WO2025043371A1 - Method for recycling materials in waste batteries by means of full-chain integrated treatment - Google Patents

Abstract

Disclosed is a method for recycling materials in waste batteries by means of full-chain integrated treatment, relating to the technical field of battery recycling. The method comprises: grafting a positive electrode sheet and a separator connected to the positive electrode sheet in a waste battery, so that the separator and a positive electrode binder for the positive electrode sheet are cross-linked by means of a graft; swelling the grafted material to reduce the bonding force between the positive electrode binder and a positive electrode current collector in the positive electrode sheet; and under the action of an external force, separating the positive electrode current collector from a positive electrode active material to which the separator is bonded. By means of the method, the positive electrode active material and the current collector in the waste battery can be effectively separated, and then the separated materials can be recycled.

Description

A recycling method for materials in waste batteries with full-chain integration Technical Field

The present disclosure relates to the technical field of battery recycling, and in particular to a recycling method for materials in waste batteries with full-chain integrated processing.

Background Art

In recent years, the global lithium-ion battery industry has developed rapidly, and electric vehicles have become an important development direction in the future. Therefore, power lithium-ion batteries have also ushered in great development opportunities. However, the life of lithium-ion batteries is limited. The use of a large number of lithium batteries will mean the emergence of a large number of waste lithium batteries. Recycling usable materials from waste batteries, such as valuable metals, can not only ease resource shortages and create economic value, but also solve the problem of environmental pollution caused by waste batteries.

At present, the recycling method of waste batteries is mainly to discharge and crush the batteries, and then use flotation, magnetic separation and wet chemical methods to separate the target valuable metals. As for some methods of separating positive electrode materials from current collectors, they are mainly carried out by removing binders and dissolving current collectors. However, the method of removing binders often requires high-temperature treatment, and the temperature control is relatively strict. It is not acceptable to be too high or too low, and the combustion of organic matter during the treatment process will cause air pollution; and the dissolution of positive electrode current collector aluminum foil is usually carried out with alkali (the reaction equation can be referred to as follows 2Al+ _2H2O +2NaOH＝ _2NaAlO2 + _3H2 ↑), which will produce a large amount of gas in the process, and the gas will bring out part of the alkali solution, which will cause certain harm to the environment and people.

In view of this, the present disclosure is proposed.

Summary of the invention

The purpose of the present disclosure includes providing a full-chain integrated recycling method for materials in waste batteries, which can at least effectively separate the positive electrode active materials and current collectors in the waste batteries, and the separated materials can be further recycled. In addition, the method is simple to operate, the conditions are easy to control, and it is environmentally friendly and safe.

The present disclosure can be implemented as follows:

The present invention provides a recycling method for materials in waste batteries with a full-chain integrated treatment, comprising: grafting a positive electrode sheet in the waste battery and a diaphragm connected to the positive electrode sheet so that the diaphragm and the positive electrode binder of the positive electrode sheet are cross-linked through the grafted material, and then swelling the grafted material to reduce the bonding force between the positive electrode binder and the positive electrode collector in the positive electrode sheet, and separating the positive electrode collector from the positive electrode active material bonded with the diaphragm under the action of an external force.

In an optional embodiment, the used batteries are used lithium-ion batteries.

In an alternative embodiment, the separator is a polymer electrolyte membrane.

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

In an alternative embodiment, the positive electrode current collector is aluminum foil.

In an optional embodiment, the grafting treatment includes: mixing the grafting raw material with the positive electrode sheet in the waste battery and the separator connected to the positive electrode sheet and performing a grafting reaction; wherein the grafting raw material includes acrylic acid, a cross-linking agent and an initiator.

In an alternative embodiment, the cross-linking agent comprises dibenzoyl peroxide; and the initiator comprises dicumyl peroxide.

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

In an alternative embodiment, the grafting raw material further includes a solvent.

In an alternative embodiment, the solvent comprises n-propanol.

In an optional embodiment, 8g-10g of acrylic acid, 1g-3g of dibenzoyl peroxide and 2g-4g of dicumyl peroxide are used per 100g of solvent.

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

Feature 1: The temperature of the grafting reaction is 60℃-80℃;

Feature 2: The grafting reaction time is 2h-6h;

Feature 3: The grafting reaction is carried out under constant temperature, closed and dry conditions.

