CN112271349A

CN112271349A - Method for recycling lithium ion positive electrode and recycled lithium ion positive electrode material

Info

Publication number: CN112271349A
Application number: CN202011097507.5A
Authority: CN
Inventors: 孙永明; 王文宇
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2020-10-14
Filing date: 2020-10-14
Publication date: 2021-01-26

Abstract

The invention discloses a lithium ion anode and a method for recycling materials, which are characterized in that a lithium ion battery in a discharge state is disassembled to obtain an anode piece, or active substances on the anode piece are separated after the disassembly, and a lithiation reagent is sprayed to the anode piece or the active substances are soaked by the solution so as to supplement lithium. The treated positive pole piece or positive active substance can be applied to the lithium ion battery again. The method realizes lithium supplement on the positive active substance of the waste lithium ion battery by a simple chemical method, and can restore the electrochemistry of the positive material of the waste lithium ion battery to the level of the initial material. Compared with the common waste lithium ion battery recovery process, the method does not involve the working procedures of dissolving active substances by using a strong acid solution and then extracting effective components, has simple process and high efficiency, and effectively solves the problems of complex process, more production waste, longer flow and the like when the anode material in the lithium ion battery is recovered.

Description

Method for recycling lithium ion positive electrode and recycled lithium ion positive electrode material

Technical Field

The invention relates to the field of lithium ion battery recovery, and particularly relates to a method for recycling a lithium ion anode and materials, a lithium ion anode active material obtained by using the method, and an anode piece.

Background

Lithium ion batteries are widely used in various fields as a battery having good safety, high energy density and long service life. According to the 'development planning of energy-saving and new energy automobile industry' (2012-2020), along with the continuous and rapid development of economy in China, the automobile industry keeps a rapid growth trend, so that the energy and environment problems caused by the development are more and more prominent, and the development of energy-saving automobiles and new energy automobiles can effectively relieve the energy and environment pressure. It is expected that in 2020, the production capacity of pure electric vehicles and plug-in hybrid vehicles will reach 200 million, the cumulative output and sales will exceed 500 million, and the cumulative scrappage of vehicular batteries will also reach 32.2 million tons. In addition, the update iteration speed of 3C devices in a new era is accelerated, 5G base station construction can also generate a large amount of lithium ion battery requirements, a large amount of scrapped batteries can be generated in the future, and the method is a valuable technology for recycling key materials of the lithium ion batteries.

At present, the commonly used recovery method of the key materials of the waste lithium ion battery mainly comprises hydrometallurgy recovery and dry metallurgy recovery, wherein the hydrometallurgy recovery is to separate and treat a positive electrode material, a current collector, a binder, a conductive agent and the like, and carry out processes of leaching, solution purification, enrichment, extraction and the like on the positive electrode material, but the process consumes a large amount of acidic and alkaline solutions, generates a large amount of waste materials, and the purity of the product is difficult to ensure. The dry recovery adopts mechanical separation to disassemble and classify the materials in the waste lithium ion batteries, and then realizes the separation and recovery of the materials through high-temperature pyrolysis. More metal can be recovered from the waste lithium battery pack, and the defects of secondary pollution and high energy consumption are caused.

Disclosure of Invention

In view of the above-mentioned drawbacks and needs for improvement of the prior art, an object of the present invention is to provide a lithium ion positive electrode and a method for recycling materials. Compared with the traditional wet recovery and dry recovery, the method is based on the chemical principle, the lithium lost in the anode is compensated by the lithiation reagent with lower potential, the electrochemical performance is improved, the repeated utilization of the lithium can be realized, and the problems of complex recovery process, long time consumption, more production waste and the like are solved compared with the prior art. The recovery method provided by the invention is realized by a chemical method, and the lithium compensation amount can be controlled by controlling the dosage of the chemical reagent, so that the structural damage caused by over compensation is prevented. The invention adopts a simple chemical method to carry out regeneration treatment on the positive active substances of the waste batteries, belongs to one-step reaction, simplifies the process steps, shortens the flow time, reduces the cost, avoids the generation of a large amount of waste acid and waste alkali, and is suitable for industrial mass recovery.

