CN114204149A

CN114204149A - A method for separating electrode materials from decommissioned lithium battery pole pieces and its application

Info

Publication number: CN114204149A
Application number: CN202111404512.0A
Authority: CN
Inventors: 孙永明; 陈子和; 陆荣华; 赵建智; 聂瑞超
Original assignee: Wuhan Weineng Battery Assets Co ltd; Huazhong University of Science and Technology
Current assignee: Wuhan Weineng Battery Assets Co ltd; Huazhong University of Science and Technology
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2022-03-18
Anticipated expiration: 2041-11-24
Also published as: CN114204149B

Abstract

The invention belongs to the technical field of lithium batteries, and particularly relates to a method for separating an electrode material from a retired lithium battery pole piece and application thereof. The method comprises the following steps: (1) disassembling a retired positive pole piece from a retired lithium battery, wherein the retired positive pole piece comprises a positive current collector and an electrode material layer covered on the positive current collector; (2) processing and removing the surface layer of the electrode to expose a relatively loose electrode material layer; (3) and (3) separating the electrode material and the current collector by treating the retired positive pole piece after surface treatment through a calcination vibration separation technology or a liquid-phase ultrasonic separation technology. On the basis of the traditional solid-phase calcination vibration separation technology and liquid-phase ultrasonic separation technology, the invention obviously improves the separation efficiency of the solid-phase calcination vibration separation technology and the liquid-phase ultrasonic separation technology by separating the compact surface layer and exposing the relatively loose inner layer, thereby having wide application prospect.

Description

Method for separating electrode material from retired lithium battery pole piece and application thereof

Technical Field

The invention belongs to the technical field of lithium batteries, and particularly relates to a method for separating an electrode material from a retired lithium battery pole piece and application thereof.

Background

The battery recovery process mainly comprises hydrometallurgy, pyrometallurgy, regeneration and repair technologies. The separation of the electrode material and the current collector is an indispensable step in the above-mentioned technology, and the mixing of heterogeneous elements needs to be avoided in the separation process to ensure the purity of the extracted metal compound or the batch consistency of the resynthesized battery active material; particularly in the process of repairing battery materials, the separation technology of the electrode materials plays an important role in the performance of the repaired materials.

The separation of the electrode material and the current collector is most popular with solid-phase calcination vibration separation technology and liquid-phase ultrasonic separation technology. The solid-phase calcination shaking-off technology mainly removes the binder and the carbon black through high-temperature calcination, weakens the acting force between the electrode material and the current collector, and then separates the electrode material and the current collector through mechanical vibration. However, the rolling process and the long cycle in the later period in the preparation of the pole piece can lead the electrode material on the surface of the pole piece to be more compact than the interior of the pole piece, thereby increasing the separation difficulty of the existing solid-phase calcining and vibrating separation technology, namely, the solid-phase calcining and separating needs longer time or higher temperature due to the existence of a compact layer; in the liquid-phase ultrasonic separation technology, the acting force between the electrode material and the current collector is weakened by dissolving the binder with solvents such as N-methylpyrrolidone (NMP), Dimethylacetamide (DMAC), N-Dimethylformamide (DMF), triethyl phosphate (TEP), dimethyl sulfoxide (DMSO) and the like, but the time required for liquid-phase ultrasonic separation is prolonged due to the compact surface layer. Increasing the strength or duration of the corresponding step often results in the generation and incorporation of aluminum chips and the possibility of cracking of the separated target product while increasing the separation yield to some extent.

CN102676827 discloses a method for recovering nickel and cobalt elements from a decommissioned lithium ion battery, wherein the separation method is to immerse a pole piece of the decommissioned battery in N-methyl pyridine/N, N-dimethyl amide to dissolve binder PVDF, so as to separate and remove electrode materials. However, the good separation effect of the method needs to be established on the basis of higher temperature, and with the development of the pole piece coating technology and the continuous increase of the compactness of the corresponding positive electrode material, the method is difficult to have the expected effect in the partially commercialized retired lithium battery.

