and impurities through a screening device with the model ABC-456, and collect the fine powder passing through the sieve;

[0054] S4 Heat treatment: Conduct heat treatment in a heat treatment furnace with the model DEF-789 to remove the binder and other organic substances;

[0055] S5 Acid leaching: Add 19 g of heat-treated graphite powder to the soaking container, and then continue to add 140 g of inorganic acid, 2 g of sodium carbonate, and 0.2 g of the fine cleaning agent, stir, and soak;

[0056] S6 Filtration and washing: Perform solid-liquid separation, and wash the filter cake with deionized water until the pH value of the washed water is close to neutral;

[0057] S7 Drying: Heat up and dry to constant weight to obtain high-purity graphite.

[0058] The heat treatment temperature of the S4 is 340 °C, and the time is 35 min.

[0059] The inorganic acid is sulfuric acid.

[0060] The soaking temperature of the S5 is 75 °C, and the time is 110 min.

[0061] The stirring rate of the S5 is 150 rpm.

[0062] The drying temperature of the S7 is 70 °C.

[0063] The preparation method of the fine cleaning agent is as follows:

[0064] 13 g of acrylamido-β-cyclodextrin (CAS No. 131991-70-3), 60 g of tetramercapto porphyrin, 3 g of 1-butene-2,3,4-tricarboxylic acid (CAS No.: 26326-05-6), 1050 g of dimethyl sulfoxide, and 0.2 g of photoinitiator are kept under ultraviolet light at 365 nm and 10 mW / cm 2 Irradiate continuously for 50 minutes, and distill off dimethyl sulfoxide to obtain the fine cleaning agent.

[0065] Example 3

[0066] A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a fine cleaning agent, and its operation steps are as follows:

[0067] S1 Manual disassembly device pretreatment: Use a general-purpose battery disassembly tool to preliminarily disassemble the waste lithium battery and separate the negative electrode sheet;

[0068] S2 Machine crushing: Use a machine crusher of model XYZ-123 to crush the negative electrode sheet into particles with a particle size less than 2 cm;

[0069] S3 Screening: Remove large particles and impurities through a screening device of model ABC-456, and collect the fine powder passing through the sieve;

[0070] S4 Heat treatment: Conduct heat treatment in a heat treatment furnace of model DEF-789 to remove the binder and other organic substances;

[0071] S5 Acid leaching: Add 21 g of heat-treated graphite powder to the soaking container, and continue to add 180 g of inorganic acid, 4 g of sodium carbonate, and 0.4 g of fine cleaning agent, stir and soak;

[0072] S6 Filtration and washing: Perform solid-liquid separation, and wash the filter cake with deionized water until the pH value of the washed water is close to neutral;

[0073] S7 Drying: Heat up and dry to constant weight to obtain high-purity graphite.

[0074] The heat treatment temperature of the S4 is 380 °C, and the time is 45 min.

[0075] The inorganic acid is nitric acid.

[0076] The soaking temperature of the S5 is 85 °C, and the time is 140 min.

[0077] The stirring rate of the described S5 is 250 rpm.

[0078] The drying temperature of the described S7 is 100 °C.

[0079] The preparation method of the described detergent is as follows:

[0080] 18 g of acrylamido-β-cyclodextrin (CAS No. 131991-70-3), 90 g of tetramercapto porphyrin, 5 g of 1-butene-2,3,4-tricarboxylic acid (CAS No.: 26326-05-6), 1150 g of dimethyl sulfoxide, and 0.4 g of photoinitiator are kept under ultraviolet light at 365 nm and 10 mW / cm 2 Irradiate continuously for 70 minutes, and distill off dimethyl sulfoxide to obtain the detergent.

[0081] Example 4

[0082] A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a detergent, and its operation steps are as follows:

[0083] S1 Pretreatment with manual disassembly device: Use a general-purpose battery disassembly tool to preliminarily disassemble the waste lithium battery and separate the negative electrode sheet;

[0084] S2 Machine crushing: Use a machine crusher with model XYZ-123 to crush the negative electrode sheet into particles with a particle size less than 2 cm;

[0085] S3 Screening: Remove large particles and impurities through a screening device with model ABC-456, and collect the fine powder passing through the sieve;

[0086] S4 Heat treatment: Conduct heat treatment in a heat treatment furnace with model DEF-789 to remove the binder and other organic substances;

[0087] S5 Acid leaching: Add 22 g of heat-treated graphite powder to the soaking container, and then add 200 g of inorganic acid, 5 g of sodium carbonate, and 0.5 g of detergent, stir, and soak;

[0088] S6 Filtration and washing: Perform solid-liquid separation, and wash the filter cake with deionized water until the pH value of the washed water is close to neutral;

[0089] S7 Drying: Heat and dry to constant weight to obtain high-purity graphite.

