Method for stripping lithium-ion battery electrode sheets and use thereof

Abstract

The present application relates to the technical field of lithium ion battery recycling, in particular to a method for stripping lithium ion battery pole piece and application thereof. The method for stripping lithium ion battery pole piece comprises: immersing the pole piece into a mixed solution containing a stripping agent and a stripping aid for reaction, and obtaining the separated active material layer and the current collector layer after a period of time; the stripping agent comprises a carboxylic acid containing at least two carboxyl groups; the stripping aid comprises at least one of sodium fluoride, potassium fluoride, ammonium fluoride, phosphoric acid, sodium phosphate, monosodium phosphate, sodium metaphosphate, potassium phosphate, monopotassium phosphate, potassium metaphosphate, ammonium phosphate, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, inositol hexaphosphate and its salt, inositol pentaphosphate and its salt, inositol tetraphosphate and its salt, and inositol triphosphate and its salt. The method can realize the separation of the active material and the current collector, the hydrogen production amount is small during the whole stripping process, the current collector obtained after stripping is intact, the separation time is short, and the separation efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery recycling technology, specifically to a method for stripping lithium-ion battery electrodes and its application; more specifically, to a method for stripping lithium-ion battery electrodes and a method for recycling lithium-ion battery electrodes. Background Technology

[0002] Recycling waste lithium-ion batteries is of great significance, and one of the key technologies is how to effectively separate the active material from the current collector.

[0003] Existing technologies often use organic solvents such as N-methylpyrrolidone, acetone, and tetrachloroethylene to strip the positive electrode sheet. However, organic solvents are harmful to the environment and are not conducive to environmental protection.

[0004] To address the aforementioned issues, CN107394299A discloses a method for recycling positive electrode sheets of lithium-ion batteries. After removing the binder PVDF by high-temperature sintering at 300-600℃, the active material and current collector are separated by physical removal. However, the high-temperature sintering process generates waste gases containing fluorine, which pollute the environment. At the same time, the pyrometallurgical process is energy-intensive, and some active material remains on the surface of the current collector, resulting in poor separation efficiency.

[0005] CN107706481A discloses a separation method in which lithium-ion battery electrodes are soaked in an alkaline solution for 10-13 hours to dissolve copper / aluminum current collectors and obtain filter residue containing electrode materials. However, this method, like the direct dissolution of copper / aluminum foil with inorganic acids (such as hydrochloric acid), generates a large amount of H2, produces a significant amount of heat during the reaction, and places high demands on equipment and control, while also requiring a long separation time. Furthermore, the conductive carbon black in the electrode sheets adsorbs high concentrations of aluminum ions from the solution, making it difficult to remove and increasing the difficulty of subsequent impurity removal processes, thus affecting the electrochemical performance of the regenerated cathode material.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The primary objective of this invention is to provide a method for stripping lithium-ion battery electrodes. This method produces less hydrogen during the stripping process, has a fast separation speed, requires less time, and has high separation efficiency. Furthermore, it does not require the use of organic solvents such as NMP, making it green and pollution-free. The stripping waste liquid generated after separation has a simple composition and is easy to treat. There is also no high-temperature calcination process, no harmful gas emissions, and low equipment requirements.

[0008] The second objective of this invention is to provide a method for recycling lithium-ion battery electrodes.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] This invention provides a method for stripping lithium-ion battery electrodes, comprising the following steps:

[0011] The electrode is immersed in a mixture containing a stripping agent and a stripping aid for reaction. After a period of time, the separated active material layer and current collector layer are obtained.

[0012] The stripping agent comprises a carboxylic acid containing at least two carboxyl groups;

[0013] The stripping agent includes at least one of sodium fluoride, potassium fluoride, ammonium fluoride, phosphoric acid, sodium phosphate, sodium monohydrogen phosphate, sodium metaphosphate, potassium phosphate, potassium monohydrogen phosphate, potassium metaphosphate, ammonium phosphate, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, inositol hexaphosphate and its salts, inositol pentaphosphate and its salts, inositol tetraphosphate and its salts, and inositol triphosphate and its salts.