In an optional embodiment, the swelling includes: soaking the grafted material in water.

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

In an optional embodiment, before the grafting treatment, the method further includes: pre-treating the waste battery;

Pre-treatment includes: removing the electrolyte and negative electrode from the used batteries.

In an optional embodiment, removing the electrolyte includes: heating the inner core of the waste battery to volatilize and remove the electrolyte.

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

In an optional embodiment, removing the negative electrode sheet includes: soaking the battery core from which the electrolyte has been 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 that has fallen off the negative electrode collector of the negative electrode sheet, and collecting the positive electrode sheet and the separator connected to the positive electrode sheet.

In an optional embodiment, the soaking time is 24h-48h.

In an alternative embodiment, the negative electrode current collector is copper foil.

In an optional embodiment, the pre-treatment further includes: modifying the positive electrode sheet and the separator connected to the positive electrode sheet.

In an optional embodiment, the modification process has at least one of the following characteristics:

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

Feature 2: The temperature of the modification treatment is 50℃-80℃;

Feature 3: The modification treatment time is 30min-90min.

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 the base to the alcohol is (1:100)-(10:100).

In an optional embodiment, the positive electrode current collector and the positive electrode active material bonded with the separator are separated by providing an external force through a negative pressure adsorption device.

In an optional embodiment, the negative pressure adsorption device includes a suction cup, which is used to be adsorbed on the surface of the positive electrode current collector and/or the separator to be separated so as to separate the positive electrode current collector and the separator under the action of negative pressure.

In an optional embodiment, the suction cup is connected to a gas circulation pipeline.

In an optional embodiment, the surface of the suction cup has a suction hole, and the suction hole is connected to the gas flow pipe.

In an optional embodiment, the negative pressure ranges from 500Pa to 1000Pa.

In an optional embodiment, the separated positive electrode active material bonded with the separator is pulverized, and the separator is removed by sorting to obtain the positive electrode active material.

The bonding between the positive electrode active material and the positive electrode collector is mainly achieved by physical adsorption formed by the Van der Waals force generated between the positive electrode binder and the positive electrode collector. The present invention simultaneously performs grafting treatment on the positive electrode binder and the separator, so that the connection between the positive electrode active material and the separator is mainly tightly cross-linked by the graft formed between the positive electrode binder and the separator; the bonding force between the positive electrode binder and the positive electrode collector is reduced by swelling the grafted material, and the positive electrode collector can be effectively separated from the positive electrode active material bonded with the separator under the action of external force.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

FIG1 is a schematic structural diagram of a negative pressure adsorption device in the present disclosure;

FIG. 2 is a schematic diagram of the structure of a suction cup in a negative pressure adsorption device in the present disclosure.

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 DESCRIPTION

In order to make the purpose, technical scheme and advantages of the embodiments of the present disclosure clearer, the technical scheme in the embodiments of the present disclosure will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

The following is a detailed description of the full-chain integrated recycling method for materials in waste batteries provided by the present invention.

The present disclosure proposes a recycling method for materials in waste batteries that is integrated throughout the entire chain, including: The positive electrode sheets in the waste batteries and the diaphragms connected to the positive electrode sheets (such as by bonding, etc.) are grafted to allow the diaphragm and the positive electrode binder of the positive electrode sheets to be cross-linked through the grafted material, and then the grafted materials are swelled to reduce the bonding force between the positive electrode binder and the positive electrode collector in the positive electrode sheet, and the positive electrode collector is separated from the positive electrode active material bonded with the diaphragm under the action of external force.

For reference, the above-mentioned waste batteries can be waste lithium-ion batteries (such as waste nickel-cobalt-manganese ternary lithium-ion batteries, lithium manganate batteries, lithium iron phosphate batteries or lithium cobalt oxide batteries, etc.), and the corresponding positive electrode active materials can illustratively include LiNi _x Co _y Mn _z O ₂ (x+y+z=1), LiMn ₂ O ₄ , LiFePO ₄ or LiCoO ₂ . The positive electrode collector can be aluminum foil. The binder used between the positive electrode active material and the positive electrode collector mainly includes polyvinylidene fluoride (PVDF). The separator is a polymer electrolyte membrane, for example, it can include polyethylene (PE).

