A method for recycling materials from waste batteries through a complete, integrated supply chain.

Abstract

This paper discloses a method for the integrated processing of materials from waste batteries, belonging to the field of battery recycling technology. The method includes: grafting the positive electrode sheet and the separator connected to the positive electrode sheet from the waste battery to achieve cross-linking between the separator and the positive electrode binder through the graft; subsequently, swelling the grafted material to reduce the adhesion between the positive electrode binder and the positive electrode current collector in the positive electrode sheet; and separating the positive electrode current collector from the positive electrode active material bonded to the separator under external force. This method can effectively separate the positive electrode active material and the current collector from waste batteries, thus enabling the recycling of the separated materials.

Description

Technical Field

[0001] This disclosure relates to the field of battery recycling technology, and more specifically, to a method for recycling materials from waste batteries through an integrated, end-to-end process. Background Technology

[0002] In recent years, the global lithium-ion battery industry has developed rapidly, with electric vehicles becoming an important future development direction, thus bringing great development opportunities to power lithium-ion batteries. However, lithium-ion batteries have a limited lifespan, and the widespread use of lithium batteries will mean a large number of waste lithium batteries. Recycling usable materials from waste batteries, such as valuable metals, can not only alleviate resource shortages and create economic value, but also solve the environmental pollution problem caused by waste batteries.

[0003] Currently, the main method for recycling used batteries is to discharge and crush them, and then use flotation, magnetic separation, and wet chemical methods to separate the target valuable metals. Regarding methods for separating the positive electrode material from the current collector, the main approaches are removing the binder and dissolving the current collector. However, the binder removal method often requires high-temperature treatment, which demands strict temperature control; temperatures that are too high or too low are undesirable. Furthermore, the combustion of organic matter during this process causes air pollution. Dissolving the positive electrode current collector aluminum foil typically involves using alkali (the reaction equation can be found as follows: 2Al + 2H₂O + 2NaOH = 2NaAlO₂ + 3H₂↑). This process generates a large amount of gas, which carries away some alkaline solution, causing harm to the environment and humans.

[0004] In view of this, this disclosure is hereby made. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method for recycling materials from waste batteries through an integrated end-to-end process. This method can effectively separate the positive electrode active material and current collector from the waste batteries. The separated materials can be further recycled. Furthermore, this method is simple to operate, has easily controllable conditions, and is environmentally friendly and safe.

[0006] This disclosure can be implemented as follows:

[0007] This disclosure provides a method for recycling materials from waste batteries through a complete integrated process, comprising: grafting a positive electrode sheet and a separator connected to the positive electrode sheet in the waste battery to crosslink the separator and the positive electrode binder of the positive electrode sheet through the graft; then swelling the grafted material to reduce the adhesion between the positive electrode binder and the positive electrode current collector in the positive electrode sheet; and separating the positive electrode current collector from the positive electrode active material bonded to the separator under the action of external force.

[0008] In an optional implementation, the waste battery is a waste lithium-ion battery.

[0009] In an optional embodiment, the diaphragm is a polymer electrolyte membrane.

[0010] In an optional embodiment, the main component of the positive electrode binder is polyvinylidene fluoride.

[0011] In an optional implementation, the positive current collector is aluminum foil.

[0012] In an optional embodiment, the grafting process includes: mixing the grafting material with the positive electrode sheet and the separator connected to the positive electrode sheet in the waste battery and carrying out a grafting reaction; wherein the grafting material includes acrylic acid, a crosslinking agent and an initiator.

[0013] In an optional embodiment, the crosslinking agent includes benzoyl peroxide; the initiator includes dicumyl peroxide.

[0014] In an optional embodiment, the mass ratio of acrylic acid to benzoyl peroxide and dicumyl peroxide is (8-10):(1-3):(2-4).

[0015] In an optional embodiment, the grafting material also includes a solvent.

[0016] In an optional embodiment, the solvent includes n-propanol.

[0017] In an optional embodiment, each 100g of solvent corresponds to 8g-10g of acrylic acid, 1g-3g of benzoyl peroxide, and 2g-4g of dicumyl peroxide.

