A method for separating positive electrode oxide active material and current collector in lithium-ion batteries and its application.

Abstract

This invention discloses a method for separating the oxide active material and current collector of a lithium-ion battery cathode, and its application. The separation method includes the following steps: acid leaching of the cathode sheet to be treated; adding a free radical generator to oxidize the binder in the cathode sheet, thereby separating the oxide active material from the current collector; wherein the oxide active material contains cobalt, and the free radical generator includes peroxide salts. This invention eliminates the need for additional metal ions, enabling efficient separation of the battery active material from the current collector on the cathode sheet. It is applicable to a wide pH range, has a simple process, low energy consumption, and low emissions. Furthermore, the recovered active material and current collector are free of impurity ions and do not require pulverizing the electrode sheet or dissolving the aluminum foil; the electrode sheet can be directly used for separation treatment. The operation is simple, and the recovered active material and current collector can also be directly used in lithium-ion battery production, resulting in high economic benefits.

Description

Technical Field

[0001] This invention relates to the field of battery recycling technology, and in particular to a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery and its application. Background Technology

[0002] With the development of manufacturing and information technology, portable micro-electronic devices, various household appliances, and new energy electric vehicles have become an indispensable part of modern life. Lithium-ion batteries (LiBs) are a renewable energy storage technology. Since their inception, they have held an irreplaceable position in meeting the mobile and portable power supply needs of humankind due to their advantages such as high energy density, light weight, long cycle life, and no memory effect. Especially in recent years, with the continuous expansion of the market for new energy electric vehicles and portable electronic devices, the demand for lithium-ion batteries has been rising continuously. However, this is accompanied by an increasing number of lithium-ion batteries being phased out of the market. On the other hand, the rapidly expanding demand has caused the prices of corresponding mineral raw materials to soar. Retired and used lithium-ion batteries contain a large amount of high-value metal resources, such as oxide active materials used as positive electrodes and aluminum foil used as current collectors. If these are not recycled, it will result in a huge waste of resources. At the same time, if toxic heavy metals such as Co and Mn are leaked, they will pollute the soil and groundwater, posing a great threat to the human ecological environment. Therefore, developing efficient, low-cost, and environmentally friendly waste lithium-ion battery recycling technologies is of great significance.

[0003] Pre-treatment of spent lithium-ion batteries is a crucial step in the recycling process. It includes three steps: discharging the spent lithium-ion batteries, dismantling and separating them, and separating the active materials. The separation of active materials primarily addresses the separation between the active materials and the current collector. The binder's role is to adhere the active materials and the current collector; therefore, solving the separation problem mainly involves using physical or chemical methods to deactivate the binder.

[0004] In the pretreatment process, the methods for separating the active material from the current collector are mainly divided into two categories: physical and chemical. Physical methods typically involve mechanical crushing, ultrasonic-assisted separation, etc., to separate the positive electrode active material from the current collector. Chemical methods utilize chemical reactions, such as pyrolysis, dissolving the binder with organic reagents (NMP, DMF, ionic liquids, etc.), and dissolving the current collector (aluminum foil) with acidic or alkaline reagents to achieve separation of the active material and the current collector. Physical methods have received considerable attention due to their universality and simplicity; however, they often still require the use of chemical reagents for auxiliary separation (Journal of Cleaner Production 2020, 258, 120943). Among chemical methods, patent document CN104362408 A discloses a pyrolysis recycling method for lithium iron phosphate waste. The electrode to be recycled is baked at high temperature to decompose and deactivate the binder, allowing the lithium iron phosphate and conductive agent to separate from the current collector aluminum foil. Subsequently, the lithium iron phosphate and conductive agent are baked at high temperature and then sieved to obtain lithium iron phosphate powder. This pyrolysis method typically has high energy consumption. Another common chemical method is to dissolve the aluminum foil using an alkaline aqueous solution (e.g., Journal of Cleaner Production 2018, 180, 64; CN 102646857 A, etc.), but this method completely destroys the aluminum foil, requiring additional steps to recover the aluminum dissolved in the alkaline solution.

[0005] Therefore, developing a high-efficiency and low-cost method for separating lithium-ion battery cathode oxide active materials and current collectors is of great significance for lithium-ion battery recycling. Summary of the Invention

[0006] This invention aims to address at least one of the technical problems existing in the prior art. To this end, this invention proposes a method for separating the positive electrode oxide active material and the current collector in lithium-ion batteries. This method can efficiently separate the positive electrode active material and the current collector, requires no high-temperature energy consumption, and does not require the introduction of additional metal ions as a catalyst, significantly reducing recycling costs.