[0014] Preferably, the stripping agent comprises at least one selected from oxalic acid, citric acid, malic acid, succinic acid, pectic acid, malonic acid, and tartaric acid.

[0015] Preferably, the mass fraction of the stripping agent in the mixture is 0.05% to 50%, more preferably 5% to 30%.

[0016] Preferably, the mass fraction of the stripping agent in the mixture is 0.005% to 10%, more preferably 0.01% to 5%.

[0017] Preferably, the mass ratio of the electrode to the mixture is 1:5 to 100, and more preferably 1:10 to 80.

[0018] Preferably, during the reaction, the temperature of the mixture is 20–80°C, more preferably 30–50°C.

[0019] Preferably, the reaction time is 1 to 15 minutes.

[0020] Preferably, the binder in the electrode includes an oil-based binder and / or a water-based binder.

[0021] Preferably, the electrode includes a positive electrode and / or a negative electrode.

[0022] The present invention also provides a method for recycling lithium-ion battery electrodes, including the method of stripping lithium-ion battery electrodes as described above.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The method for stripping lithium-ion battery electrodes provided by the present invention, by using a combination of specific stripping agents and stripping aids, can not only achieve the separation of active material and current collector, but also produce less hydrogen during the entire stripping process and the current collector obtained after stripping is intact.

[0025] (2) The method for stripping lithium-ion battery electrodes provided by the present invention has a short separation time, high separation efficiency, and can achieve 100% separation of active material and current collector.

[0026] (3) The method for stripping lithium-ion battery electrodes provided by the present invention does not use highly toxic organic solvents such as NMP, is green and pollution-free, and the stripping waste liquid generated after separation has simple composition and is easy to treat, with low environmental protection costs; there is no high-temperature calcination process, so energy consumption is low, and there is no corrosive waste gas containing fluorine due to the decomposition of binder, which reduces the emission of harmful gases and has little pollution to the atmospheric environment; the equipment requirements are low and it can be mass-produced.

[0027] (4) The method for peeling off lithium-ion battery electrodes provided by the present invention is applicable to both oil-based and water-based adhesives, and can be used to peel off various positive and negative electrode sheets, with a wide range of applications. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0029] In a first aspect, the present invention provides a method for stripping lithium-ion battery electrodes, comprising the following steps:

[0030] The electrode is immersed in a mixture containing a stripping agent and a stripping aid for reaction. After a period of time, the separated active material layer and current collector layer are obtained.

[0031] In some specific embodiments of the present invention, the electrode includes a current collector layer and an active material layer stacked together; optionally (optionally optional) it also includes a transition layer, which is disposed between the current collector layer and the active material layer.

[0032] In some specific embodiments of the present invention, the active material layer and / or the transition layer are mainly composed of at least one of the active material, alumina, and binder.

[0033] The stripping agent includes a carboxylic acid, which contains at least two carboxyl groups.

[0034] The stripping agent includes at least one of sodium fluoride, potassium fluoride, ammonium fluoride, phosphoric acid, sodium phosphate, sodium monohydrogen phosphate, sodium metaphosphate, potassium phosphate, potassium monohydrogen phosphate, potassium metaphosphate, ammonium phosphate, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, inositol hexaphosphate and its salts, inositol pentaphosphate and its salts, inositol tetraphosphate and its salts, and inositol triphosphate and its salts.

[0035] The inositol hexaphosphate and its salts refer to at least one of inositol hexaphosphate and inositol hexaphosphate, and inositol hexaphosphate includes, but is not limited to, at least one of sodium inositol hexaphosphate and potassium inositol hexaphosphate.

[0036] Inositol pentaphosphate and its salts refer to at least one of inositol pentaphosphate and inositol pentaphosphate, and inositol pentaphosphate includes, but is not limited to, at least one of sodium inositol pentaphosphate and potassium inositol pentaphosphate.