[0018] In an optional embodiment, the grafting reaction has at least one of the following characteristics:

[0019] Feature 1: The grafting reaction temperature is 60℃-80℃;

[0020] Feature 2: The grafting reaction takes 2-6 hours;

[0021] Feature 3: The grafting reaction is carried out under constant temperature, sealed and dry conditions.

[0022] In an optional embodiment, swelling includes immersing the grafted material in water.

[0023] In an optional embodiment, the soaking temperature is 20°C-30°C; and / or the soaking time is 18h-24h.

[0024] In an optional embodiment, prior to the grafting process, the waste battery is further pretreated.

[0025] Pre-treatment includes removing electrolyte and negative electrode from used batteries.

[0026] In an optional embodiment, removing the electrolyte includes heating the core of the used battery to evaporate and remove the electrolyte.

[0027] In an optional embodiment, the heating temperature is 140°C-150°C; and / or the heating time is 1h-2h.

[0028] In an optional embodiment, removing the negative electrode sheet includes: immersing the battery core with the electrolyte removed in water to dissolve the negative electrode binder in the negative electrode sheet in the water, removing the negative electrode sheet and the negative electrode active material detached from the negative electrode current collector of the negative electrode sheet, and collecting the positive electrode sheet and the separator connected to the positive electrode sheet.

[0029] In an optional implementation, the soaking time is 24h-48h.

[0030] In an optional implementation, the negative current collector is a copper foil.

[0031] In an optional embodiment, the pretreatment further includes: modifying the positive electrode and the separator connected to the positive electrode.

[0032] In an optional implementation, the modification treatment has at least one of the following characteristics:

[0033] Feature 1: The treatment reagent used in the modification process is a mixed solution of alkali and alcohol;

[0034] Feature 2: The modification treatment temperature is 50℃-80℃;

[0035] Feature 3: The modification treatment time is 30-90 minutes.

[0036] In an optional embodiment, the base includes at least one of KOH and NaOH; and / or, the alcohol includes ethanol; and / or, the mass ratio of base to alcohol is (1:100) to (10:100).

[0037] In an optional implementation, the positive current collector is separated from the positive active material bonded with a diaphragm by providing external force through a negative pressure adsorption device.

[0038] In an optional embodiment, the negative pressure adsorption device includes a suction cup for adsorbing onto the surface of the positive current collector and / or the separator to be separated, so as to separate the positive current collector and the separator under negative pressure.

[0039] In an optional implementation, the suction cup is connected to a gas flow channel.

[0040] In an optional embodiment, the suction cup has suction holes on its surface, which are connected to a gas flow channel.

[0041] In an optional implementation, the negative pressure range is 500Pa-1000Pa.

[0042] In an optional embodiment, the separated positive electrode active material with the membrane bonded together is crushed, and the membrane is removed by sorting to obtain the positive electrode active material.

[0043] The bonding between the positive electrode active material and the positive electrode current collector is mainly achieved by physical adsorption formed by van der Waals forces generated between the positive electrode binder and the positive electrode current collector. This disclosure simultaneously grafts the positive electrode binder and the separator, so that the connection between the positive electrode active material and the separator is mainly achieved by the tight cross-linking of the graft formed between the positive electrode binder and the separator. By swelling the grafted material, the bonding force between the positive electrode binder and the positive electrode current collector is reduced, and the positive electrode current collector can be effectively separated from the positive electrode active material with the separator bonded under the action of external force. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the negative pressure adsorption device in this disclosure;

[0046] Figure 2 This is a schematic diagram of the suction cup structure in the negative pressure adsorption device of this disclosure.

[0047] Icons: 11-First separator; 12-First positive electrode active material layer; 13-Aluminum foil layer; 14-Second positive electrode active material layer; 15-Second separator; 20-Suction cup; 21-First suction cup; 22-Second suction cup; 23-Suction hole. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions in the embodiments of this disclosure will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0049] The following is a detailed explanation of the integrated, end-to-end recycling method for materials from waste batteries provided in this disclosure.