[0007] The present invention also proposes a method for recycling lithium-ion batteries.

[0008] According to one aspect of the present invention, a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery is provided, comprising the following steps:

[0009] The positive electrode sheet to be treated is acid-impregnated; a free radical generator is added to oxidize the binder in the positive electrode sheet, so that the oxide active material is separated from the current collector;

[0010] The oxide active material contains cobalt, and the free radical generator includes peroxide salts.

[0011] According to a preferred embodiment of the present invention, at least the following beneficial effects are achieved: the separation method of the present invention requires only a small amount of acid-base reagents and inexpensive free radical generators to remove the adhesive in the positive electrode sheet; it can efficiently separate the battery active material on the positive electrode sheet from the current collector without the need for additional metal ions, has a wide applicable pH range, and is simple in process, with low energy consumption and low emissions; simultaneously, the recovered active material and current collector are free of impurity ions and do not require pulverizing the electrode sheet or dissolving the aluminum foil, allowing the electrode sheet to be directly used for separation processing, simplifying the operation; the recovered active material and current collector can also be directly used in lithium-ion battery production, resulting in high economic benefits. This method has good industrial application prospects and is suitable for large-scale production applications.

[0012] In some embodiments of the present invention, the peroxyate salt comprises at least one of persulfate or monopersulfate. This causes SO4 to be generated in the system. ·- Oxidizing free radicals oxidizes the organic binders contained in the positive electrode sheets of waste lithium-ion batteries, rendering them ineffective and achieving separation of the positive electrode active material / current collector.

[0013] In some preferred embodiments of the present invention, the monopersulfate is selected from potassium monopersulfate (OXONE).

[0014] In some preferred embodiments of the present invention, the persulfate is selected from at least one of sodium persulfate, ammonium persulfate, and potassium persulfate.

[0015] In some embodiments of the present invention, the peroxyate is OXONE.

[0016] In some preferred embodiments of the present invention, the oxide active material is selected from at least one of lithium cobalt oxide, nickel cobalt manganese cathode material (NCM), or nickel cobalt aluminum cathode material (NCA).

[0017] In some preferred embodiments of the present invention, the oxide active material is selected from LiCoO2 and LiNi. 1 / 3Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2 or LiNi 0.8 Co 0.15 Al 0.05At least one of O2. The present invention is applicable to the recycling of various cobalt-containing oxide active materials.

[0018] In some preferred embodiments of the present invention, the lithium-ion battery is a used lithium-ion battery. It can be an old lithium-ion battery nearing the end of its service life, or a defective product discarded during the production process.

[0019] In some preferred embodiments of the present invention, the acid leaching is performed at room temperature. A small amount of metal ions (Co) are dissolved through acid leaching. 2+ or Co 3+ (etc.) as catalysts.

[0020] In some preferred embodiments of the present invention, the acid leaching time does not exceed 5 minutes. Excessive acid leaching time will cause the active material to dissolve, affecting the separation effect.

[0021] In some preferred embodiments of the present invention, the acid leaching time is not less than 1 / 6 minute. The present invention requires only a very short time and has high separation efficiency.

[0022] In some preferred embodiments of the present invention, the concentration of the acid used in the acid leaching is 10 to 100 mmol / L.

[0023] In some preferred embodiments of the present invention, the concentration of the acid used in the acid leaching is 25 to 50 mmol / L.

[0024] In some embodiments of the present invention, the acid used in the acid leaching is selected from at least one of inorganic acids or organic acids.

[0025] In some preferred embodiments of the present invention, the acid used in the acid leaching is an inorganic acid.

[0026] In some preferred embodiments of the present invention, the inorganic acid is selected from at least one of sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid.

[0027] In some preferred embodiments of the present invention, the organic acid is selected from at least one of citric acid, tartaric acid, oxalic acid, malic acid, citric acid, ascorbic acid, or benzoic acid.

[0028] In some embodiments of the present invention, after acid leaching and before adding the free radical generator, a step of adjusting the pH to 2-10 is included. The present invention has a wide applicable pH range.

[0029] In some embodiments of the present invention, a step of adjusting the pH to 2-8 is performed after acid leaching and before adding a free radical generator.

[0030] In some preferred embodiments of the present invention, the step of adjusting the pH to 7 is performed after acid leaching and before adding the free radical generator.

[0031] In some embodiments of the present invention, the pH is adjusted by adding an alkaline reagent, which includes at least one of sodium hydroxide, ammonia, potassium hydroxide, and lithium hydroxide.

[0032] In some preferred embodiments of the present invention, the alkaline reagent includes sodium hydroxide.