[0037] Inositol tetraphosphate and its salts refer to at least one of inositol tetraphosphate and inositol tetraphosphate, and inositol tetraphosphate includes, but is not limited to, at least one of sodium inositol tetraphosphate and potassium inositol tetraphosphate.

[0038] Inositol triphosphate and its salts refer to at least one of inositol triphosphate and inositol triphosphate, and inositol triphosphate includes, but is not limited to, at least one of sodium inositol triphosphate and potassium inositol triphosphate.

[0039] This invention involves immersing (soaking) waste electrodes in a specific stripping reagent (i.e., a mixture containing a stripping agent and a stripping aid). The stripping agent reacts with substances such as alumina at the electrode interface and / or the surface of the current collector to generate metal ions, such as aluminum ions. Simultaneously, the stripping aid and / or the stripping agent react with metal ions such as aluminum ions to form insoluble precipitates or strong complexes. On the one hand, this promotes the reaction between carboxylic acid and substances such as alumina and / or the surface of the current collector, corroding the interface layer and achieving the separation of the active material from the current collector, thus improving the separation efficiency. On the other hand, the generated precipitates or complexes cover the surface of the current collector to prevent further corrosion of the current collector by the carboxylic acid.

[0040] The method for stripping lithium-ion battery electrodes provided by this invention produces little hydrogen during the entire stripping process, the current collector obtained after stripping is intact, the separation time is short, the separation efficiency is high, and it can achieve 100% separation of active material from the current collector (there is no active material on the current collector after stripping).

[0041] Furthermore, the method for stripping lithium-ion battery electrodes provided by this invention does not use highly toxic organic solvents such as NMP, making it green and pollution-free. The stripping waste liquid generated after separation has a simple composition and is easy to treat, resulting in low environmental protection costs. There is no high-temperature calcination process, resulting in low energy consumption. It does not generate corrosive waste gas containing fluorine due to the decomposition of binders, reducing the emission of harmful gases and minimizing air pollution. It also has low equipment requirements and can be mass-produced.

[0042] In some specific embodiments of the present invention, the stripping agent can react with metal ions such as aluminum ions to form insoluble precipitates or strong complexes, and some stripping agents can also react with metal ions such as aluminum ions to form insoluble precipitates or strong complexes.

[0043] In some specific embodiments of the present invention, when the active material layer and the current collector layer have been observed to have separated after a period of reaction, the reaction can be stopped, and the separated active material layer and current collector layer can be taken out from the mixture respectively.

[0044] Preferably, the stripping agent comprises at least one selected from oxalic acid, citric acid, malic acid, succinic acid, pectic acid, malonic acid, and tartaric acid.

[0045] The present invention can control the stripping efficiency, the amount of active material dissolved, and the amount of hydrogen produced by adjusting parameters such as the concentration of the stripping agent and stripping aid, and the reaction temperature.

[0046] To further consider the stripping efficiency, the amount of active material dissolved, and the amount of hydrogen generated, this invention optimizes parameters such as the mass fraction of the stripping agent and stripping aid, the ratio of the electrode to the mixture, the reaction temperature, and the time.

[0047] Preferably, the mass fraction of the stripping agent in the mixture is 0.05% to 50%, including but not limited to any one of 0.08%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 35%, 40%, 45%, and 48%, or a range between any two; more preferably, it is 5% to 30%.

[0048] Preferably, the mass fraction of the stripping agent in the mixture is 0.005% to 10%, including but not limited to any one of 0.008%, 0.01%, 0.02%, 0.03%, 0.05%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%, 0.9%, 1%, 3%, 5%, and 8%, or a range between any two; more preferably, it is 0.01% to 5%.

[0049] Preferably, the mass ratio of the electrode to the mixture is 1:5 to 100, including but not limited to any one of 1:8, 1:10, 1:15, 1:20, 1:25, 1:28, 1:35, 1:40, 1:50, 1:60, 1:70, 1:80, and 1:90, or any range between the two; more preferably, it is 1:10 to 80.