CN109346789A discloses a recycling process of lithium iron phosphate positive electrode material and a regenerated positive electrode material, and particularly discloses a method for separating a lithium iron phosphate positive electrode material from a monomer battery cell; after processing the lithium iron phosphate battery positive electrode material, adding a lithium source, an iron source, a titanium source, a phosphorus source and a carbon source to obtain a precursor; adding a solvent medium into the precursor, and uniformly mixing to obtain an intermediate; and calcining the intermediate in an inert atmosphere to obtain the regenerated lithium iron phosphate anode material. The method for separating the electrode material comprises the following steps: and heating the positive plate by hot water vapor to separate the positive material of the lithium iron phosphate battery from the positive current collector, and drying, grinding and screening the positive material to obtain the lithium iron phosphate battery. The technical scheme is more complicated to process, other active ingredients are added, the difficulty of separating the electrode material is increased, and an improvement space is provided.

In summary, the prior art still lacks a separation method capable of improving the yield of the conventional solid-phase calcination vibration separation technology and liquid-phase ultrasonic separation technology and avoiding aluminum scraps from mixing into electrode materials.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides a method for separating an electrode material from a retired lithium battery pole piece, aiming at the fact that the electrode material on the surface of the pole piece is relatively tightly bonded, a surface treatment process is introduced before the separation step, the yield and the purity of the traditional solid-phase calcination vibration separation technology and liquid-phase ultrasonic separation technology are obviously improved, the method has good tolerance and is suitable for recycling all types of retired lithium battery electrode materials.

To achieve the above object, according to one aspect of the present invention, there is provided a method for separating an electrode material from a pole piece of a retired lithium battery, comprising the steps of:

(1) disassembling a retired positive pole piece from a retired lithium battery, wherein the retired positive pole piece comprises a positive current collector and an electrode material layer covered on the positive current collector;

(2) carrying out surface treatment on the active material layer to expose the relatively loose electrode material layer;

(3) and (3) separating the electrode material and the current collector by treating the retired positive pole piece after surface treatment through a calcination vibration separation technology or a liquid-phase ultrasonic separation technology.

Preferably, in the step (2), the surface treatment is specifically: stripping or destroying the surface compact part of the electrode material layer, wherein the surface treatment specifically comprises the following steps: and stripping or destroying the surface compact part of the electrode material layer, wherein the surface compact part refers to the surface layer part with the average density higher than the overall density of the electrode by more than 20%.

Densification refers to the ratio of the volume occupied by atoms in a cell to the volume occupied by the cell, and the surface densified portions are measured by X-ray microscopy computed tomography. The surface compaction portion correlation calculation is based on: average density of surface layer/average density of electrode 100%.

Preferably, the surface treatment includes one of scraping, brushing, mesh-side rolling separation, and matte-side press separation.

Preferably, the scraping is performed by peeling a surface-densified portion of the electrode material layer by a doctor blade.

Preferably, the brushing is to peel off the surface densified portion of the electrode material layer by a brush-shaped tool, which is one of a brush, a steel brush, and a plastic brush.

Preferably, the rolling separation of the mesh surface is that the mesh surface is pressed by rolling wheels at two sides, and the surface compact part of the electrode material layer is damaged through stress conduction, the mesh surface is one of a copper mesh, a steel mesh and a polymer mesh, the mesh number of the mesh surface is 5-400 meshes, and the thickness is 50-1000 μm.

Preferably, the rough-surface pressing plate is separated into a state that the rough-surface pressing plate presses the retired pole piece to damage the surface compact part of the electrode material layer.

Preferably, the calcination vibration-separation technology is to make the electrode material fall off from the current collector through mechanical vibration after the retired positive pole piece is calcined, the calcination temperature is 500-1000 ℃, and the calcination atmosphere is air or oxygen.

Preferably, the liquid-phase ultrasonic separation technology comprises the steps of immersing a retired positive electrode plate into a solution, dissolving or deactivating the binder, then enabling the electrode material to fall off from a current collector through ultrasound, and drying to obtain the electrode material.

According to another aspect of the present invention, there is provided a use of the method as described above in the separation and recovery of electrode material of a decommissioned lithium battery, preferably, the decommissioned lithium battery comprises one of lithium iron phosphate, lithium cobaltate, nickel cobalt manganese, nickel cobalt aluminum, lithium manganate, lithium titanate and titanium niobate battery.