To achieve the above object, according to one aspect of the present invention, there is provided a method for recycling a lithium ion positive electrode, comprising the steps of:

(1) discharging and disassembling the battery to obtain a positive pole piece, cleaning residual lithium salt on the surface of the positive pole piece by using an electrolyte solvent, and drying to remove the electrolyte solvent on the surface of the positive pole piece;

(2) determining the amount of lithium to be compensated according to the capacity attenuation condition of the positive pole piece, and preparing a lithiation reagent with proper concentration in an inert atmosphere;

(3) and (2) spraying the lithiation reagent prepared in the step (2) on the positive pole piece prepared in the step (1) in an inert atmosphere or soaking the positive pole piece prepared in the step (1) in the lithiation reagent prepared in the step (2), and washing and drying the positive pole piece after reaction to obtain a regenerated positive pole piece.

Further, in the step (1), the anode of the waste lithium ion battery consists of the following components: 5 to 99.5 percent of active substance, 0.5 to 95 percent of conductive agent and adhesive.

Further, in the step (1), the solvent used for cleaning is one or more of esters such as propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, alcohols such as methanol, ethanol, ketones, carboxylic acids, amides, sulfones, tetrahydrofuran, and water.

Further, in the step (2), the solvent of the lithiation reagent is an organic solvent, and is preferably one or more of diethyl ether, ethylene glycol dimethyl ether, acetonitrile, N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran.

Further, in the step (2), the solute of the lithiation reagent is one or more of indene lithium, anthracene lithium, naphthalene lithium, phenanthrene lithium, pyrene lithium, 1-methylnaphthalene lithium, 2-methylnaphthalene lithium, benzophenone lithium and biphenyl lithium.

Furthermore, in the step (2), the concentration of the prepared lithiation reagent is 0.01-10 mol/L.

Further, in the step (3), the molar ratio of the active material of the positive pole piece to lithium in the lithiation reagent during the reaction is 1:0.01-10, and the reaction time is 1s-24 h.

Further, in the step (3), the reagent for washing the positive electrode plate after the reaction is one or more of diethyl ether, ethylene glycol dimethyl ether, acetonitrile, N-dimethylformamide, dimethyl sulfoxide and tetrahydrofuran.

According to another aspect of the present invention, there is provided a method for recycling a lithium ion positive electrode material, comprising the steps of:

(2) separating the positive active material from the current collector;

(3) and (3) determining the amount of lithium to be compensated according to the capacity fading condition of the positive pole piece, preparing a lithiation reagent with appropriate concentration under an inert atmosphere to react with the positive pole active material obtained in the step (2), and washing and drying the positive pole active material after reaction to obtain a regenerated active material.

Further, the step (2) may further include a step of heat-treating the separated positive electrode active material. The purpose of the heat treatment step is to remove the binder and the conductive agent in the positive electrode material or repair the microstructure of the positive electrode material.

Further, the step (3) further comprises a step of performing heat treatment on the active material obtained after the reaction. And (3) carrying out heat treatment on the reacted active substance, wherein the heat treatment step is used for continuously repairing the microstructure of the positive electrode material, and whether the heat treatment is carried out or not can be selected according to the actual condition of the material.

In the step (1), the solvent used for cleaning is one or more of esters such as propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate, alcohols such as methanol and ethanol, ketones, carboxylic acids, amides, sulfones, tetrahydrofuran, water and the like.

Further, in the step (2), the heat treatment temperature may range from 200 ℃ to 1000 ℃, the heat treatment time may range from 0.2 to 24 hours, and the heat treatment atmosphere includes, but is not limited to, nitrogen, argon-hydrogen mixture, oxygen, air, and the like.

Further, in the step (3), the solvent of the lithiation reagent is an organic solvent, and is preferably one or more of diethyl ether, ethylene glycol dimethyl ether, acetonitrile, N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran.

Further, in the step (3), the solute which is the lithiation reagent can be one or more of indene lithium, anthracene lithium, naphthalene lithium, phenanthrene lithium, pyrene lithium, 1-methylnaphthalene lithium, 2-methylnaphthalene lithium, benzophenone lithium, biphenyl lithium or a mixture thereof.