[0050] Preferably, during the reaction process, the temperature of the mixture is 20 to 80°C, including but not limited to any one of 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, and 75°C, or a range between any two; more preferably, it is 30 to 50°C.

[0051] Preferably, the reaction time is 1 to 15 minutes, including but not limited to any one of 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, and 14 minutes, or any range between two of them.

[0052] In some specific embodiments of the present invention, during the reaction process, the pH of the mixture is <5, including but not limited to any one of 4.5, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.5, or a range between any two. Specifically, the pH of the mixture can be controlled by adjusting the concentration and amount of the stripping agent and / or stripping aid.

[0053] In some specific embodiments of the present invention, during the reaction process, the electrode and the mixture are uniformly mixed by perturbation. Preferably, the perturbation method includes at least one of stirring, ultrasound, and gas introduction, but is not limited thereto.

[0054] Preferably, the binder in the electrode includes an oil-based binder and / or a water-based binder.

[0055] Some existing stripping agents utilize the ionization of weak acids or alkali metal phosphates to release H+. + / OH - It interrupts and disrupts the ion-dipole interactions and hydrogen bonding interactions between the copolymer binder contained in the coating and the surface of the metal substrate. However, this stripping agent can only handle water-based binders, has a limited scope of application, and low stripping efficiency.

[0056] The method for stripping lithium-ion battery electrodes provided by this invention utilizes H in organic acids. +The active material reacts with the oxide layer, such as Al2O3, on the surface of the current collector and / or Al on the surface of the current collector, thereby destroying the interfacial layer and achieving separation of the active material from the current collector. This method is applicable to both oil-based and water-based binders and can be used to peel off various positive and negative electrode sheets. It has a wide range of applications and high peeling efficiency.

[0057] Taking the oxide layer containing Al2O3 and the aluminum current collector as an example, the reaction equations involved include: 6H + +Al₂O₃→2Al 3+ +3H₂O;6H + +2Al→2Al 3+ +3H2↑.

[0058] Preferably, the electrode includes a positive electrode and / or a negative electrode.

[0059] Secondly, the present invention provides a method for recycling lithium-ion battery electrodes, including the method for stripping lithium-ion battery electrodes as described above.

[0060] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0061] In the following embodiments of the present invention, the binder used in the waste positive electrode sheets is an oil-based binder, polyvinylidene fluoride (PVDF).

[0062] Example 1

[0063] The method for stripping lithium-ion battery electrodes provided in this embodiment includes the following steps:

[0064] The discarded NCM111 positive electrode sheet was cut into 2.5cm × 2.5cm pieces and immersed in a mixture containing KF and malic acid. The mass fraction of KF in the mixture was 0.5%, the mass fraction of malic acid in the mixture was 5%, and the mass ratio of the electrode sheet to the volume of the mixture was 1:20. The reaction was carried out at 35°C with magnetic stirring at 400 rpm. After 11 minutes of reaction, the active material layer and the current collector layer were removed. It was found that the current collector and the active material were completely separated (no active material was adhering to the surface of the current collector), with a separation efficiency of 100%. The obtained Al foil (aluminum current collector) was intact, and the amount of hydrogen produced during the reaction was 14 ml.

[0065] Example 2

[0066] The method for stripping lithium-ion battery electrodes provided in this embodiment includes the following steps:

[0067] The discarded NCM523 positive electrode sheet was cut into 2.5cm × 2.5cm pieces and immersed in a mixture containing NaF and citric acid. The mass fraction of NaF in the mixture was 0.1%, and the mass fraction of citric acid was 10%. The mass ratio of the electrode sheet to the volume of the mixture was 1:80. The reaction was carried out at 30°C with magnetic stirring at 400 rpm. After 10 minutes of reaction, the active material layer and the current collector layer were removed. It was found that the current collector and the active material were completely separated (no active material was adhering to the surface of the current collector), with a separation efficiency of 100%. The obtained Al foil (aluminum current collector) was intact, and the amount of hydrogen produced during the reaction was 10 ml.