The invention has the following beneficial effects:

(1) on the basis of the traditional solid-phase calcination vibration separation technology and the liquid-phase ultrasonic separation technology, aiming at the problems that the compacted density of the electrode plate is continuously increased and the surface of the electrode plate is compact after circulation at the present stage, the surface compact layer is separated through surface treatment, and the inner part of the electrode plate is relatively loose, so that the yield and the purity of the traditional solid-phase calcination vibration separation technology and the traditional liquid-phase ultrasonic separation technology are obviously improved, the electrode plate has better tolerance, is suitable for recovering all kinds of retired lithium battery electrode materials, does not provide higher requirements for hardware equipment, can be directly put into operation based on the industrial modern industrial level, and has wide application prospect.

(2) The invention improves the separation yield and reduces the energy consumption by the surface treatment technology: through more detailed analysis of the electrode sheet structure, the electrode material compact layer on the surface of the electrode is separated before separation operation, so that the efficiency of the subsequent separation step is improved, and the separation of more than 99 wt% of the electrode material can be realized within the shortest separation time of 1 minute;

(3) the invention avoids the mixing of aluminum scraps and reduces the damage degree of the separated electrode material by a surface treatment technology: the traditional extensive separation technology represented by a solid-phase calcination vibration separation technology and a liquid-phase ultrasonic separation technology needs long separation time or high strength to improve the separation yield, and is easy to cause the phenomena of mixing of heterogeneous elements such as aluminum, iron and the like, electrode material particle pulverization and crack. The electrode material with the relatively compact surface is bonded on the surface of the electrode for separation, so that the energy consumption required by the separation is reduced, and the problems are avoided to a great extent.

Drawings

FIG. 1 is a schematic view of the production process of the present invention.

Fig. 2 is a schematic structural composition diagram of a device in the scratch-off technology.

Fig. 3 is a schematic structural composition diagram of a device in the brush-off technology.

Fig. 4 is a schematic structural composition diagram of a core device in a roll separation technique.

Fig. 5 is a schematic structural composition diagram of a core device in a rough-surface pressing plate separation technology.

FIG. 6 is a physical representation of ultrasonic separation in water of example 1 and comparative example 1.

FIG. 7 is a physical representation of the suction filtration results after ultrasonic separation in example 3 and comparative example 2.

FIG. 8 is a physical representation of the results of the calcination in a muffle furnace of the treated pole pieces of example 5 of the invention and comparative example 3.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is 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 embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Example 1

(1) Disassembling a positive pole piece from a decommissioned nickel-cobalt-manganese-lithium battery, wherein the thickness of the positive pole piece is 300 mu m, and the thickness of a surface compact part (a part of which the surface average density is more than 20% higher than the whole density of the electrode) is 9.8 mu m measured by an X-ray display microcomputer tomography technology;

(2) removing the surface compact part of the positive pole piece by a scraping technology: after the pitch of the double-sided scrapers is set to be 300 mu m for positive scanning, the pitch is reduced to 290 mu m for positive scanning, and then the pitch of the scrapers is set to be 280 mu m for bonding compact electrode materials on the surfaces of the flyback layer-by-layer separated current collectors;

(3) the pole pieces treated by the doctor blade were subjected to ultrasonic separation in water for 30 seconds using ultrasonic waves having a frequency of 28kHz and a power of 800W. After collecting the precipitate and drying, the separation rate after sonication was calculated to be 99.1 wt%.

Example 2

This example is different from example 1 in that the surface densified portion is not completely peeled off in step (2), as described below:

(2) removing the surface compact part of the positive pole piece by a scraping technology: after the pitch of the double-sided scraper is set to be 300 mu m, the pitch is reduced to 290 mu m for positive scanning, so that compact electrode materials with the thickness of 4.8 mu m are still remained on the surface of the pole piece after the separation process;

(3) and (3) carrying out ultrasonic separation on the treated pole pieces in water for 30 seconds by using ultrasonic waves with the frequency of 28kHz and the power of 800W, collecting precipitates, drying, and calculating to obtain the separation rate of 51.2 wt% after ultrasonic separation.

Comparative example 1

This example is different from example 1 in that the positive electrode sheet was not surface-treated.

The untreated positive electrode piece was subjected to ultrasonic separation in water for 30 seconds using ultrasonic waves having a frequency of 28kHz and a power of 800W. After the precipitate was collected and dried, the separation rates of the untreated pole pieces after sonication were calculated to be 21.2 and 99.1 wt%, respectively.

