CN108963374B

CN108963374B - Method and system for recovering electrolyte of battery

Info

Publication number: CN108963374B
Application number: CN201810865615.9A
Authority: CN
Inventors: 张志文; 邹康迪
Original assignee: Qiantai Technology (shenshan Special Cooperation Zone) Co Ltd; Shenzhen Dry Energy Recycling Technology Co Ltd; NALON BATTERY (SHEN ZHEN) CO Ltd
Current assignee: Qiantai Technology (shenshan Special Cooperation Zone) Co Ltd; Shenzhen Dry Energy Recycling Technology Co Ltd; NALON BATTERY (SHEN ZHEN) CO Ltd
Priority date: 2018-08-01
Filing date: 2018-08-01
Publication date: 2020-03-10
Anticipated expiration: 2038-08-01
Also published as: CN108963374A

Abstract

The invention relates to a method and a system for recovering electrolyte of a battery. The method for recovering the electrolyte of the battery comprises the following steps: crushing the battery in a protective gas atmosphere to obtain a crushed material, wherein the particle size of the crushed material is 0.2-5 mm; subcritical fluid is adopted to carry out subcritical extraction on the crushed material to obtain extraction liquid, wherein the extraction temperature is 20-40 ℃, the extraction pressure is 0.3-0.8 MPa, and the subcritical fluid is normal butane in a subcritical state; and carrying out reduced pressure treatment on the extract liquor to obtain the electrolyte. The recovery method is environment-friendly, and has high recovery rate of the electrolyte and high purity of the recovered electrolyte.

Description

Method and system for recovering electrolyte of battery

Technical Field

The invention relates to the field of solid waste recycling, in particular to a method and a system for recycling electrolyte of a battery.

Background

With the wide application of lithium ion batteries in China, particularly the rapid development of new energy electric vehicles, a large number of waste lithium batteries are eliminated and scrapped in the future. The accumulated scrappage of the automobile power battery in China is predicted to exceed the scale of 20 million tons by 2020. The future life cycle of power lithium batteries will open the billion lithium battery recycling market. At present, the electrolyte of the abandoned lithium ion battery is treated mainly by direct incineration, and some electrolyte is treated by adopting a natural volatilization mode. These treatment modes seriously pollute the environment and are not beneficial to the sustainable development of ecology. In order to avoid pollution to the environment, some researches collect the electrolyte by a centrifugal mode after cutting waste lithium ions so as to recover the electrolyte. However, the electrolyte has low recovery rate and low purity.

Disclosure of Invention

Accordingly, there is a need for a method and system for recovering an electrolyte solution of a battery. The recovery method is environment-friendly, and has high recovery rate of the electrolyte and high purity of the recovered electrolyte.

Crushing a battery in a protective gas atmosphere to obtain a crushed material, wherein the particle size of the crushed material is 0.2-5 mm;

subcritical fluid is adopted to carry out subcritical extraction on the crushed object to obtain extraction liquid, wherein the extraction temperature is 20-40 ℃, the extraction pressure is 0.3-0.8 MPa, and the subcritical fluid is n-butane in a subcritical state; and

and carrying out reduced pressure treatment on the extract liquor to obtain the electrolyte.

In the method for recovering the electrolyte of the battery, the battery is crushed in the protective gas atmosphere, so that the battery can be crushed to enable the electrolyte to flow out, and oxygen or water vapor can be prevented from reacting with the electrolyte to ensure the stability and purity of the electrolyte; the subcritical n-butane can be used for quickly extracting the electrolyte from the scrapped battery, the n-butane is stable in property and cannot react with the electrolyte so as to ensure the purity of the electrolyte, the subcritical extraction has a good extraction effect on the electrolyte and a high recovery rate on the electrolyte, and meanwhile, the subcritical extraction is environment-friendly and cannot pollute the environment; and the discharged gaseous n-butane can be recovered and reproduced into subcritical fluid for recycling, so that the environment pollution caused by the discharge of waste gas is avoided, and the recovery cost of the electrolyte is reduced. Tests prove that by adopting the recovery method, the recovery rate of the electrolyte is over 95 percent, and the recovered electrolyte is approximately consistent with the components and the proportion of the original electrolyte in the battery, has high purity and can be directly added into a battery cell for recycling. The recovery method is environment-friendly, and has high recovery rate of the electrolyte and high purity of the recovered electrolyte.

In one embodiment, the protective gas is selected from at least one of nitrogen and argon.

In one embodiment, before the step of crushing the battery in the protective gas atmosphere, the method further comprises a step of performing replacement treatment on the battery by using the protective gas, wherein the replacement time is 10-60 min.

In one embodiment, the step of pulverizing the battery in a protective gas atmosphere comprises: roughly crushing the battery into roughly crushed objects in the protective gas atmosphere, wherein the diameter of the roughly crushed objects is 5-20 mm; and

and crushing the coarse crushed material in the protective gas atmosphere to obtain the crushed material.

In one embodiment, the operation of performing subcritical extraction on the crushed material by using a subcritical fluid to obtain an extraction liquid specifically comprises: and introducing the subcritical fluid with the flow speed of 100-300L/h into 500-1200 g of the crushed material, and stirring at the rotation speed of 15-30 rpm for 10-60 min to obtain the extract.

