CN-115939554-B - Method for circularly stripping waste positive plate current collector and positive material by NMP

CN115939554BCN 115939554 BCN115939554 BCN 115939554BCN-115939554-B

Abstract

The invention discloses a method for circularly stripping a waste positive plate current collector and a positive material by NMP, which comprises the following steps of adding a positive plate into NMP solution, stirring, sieving to obtain positive cleaning filtrate and aluminum foil; adding flocculant into positive electrode cleaning filtrate, stirring, standing, and performing solid-liquid separation to obtain NMP crude liquid and positive electrode material powder, adding dehydrating agent into NMP crude liquid, filtering to remove solid to obtain NMP recovered liquid, and recycling the NMP recovered liquid for sorting positive electrode plate current collector and positive electrode material. In addition, by introducing non-solvent water into the system, the thermodynamic stability of the system is changed, the solubility of PVDF is increased, and the dissolution rate is also accelerated.

Inventors

HU JUNJIE
LI CHANGDONG
RUAN DINGSHAN
ZHOU YOU
CHEN SONG
SHAO JIAWEN

Assignees

广东邦普循环科技有限公司
湖南邦普循环科技有限公司

Dates

Publication Date: 20260505
Application Date: 20221102

Claims (8)

1. The method for circularly stripping the waste positive plate current collector and the positive material by using the NMP is characterized by comprising the following steps of: S1, adding a positive plate into NMP solution, stirring, and sieving to obtain positive cleaning filtrate and aluminum foil; s2, adding a flocculating agent into the positive electrode cleaning filtrate obtained in the step S1, stirring, standing, and performing solid-liquid separation to obtain NMP crude liquid and positive electrode material powder; s3, adding a dehydrating agent into the NMP crude liquid obtained in the step S2, and filtering to remove solids to obtain NMP recovered liquid, wherein the NMP recovered liquid is used for sorting the positive plate current collector and the positive electrode material in the steps S1-S2; in the step S1, the concentration of the NMP solution is 95-99wt%, and the solid-to-liquid ratio of the positive plate to the NMP solution is 1g (2-100) mL; In the step S3, water is added to make the concentration of the NMP recovery liquid be 95-97 wt%.
2. The method for circularly stripping waste positive electrode sheet current collector and positive electrode material by using NMP according to claim 1, wherein in the step S1, the stirring is accompanied by heating, the heating temperature is 60-90 ℃, and the heating time is 60-120min.
3. The method for circularly stripping the waste positive plate current collector and the positive material by using the NMP according to claim 1, wherein in the step S1, the stirring is accompanied by ultrasonic waves, the frequency of the ultrasonic waves is 30-60kHz, and the time of the ultrasonic waves is 60-120min.
4. The method for circularly stripping the waste positive plate current collector and the positive material by using the NMP according to claim 1, wherein in the step S2, the flocculant comprises a flocculant solution and a coagulant aid, and the flocculant solution is at least one of a polyacrylamide solution and a ferrous sulfate solution.
5. The method for circularly stripping waste positive electrode plate current collector and positive electrode material by using NMP according to claim 4, wherein the concentration of the flocculant solution is 0.5-0.5 wt.0 wt%.
6. The method for circularly stripping the waste anode plate current collector and the anode material by using NMP according to claim 4, wherein the coagulant aid is at least one of diatomite, activated carbon and graphite.
7. The method for circularly stripping waste positive electrode plate current collector and positive electrode material by using NMP according to claim 4, wherein in the step S2, the dosage of the flocculant is 8% -12% of the mass of the positive electrode cleaning filtrate, and the ratio of the flocculant to the coagulant aid is (10:0) - (3:7).
8. The method for circularly stripping the waste positive plate current collector and the positive material by using the NMP according to claim 1, wherein in the step S3, the dehydrating agent is at least one of calcium chloride and magnesium chloride.