As shown in fig. 6, the untreated pole piece had only a small amount of electrode material dispersed in the water after 30 seconds of sonication; the pole piece treated by the scraper is dispersed with a large amount of electrode materials in water after being subjected to ultrasonic treatment; the current collector is taken out, and only a small amount of residues are left on the surface, which shows that the treatment process can effectively promote the separation of the electrode material of the retired battery.

Example 3

(1) Disassembling a positive pole piece from a decommissioned nickel-cobalt-aluminum lithium battery, wherein the thickness of the positive pole piece is 280 microns, and the thickness of a surface compact part (a part of which the surface average density is more than 20% higher than the whole density of the electrode) is 14.3 microns measured by an X-ray display microcomputer tomography technology;

(2) removing the surface compact part of the positive pole piece by a brushing technology: setting the brush pitch to 250 μm, moving, rubbing, and separating the surface of the current collector to adhere to the compact electrode material;

(3) and (3) carrying out ultrasonic separation on the pole piece subjected to brushing treatment in NMP for 45 seconds by using ultrasonic waves with the frequency of 20kHz and the power of 400W, taking out the separated pole piece, carrying out suction filtration on the residual solution, collecting, precipitating and drying, and calculating to obtain the pole piece separation rate of 99.2 wt% after the pole piece is subjected to brushing treatment.

Example 4

This example is different from example 3 in that the surface densified portion is not completely peeled off in step (2), as described below:

(2) removing the surface compact part of the positive pole piece by a brushing technology: setting the brush spacing to be 270 mu m for moving friction separation, and keeping compact electrode materials with the thickness of 9.3 mu m on the surface of the pole piece after the separation process;

(3) and (3) respectively carrying out ultrasonic separation on the pole pieces subjected to brushing treatment in NMP for 45 seconds by using ultrasonic waves with the frequency of 20kHz and the power of 400W, taking out the separated pole pieces, carrying out suction filtration on the residual solution, collecting, precipitating and drying, and calculating to obtain the pole piece separation rate of 48.5 wt% subjected to brushing treatment.

Comparative example 2

The difference between this embodiment and embodiment 3 is that the positive electrode sheet is not surface-treated, as follows:

carrying out ultrasonic separation on the untreated pole piece in NMP for 45 seconds by using ultrasonic waves with the frequency of 20kHz and the power of 400W, taking out the separated pole piece, carrying out suction filtration on the residual solution, collecting, precipitating and drying, and calculating to obtain the pole piece separation rate of 23.8.

As shown in fig. 7, the untreated pole piece of comparative example 2 separated less electrode material, and it was clearly found that the aluminum debris pulverized after the ultrasonic treatment was also doped; the electrode material separated from the electrode plate treated by the scraper in the embodiment 3 is more and has no obvious aluminum scraps, which shows that the electrode plate has higher purity.

Example 5

(1) Disassembling a positive pole piece from a retired lithium iron phosphate battery, wherein the thickness of the positive pole piece is 300 mu m, and the thickness of a surface compact part (a part of which the surface average density is more than 20% higher than the whole density of the electrode) is 19.8 mu m measured by an X-ray display microcomputer tomography technology;

(2) damaging the surface compact part of the positive pole piece by a rolling separation technology: setting the distance between the rollers to 800 μm, adding a stainless steel net with thickness of 270 μm and mesh number of 400 between the rollers and the pole piece, rolling, and adhering the net surface to the pole piece to destroy the compact part of the surface;

(3) and transferring the rolled pole piece into a muffle furnace at 500 ℃ and then vibrating and separating, wherein the separation rate of the pole piece after rolling treatment of the stainless steel mesh is 99.5 wt% by calculation.

Comparative example 3

This example is different from example 5 in that the positive electrode sheet was not surface-treated. The details are as follows:

the untreated pole pieces were transferred to a 500 ℃ muffle furnace and shaken off. The separation of the untreated pole piece was calculated to be 74.8 wt%.