[0033] In some embodiments of the present invention, the concentration of the free radical generator is from 0.1 to 10 mmol / L. Controlling the free radical generator within a reasonable range avoids excessively low concentrations that could negatively impact separation efficiency.

[0034] In some preferred embodiments of the present invention, the concentration of the free radical generator is 1 mmol / L.

[0035] In some embodiments of the present invention, the reaction is carried out at room temperature after the addition of a free radical generator.

[0036] In some embodiments of the present invention, the ambient temperature is 10°C to 40°C.

[0037] In some embodiments of the present invention, the reaction is carried out under ultrasonic assistance after the addition of a free radical generator. Ultrasonication can significantly improve the separation efficiency.

[0038] In some preferred embodiments of the present invention, the ultrasonic power is 1-90W.

[0039] In some preferred embodiments of the present invention, the ultrasonic power is 20W.

[0040] In some preferred embodiments of the present invention, the ultrasound duration is 0.5-5 minutes.

[0041] In some more preferred embodiments of the present invention, the ultrasound duration is 2 minutes.

[0042] In some embodiments of the present invention, the adhesive includes at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTEE), polyacrylonitrile (PAN), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), or sodium alginate (SA). The present invention is applicable to a variety of adhesives and has broad application prospects.

[0043] In some embodiments of the present invention, the separation method further includes the following steps: collecting the oxidized solution, and adding the positive electrode sheet to be treated and a free radical generator to the solution again. This recycling of the waste liquid eliminates the need for acid leaching to dissolve cobalt ions as a catalyst, further simplifying the process, saving costs, and preventing environmental pollution from residual acid in the waste liquid.

[0044] According to another aspect of the present invention, a lithium-ion battery recycling method is provided, comprising the step of recycling the positive electrode sheet of the lithium-ion battery by the separation method described above.

[0045] The recycling method according to a preferred embodiment of the present invention has at least the following beneficial effects: the separation method of the present invention can safely and simply recycle lithium-ion batteries. The recycling process directly utilizes the cobalt ions contained in the positive electrode oxide active material as a catalyst, without the need to add an additional catalyst, and quickly and efficiently separates the positive electrode oxide active material from the current collector.

[0046] In some embodiments of the present invention, the recycling method further includes using the oxidized solution for separating the active material and the current collector in the negative electrode sheet. The waste liquid from the present invention, after recycling, can be used not only for the recycling of the positive electrode sheet but also for the separation of the negative electrode active material and the current collector.

[0047] In some embodiments of the present invention, the recycling method further includes collecting the oxidized solution and adding the negative electrode sheet to be treated and a free radical generator to the solution.

[0048] In some embodiments of the present invention, the negative electrode active material includes at least one of artificial graphite, natural graphite, mesophase carbon microspheres, petroleum coke, or carbon fiber.

[0049] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0050] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0051] Figure 1 These are schematic diagrams illustrating the operation flow of embodiments 1 to 372 of the present invention;

[0052] Figure 2 Optical photographs of waste lithium-ion battery electrode sheets (left) before recycling and current collector aluminum foil (right) after recycling in Embodiment 1 of the present invention;

[0053] Figure 3The image shows the XRD pattern of the current collector aluminum foil recovered in Example 1 of this invention. Detailed Implementation

[0054] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available. Unless otherwise specified, the same parameter value is the same in all embodiments. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0055] The spent lithium-ion battery electrodes used in Examples 1-367 and Comparative Examples 1-5 below were obtained from the dismantling of self-made coin cells after multiple electrochemical cycles. Specifically, the preparation, electrochemical, and dismantling processes of the lithium-ion batteries are as follows:

[0056] A uniform slurry is prepared by mixing the positive electrode active material, conductive carbon, and binder in a mass ratio of 8:1:1 with an appropriate amount of solvent. The slurry is then uniformly coated onto the current collector aluminum foil using an electrode coating device. The active material loading is approximately 5-6 mg / cm³. 2 After vacuum drying in an oven, the electrodes were cut into 10mm diameter circular sheets. Battery assembly was then performed in an argon-filled glove box. The negative electrode was lithium metal, and the electrolyte was a commercially available lithium-ion battery electrolyte. The resulting batteries underwent long-cycle testing. The active materials were LiCoO2 and LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2 and LiNi 0.8 Co 0.15 Al 0.05 One of the O2 components; PVDF is selected as the adhesive.

[0057] The battery was charged and discharged at a 1C rate until its discharge capacity fell below 70% of the capacity of the first cycle. The long-cycle test was then stopped, and the battery was disassembled in a glove box. The disassembled waste lithium-ion battery positive electrode was cleaned with dimethyl carbonate (DMC) and air-dried in a glove box to obtain the experimental materials used in each embodiment.