Furthermore, in the step (3), the concentration of the prepared lithiation reagent is 0.01-10 mol/L.

Further, in the step (3), the heat treatment temperature may range from 200 ℃ to 1000 ℃, the heat treatment time may range from 0.2 to 24 hours, and the heat treatment atmosphere includes, but is not limited to, nitrogen, argon-hydrogen mixture, oxygen, air, and the like.

Further, the recycling method is used for obtaining the regenerated lithium ion positive pole piece and the regenerated lithium ion positive active material.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention adopts a simple chemical method to recover the lithium ion battery, has mild reaction and controllable process, avoids the use of a large amount of acid liquor and alkali liquor and improves the recovery safety.

2. The prior art is element recovery, mainly recovers lithium element, cobalt element, iron element, copper element and the like in the battery, and can separate and treat a current collector, a conductive agent, a binding agent and the like.

3. The production method is simple and convenient to operate by spraying the lithium supplement reagent on the electrode obtained after the battery is disassembled or soaking the electrode or the active material obtained after the battery is disassembled and assembled by the lithium supplement reagent, belongs to one-step reaction, simplifies the process steps, shortens the flow time, reduces the cost, can directly manufacture the battery by adopting the existing battery process for the recycled material, and has better matching property with industrial production.

4. The recovery method provided by the invention can control the lithium compensation amount by controlling the dosage of the chemical reagent, the compensated lithium content is controllable, and the structural damage caused by over compensation is prevented.

Drawings

FIG. 1 is a schematic view of the recovery scheme of the process of the present invention;

FIG. 2 is a graph showing the first-turn charging and discharging curves of a half-cell before and after recycling of waste lithium iron phosphate pole pieces;

FIG. 3 is a first-circle charge-discharge curve diagram of a full battery before and after recovery of waste lithium iron phosphate pole pieces;

FIG. 4 is a first-cycle charge-discharge curve diagram of a half-cell before and after recovery of waste nickel cobalt lithium manganate powder;

FIG. 5 is a first-cycle charge-discharge curve diagram of a full battery after heat treatment before and after recovery of waste lithium nickel cobalt manganese oxide powder;

fig. 6 is a first circle charge and discharge curve diagram of a half-cell before and after recovery of waste lithium cobaltate powder.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the respective embodiments described below may be combined with each other as long as they do not conflict with each other.

FIG. 1 is a flow chart of an experiment according to the recovery method of the present invention, and the flow of the steps in the experimental process is shown in the figure.

Example one

Discharging the waste lithium iron phosphate battery to a voltage of 2.5V, disassembling the battery under the protection of inert atmosphere to obtain components of a positive pole piece, a negative pole piece, a diaphragm and the like of the battery, washing the positive pole piece by using dimethyl carbonate (DMC), and drying. Dissolving 0.1mol/L naphthalene in Tetrahydrofuran (THF), adding metal lithium with the same molar ratio as naphthalene, stirring to dissolve, preparing 0.1mol/L naphthalene lithium solution, then soaking a positive pole piece disassembled from a waste battery in the naphthalene lithium solution for 10 minutes, taking out the pole piece after complete reaction, cleaning with tetrahydrofuran, drying and then reassembling the battery.

Example two

Discharging the waste lithium iron phosphate battery to a voltage of 2.5V, disassembling the battery under the protection of inert atmosphere to obtain components of a positive pole piece, a negative pole piece, a diaphragm and the like of the battery, washing the positive pole piece by using dimethyl carbonate (DMC), and drying. Separating the positive electrode material from a current collector, carrying out heat treatment on the positive electrode material at 500 ℃ for 2h in an argon atmosphere to remove part of the binder, dissolving 0.1mol/L naphthalene in Tetrahydrofuran (THF), adding metal lithium with the molar ratio equal to that of the naphthalene, stirring and dissolving to prepare 0.1mol/L naphthalene lithium solution, reacting with appropriate volume of naphthalene lithium solution according to the consumption of positive electrode active substance lithium, separating the positive electrode material from the solution after complete reaction, washing with tetrahydrofuran, and drying to prepare the pole piece again.