As shown in fig. 8, the surface of the untreated pole piece still has more electrode material residue after vibration, while the surface of the pole piece after the scraper treatment is clean and has no obvious electrode material residue after vibration,

example 6

(1) Disassembling a positive pole piece from a retired cobalt acid lithium battery, wherein the thickness of the positive pole piece is 300 mu m, and the thickness of a surface compact part (a part of which the surface average density is more than 20% higher than the whole density of the electrode) is 2.1 mu m measured by an X-ray display microcomputer tomography technology;

(2) the surface compact part of the positive pole piece is damaged by a rough surface pressing plate separation technology: after the pole pieces are squeezed by two highly meshed pressing plates to clamp the pole pieces, the horizontal friction displacement is 0.2cm, and the compact part of the electrode material on the surface of the pole pieces is damaged;

(3) and (3) carrying out ultrasonic separation on the brushed pole piece in DMSO for 45 seconds by using ultrasonic waves with the frequency of 15kHz and the power of 600W, taking out the separated pole piece, carrying out suction filtration on the residual solution, collecting, precipitating and drying, and calculating to obtain the separation rate of the pole piece electrode material processed by the rough surface pressing plate to be 99.3 wt%.

Comparative example 4

The difference between this embodiment and embodiment 6 is that the positive electrode sheet is not subjected to surface treatment, which is specifically described as follows:

and (3) carrying out ultrasonic separation on the untreated pole piece in DMSO for 45 seconds by using ultrasonic waves with the frequency of 15kHz and the power of 600W, taking out the separated pole piece, carrying out suction filtration on the residual solution, collecting, precipitating and drying, and calculating to obtain the separation rate of the pole piece electrode material of the untreated pole piece, wherein the separation rate is 25.2 wt%.

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 separating electrode material from decommissioned lithium battery pole piece, is characterized in that, comprises the following steps:

(1) Disassemble the decommissioned lithium battery into a decommissioned positive electrode piece, which includes a positive electrode current collector and an electrode material layer covering the positive electrode current collector;

(2) Surface treatment of the electrode material layer to expose the relatively loose electrode material layer;

(3) Separating the surface-treated decommissioned positive electrode pieces by calcination vibration separation technology or liquid-phase ultrasonic separation technology to separate electrode materials and current collectors.

2 . The method according to claim 1 , wherein in step (2), the surface treatment is specifically: peeling off or destroying the surface compacted portion of the electrode material layer, and the surface compacted portion refers to the average density. 3 . The surface layer is more than 20% denser than the entire electrode.

3. The method according to claim 2, wherein the surface treatment comprises one of scraping off, brushing off, wire surface roll separation and matte surface platen separation.

4 . The method according to claim 3 , wherein the scraping off is peeling off the surface-compacted portion of the electrode material layer by a scraper. 5 .

5 . The method according to claim 3 , wherein the brushing off is to peel off the surface solid portion of the electrode material layer by a brush-shaped tool, and the brush-shaped tool is one of a hair brush, a steel brush and a plastic brush. 6 . A sort of.

6 . The method according to claim 3 , wherein the rolling separation of the mesh surface consists of squeezing the mesh surface by rolling rollers on both sides, and destroying the surface compact portion of the electrode material layer through stress conduction, and the mesh surface is destroyed. 7 . The surface is one of copper mesh, steel mesh and polymer mesh, the mesh number of the mesh surface is 5-400 mesh, and the thickness is 50-1000μm.

7 . The method according to claim 3 , wherein the matte-surface pressing plate is separated by pressing the retired pole piece through the matte-surface pressing plate to destroy the surface compact portion of the electrode material layer. 8 .

8 . The method according to claim 1 , wherein the calcination and vibration separation technology is to calcine the decommissioned positive pole piece, and then mechanically vibrate the electrode material from the current collector, and the calcination temperature is 500-1000° C. 9 . , the calcination atmosphere is air or oxygen.

9 . The method according to claim 1 , wherein the liquid-phase ultrasonic separation technology is to immerse the retired positive electrode piece in a solution, and the solution is used to dissolve or invalidate the binder, and then pass The electrode material is peeled off from the current collector by ultrasound, and the electrode material is obtained by drying.

10. The application of the method according to any one of claims 1 to 9 in the separation and recovery of electrode materials for decommissioned lithium batteries, preferably, the decommissioned lithium batteries include lithium iron phosphate, lithium cobalt oxide, nickel cobalt manganese, nickel cobalt One of aluminum, lithium manganate, lithium titanate and titanium niobate batteries.