[0058] Take a 50mL beaker, add 20mL of acidic aqueous solution, and perform the operations described in the following examples sequentially at room temperature (10-40 degrees Celsius). In each example, 20 waste lithium-ion battery electrodes are used.

[0059] Example 1

[0060] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector in a lithium-ion battery, such as... Figure 1 As shown, the specific process is as follows:

[0061] S1: Immerse the positive electrode sheet of the waste lithium-ion battery containing LiCoO2 into the hydrochloric acid aqueous solution for 0.5 minutes to dissolve a small amount of metal ions;

[0062] S2: Add sodium hydroxide aqueous solution to adjust the pH of the solution to 7;

[0063] S3: Add OXONE to a concentration of 1.0 mmol / L and stir well (stir manually for about 20 seconds);

[0064] S4: Sonicate at 20W for 2 minutes to generate SO4 in the system. ·- Free radicals cause the separation of positive electrode active material / current collector.

[0065] Example 2-10

[0066] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Embodiment 1 is that different types of acids are used for acid leaching. The specific types of acids are shown in Table 1.

[0067] Examples 11-19

[0068] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Embodiment 1 is that different acid immersion times are used. The specific acid immersion times are shown in Table 1.

[0069] Examples 20-22

[0070] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 1 is that different alkaline reagents are used to adjust the pH. The specific alkaline reagents are shown in Table 1.

[0071] Examples 23-32

[0072] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 1 is that the pH value adjusted in step S2 is different. The specific pH value is shown in Table 1.

[0073] Examples 33-35

[0074] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 1 is that the free radical generator used is different. The specific free radical generators are shown in Table 1.

[0075] Examples 36-44

[0076] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 1 is that the concentration of the free radical generator is different. The specific concentration of the free radical generator is shown in Table 1.

[0077] Examples 45-53

[0078] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Embodiment 1 is that the ultrasonic power is different. The specific ultrasonic power is shown in Table 1.

[0079] Examples 54-63

[0080] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 1 is that the ultrasonic time is different. The specific ultrasonic power is shown in Table 1. In Embodiment 54, step S4 changes the ultrasonic process to a standing period of half an hour.

[0081] Example 64

[0082] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector in a lithium-ion battery, such as... Figure 1 As shown, the specific process is as follows:

[0083] S1: Containing LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 immerses the positive electrode of a waste lithium-ion battery in hydrochloric acid solution for 1 minute, which dissolves a small amount of metal ions.

[0084] S2: Add sodium hydroxide aqueous solution to adjust the pH of the solution to 7;

[0085] S3: Add OXONE to a concentration of 1.0 mmol / L and stir well (stir manually for about 20 seconds);

[0086] S4: Sonicate at 20W for 2 minutes to generate SO4 in the system. ·- Free radicals cause the separation of positive electrode active material / current collector.

[0087] Examples 65-73

[0088] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 64 is that different types of acids are used for acid leaching. The specific types of acids are shown in Table 1.

[0089] Examples 74-82

[0090] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 64 is that different acid immersion times are used. The specific acid immersion times are shown in Table 1.

[0091] Examples 83-85

[0092] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 64 is that different alkaline reagents are used to adjust the pH. The specific alkaline reagents are shown in Table 1.

[0093] Examples 86-93

[0094] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 64 is that the pH value adjusted in step S2 is different. The specific pH value is shown in Table 1.

[0095] Examples 94-96

[0096] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 64 is that the free radical generator used is different. The specific free radical generators are shown in Table 1.

[0097] Examples 97-105

[0098] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 64 is that the concentration of the free radical generator is different. The specific concentration of the free radical generator is shown in Table 1.

[0099] Examples 106-114

[0100] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 64 is that the ultrasonic power is different. The specific ultrasonic power is shown in Table 1.

[0101] Examples 115-123

[0102] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 64 is that the ultrasonic time is different, and the specific ultrasonic power is shown in Table 1.

[0103] Example 124

[0104] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector in a lithium-ion battery, such as... Figure 1 As shown, the specific process is as follows:

[0105] S1: Containing LiNi 0.5 Co 0.2 Mn 0.3 O2 was used lithium-ion battery positive electrode sheets were immersed in hydrochloric acid aqueous solution for 1.5 minutes, and a small amount of metal ions were dissolved.

[0106] S2: Add sodium hydroxide aqueous solution to adjust the pH of the solution to 7;

[0107] S3: Add OXONE to a concentration of 1.0 mmol / L and stir well (stir manually for about 20 seconds);

[0108] S4: Sonicate at 20W for 2 minutes to generate SO4 in the system. ·- Free radicals cause the separation of positive electrode active material / current collector.