Description

Method for circularly stripping waste positive plate current collector and positive material by NMP Technical Field The invention belongs to the technical field of electrode material recovery treatment, and particularly relates to a method for circularly stripping waste positive plate current collector and positive electrode material by using NMP. Background In recent years, the new energy electric automobile industry is rapidly developed under the promotion of national policy, the sales of the new energy electric automobile reaches 37 ten thousand in 2015, the sales of the new energy electric automobile reaches about 106 ten thousand in 2020, the sales of the new energy electric automobile reaches 160 ten thousand in 2022, and a large amount of waste batteries are generated as the power batteries reach the service life. The waste battery contains various rare noble metals, and the method for searching the waste battery with low cost and effective recovery can achieve good social and economic benefits. The adhesive used for the battery anode is mainly polyvinylidene fluoride (PVDF), and the polyvinylidene fluoride serving as the battery adhesive has good mechanical strength, chemical stability, electrochemical stability, thermal stability and good affinity to electrolyte. The conventional method for removing the adhesive is high-temperature incineration under the protection of nitrogen, and the method has high energy consumption and low recovery rate and can cause great pollution to the environment. Polyvinylidene fluoride (PVDF) is insoluble as a stable adhesive in most solvents and only in a few solvents including N-methylpyrrolidone (NMP). Under the combined action of mechanical effect and cavitation effect of the equipment, the stripping of the waste anode plate current collector and the anode material can be realized, but the cost of the NMP solvent used is higher, and the environment is polluted without relevant treatment. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the prior art described above. Therefore, the invention provides the method for circularly stripping the waste positive plate current collector and the positive material by using the NMP, which can recycle the NMP, reduce the use cost of the solvent and reduce the discharge of waste liquid to the environment. According to one aspect of the invention, a method for circularly stripping a waste positive plate current collector and a positive material by using NMP is provided, which comprises the following steps: S1, adding a positive plate into NMP solution, stirring, and sieving to obtain positive cleaning filtrate and aluminum foil; s2, adding a flocculating agent into the positive electrode cleaning filtrate obtained in the step S1, stirring, standing, and performing solid-liquid separation to obtain NMP crude liquid and positive electrode material powder; And S3, adding a dehydrating agent into the NMP crude liquid obtained in the step S2, and filtering to remove solids to obtain NMP recovered liquid, wherein the NMP recovered liquid is used for sorting the positive plate current collector and the positive electrode material in the steps S1-S2. In some embodiments of the present invention, in step S1, the positive electrode sheet is prepared by shredding the recovered waste positive electrode sheet by a double-shaft shredder to obtain a positive electrode sheet with an area of (2 cm x 2 cm) - (5 cm x 5 cm) and an original irregular thickness. In some embodiments of the invention, in step S1, the NMP solution concentration is 95wt% to 99wt% and the solid-to-liquid ratio of the positive electrode sheet to the NMP solution is 1g (2-100) mL. In some preferred embodiments of the present invention, in step S1, the NMP solution is prepared by taking NMP solution with concentration of 99.9% or more, and adding deionized water to prepare NMP solution with concentration of 95wt% to 99 wt%. In some more preferred embodiments of the present invention, the NMP solution concentration in step S1 is about 95wt%. In some embodiments of the invention, in step S1, the stirring is also accompanied by heating, the temperature of which is 60-90 ℃, the time of which is 60-120min. In some embodiments of the invention, in step S1, the stirring is also accompanied by ultrasound, the frequency of which is 30-60kHz, and the time of which is 60-120min. In some preferred embodiments of the invention, in step S1, the stirring is also accompanied by ultrasound, the frequency of which is about 40kHz, the ultrasound time being about 60min. In some embodiments of the invention, in step S1, the mesh number of the screen is 30-100 mesh. In some preferred embodiments of the present invention, in step S1, the mesh number of the sieving is 40 mesh. In some more preferred embodiments of the present invention, in step S1, the sieving is further subjected to water washing. In some embodiments of the invention, in step S2, t