[0068] Example 3

[0069] The method for stripping lithium-ion battery electrodes provided in this embodiment includes the following steps:

[0070] The discarded NCM622 positive electrode sheet was cut into 2.5cm × 2.5cm pieces and immersed in a mixture containing sodium phosphate and citric acid. The mass fraction of sodium phosphate in the mixture was 0.5%, and the mass fraction of citric acid in the mixture was 5%. The mass ratio of the electrode sheet to the volume of the mixture was 1:80. The reaction was carried out at 30°C with magnetic stirring at 400 rpm. After 13 minutes of reaction, the active material layer and the current collector layer were removed. It was found that the current collector and the active material were completely separated (no active material was adhering to the surface of the current collector), with a separation efficiency of 100%. The obtained Al foil (aluminum current collector) was intact, and the amount of hydrogen produced during the reaction was 16 ml.

[0071] Example 4

[0072] The method for stripping lithium-ion battery electrodes provided in this embodiment includes the following steps:

[0073] The discarded NCM811 positive electrode sheet was cut into 2.5cm × 2.5cm pieces and immersed in a mixture containing potassium phosphate and oxalic acid. The mass fraction of potassium phosphate in the mixture was 0.5%, and the mass fraction of oxalic acid in the mixture was 5%. The mass ratio of the electrode sheet to the volume of the mixture was 1:80. The reaction was carried out at 30°C with magnetic stirring at 400 rpm. After 12 minutes of reaction, the active material layer and the current collector layer were removed. It was found that the current collector and the active material were completely separated (no active material was adhering to the surface of the current collector), with a separation efficiency of 100%. The obtained Al foil (aluminum current collector) was intact, and the amount of hydrogen produced during the reaction was 15 ml.

[0074] Example 5

[0075] The method for stripping lithium-ion battery electrodes provided in this embodiment includes the following steps:

[0076] Waste Ni90 positive electrode sheets were cut into 2.5cm × 2.5cm pieces and immersed in a mixture containing ammonium fluoride and citric acid. The mass fraction of ammonium fluoride in the mixture was 0.3%, and the mass fraction of citric acid was 8%. The mass ratio of the electrode sheet to the volume of the mixture was 1:60. The reaction was carried out at 30°C with magnetic stirring at 400 rpm. After 10 minutes of reaction, the active material layer and the current collector layer were removed. It was found that the current collector and the active material were completely separated (no active material was adhering to the surface of the current collector), with a separation efficiency of 100%. The obtained Al foil (aluminum current collector) was intact, and the amount of hydrogen produced during the reaction was 12 ml.

[0077] Example 6

[0078] The method for stripping lithium-ion battery electrodes provided in this embodiment includes the following steps:

[0079] Waste LFP positive electrode sheets were cut into 2.5cm × 2.5cm pieces and immersed in a mixture containing sodium metaphosphate and citric acid. The mass fraction of sodium metaphosphate in the mixture was 0.5%, and the mass fraction of citric acid was 5%. The mass ratio of the electrode sheet to the volume of the mixture was 1:80. The reaction was carried out at 30°C with magnetic stirring at 400 rpm. After 4 minutes of reaction, the active material layer and the current collector layer were removed. It was found that the current collector and the active material were completely separated (no active material was adhering to the surface of the current collector), with a separation efficiency of 100%. The obtained Al foil (aluminum current collector) was intact, and the amount of hydrogen produced during the reaction was 10 ml.

[0080] Example 7

[0081] The method for stripping lithium-ion battery electrodes provided in this embodiment is basically the same as that in embodiment 6, except that: the waste LFP positive electrode is replaced with the waste LCO positive electrode, the sodium metaphosphate is replaced with sodium phosphate (but the concentration remains unchanged), and the active material layer and the current collector layer are removed after reacting for 15 minutes.

[0082] In this embodiment, the current collector and the active material have been completely separated (the active material no longer adheres to the surface of the current collector), the separation efficiency is 100%, the obtained Al foil (aluminum current collector) is intact, and the amount of hydrogen generated during the process is 15 ml.