[0109] Examples 125-133

[0110] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 124 is that different types of acids are used for acid leaching. The specific types of acids are shown in Table 1.

[0111] Examples 134-141

[0112] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 124 is that different acid immersion times are used. The specific acid immersion times are shown in Table 1.

[0113] Example 142

[0114] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 124 is that different acid leaching times and pH values ​​are used. The specific acid leaching times and pH values ​​are shown in Table 1.

[0115] Examples 143-145

[0116] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 124 is that different alkaline reagents are used to adjust the pH. The specific alkaline reagents are shown in Table 1.

[0117] Examples 146-152

[0118] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 124 is that the pH value adjusted in step S2 is different. The specific pH value is shown in Table 1.

[0119] Example 153

[0120] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 124 is that the pH value adjusted in step S2 and the free radical generator used are different. The specific pH value and the free radical generator used are shown in Table 1.

[0121] Examples 154-156

[0122] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 124 is that the free radical generator used is different. The specific free radical generator is shown in Table 1.

[0123] Examples 157-165

[0124] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 124 is that the concentration of the free radical generator is different. The specific concentration of the free radical generator is shown in Table 1.

[0125] Examples 166-174

[0126] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 124 is that the ultrasonic power is different. The specific ultrasonic power is shown in Table 1.

[0127] Examples 175-183

[0128] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 124 is that the ultrasonic time is different, and the specific ultrasonic power is shown in Table 1.

[0129] Example 184

[0130] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector in a lithium-ion battery, such as... Figure 1 As shown, the specific process is as follows:

[0131] S1: Containing LiNi 0.6 Co 0.2 Mn 0.2 O2 was used lithium-ion battery positive electrode sheets were immersed in hydrochloric acid solution for 1.5 minutes.

[0132] S2: Add sodium hydroxide aqueous solution to adjust the pH of the solution to 7;

[0133] S3: Add OXONE to a concentration of 1.0 mmol / L and stir well (stir manually for about 20 seconds);

[0134] S4: Sonicate at 20W for 2 minutes to generate SO4 in the system. ·- Free radicals cause the separation of positive electrode active material / current collector.

[0135] Examples 185-192

[0136] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 184 is that different types of acids are used for acid leaching. The specific types of acids are shown in Table 1.

[0137] Example 193

[0138] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 184 is that different types of acids are used for acid leaching, and the types of free radical generators are adjusted. The specific types of acids and free radical generators are shown in Table 1.

[0139] Examples 194-202

[0140] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 184 is that different acid immersion times are used. The specific acid immersion times are shown in Table 1.

[0141] Examples 203-205

[0142] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 184 is that different alkaline reagents are used to adjust the pH. The specific alkaline reagents are shown in Table 1.

[0143] Examples 206-213

[0144] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 184 is that the pH value adjusted in step S2 is different. The specific pH value is shown in Table 1.

[0145] Examples 214-216

[0146] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 184 is that the free radical generator used is different. The specific free radical generators are shown in Table 1.

[0147] Examples 217-225

[0148] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 184 is that the concentration of the free radical generator is different. The specific concentration of the free radical generator is shown in Table 1.

[0149] Examples 226-234

[0150] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 184 is that the ultrasonic power is different. The specific ultrasonic power is shown in Table 1.

[0151] Examples 235-243

[0152] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 184 is that the ultrasonic time is different, and the specific ultrasonic power is shown in Table 1.

[0153] Example 244

[0154] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector in a lithium-ion battery, such as... Figure 1 As shown, the specific process is as follows:

[0155] S1: Containing LiNi 0.8 Co 0.1 Mn 0.1 O2 was used lithium-ion battery positive electrode sheets were immersed in hydrochloric acid solution for 1.5 minutes.

[0156] S2: Add sodium hydroxide aqueous solution to adjust the pH of the solution to 7;

[0157] S3: Add OXONE to a concentration of 1.0 mmol / L and stir well (stir manually for about 20 seconds);

[0158] S4: Sonicate at 20W for 2 minutes to generate SO4 in the system. ·- Free radicals cause the separation of positive electrode active material / current collector.

[0159] Examples 245-253

[0160] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 244 is that different types of acids are used for acid leaching. The specific types of acids are shown in Table 1.

[0161] Examples 254-262

[0162] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 244 is that different acid immersion times are used. The specific acid immersion times are shown in Table 1.

[0163] Examples 263-265

[0164] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 244 is that different alkaline reagents are used to adjust the pH. The specific alkaline reagents are shown in Table 1.