EXAMPLE III

Discharging the waste lithium iron phosphate battery to a voltage of 2.5V, disassembling the battery under the protection of inert atmosphere to obtain components of a positive pole piece, a negative pole piece, a diaphragm and the like of the battery, washing the positive pole piece by using dimethyl carbonate (DMC), and drying. Naphthalene was dissolved in Tetrahydrofuran (THF) at a concentration of 0.1mol/L, and metal lithium was added in an equimolar ratio to naphthalene, and the mixture was dissolved by stirring to prepare a 0.1mol/L naphthalene lithium solution. And then spraying the prepared naphthalene lithium solution on the surface of the waste pole piece, wherein the reaction time is 10 minutes, then cleaning the pole piece by using tetrahydrofuran, and drying to reassemble the battery.

Example four

Discharging the waste nickel cobalt lithium manganate ternary battery to a voltage of 2.5V, disassembling the battery under the protection of inert atmosphere to obtain components of a positive pole piece, a negative pole piece, a diaphragm and the like of the battery, washing the positive pole piece by using dimethyl carbonate (DMC), and drying. Dissolving 0.1mol/L naphthalene in Tetrahydrofuran (THF), adding metal lithium with the same molar ratio as naphthalene, stirring to dissolve, preparing 0.1mol/L naphthalene lithium solution, then soaking a positive pole piece disassembled from a waste battery in the naphthalene lithium solution for 5 minutes, taking out the pole piece after complete reaction, cleaning with tetrahydrofuran, drying and then reassembling the battery.

EXAMPLE five

Discharging the waste nickel cobalt manganese acid lithium battery to the voltage of 2.5V, disassembling the battery under the protection of inert atmosphere to obtain components of a positive pole piece, a negative pole piece, a diaphragm and the like of the battery, washing the positive pole piece by using dimethyl carbonate (DMC), and then drying. Separating a positive electrode material from a current collector, dissolving naphthalene with the concentration of 0.1mol/L in Tetrahydrofuran (THF), adding metal lithium with the molar ratio equal to that of the naphthalene, stirring and dissolving to prepare a 0.1mol/L naphthalene lithium solution, reacting the naphthalene lithium solution with a proper volume according to the consumption of positive electrode active substance lithium, separating the positive electrode material from the solution after the reaction is completed, cleaning with tetrahydrofuran, drying, and then carrying out heat treatment at 400-900 ℃ for 1-24 h in an oxygen atmosphere to help the microstructure of the waste nickel cobalt lithium manganate to be reformed, so that the obtained powder can be used for manufacturing pole pieces again.

The lithium batteries obtained in examples 1 to 5 were tested,

fig. 2 shows a first-cycle voltage-specific capacity curve of a half-cell reassembled by waste lithium iron phosphate pole pieces and lithium iron phosphate pole pieces recovered by spraying and soaking, wherein the first charging capacity of the waste lithium iron phosphate is 100mAh/g, the capacity is increased to 145mAh/g after the spraying and recovering process, and the capacity is increased to 150mAh/g after the soaking and recovering process, which indicates that the lost capacity can be completely supplemented.

Fig. 3 shows that the waste lithium iron phosphate pole pieces and the recycled lithium iron phosphate pole pieces are made into pole pieces again to be assembled into a first-circle voltage-specific capacity curve of the full battery, the first charging capacity of the waste lithium iron phosphate is 90mAh/g, and the capacity is increased to 130mAh/g after the recycling process.

Fig. 4 is a first-turn voltage-capacity curve of a half-cell reassembled by waste nickel cobalt lithium manganate powder and recycled nickel cobalt lithium manganese powder, the first charge capacity of the waste nickel cobalt lithium manganese is 1.4mAh, and after the recycling process, the capacity is increased to 2.4mAh, which indicates that the lost capacity can be completely supplemented.