In the present disclosure, the grafting treatment includes: mixing the grafting raw material with the positive electrode sheet in the waste battery and the separator connected to the positive electrode sheet and performing a grafting reaction; wherein the grafting raw material includes acrylic acid, a cross-linking agent and an initiator.

For reference, the crosslinking agent may include dibenzoyl peroxide, and the initiator may include dicumyl peroxide. The crosslinking agent and initiator are used to initiate free radical polymerization to introduce hydroxyl groups in acrylic acid into the molecular chains of PVDF and the diaphragm and perform a crosslinking reaction.

In some embodiments, the mass ratio of acrylic acid to dibenzoyl peroxide and diisopropylbenzene 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, or it can be any other value within the range of (8-10):(1-3):(2-4).

If the amount of dibenzoyl peroxide is too little or too much, the grafting rate will be reduced. If the amount of dicumyl peroxide is too much, it will not be conducive to improving the reaction efficiency; if the amount of dicumyl peroxide is too much, side reactions are likely to occur, resulting in reduced stability of the graft copolymer.

Furthermore, the grafting raw material also includes a solvent. For example, the solvent may include n-propanol. In addition, it is not excluded that other solvents that can dissolve acrylic acid and the above-mentioned crosslinking agent and initiator may be used.

In some embodiments, 8 g to 10 g (e.g., 8 g, 8.5 g, 9 g, 9.5g or 10g) of acrylic acid, 1g-3g (such as 1g, 1.5g, 2g, 2.5g or 3g) of dibenzoyl peroxide and 2g-4g (such as 2g, 2.5g, 3g, 3.5g or 4g) of diisopropylbenzene peroxide.

In the present disclosure, the temperature of the grafting reaction may be 60°C-80°C, such as 60°C, 65°C, 70°C, 75°C or 80°C, etc., or any other value within the range of 60°C-80°C.

If the temperature of the grafting reaction is lower than 60°C, the reaction efficiency is reduced and the grafting rate is affected; if the temperature of the grafting reaction is higher than 80°C, it is easy to cause side reactions and reduce the stability of the grafted copolymer.

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

If the grafting reaction time is shorter than 2 hours, it is not conducive to the full grafting cross-linking reaction, thereby reducing the bonding effect; if the grafting reaction time is longer than 6 hours, side reactions are likely to occur, resulting in reduced stability of the grafted copolymer.

The grafting reaction can be carried out under constant temperature, sealed and dry conditions to prevent solvent volatilization.

Continuing from the above, the principle of the above grafting reaction includes: primary free radicals are generated by initiators, and the primary free radicals further capture hydrogen atoms on the main chains of PVDF and diaphragms (the main component is PE) to form PVDF macromolecular free radicals and PE macromolecular free radicals, which then undergo grafting copolymerization with the added monomers. At the same time, the coupling reaction between PVDF macromolecular free radicals and PE macromolecular free radicals will lead to branching and cross-linking of their molecular chains.

By simultaneously grafting hydrophilic acrylic acid onto PVDF and the separator, the connection between the positive active material and the separator can be mainly made by the tight cross-linking of the graft formed between the positive binder and the separator (acrylic acid as a hydrophilic monomer grafted onto the PVDF surface can improve its hydrophilicity, and acrylic acid will be converted into an excited dimer under the action of a free radical initiator to participate in the grafting reaction, and has a high affinity with the main chain of PVDF and the separator, and a high grafting rate can be obtained), while the bonding between the positive active material and the positive current collector is mainly achieved by the physical adsorption formed by the van der Waals force generated between the positive binder and the positive current collector. That is, the bonding force between the positive active material and the separator is stronger than the bonding force between the positive active material and the positive current collector.

In the present disclosure, swelling may include: soaking the grafted material in water.

For reference, the soaking temperature can be 20°C-30°C, such as 20°C, 22°C, 25°C, 28°C Or 30°C, etc., it can also be any other value within the range of 20°C-30°C.

The soaking time may be 18 hours to 24 hours, such as 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours or 24 hours, or any other value within the range of 18 hours to 24 hours.