[0165] Examples 266-273

[0166] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 244 is that the pH value adjusted in step S2 is different. The specific pH value is shown in Table 1.

[0167] Examples 274-276

[0168] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 244 is that the free radical generator used is different. The specific free radical generator is shown in Table 1.

[0169] Examples 277-285

[0170] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 244 is that the concentration of the free radical generator is different. The specific concentration of the free radical generator is shown in Table 1.

[0171] Examples 286-294

[0172] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 244 is that the ultrasonic power is different. The specific ultrasonic power is shown in Table 1.

[0173] Examples 295-303

[0174] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 244 is that the ultrasonic time is different, and the specific ultrasonic power is shown in Table 1.

[0175] Example 304

[0176] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector in a lithium-ion battery, such as... Figure 1 As shown, the specific process is as follows:

[0177] S1: Containing LiNi 0.8 Co 0.15 Al 0.05 O2 was used lithium-ion battery positive electrode sheets were immersed in hydrochloric acid solution for 1.5 minutes.

[0178] S2: Add sodium hydroxide aqueous solution to adjust the pH of the solution to 7;

[0179] S3: Add OXONE to a concentration of 1.0 mmol / L and stir well (stir manually for about 20 seconds);

[0180] S4: Sonicate at 20W for 2 minutes to generate SO4 in the system. ·- Free radicals cause the separation of positive electrode active material / current collector.

[0181] Examples 305-313

[0182] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 304 is that different types of acids are used for acid leaching. The specific types of acids are shown in Table 1.

[0183] Examples 314-322

[0184] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 304 is that different acid immersion times are used. The specific acid immersion times are shown in Table 1.

[0185] Examples 323-325

[0186] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 304 is that different alkaline reagents are used to adjust the pH. The specific alkaline reagents are shown in Table 1.

[0187] Examples 326-333

[0188] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 304 is that the pH value adjusted in step S2 is different. The specific pH value is shown in Table 1.

[0189] Examples 334-336

[0190] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 304 is that the free radical generator used is different. The specific free radical generators are shown in Table 1.

[0191] Examples 337-345

[0192] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 304 is that the concentration of the free radical generator is different. The specific concentration of the free radical generator is shown in Table 1.

[0193] Examples 346-354

[0194] This embodiment proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and that of Embodiment 304 is that the ultrasonic power is different. The specific ultrasonic power is shown in Table 1.

[0195] Examples 355-363

[0196] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 304 is that the ultrasonic time is different, and the specific ultrasonic power is shown in Table 1.

[0197] Examples 364-367

[0198] This embodiment proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 304 is that the concentration of the acid is different. The specific concentration of the acid is shown in Table 1.

[0199] Table 1. Summary of experimental conditions for Examples 1 to 367 of the present invention

[0200]

[0201]

[0202]

[0203]

[0204]

[0205]

[0206]

[0207]

[0208]

[0209]

[0210]

[0211] Comparative Example 1

[0212] This comparative example proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 1 is that step S1 is not performed.

[0213] Comparative Example 2

[0214] This comparative example proposes a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 1 is that step S3 is not performed.

[0215] Comparative Example 3

[0216] This comparative example proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 1 is that steps S1-S3 are changed to: take a 50 mL beaker, add 20 mL of distilled water, add FeCl2 and H2O2 to the beaker until their concentrations are 0.1 mmol / L and 1 mmol / L respectively, and add hydrochloric acid to adjust the pH to 2.

[0217] Comparative Example 4

[0218] This comparative example proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 1 is that steps S1-S3 are changed to: take a 50 mL beaker, add 20 mL of distilled water, add FeCl2 and H2O2 to the beaker until their concentrations are 0.1 mmol / L and 1 mmol / L respectively, and add hydrochloric acid to adjust the pH to 7.

[0219] Comparative Example 5

[0220] This comparative example proposes a method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 1 is that steps S1-S3 are changed to: take a 50 mL beaker, add 20 mL of distilled water, add FeCl2 and OXONE to the beaker until their concentrations are 0.1 mmol / L and 1 mmol / L respectively, and add hydrochloric acid to adjust the pH to 7.

[0221] Test case

[0222] This experiment tested the separation effect of the examples and comparative examples. Specifically:

[0223] 1) Characterization of optical effects

[0224] Optical photographs of the battery positive electrode sheet before and after separation in Example 1 are shown below. Figure 2 As shown. From Figure 2 As can be seen, the surface of the current collector aluminum foil after separation exhibits a typical metallic color, with no obvious residue of positive electrode active material.