[0083] Example 8

[0084] The method for stripping lithium-ion battery electrodes provided in this embodiment includes the following steps:

[0085] The discarded NCM111 positive electrode sheet was cut into 2.5cm × 2.5cm pieces and immersed in a mixture containing tetrasodium ethylenediaminetetraacetate (EDTA) and succinic acid. The mass fraction of EDTA in the mixture was 1%, and the mass fraction of succinic acid was 20%. The mass ratio of the electrode sheet to the volume of the mixture was 1:40. The reaction was carried out at 50°C with magnetic stirring at 300 rpm. After 8 minutes of reaction, the active material layer and the current collector layer were removed. It was found that the current collector and the active material were completely separated (no active material adhered to the surface of the current collector), with a separation efficiency of 100%. The obtained Al foil (aluminum current collector) was intact, and the amount of hydrogen produced during the reaction was 15 ml.

[0086] Example 9

[0087] The method for stripping lithium-ion battery electrodes provided in this embodiment is basically the same as that in Embodiment 2, except that the mass fraction of citric acid is replaced with 30%.

[0088] In this embodiment, the current collector and the active material have been completely separated (the active material no longer adheres to the surface of the current collector), the separation efficiency is 100%, the obtained Al foil (aluminum current collector) is intact, and the amount of hydrogen generated during the process is 15 ml.

[0089] Example 10

[0090] The method for stripping lithium-ion battery electrodes provided in this embodiment is basically the same as that in Embodiment 2, except that the mass fraction of NaF is replaced with 0.01%, and the active material layer and current collector layer are removed after reacting for 15 minutes.

[0091] In this embodiment, the current collector and the active material have been completely separated (the active material no longer adheres to the surface of the current collector), the separation efficiency is 100%, the obtained Al foil (aluminum current collector) is intact, and the amount of hydrogen generated during the process is 14 ml.

[0092] Example 11

[0093] The method for stripping lithium-ion battery electrodes provided in this embodiment is basically the same as that in Embodiment 2, except that the reaction temperature is replaced with 70°C, and the active material layer and current collector layer are removed after 5 minutes of reaction.

[0094] In this embodiment, the current collector and the active material have been completely separated (the active material no longer adheres to the surface of the current collector), the separation efficiency is 100%, the obtained Al foil (aluminum current collector) is intact, and the amount of hydrogen generated during the process is 13 ml.

[0095] Example 12

[0096] The method for stripping lithium-ion battery electrodes provided in this embodiment is basically the same as that in Embodiment 2, except that the reaction time is replaced with 20 min.

[0097] In this embodiment, the current collector and the active material have been completely separated (the active material no longer adheres to the surface of the current collector), the separation efficiency is 100%, the obtained Al foil (aluminum current collector) is intact, and the amount of hydrogen generated during the process is 17 ml.

[0098] Comparative Example 1

[0099] The method for stripping lithium-ion battery electrodes provided in this comparative example is basically the same as that in Example 2, except that NaF is replaced with NaCl (but its concentration and reaction time remain unchanged). Obvious gas production can be seen during the experiment.

[0100] In this comparative example, the Al foil (aluminum current collector) in the electrode partially dissolved, a small amount of active material dissolved, the separation efficiency was almost 0%, and the amount of hydrogen produced during the period was 50 ml.

[0101] Comparative Example 2

[0102] The method for stripping lithium-ion battery electrodes provided in this comparative example is basically the same as that in Example 2, except that citric acid is replaced with dilute hydrochloric acid (but the hydrogen ion concentration in the mixture remains unchanged), and the mixture does not contain NaF.

[0103] In this comparative example, the Al foil (aluminum current collector) in the electrode was completely dissolved, the separation efficiency was almost 0%, and the amount of hydrogen produced during the process was 210 ml.

[0104] Comparative Example 3

[0105] The method for stripping lithium-ion battery electrodes provided in this comparative example is basically the same as that in Example 2, except that citric acid is replaced with dilute hydrochloric acid (but the hydrogen ion concentration in the mixture remains unchanged).