[0050] This disclosure proposes a whole-chain integrated recycling method for materials from waste batteries, including: grafting the positive electrode sheet and the separator connected to the positive electrode sheet (e.g., by bonding) in the waste battery to cross-link the separator and the positive electrode binder of the positive electrode sheet through the graft; then swelling the grafted material to reduce the adhesion between the positive electrode binder and the positive electrode current collector in the positive electrode sheet; and separating the positive electrode current collector from the positive electrode active material bonded to the separator under the action of external force.

[0051] For reference, the aforementioned waste batteries can be waste lithium-ion batteries (such as waste nickel-cobalt-manganese ternary lithium-ion batteries, lithium manganese oxide batteries, lithium iron phosphate batteries, or lithium cobalt oxide batteries, etc.), and the corresponding positive electrode active material can, for example, include LiNi. x Co y Mn z O2 (x+y+z=1), LiMn2O4, LiFePO4, or LiCoO2. The positive electrode current collector can be aluminum foil. The binder used between the positive electrode active material and the positive electrode current collector mainly includes polyvinylidene fluoride (PVDF). The separator is a polymer electrolyte membrane, such as polyethylene (PE).

[0052] In this disclosure, the grafting process includes: mixing the grafting material with the positive electrode sheet and the separator connected to the positive electrode sheet in the waste battery and carrying out a grafting reaction; wherein the grafting material includes acrylic acid, crosslinking agent and initiator.

[0053] For reference, the crosslinking agent may include benzoyl peroxide, and the initiator may include dicumyl peroxide. By using the above-mentioned crosslinking agent and initiator in combination to initiate free radical polymerization, hydroxyl groups in acrylic acid are introduced into the molecular chains of PVDF and the membrane and crosslinking reaction is carried out.

[0054] In some embodiments, the mass ratio of acrylic acid to benzoyl peroxide and dicumyl peroxide is (8-10):(1-3):(2-4), such as 8:1:2, 8:1:3, 8:1:4, 8:2:2, 8:2:3, 8:2:4, 8:3:2, 8:3:3, 8:3:4, 9:1:2, 9:1:3, 9:1:4, 9:2:2, 9:2:3, 9:2:4, 9:3:2, 9:3:3, 9:3:4, 10:1:2, 10:1:3, 10:1:4, 10:2:2, 10:2:3, 10:2:4, 10:3:2, 10:3:3, or 10:3:4, etc., or any other value within the range of (8-10):(1-3):(2-4).

[0055] Too little or too much benzoyl peroxide will reduce the grafting rate. Too little dicumyl peroxide will hinder the improvement of reaction efficiency; too much dicumyl peroxide will easily cause side reactions, leading to a decrease in the stability of the graft copolymer.

[0056] Furthermore, the grafting material also includes a solvent. For example, the solvent may include n-propanol. In addition, other solvents capable of dissolving acrylic acid and the aforementioned crosslinking agent and initiator are also possible.

[0057] In some embodiments, each 100g of solvent may correspond to 8g-10g (e.g., 8g, 8.5g, 9g, 9.5g or 10g, etc.) of acrylic acid, 1g-3g (e.g., 1g, 1.5g, 2g, 2.5g or 3g, etc.) of benzoyl peroxide and 2g-4g (e.g., 2g, 2.5g, 3g, 3.5g or 4g, etc.) of dicumyl peroxide.

[0058] In this disclosure, the grafting reaction temperature can be 60℃-80℃, such as 60℃, 65℃, 70℃, 75℃ or 80℃, or any other value within the range of 60℃-80℃.

[0059] If the grafting reaction temperature is below 60℃, the reaction efficiency will be reduced, affecting the grafting rate; if the grafting reaction temperature is above 80℃, side reactions are likely to occur, leading to a decrease in the stability of the grafted copolymer.

[0060] The grafting reaction time can be 2h-6h, such as 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, or any other value within the range of 2h-6h.

[0061] If the grafting reaction time is less than 2 hours, it is not conducive to the full cross-linking reaction and reduces the bonding effect; if the grafting reaction time is longer than 6 hours, side reactions are more likely to occur, leading to a decrease in the stability of the graft copolymer.