[0225] 2) X-ray diffraction (XRD) results

[0226] The XRD results of the current collector aluminum foil after separation in Example 1 are as follows: Figure 3 As shown. From Figure 3 As can be seen from the comparison with the standard PDF card, the diffraction spectrum only shows peaks for metallic aluminum and aluminum oxide, indicating that the lithium cobalt oxide cathode has been basically completely separated.

[0227] 3) Separation efficiency calculation

[0228] Before and after separation, the positive electrode sheets of the waste lithium-ion batteries are dried and weighed, with masses w1 and w2 respectively. The current collector is observed for any residual active material; any residual material is scraped off with a scraper, and its mass is marked as w3. The mass of the current collector obtained after recycling is W = w2 - w3, and the positive electrode separation efficiency is:

[0229] η=(w1-w2) / w1-(w2-w3)*100%.

[0230] The separation efficiencies of each embodiment and comparative example are shown in Table 2 below:

[0231] Table 2 Summary of Separation Efficiency in Examples 1-367

[0232]

[0233]

[0234] Analysis of the experimental results in Table 2 leads to the following conclusions:

[0235] (I) Regarding the Implementation Examples

[0236] 1. The comparison results between Examples 2-10 and Example 1 show that inorganic acids with strong acidity can achieve good separation effect, with hydrochloric acid being the preferred choice;

[0237] 2. The comparison results between Examples 11-19 and Example 1 show that: as the acid leaching time increases, the separation effect gradually increases until the optimal acid leaching time (0.5 minutes) is reached; if the acid leaching time is increased again, the active material will dissolve and the separation effect will decrease.

[0238] 3. The comparison results between Examples 20-22 and Example 1 show that the use of different types of alkaline reagents has little effect on the separation effect, and sodium hydroxide is preferred;

[0239] 4. The comparison results between Examples 23-32 and Example 1 show that the separation of active materials can be achieved at pH values ​​of 1-11, preferably 2-10, and more preferably 7.

[0240] 5. The comparison results between Examples 33-35 and Example 1 show that OXONE is the preferred free radical generator;

[0241] 6. The comparison results between Examples 36-44 and Example 1 show that the separation efficiency reaches its optimal level when the concentration of the free radical generator increases to 1 mmol / L; further increases in concentration do not increase the separation efficiency further.

[0242] 7. The comparison results between Examples 45-53 and Example 1 show that: as the ultrasonic power increases to 20W, the separation efficiency reaches the optimal level; further increases in power do not increase the separation efficiency further.

[0243] 8. The comparison results between Examples 54-63 and Example 1 show that ultrasound can significantly improve separation efficiency. As the ultrasound time increases to 2 minutes, the separation efficiency reaches its optimal level; further increases in time do not increase the separation efficiency further.

[0244] Examples 64-123, 124-183, 184-243, 244-303, and 304-363 are respectively for LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2 and LiNi 0.8 Co 0.1 Mn 0.1 The embodiments for separating O2 from waste lithium-ion battery positive electrode sheets are shown in Table 2. As can be seen from the table, except for the different optimal acid leaching times (1 minute, 1.5 minutes, 1.5 minutes, 2 minutes, and 2 minutes respectively), the influence trends of other parameters are consistent, indicating that the present invention is applicable to various cobalt-containing positive electrode active materials and can achieve similar results.

[0245] Examples 364-367 are for LiNi-containing 0.8 Co 0.1 Mn 0.1The example of separating the positive electrode sheet of waste lithium-ion batteries using O2, compared with the results of Example 304, shows that when acid leaching is performed with different concentrations of acid, the separation effect is relatively poor when the concentration is lower than the optimal value (50 mmol / L); when the concentration is higher than the optimal value, the separation efficiency gradually decreases with increasing concentration, which is due to the dissolution loss of the positive electrode material in the acid.

[0246] (II) Regarding the Examples and Comparative Examples

[0247] 1. The results of Example 1 and Comparative Example 1 show that short-time acid leaching of metal ions as a catalyst can effectively improve separation efficiency.

[0248] 2. The results of Example 1 and Comparative Example 2 show that adding the free radical generator OXONE can effectively improve the separation efficiency;

[0249] 3. The results of Example 1 and Comparative Examples 3-4 show that when FeCl2 is added as a catalyst and H2O2 is used as an oxidant, although it can still react with the binder, the separation efficiency of the mixed solution system is weaker than that of the embodiment of the present invention, regardless of whether the pH of the mixed solution system is 2 or 7.

[0250] 4. The results of Example 1 and Comparative Example 5 show that even with the addition of OXONE as a free radical generator and FeCl2 as a catalyst, the separation efficiency is significantly lower than that of the embodiments of the present invention. At this pH value, the added Fe... 2+ This will form corresponding hydroxide precipitates, causing the catalyst to become ineffective. The method described in this invention, however, is applicable to a wide pH range.