Through the above treatment, PVDF can be swollen, the distance between PVDF and the positive current collector is increased, and the viscosity between PVDF and the positive current collector is weakened; and the positive active material and the separator are cross-linked through the graft, which has a strong bonding force. Therefore, the positive active material and the separator as a whole can be separated from the positive current collector under the action of external force. This method can avoid the use of high-energy heat treatment (treatment temperature is about 500-600℃) and the use of a large amount of acid or alkaline solution treatment. This method is simple and effective for separating the positive material and the positive current collector, and takes into account low energy consumption, low cost, safety and environmental protection.

It should be noted that the above-mentioned “external force” includes any means such as pulling force or pushing force that can separate the positive electrode active material and the separator as a whole from the positive electrode current collector.

In the present disclosure, the waste battery can be pre-treated before the grafting treatment, and the pre-treatment includes: removing the electrolyte and the negative electrode sheet in the waste battery.

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

The electrolyte can be removed by heating the inner core of the used battery to volatilize and remove the electrolyte.

For example, the heating temperature may be 140° C.-150° C., such as 140° C., 142° C., 145° C., 148° C. or 150° C., or any other value within the range of 140° C.-150° C. The heating time may be 1 h-2 h, such as 1 h, 1.5 h or 2 h, or any other value within the range of 1 h-2 h.

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

The negative electrode can be removed by soaking the battery core with the electrolyte removed in water, so that the aqueous negative electrode binder (mainly composed of styrene-butadiene rubber latex, SBR) in the negative electrode sheet is dissolved in water. Under this condition, the graphite can fall off naturally. Subsequently, the negative electrode sheet and the fallen negative electrode active material are removed, and the positive electrode sheet and the separator connected to the positive electrode sheet are collected for grafting treatment.

For reference, the battery core with the electrolyte removed may be immersed in water for 24 hours to 48 hours, such as 24 hours, 30 hours, 36 hours, 42 hours or 48 hours, or any other value within the range of 24 hours to 48 hours.

In some embodiments, the pre-treatment may further include: modifying the positive electrode sheet and the separator connected to the positive electrode sheet.

The treatment reagent used in the above modification treatment may be a mixed solution of alkali and alcohol.

The base may exemplarily include at least one of KOH and NaOH, and the alcohol may exemplarily include ethanol.

The mass ratio of the alkali to the alcohol can be (1:100)-(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)-(10:100).

For reference, the temperature of the modification treatment may be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, etc., or any other value within the range of 50°C-80°C.

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

Through modification treatment, the active groups on PVDF and the diaphragm can be increased, so that carbon-carbon conjugated double bonds are formed on PVDF and the diaphragm, which is conducive to the generation of more free radical active points on the molecular chain, thereby increasing the active sites of the reaction and improving the grafting rate.

In the present disclosure, the positive electrode current collector and the positive electrode active material bonded with the separator may be separated by providing an external force through a negative pressure adsorption device.

Referring to FIG. 1 , the negative pressure adsorption device includes a suction cup 20. The number of the suction cups 20 may be only one or multiple (such as two, three or more). The suction cup 20 is used to adsorb on the surface of the positive electrode current collector and/or the separator to be separated according to actual needs to separate the positive electrode current collector and the separator under the action of negative pressure.

The suction cup 20 is connected to a gas flow pipe (not shown). As shown in FIG2 , the surface of the suction cup 20 has a suction hole 23 (the number can be one or more), the suction hole 23 is connected to one end of the gas flow pipe, and the other end of the gas flow pipe is connected to a pump device (not shown).

In some embodiments, taking the battery core as a wound type as an example, a partial area is wound in sequence by a first negative electrode sheet, a first separator 11, a first positive electrode sheet, a second separator 15 and a second negative electrode sheet. After removing the first negative electrode sheet and the second negative electrode sheet according to the above process, the first separator 11, the first positive electrode sheet (the first positive electrode active material layer 12, the aluminum foil layer 13, the second positive electrode active material layer 14) and the second separator 15 are left, wherein the first positive electrode active material layer 12 is arranged opposite to the first separator 11, and the second positive electrode active material layer 14 is arranged 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 on the first separator 11, and the other suction cup 20 (defined as the second suction cup 22) is adsorbed on the second separator 15, the negative pressure adsorption device is started, and the gas flow pipe is evacuated to the outside through the pump device to achieve negative pressure between the suction cup 20 and the surface of the adsorbed object, and then the positive electrode current collector and the positive electrode active material bonded to the separator are separated by making the first suction cup 21 and the second suction cup 22 move relative to each other.