[0062] The grafting reaction described above can be carried out under constant temperature, sealed and dry conditions to avoid solvent evaporation.

[0063] As mentioned above, the principle of the grafting reaction includes: primary free radicals are generated through an initiator, which further abstract hydrogen atoms from the main chains of PVDF and the membrane (mainly composed of PE) to form PVDF macromolecular free radicals and PE macromolecular free radicals. The PVDF macromolecular free radicals and PE macromolecular free radicals then undergo graft copolymerization with the added monomers. At the same time, the coupling reaction between the PVDF macromolecular free radicals and PE macromolecular free radicals leads to the branching and cross-linking of their molecular chains.

[0064] By simultaneously grafting hydrophilic acrylic acid onto PVDF and the separator, the connection between the positive electrode active material and the separator is primarily achieved through tight cross-linking of the grafted material formed between the positive electrode binder and the separator. (Acrylic acid, as a hydrophilic monomer, can enhance the hydrophilicity of PVDF by grafting onto its surface. Furthermore, under the action of a free radical initiator, acrylic acid is converted into an excited-state dimer to participate in the grafting reaction, exhibiting high affinity for both the PVDF and separator backbones, resulting in a high grafting rate.) Meanwhile, the adhesion between the positive electrode active material and the positive electrode current collector is mainly achieved through physical adsorption formed by van der Waals forces between the positive electrode binder and the positive electrode current collector. In other words, the adhesion between the positive electrode active material and the separator is stronger than the adhesion between the positive electrode active material and the positive electrode current collector.

[0065] In this disclosure, swelling may include immersing the grafted material in water.

[0066] For reference, the immersion temperature can be 20℃-30℃, such as 20℃, 22℃, 25℃, 28℃ or 30℃, or any other value within the range of 20℃-30℃.

[0067] The soaking time can be 18h-24h, such as 18h, 19h, 20h, 21h, 22h, 23h or 24h, or any other value within the range of 18h-24h.

[0068] Through the above treatment, PVDF swells, increasing the distance between PVDF and the positive electrode current collector, thus reducing their adhesion. Meanwhile, the positive electrode active material and the separator are cross-linked through grafts, exhibiting strong adhesion. Therefore, under external force, the positive electrode active material and separator can be completely separated from the positive electrode current collector. This method avoids the use of energy-intensive heat treatment (processing temperature approximately 500-600℃) and methods involving large amounts of acid or alkali solutions. This method is simple and effective for separating the positive electrode material and the positive electrode current collector, while also being energy-efficient, low-cost, safe, and environmentally friendly.

[0069] It should be noted that the aforementioned "external force" includes any method that can separate the positive electrode active material and the separator from the positive electrode current collector, such as tension or thrust.

[0070] In this disclosure, the waste batteries may undergo pretreatment before grafting. Pretreatment includes removing the electrolyte and negative electrode from the waste batteries.

[0071] Used batteries can be disassembled first, the outer casing removed, and the inner core containing the positive electrode, separator and negative electrode can be obtained.

[0072] Electrolyte can be removed by heating the inner core of the used battery to cause the electrolyte to evaporate.

[0073] For example, the heating temperature can be 140℃-150℃, such as 140℃, 142℃, 145℃, 148℃, or 150℃, or any other value within the range of 140℃-150℃. The heating time can be 1h-2h, such as 1h, 1.5h, or 2h, or any other value within the range of 1h-2h.

[0074] The above heating process can be carried out in a muffle furnace or in other heating devices.

[0075] Removing the negative electrode can be achieved by immersing the battery core (after removing the electrolyte) in water. This dissolves the aqueous negative electrode binder (mainly composed of styrene-butadiene rubber latex, SBR) in the water, allowing the graphite to detach naturally. Subsequently, the negative electrode and the detached negative electrode active material are removed, and the positive electrode and the separator connected to the positive electrode are collected for grafting.

[0076] For reference, the immersion time of the battery core, excluding the electrolyte, in water can be 24h-48h, such as 24h, 30h, 36h, 42h or 48h, or any other value within the range of 24h-48h.