[0251] Examples 368-372

[0252] Examples 368-372 present a method for separating the positive oxide active material and the current collector of a lithium-ion battery. The difference between this method and Example 1 is that the types of binders used are different. The binders in Examples 368-372 are PTEE, PAN, SBR, CMC and SA, respectively.

[0253] The separation efficiencies of Examples 368-372 are shown in Table 3.

[0254] Table 3 Summary of Separation Efficiency in Examples 368-372

[0255] Example Separation efficiency 368 96.60％ 369 97.70％ 370 97.10％ 371 98.40％ 372 98.50％

[0256] Based on the data in Tables 3 and 2, the following conclusions can be drawn:

[0257] Under the same experimental conditions, the present invention is applicable to positive electrode sheets using different binders and achieves similar results. The present invention can efficiently peel the positive electrode active material from the current collector for positive electrode sheets using different binders. This peeling method is universal and applicable to positive electrode sheets containing different types of binders.

[0258] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery, characterized in that: Includes the following steps: The positive electrode sheet to be treated is acid-impregnated; a free radical generator is added to oxidize the binder in the positive electrode sheet, so that the oxide active material is separated from the current collector; The oxide active material contains cobalt, and the oxide active material is selected from at least one of lithium cobalt oxide, NCM or NCA. The free radical generator includes peroxide, and the acid leaching time does not exceed 5 minutes. After acid leaching and before adding the free radical generator, the pH is adjusted to 2-7.

2. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The peroxy acid salt includes at least one of persulfate or monopersulfate.

3. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 2, characterized in that: The monopersulfate is selected from OXONE.

4. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 2, characterized in that: The persulfate is selected from at least one of sodium persulfate, ammonium persulfate, and potassium persulfate.

5. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The oxide active material is selected from LiCoO2 and LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2 or LiNi 0.8 Co 0.15 Al 0.05 At least one of O2.

6. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The lithium-ion battery in question is a used lithium-ion battery.

7. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The acid leaching is carried out at room temperature.

8. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The acid leaching time shall not be less than 1 / 6 minute.

9. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The concentration of the acid used in the pickling process is 25-50 mmol / L.

10. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The acid used in the pickling is selected from at least one of inorganic or organic acids.

11. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 10, characterized in that: The inorganic acid is selected from at least one of sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid.

12. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 10, characterized in that: The organic acid is selected from at least one of citric acid, tartaric acid, oxalic acid, malic acid, citric acid, ascorbic acid, or benzoic acid.

13. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The pH is adjusted by adding an alkaline reagent, which includes at least one of sodium hydroxide, ammonia, potassium hydroxide, and lithium hydroxide.

14. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The concentration of the free radical generator is from 0.1 to 10 mmol / L.

15. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 14, characterized in that: The concentration of the free radical generator is 1 mmol / L.

16. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The reaction is carried out at room temperature after the addition of a free radical generator.

17. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 16, characterized in that: The ambient temperature is 10℃~40℃.

18. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The reaction was carried out under ultrasonic assistance after the addition of a free radical generator.

19. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 18, characterized in that: The ultrasonic power is 1-90 W.

20. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 19, characterized in that: The ultrasonic power is 20 W.

21. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 18, characterized in that: The ultrasound duration is 0.5-5 minutes.

22. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 21, characterized in that: The ultrasound duration is 2 minutes.

23. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to claim 1, characterized in that: The adhesive includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, styrene-butadiene rubber, sodium carboxymethyl cellulose, or sodium alginate.

24. The method for separating the positive electrode oxide active material and the current collector of a lithium-ion battery according to any one of claims 1 to 23, characterized in that: The separation method further includes the following steps: collecting the oxidized solution, and adding the positive electrode sheet to be treated and the free radical generator to the solution again.

25. A method for recycling lithium-ion batteries, characterized in that: The step includes recovering the positive electrode sheet of a lithium-ion battery by means of the separation method described in any one of claims 1 to 24.

26. The recycling method according to claim 25, characterized in that: It also includes the step of using the oxidized solution to separate the active material from the current collector in the negative electrode sheet.

27. The recycling method according to claim 26, characterized in that: The recovery method further includes collecting the oxidized solution and adding the negative electrode sheet to be treated and a free radical generator to the solution.

28. The recycling method according to claim 26, characterized in that: The active material in the negative electrode sheet includes at least one of artificial graphite, natural graphite, mesophase carbon microspheres, petroleum coke, or carbon fiber.

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