[0090] The heat treatment temperature of the described S4 is 400 °C, and the time is 50 min.

[0091] The inorganic acid is hydrochloric acid.

[0092] The soaking temperature of the described S5 is 90 °C, and the time is 150 min.

[0093] The stirring rate of the described S5 is 300 rpm.

[0094] The drying temperature of the described S7 is 120 °C.

[0095] The preparation method of the described detergent is as follows:

[0096] 20 g of acrylamido-β-cyclodextrin (CAS No. 131991-70-3), 100 g of tetramercapto porphyrin, 6 g of 1-butene-2,3,4-tricarboxylic acid (CAS No.: 26326-05-6), 1200 g of dimethyl sulfoxide, and 0.5 g of photoinitiator are kept under ultraviolet light at 365 nm and 10 mW / cm 2 continuously irradiated for 80 minutes, and the dimethyl sulfoxide is removed by distillation to obtain the detergent.

[0097] Comparative Example 1

[0098] The detergent is not added, and the others are the same as in Example 1.

[0099] Comparative Example 2

[0100] Tetramercapto porphyrin is not added, and the others are the same as in Example 1.

[0101] Comparative Example 3

[0102] 1-Butene-2,3,4-tricarboxylic acid is not added, and the others are the same as in Example 1.

[0103] Fixed carbon content / % Example 1 99.88 Example 2 99.91 Example 3 99.95 Example 4 99.98 Comparative Example 1 88.67 Comparative Example 2 95.32 Comparative Example 3 96.19

[0104] Through the data analysis of the above examples and comparative examples, the fixed carbon content of the recovered graphite in the present invention can be as high as 99.98%.

[0105] As mentioned above, it is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a refining agent, and its operation steps are as follows: S1 Pretreatment of manual disassembly device: Use a general-purpose battery disassembly tool to preliminarily disassemble the waste lithium battery and separate the negative electrode sheet; S2 Machine crushing: Use a machine crusher to crush the negative electrode sheet into particles with a particle size less than 2 cm; S3 Screening: Remove large particles and impurities through a screening device and collect the fine powder passing through the sieve; S4 Heat treatment: Conduct heat treatment in a heat treatment furnace to remove the binder and other organic substances; S5 Acid leaching: Add 17 - 22 parts of the heat-treated graphite powder to an immersion container, and then continue to add 100 - 200 parts of inorganic acid, 1 - 5 parts of sodium carbonate, and 0.05 - 0.5 parts of the refining agent, stir, and immerse; S6 Filtration and washing: Perform solid-liquid separation and wash the filter cake with deionized water until the pH value of the washed water is close to neutral; S7 Drying: Heat up and dry to constant weight to obtain high-purity graphite.

2. A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a refining agent, characterized in that: The heat treatment temperature in S4 is 300 - 400 °C, and the time is 30 - 50 min.

3. A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a refining agent, characterized in that: The inorganic acid is one of phosphoric acid, sulfuric acid, nitric acid, and hydrochloric acid.

4. A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a refining agent, characterized in that: The immersion temperature in S5 is 70 - 90 °C, and the time is 100 - 150 min.

5. A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a refining agent, characterized in that: The stirring rate in S5 is 100 - 300 rpm.

6. A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a refining agent, characterized in that: The drying temperature in S7 is 50 - 120 °C.

7. A method for recycling high-purity graphite from the negative electrode of waste lithium batteries using a refining agent, characterized in that: The preparation method of the refining agent is as follows: According to the mass parts, 10 - 20 parts of acrylamide - β - cyclodextrin, 50 - 100 parts of tetramercapto porphyrin, 2 - 6 parts of 1 - butene - 2,3,4 - tricarboxylic acid, 1000 - 1200 parts of dimethyl sulfoxide, and 0.05 - 0.5 part of photoinitiator are kept under ultraviolet light at 365 nm and 10 mW / cm 2 for continuous irradiation reaction for 30 - 80 minutes, and dimethyl sulfoxide is removed by distillation to obtain a fine washing agent.