[0077] In some embodiments, the pretreatment may further include: modifying the positive electrode and the separator connected to the positive electrode.

[0078] The treatment reagent used in the above modification treatment can be a mixed solution of alkali and alcohol.

[0079] The base may, by way of example, include at least one of KOH and NaOH, and the alcohol may, by way of example, include ethanol.

[0080] The mass ratio of alkali to alcohol can be (1:100) to (10:100), such as 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100 or 1:100, or any other value within the range of (1:100) to (10:100).

[0081] For reference, the modification treatment temperature can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃, or any other value within the range of 50℃-80℃.

[0082] The modification treatment time can be 30 min, 40 min, 50 min, 60 min, 70 min, 80 min or 90 min, or any other value within the range of 30 min to 90 min.

[0083] Modification treatment can increase the active groups on PVDF and the membrane, forming carbon-carbon conjugated double bonds on PVDF and the membrane. This is beneficial for generating more free radical active sites on the molecular chain, thereby increasing the active sites for the reaction and improving the grafting rate.

[0084] In this disclosure, the positive electrode current collector and the positive electrode active material bonded with a diaphragm can be separated by an external force provided by a negative pressure adsorption device.

[0085] Please refer to Figure 1 The negative pressure adsorption device includes a suction cup 20, which can be a single suction cup or multiple suction cups (e.g., two, three, or more). The suction cup 20 is used to adsorb onto the surface of the positive current collector and / or the membrane to be separated, according to actual needs, so as to separate the positive current collector and the membrane under negative pressure.

[0086] The suction cup 20 is connected to a gas flow channel (not shown in the figure). For example... Figure 2 As shown, the suction cup 20 has suction holes 23 on its surface (the number can be one or more). The suction holes 23 are connected to one end of the gas flow pipe, and the other end of the gas flow pipe is connected to the pump device (not shown).

[0087] In some embodiments, taking a wound battery core as an example, a portion of the battery core is formed by winding a first negative electrode sheet, a first separator 11, a first positive electrode sheet, a second separator 15, and a second negative electrode sheet in sequence. After removing the first negative electrode sheet and the second negative electrode sheet according to the above process, the remaining components are the first separator 11, the first positive electrode sheet (which is in sequence a first positive electrode active material layer 12, an aluminum foil layer 13, and a second positive electrode active material layer 14) and the second separator 15. The first positive electrode active material layer 12 is disposed opposite to the first separator 11, and the second positive electrode active material layer 14 is disposed opposite to the second separator 15. Accordingly, one of the suction cups 20 (defined as the first suction cup 21) of the negative pressure adsorption device is adsorbed onto the first diaphragm 11, and the other suction cup 20 (defined as the second suction cup 22) is adsorbed onto the second diaphragm 15. The negative pressure adsorption device is started, and the gas flow pipe is pumped to the outside through the pump device to generate negative pressure between the suction cup 20 and the surface of the adsorbed object. Then, by causing the first suction cup 21 and the second suction cup 22 to move relative to each other, the positive current collector can be separated from the positive active material of the bonding diaphragm.

[0088] For example, the negative pressure range can be 500Pa-1000Pa, such as 500Pa, 600Pa, 700Pa, 800Pa, 900Pa or 1000Pa, or any other value within the range of 500Pa-1000Pa.

[0089] Further, the separated positive electrode active material with the membrane bonded together is crushed and the membrane is removed by sorting to obtain the positive electrode active material.

[0090] It should be noted that the positive electrode active material, negative electrode active material, positive electrode current collector, negative electrode current collector, and separator obtained during the recycling process provided in this disclosure can all be recycled and reused as needed.

[0091] The features and performance of this disclosure will be further described in detail below with reference to embodiments.

[0092] Example 1

[0093] This embodiment provides a method for recycling materials from waste batteries through a complete, integrated process, which includes the following steps:

[0094] S1: Manually disassembled and recycled nickel-cobalt-manganese ternary lithium-ion batteries, removing the outer aluminum shell to obtain the battery core containing the positive electrode, separator, and negative electrode.