Exemplarily, the negative pressure range may be 500Pa-1000Pa, such as 500Pa, 600Pa, 700Pa, 800Pa, 900Pa or 1000Pa, etc., or any other value within the range of 500Pa-1000Pa.

Furthermore, the separated positive electrode active material bonded with the separator is crushed, and the separator is removed by sorting to obtain the positive electrode active material.

It should be noted that the positive electrode active material, negative electrode active material, positive electrode current collector, negative electrode current collector, separator, etc. obtained during the recycling method provided in the present disclosure can be recycled as needed.

The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

Example 1

This embodiment provides a method for recycling materials in waste batteries by integrating the whole chain, which comprises the following steps:

S1: Manually disassemble the recycled nickel-cobalt-manganese ternary lithium-ion battery, remove the external aluminum shell, and obtain the battery core containing the positive electrode, separator and negative electrode.

Among them, the separator of the nickel-cobalt-manganese ternary lithium-ion battery is PE, the positive electrode collector is aluminum foil, the negative electrode collector is copper foil, the positive electrode active material is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , the negative electrode active material is graphite, the positive electrode binder is mainly PVDF, and the negative electrode binder is mainly SBR.

S2: Place the battery core in a muffle furnace and heat at 145°C for 1.5 hours. The furnace is cooled and the electrolyte is removed.

S3: Place the battery core with the electrolyte removed into pure water and soak it at room temperature for 36 hours to dissolve the aqueous binder SBR on the negative electrode sheet. The graphite falls off naturally, and the positive electrode sheet and separator of the battery core are collected.

S4: Soak the positive electrode sheet and the separator in a NaOH-ethanol mixed solution with an alcohol mass fraction of 5 wt % at a soaking temperature of 75° C. for 60 min.

S5: Soak the modified positive electrode sheet and diaphragm in a n-propanol solution containing 9wt% acrylic acid, 2wt% dibenzoyl peroxide, and 3wt% diisopropyl peroxide, and place them in a constant temperature drying oven for a closed reaction for 4 hours at a reaction temperature of 70°C. After the reaction, take them out and immerse them in deionized water, and soak them at room temperature (25°C) for 21 hours. After the soaking is completed, take them out and dry them. The hydrophilic acrylic acid can be grafted onto the PVDF and the diaphragm at the same time.

S6: Use a negative pressure adsorption device (as shown in FIG1 ) to separate the aluminum foil and the positive electrode active material. Specifically, the first suction cup 21 in the negative pressure adsorption device is adsorbed on the first diaphragm 11, and the second suction cup 22 is adsorbed on the second diaphragm 15. The negative pressure adsorption device is started, and the negative pressure is 800 Pa, so that the first suction cup 21 and the second suction cup 22 move relative to each other, so that the aluminum foil layer 13 is separated from the positive electrode active material bonded to the diaphragm (the first positive electrode active material layer 12 bonded to the first diaphragm 11 and the second positive electrode active material layer 14 bonded to the second diaphragm 15).

S7: crushing the positive electrode active material bonded with the separator, sorting and removing the separator, and obtaining the positive electrode active material.

Example 2

This embodiment provides a method for recycling materials in waste batteries by integrating the whole chain, which comprises the following steps:

S1: Same as Example 1.

S2: Place the battery core in a muffle furnace, heat it at 140°C for 1 hour, and then cool it in the furnace to remove the electrolyte.

S3: Place the battery core with the electrolyte removed into pure water and soak it at room temperature for 24 hours to dissolve the aqueous binder SBR on the negative electrode sheet, so that the graphite falls off naturally and the positive electrode sheet and separator of the battery core are collected.

S4: Soak the positive electrode sheet and the separator in a KOH-ethanol mixed solution with a mass fraction of 1wt% of alcohol The soaking temperature is 80℃ and the soaking time is 90min.