[0106] In this comparative example, the Al foil (aluminum current collector) in the electrode was completely dissolved, the separation efficiency was about 0%, and obvious gas production was observed during the experiment, with a hydrogen production of 205 ml.

[0107] Comparative Example 4

[0108] The method for stripping lithium-ion battery electrodes provided in this comparative example is basically the same as that in Example 2, except that citric acid is replaced with acetic acid (but the hydrogen ion concentration in the mixture remains unchanged), and the mixture does not contain NaF.

[0109] In this comparative example, the current collector and the active material were partially separated (separation efficiency was approximately 20%), during which 8 ml of hydrogen was generated.

[0110] Comparative Example 5

[0111] The method for stripping lithium-ion battery electrodes provided in this comparative example is basically the same as that in Example 2, except that citric acid is replaced with boric acid (but the hydrogen ion concentration in the mixture remains unchanged), and the mixture does not contain NaF.

[0112] In this comparative example, the current collector and the active material did not separate (the separation efficiency was almost 0%).

[0113] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for stripping lithium-ion battery electrodes, characterized in that, Includes the following steps: The electrode is immersed in a mixture containing a stripping agent and a stripping aid for reaction. After a period of time, the separated active material layer and current collector layer are obtained. The stripping agent comprises a carboxylic acid containing at least two carboxyl groups; The stripping agent includes at least one of sodium fluoride, potassium fluoride, ammonium fluoride, phosphoric acid, sodium phosphate, sodium monohydrogen phosphate, sodium metaphosphate, potassium phosphate, potassium monohydrogen phosphate, potassium metaphosphate, ammonium phosphate, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, inositol hexaphosphate and its salt, inositol pentaphosphate and its salt, inositol tetraphosphate and its salt, and inositol triphosphate and its salt. The stripping agent reacts with the electrode interface layer and / or the current collector surface layer to generate metal ions. The stripping aid reacts with the metal ions to form an insoluble precipitate or a strong complex. The generated precipitate or complex covers the current collector surface layer.

2. The method for stripping lithium-ion battery electrodes according to claim 1, characterized in that, The stripping agent includes at least one of oxalic acid, citric acid, malic acid, succinic acid, pectic acid, malonic acid, and tartaric acid.

3. The method for stripping lithium-ion battery electrodes according to claim 1, characterized in that, The mass fraction of the stripping agent in the mixture is 0.05% to 50%.

4. The method for stripping lithium-ion battery electrodes according to claim 3, characterized in that, The mass fraction of the stripping agent in the mixture is 5% to 30%.

5. The method for stripping lithium-ion battery electrodes according to claim 1, characterized in that, The mass fraction of the stripping agent in the mixture is 0.005%~10%.

6. The method for stripping lithium-ion battery electrodes according to claim 5, characterized in that, The mass fraction of the stripping agent in the mixture is 0.01% to 5%.

7. The method for stripping lithium-ion battery electrodes according to claim 1, characterized in that, The mass ratio of the electrode to the mixture is 1:5~100.

8. The method for stripping lithium-ion battery electrodes according to claim 7, characterized in that, The mass ratio of the electrode to the mixture is 1:10~80.

9. The method for stripping lithium-ion battery electrodes according to claim 1, characterized in that, During the reaction, the temperature of the mixture is 20~80℃.

10. The method for stripping lithium-ion battery electrodes according to claim 9, characterized in that, During the reaction, the temperature of the mixture is 30~50℃.

11. The method for stripping lithium-ion battery electrodes according to claim 1, characterized in that, The reaction time is 1 to 15 minutes.

12. The method for stripping lithium-ion battery electrodes according to claim 1, characterized in that, The binder in the electrode includes oil-based binders and / or water-based binders.

13. The method for stripping lithium-ion battery electrodes according to claim 1, characterized in that, The electrode includes a positive electrode and / or a negative electrode.

14. A method for recycling lithium-ion battery electrodes, characterized in that, Including the method for stripping lithium-ion battery electrodes as described in any one of claims 1 to 13.