[0095] The separator of this nickel-cobalt-manganese ternary lithium-ion battery is made of PE, the positive electrode current collector is aluminum foil, the negative electrode current collector is copper foil, and the positive electrode active material is LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2, the negative electrode active material is graphite, the positive electrode binder is mainly PVDF, and the negative electrode binder is mainly SBR.

[0096] S2: Place the battery core into a muffle furnace and heat it at 145°C for 1.5 hours. Then cool it with the furnace to remove the electrolyte.

[0097] S3: Place the battery core with the electrolyte removed into pure water and soak it at room temperature for 36 hours to dissolve the water-based binder SBR on the negative electrode. The graphite will fall off naturally, and the positive electrode and separator of the battery core will be collected.

[0098] S4: Immerse the positive electrode and the separator in a NaOH-ethanol mixed solution with a mass fraction of 5 wt% alcohol at a temperature of 75 ℃ for 60 min.

[0099] S5: The modified positive electrode and separator are immersed in a solution of n-propanol containing 9wt% acrylic acid, 2wt% benzoyl peroxide and 3wt% dicumyl peroxide, and then placed in a constant temperature drying oven for 4 hours in a sealed environment at a reaction temperature of 70℃. After the reaction is completed, the separator is removed and immersed in deionized water at room temperature (25℃) for 21 hours. After the immersion is completed, the separator is removed and dried, thus simultaneously grafting hydrophilic acrylic acid onto PVDF and separator.

[0100] S6: Use a negative pressure adsorption device (such as...) Figure 1(As shown) the aluminum foil and the positive electrode active material are separated. Specifically, the first suction cup 21 in the negative pressure adsorption device is adsorbed onto the first diaphragm 11, and the second suction cup 22 is adsorbed onto the second diaphragm 15. The negative pressure adsorption device is activated, and the negative pressure is 800 Pa, causing the first suction cup 21 and the second suction cup 22 to move relative to each other, thereby separating the aluminum foil layer 13 from the positive electrode active material (the first positive electrode active material layer 12 adhering to the first diaphragm 11 and the second positive electrode active material layer 14 adhering to the second diaphragm 15) of the bonding diaphragm.

[0101] S7: Crush the positive electrode active material with the membrane attached, sort and remove the membrane to obtain the positive electrode active material.

[0102] Example 2

[0103] This embodiment provides a method for recycling materials from waste batteries through a complete, integrated process, which includes the following steps:

[0104] S1: Same as Example 1.

[0105] S2: Place the battery core into a muffle furnace and heat it at 140°C for 1 hour. Then cool it with the furnace to remove the electrolyte.

[0106] S3: Place the battery core with the electrolyte removed into pure water and soak it at room temperature for 24 hours to dissolve the water-based binder SBR on the negative electrode. The graphite will fall off naturally, and the positive electrode and separator of the battery core will be collected.

[0107] S4: Immerse the positive electrode and the separator in a KOH-ethanol mixed solution with a mass fraction of 1 wt% at a temperature of 80°C for 90 min.

[0108] S5: The modified positive electrode and separator are immersed in a solution of n-propanol containing 8wt% acrylic acid, 1wt% benzoyl peroxide and 2wt% dicumyl peroxide, and then placed in a constant temperature drying oven for 2 hours in a sealed environment at a reaction temperature of 60℃. After the reaction is completed, the separator is removed and immersed in deionized water at room temperature (20℃) for 18 hours. After immersion, the separator is removed and dried, thus simultaneously grafting hydrophilic acrylic acid onto PVDF and the separator.

[0109] S6: Set the negative pressure to 1000Pa, and the rest is the same as in Example 1.

[0110] S7: Crush the positive electrode active material with the membrane attached, sort and remove the membrane to obtain the positive electrode active material.

[0111] Example 3

[0112] This embodiment provides a method for recycling materials from waste batteries through a complete, integrated process, which includes the following steps:

[0113] S1: Same as Example 1.

[0114] S2: Place the battery core into a muffle furnace and heat it at 150°C for 2 hours. Then cool it with the furnace to remove the electrolyte.