S5: Soak the modified positive electrode sheet and diaphragm in a n-propanol solution containing 8wt% acrylic acid, 1wt% dibenzoyl peroxide, and 2wt% diisopropyl peroxide, and place them in a constant temperature drying oven for a closed reaction for 2 hours at a reaction temperature of 60°C. After the reaction, take them out and immerse them in deionized water, and soak them at room temperature (20°C) for 18 hours. After the soaking is completed, take them out and dry them. The hydrophilic acrylic acid can be grafted onto the PVDF and the diaphragm at the same time.

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

S7: crushing the positive electrode active material bonded with the separator, sorting and removing the separator, and obtaining the positive electrode active material.

Example 3

This embodiment provides a method for recycling materials in waste batteries by integrating the whole chain, which comprises the following steps:

S1: Same as Example 1.

S2: Place the battery core in a muffle furnace, heat it at 150°C for 2 hours, and then cool it in the furnace to remove the electrolyte.

S3: Place the battery core with the electrolyte removed into pure water and soak it at room temperature for 48 hours to dissolve the aqueous binder SBR on the negative electrode sheet, so that the graphite falls off naturally and the positive electrode sheet and separator of the battery core are collected.

S4: Soak the positive electrode sheet and the separator in a NaOH-ethanol mixed solution with an alcohol mass fraction of 10 wt % at a soaking temperature of 50° C. for 30 min.

S5: Soak the modified positive electrode sheet and diaphragm in a n-propanol solution containing 10wt% acrylic acid, 3wt% dibenzoyl peroxide, and 4wt% diisopropyl peroxide, and place them in a constant temperature drying oven for a closed reaction for 6 hours at a reaction temperature of 80°C. After the reaction, take them out and immerse them in deionized water, and soak them at room temperature (30°C) for 24 hours. After the soaking is completed, take them out and dry them. The hydrophilic acrylic acid can be grafted onto the PVDF and the diaphragm at the same time.

S6: The negative pressure is set to 500 Pa, and the rest is the same as in Example 1.

S7: crushing the positive electrode active material bonded with the separator, sorting and removing the separator, and obtaining the positive electrode active material.

Comparative Example 1

After disassembling the same waste battery as in Example 1 to obtain the battery core, the battery core was disassembled to obtain the positive electrode sheet. The disassembled positive electrode sheet was placed in a graphite crucible and heated at 500° C. for 4 minutes in a muffle furnace, and the heating process was carried out in an air atmosphere; after natural cooling, the powder on the surface of the positive electrode sheet was sieved and separated to obtain aluminum foil and positive electrode material.

Comparative Example 2

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

Comparative Example 3

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

Comparative Example 4

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

Comparative Example 5

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

Comparative Example 6

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

Comparative Example 7

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

Comparative Example 8

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

Comparative Example 9

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

Comparative Example 10

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

Comparative Example 11

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

Test example

The recovery rates of the positive electrode active materials obtained in Examples 1-3 and Comparative Examples 1-11 and the purity of the positive electrode current collectors (aluminum foils) obtained were measured, and the results are shown in Table 1.

Table 1 Test results

It can be seen from Table 1 that the methods provided in Examples 1-3 of the present disclosure can achieve a higher recovery rate of positive electrode active materials on the one hand, and can also recover a positive electrode current collector with a higher purity on the other hand.

Industrial Applicability

The method provided by the present disclosure can at least effectively separate the positive electrode active material and the current collector in the waste battery, and the separated materials can be further recycled. The method is simple to operate, the conditions are easy to control, and the energy consumption is low. Low cost, environmentally friendly and safe.

Claims (26)