Fig. 5 is a first-circle voltage-capacity curve of a full battery formed by reassembling waste nickel cobalt lithium manganate powder after a soaking recovery process, wherein the first charging capacity of the waste nickel cobalt lithium manganate is 0.9mAh, the capacity is increased to 1.5mAh after the waste nickel cobalt lithium manganate powder is subjected to a direct soaking recovery process, and the capacity is further increased by 1.9mAh after the waste nickel cobalt lithium manganate powder is subjected to heat treatment.

Fig. 6 is a first-turn voltage-specific capacity curve of a full battery assembled by lithium cobaltate powder after the process, and the process can effectively improve the capacity of the material, wherein the capacity is improved from 140mAh/g to 170mAh/g, and the improvement is obvious.

It is to be noted that variations and modifications can be made on the above-described embodiments by those skilled in the art, based on the disclosure and description of the above specification. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some equivalent modifications and variations of the present invention should be covered by the protection scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for reusing a lithium ion positive electrode is characterized by comprising the following steps:

(1) obtaining a positive pole piece needing to be recycled and regenerated from a waste lithium ion battery, and cleaning lithium salt remained on the positive pole piece by using a solvent;

(2) in an inert atmosphere or a dry air atmosphere, spraying a lithiation reagent on the positive pole piece in the step (1) or soaking the positive pole piece in the step (1) in the lithiation reagent; and washing and drying the positive pole piece after reaction to obtain the regenerated positive pole piece.

2. The method for recycling the lithium ion positive electrode according to claim 1, wherein in the step (1), the solvent for cleaning is one or more of esters, alcohols, carboxylic acids, amides, sulfones, tetrahydrofuran and water; the solvent of the lithiation reagent is one or more of diethyl ether, ethylene glycol dimethyl ether, acetonitrile, N-dimethylformamide, dimethyl sulfoxide and tetrahydrofuran.

3. The method for recycling the lithium-ion positive electrode according to claim 1, wherein the solute of the lithiation reagent is one or more of indene lithium, anthracene lithium, naphthalene lithium, phenanthrene lithium, pyrene lithium, 1-methylnaphthalene lithium, 2-methylnaphthalene lithium, benzophenone lithium, and biphenyl lithium.

4. The method for recycling the lithium ion positive electrode according to claim 1, wherein in the step (3), the molar ratio of the active material of the positive electrode plate to the lithium in the lithiation reagent during the reaction is 1:0.01-10, and the reaction time is 1s-24 h.

5. A method for recycling a lithium ion cathode material is characterized by comprising the following steps:

(2) separating active substances on the positive pole piece from a current collector;

(3) and (3) determining the amount of lithium to be compensated according to the capacity fading condition of the positive pole piece, and preparing a lithiation reagent with appropriate concentration to react with the positive active material obtained in the step (2) in an inert atmosphere. And washing and drying the positive electrode active substance after the reaction to obtain the regenerated positive electrode active substance.

6. The method for reusing a lithium ion positive electrode according to claim 5, wherein the step (2) further comprises a step of heat-treating the separated positive electrode active material; and/or the step (3) further comprises the step of carrying out heat treatment on the active substance obtained after the reaction.

7. The method for recycling the lithium-ion positive electrode according to claim 6, wherein the solute of the lithiation reagent is one or more of indene lithium, anthracene lithium, naphthalene lithium, phenanthrene lithium, pyrene lithium, 1-methylnaphthalene lithium, 2-methylnaphthalene lithium, benzophenone lithium and biphenyl lithium; the solvent of the lithiation reagent is one or more of diethyl ether, ethylene glycol dimethyl ether, acetonitrile, N-dimethylformamide, dimethyl sulfoxide and tetrahydrofuran.

8. The method for recycling the lithium ion positive electrode according to claim 5, wherein in the step (3), the molar ratio of the active material of the positive electrode plate to the lithium in the lithiation reagent during the reaction is 1:0.01-10, and the reaction time is 1s-24 h.

9. A regenerated lithium ion positive pole piece is characterized by being prepared by the method for recycling the lithium ion positive pole in any one of claims 1 to 4.

10. A regenerated lithium ion positive electrode active material produced by a method of recycling the lithium ion positive electrode according to any one of claims 5 to 8.