[0115] S3: Place the battery core with the electrolyte removed into pure water and soak it at room temperature for 48 hours to dissolve the water-based binder SBR on the negative electrode. The graphite will fall off naturally, and the positive electrode and separator of the battery core will be collected.

[0116] S4: Immerse the positive electrode and the separator in a NaOH-ethanol mixed solution with a mass fraction of 10wt% alcohol at a temperature of 50℃ for 30 minutes.

[0117] S5: The modified positive electrode and separator are immersed in a solution of n-propanol containing 10wt% acrylic acid, 3wt% benzoyl peroxide and 4wt% dicumyl peroxide, and then placed in a constant temperature drying oven for 6 hours in a sealed environment at a reaction temperature of 80℃. After the reaction is completed, the separator is removed and immersed in deionized water at room temperature (30℃) for 24 hours. After the immersion is completed, the separator is removed and dried. This allows hydrophilic acrylic acid to be grafted onto PVDF and the separator simultaneously.

[0118] S6: Set the negative pressure to 500Pa, and the rest is the same as in Example 1.

[0119] S7: Crush the positive electrode active material with the membrane attached, sort and remove the membrane to obtain the positive electrode active material.

[0120] Comparative Example 1

[0121] After dismantling the waste battery as in Example 1 to obtain the battery cell, the battery cell is further dismantled to obtain the positive electrode sheet. The dismantled positive electrode sheet is placed in a graphite crucible and heated in a muffle furnace at 500°C for 4 minutes. The heating process is carried out in an air atmosphere. After natural cooling, the powdery material on the surface of the positive electrode sheet is sieved to separate it, obtaining aluminum foil and positive electrode material.

[0122] Comparative Example 2

[0123] The difference between this comparative example and Example 1 is that the mass ratio of acrylic acid to benzoyl peroxide and dicumyl peroxide is 9:0.5:3.

[0124] Comparative Example 3

[0125] The difference between this comparative example and Example 1 is that the mass ratio of acrylic acid to benzoyl peroxide and dicumyl peroxide is 9:4:3.

[0126] Comparative Example 4

[0127] The difference between this comparative example and Example 1 is that the mass ratio of acrylic acid to benzoyl peroxide and dicumyl peroxide is 9:2:1.

[0128] Comparative Example 5

[0129] The difference between this comparative example and Example 1 is that the mass ratio of acrylic acid to benzoyl peroxide and dicumyl peroxide is 9:2:5.

[0130] Comparative Example 6

[0131] The difference between this comparative example and Example 1 is that the grafting reaction temperature is 50°C.

[0132] Comparative Example 7

[0133] The difference between this comparative example and Example 1 is that the grafting reaction temperature is 90°C.

[0134] Comparative Example 8

[0135] The difference between this comparative example and Example 1 is that the grafting reaction time is 1 hour.

[0136] Comparative Example 9

[0137] The difference between this comparative example and Example 1 is that the grafting reaction time is 8 hours.

[0138] Comparative Example 10

[0139] The difference between this comparative example and Example 1 is that no modification treatment was performed before grafting.

[0140] Comparative Example 11

[0141] The difference between this comparative example and Example 1 is that no swelling treatment was performed after grafting.

[0142] Test case

[0143] The recovery rate of the positive electrode active material and the purity of the positive electrode current collector (aluminum foil) obtained in Examples 1-3 and Comparative Examples 1-11 were measured, and the results are shown in Table 1.

[0144] Table 1 Test Results

[0145]

[0146]

[0147] As can be seen from Table 1, the methods provided in Examples 1-3 of this disclosure can achieve a high recovery rate of positive electrode active material and also recover positive electrode current collectors with high purity.

[0148] Industrial applicability

[0149] The method disclosed herein can effectively separate the positive electrode active material and current collector from waste batteries. The separated materials can be further recycled. The method is simple to operate, easy to control, low in energy consumption, low in cost, environmentally friendly, and safe.