A method for recycling materials in waste batteries with a full-chain integrated process, characterized in that it includes: grafting a positive electrode sheet in the waste battery and a diaphragm connected to the positive electrode sheet so that the diaphragm and the positive electrode binder of the positive electrode sheet are cross-linked through the grafted material, then swelling the grafted material to reduce the bonding force between the positive electrode binder and the positive electrode collector in the positive electrode sheet, and separating the positive electrode collector from the positive electrode active material bonded with the diaphragm under the action of an external force. The recycling method according to claim 1 is characterized in that the waste battery is a waste lithium-ion battery; and/or the separator is a polymer electrolyte membrane; and/or the main component of the positive electrode binder is polyvinylidene fluoride; and/or the positive electrode current collector is aluminum foil. The recycling method according to claim 1 or 2 is characterized in that the grafting treatment comprises: mixing the grafting raw material with the positive electrode sheet in the waste battery and the diaphragm connected to the positive electrode sheet and performing a grafting reaction; wherein the grafting raw material comprises acrylic acid, a cross-linking agent and an initiator. The recycling method according to claim 3 is characterized in that the cross-linking agent includes dibenzoyl peroxide; and/or the initiator includes dicumyl peroxide. The recovery method according to claim 4 is characterized in that the mass ratio of the acrylic acid to the dibenzoyl peroxide and the dicumyl peroxide is (8-10):(1-3):(2-4). The recovery method according to claim 4 or 5, characterized in that the grafting raw material also includes a solvent. The recovery method according to claim 6, characterized in that the solvent comprises n-propanol. The recovery method according to claim 6 or 7 is characterized in that, for every 100g of the solvent, 8g-10g of the acrylic acid, 1g-3g of the dibenzoyl peroxide and 2g-4g of diisopropylbenzene peroxide are used. The recovery method according to any one of claims 2 to 8, characterized in that the grafting reaction has at least one of the following characteristics: Feature 1: The temperature of the grafting reaction is 60℃-80℃; Feature 2: The grafting reaction time is 2h-6h; Feature 3: The grafting reaction is carried out under constant temperature, closed and dry conditions. The recycling method according to any one of claims 1 to 9 is characterized in that the swelling comprises: soaking the grafted material in water. The recovery method according to claim 10 is characterized in that the soaking temperature is 20°C-30°C; and/or the soaking time is 18h-24h. The recycling method according to any one of claims 1 to 11, characterized in that before the grafting treatment, it also includes: pre-treating the waste battery; Pre-treatment includes: removing the electrolyte and negative electrode from the used batteries. The recycling method according to claim 12 is characterized in that removing the electrolyte includes: heating the inner core of the waste battery to volatilize and remove the electrolyte. The recovery method according to claim 13 is characterized in that the heating temperature is 140° C.-150° C.; and/or the heating time is 1 h-2 h. The recycling method according to claim 12 is characterized in that removing the negative electrode sheet comprises: soaking the battery core from which the electrolyte has been removed in water so that the negative electrode binder in the negative electrode sheet is dissolved in the water, removing the negative electrode sheet and the negative electrode active material that has fallen off the negative electrode collector of the negative electrode sheet, and collecting the positive electrode sheet and the separator connected to the positive electrode sheet. The recovery method according to claim 15 is characterized in that the soaking time is 24h-48h. The recycling method according to claim 15 or 16, characterized in that the negative electrode current collector is copper foil. The recycling method according to any one of claims 15 to 17 is characterized in that the pre-treatment further comprises: modifying the positive electrode sheet and the diaphragm connected to the positive electrode sheet. The recycling method according to claim 18, characterized in that the modification process has at least one of the following characteristics: Feature 1: The treatment reagent used in the modification treatment is a mixed solution of alkali and alcohol; Feature 2: The temperature of the modification treatment is 50℃-80℃; Feature 3: The modification treatment time is 30min-90min. The recovery method according to claim 19, 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)-(10:100). The recycling method according to any one of claims 1 to 20 is characterized in that the separation of the positive electrode current collector and the positive electrode active material bonded to the separator is performed by providing external force through a negative pressure adsorption device. The recycling method according to claim 21 is characterized in that the negative pressure adsorption device includes a suction cup, which is used to adsorb on the surface of the positive electrode collector and/or the diaphragm to be separated so as to separate the positive electrode collector and the diaphragm under the action of negative pressure. The recovery method according to claim 22 is characterized in that the suction cup is connected to a gas circulation pipeline. The recovery method according to claim 23 is characterized in that the surface of the suction cup has a suction hole, and the suction hole is connected to the gas circulation pipeline. The recovery method according to any one of claims 23-24 is characterized in that the negative pressure range is 500Pa-1000Pa. The recycling method according to any one of claims 21 to 25 is characterized in that the separated positive electrode active material bonded with the separator is crushed, and the separator is sorted and removed to obtain the positive electrode active material.