Claims

1. A method for recycling materials from waste batteries through a complete, integrated supply chain, characterized in that, include: Grafting treatment is performed on the positive electrode sheet and the separator connected to the positive electrode sheet in the waste battery so that the separator and the positive electrode binder of the positive electrode sheet are cross-linked through the graft. Then, the grafted material is swollen to reduce the adhesion between the positive electrode binder and the positive electrode current collector in the positive electrode sheet. Under the action of external force, the positive electrode current collector is separated from the positive electrode active material with the separator bonded. The main component of the positive electrode binder is polyvinylidene fluoride; The grafting process includes: mixing the grafting material with a positive electrode sheet and a separator connected to the positive electrode sheet from a waste battery and carrying out a grafting reaction; wherein the grafting material includes acrylic acid, a crosslinking agent, and an initiator; the crosslinking agent includes benzoyl peroxide; and / or, the initiator includes dicumyl peroxide; the mass ratio of acrylic acid to benzoyl peroxide and dicumyl peroxide is (8-10):(1-3):(2-4); the grafting reaction temperature is 60℃-80℃; and the grafting reaction time is 2h-6h. Before grafting, the process includes: pre-treatment of the waste batteries; the pre-treatment includes: removing the electrolyte and negative electrode from the waste batteries; the pre-treatment also includes: modifying the positive electrode and the separator connected to the positive electrode; the treatment reagent used for modification is a mixed solution of alkali and alcohol; the temperature of modification is 50℃-80℃; the modification time is 30min-90min.

2. The recycling method according to claim 1, characterized in that, The waste battery is a waste lithium-ion battery; and / or, the separator is a polymer electrolyte membrane; and / or, the positive electrode current collector is aluminum foil.

3. The recycling method according to claim 1, characterized in that, The grafting material also includes a solvent.

4. The recycling method according to claim 3, characterized in that, The solvent includes n-propanol.

5. The recycling method according to claim 4, characterized in that, For every 100g of the solvent, 8g-10g of the acrylic acid, 1g-3g of the benzoyl peroxide, and 2g-4g of the dicumyl peroxide are used.

6. The recycling method according to claim 1, characterized in that, The grafting reaction is carried out under constant temperature, closed and dry conditions.

7. The recycling method according to claim 1, characterized in that, Removing the electrolyte includes heating the inner core of the waste battery to evaporate and remove the electrolyte.

8. The recycling method according to claim 7, characterized in that, The heating temperature is 140℃-150℃; and / or the heating time is 1h-2h.

9. The recycling method according to claim 1, characterized in that, Removing the negative electrode sheet includes: immersing the battery core (after removing the electrolyte) in water to dissolve the negative electrode binder in the negative electrode sheet in the water, removing the negative electrode sheet and the negative electrode active material detached from the negative electrode current collector of the negative electrode sheet, and collecting the positive electrode sheet and the separator connected to the positive electrode sheet.

10. The recycling method according to claim 9, characterized in that, Soaking time is 24-48 hours.

11. The recycling method according to claim 9, characterized in that, The negative electrode current collector is copper foil.

12. The recycling method according to claim 1, characterized in that, The base includes at least one of KOH and NaOH; and / or, the alcohol includes ethanol; and / or, the mass ratio of the base to the alcohol is (1:100) to (10:100).

13. The recycling method according to claim 1, characterized in that, The positive electrode current collector is separated from the positive electrode active material bonded to the membrane by providing external force through a negative pressure adsorption device.

14. The recycling method according to claim 13, characterized in that, The negative pressure adsorption device includes a suction cup, which is used to adsorb onto the surface of the positive current collector and / or the membrane to be separated under negative pressure.

15. The recycling method according to claim 14, characterized in that, The suction cup is connected to a gas flow pipe.

16. The recycling method according to claim 15, characterized in that, The suction cup has suction holes on its surface, and these suction holes are connected to the gas flow pipe.

17. The recycling method according to claim 14, characterized in that, The negative pressure range is 500Pa-1000Pa.

18. The recycling method according to claim 14, characterized in that, The positive electrode active material bonded with the membrane obtained by separation is crushed, and the membrane is removed by sorting to obtain the positive electrode active material.

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