In one embodiment, the operation of performing reduced pressure treatment on the extract to obtain the electrolyte specifically comprises: and decompressing the extract liquid to 0MPa to 0.05MPa at the temperature of 20-40 ℃ to obtain the electrolyte and the gaseous n-butane.

In one embodiment, after the operation of performing the pressure reduction treatment on the extraction liquid to obtain the electrolyte, the following operation is further included: compressing and condensing the n-butane in a gaseous state into the n-butane in a subcritical state.

In one embodiment, after the operation of performing subcritical extraction on the crushed object by using a subcritical fluid to obtain an extraction liquid, before the operation of performing reduced pressure treatment on the extraction liquid to obtain an electrolyte, the method further comprises filtering the extraction liquid.

In one embodiment, the operation of filtering the extract liquid specifically includes: and filtering the extract liquor by adopting a screen with 50-150 meshes to obtain the filtered extract liquor.

A system for recycling electrolyte of a battery, comprising:

the pretreatment device is used for crushing the battery in a protective gas atmosphere to obtain crushed materials, and the particle size of the crushed materials is 0.2-5 mm;

the subcritical extraction device is communicated with the pretreatment device and is used for performing subcritical extraction on the crushed object to obtain an extraction liquid, wherein an extraction solvent is n-butane in a subcritical state, the extraction temperature is 20-40 ℃, and the extraction pressure is 0.3-0.8 MPa;

the decompression separation device is communicated with the subcritical extraction device and is used for decompressing the extraction liquid to obtain electrolyte and the gaseous n-butane; and

and the compression device is communicated with the decompression separation device and the subcritical extraction device and is used for converting the gaseous n-butane into the n-butane in the subcritical state and conveying the n-butane in the subcritical state into the subcritical extraction device.

Drawings

Fig. 1 is a schematic structural view of an electrolyte recovery system of a battery according to an embodiment;

fig. 2 is a schematic structural view of the recovery system shown in fig. 1, with a loading device and a protective gas storage device omitted.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

A method for recovering an electrolyte solution of a battery according to an embodiment includes operations S110 to S130 of:

and S110, crushing the battery in a protective gas atmosphere to obtain a crushed material, wherein the particle size of the crushed material is 0.2-5 mm.

The battery is crushed in the protective gas atmosphere, so that the battery can be crushed to enable the electrolyte to flow out, and oxygen or water vapor can be prevented from reacting with the electrolyte to ensure the stability and purity of the electrolyte. Meanwhile, the undersize particle size of the crushed material is not beneficial to the collection of the crushed material, and the oversized particle size is not beneficial to the diffusion and extraction of the extraction solvent in the crushed material. The battery is crushed to the particle size of 0.2 mm-5 mm, which is more beneficial to quickly extracting the electrolyte from the crushed material and more fully extracting the electrolyte to ensure the recovery rate of the electrolyte.

In one embodiment, the battery is a lithium battery. The battery is a waste lithium battery.

In one embodiment, the protective gas is nitrogen with a purity of 99.999%. The nitrogen is used as protective gas, so that the electrolyte can be prevented from being oxidized by oxygen or water vapor, the stability of the electrolyte is ensured, and the cost of electrolyte recovery is reduced.

In one embodiment, the temperature during the crushing is between 23 ℃ and 27 ℃.

In one embodiment, the step of S110 includes: roughly crushing the battery into roughly crushed objects in a protective gas atmosphere, wherein the diameter of the roughly crushed objects is 5-20 mm; and (4) crushing the coarse crushed material in a protective gas atmosphere to obtain a crushed material.

Through twice crushing, the grain diameter of the crushed material is more uniform, so that the full extraction of the electrolyte is facilitated, and the recovery rate of the electrolyte is improved. The operation of S110 is not limited to the above-described operation, and the battery may be pulverized at once in a protective gas atmosphere to obtain a pulverized product having a particle size of 0.2mm to 5 mm.

In one embodiment, before S110, the method further includes a step of performing a replacement process on the battery with a protective gas, wherein the replacement time is 10min to 60 min. Further, the replacement time is 20min to 40 min. Further, nitrogen gas with a purity of 99.999% was used as a protective gas, and the substitution time was 10 min.

In one embodiment, before S110, the operation of fully discharging and cleaning the battery is further included.

And S120, subcritical extracting the crushed material by using subcritical fluid to obtain an extraction liquid, wherein the extraction temperature is 20-40 ℃, the extraction pressure is 0.3-0.8 MPa, and the subcritical fluid is subcritical n-butane.

The subcritical n-butane can be used for rapidly extracting the electrolyte from the scrapped battery, the n-butane is stable in property and cannot react with the electrolyte, so that the purity of the electrolyte is ensured, the subcritical extraction has a good extraction effect on the electrolyte, the recovery rate of the electrolyte is high, and meanwhile, the subcritical extraction is environment-friendly and cannot pollute the environment.

In one embodiment, the operation of S120 is specifically: and introducing subcritical fluid into the crushed material and stirring to obtain an extract liquid. The flow rate of the subcritical fluid is proportional to the mass of the pulverized material. Subcritical fluid is directly introduced into the crushed materials, so that the subcritical fluid can be directly mixed with the crushed materials, and the recovery time is favorably shortened. Make subcritical fluid can more fully mix with the thing that pulverizes through the stirring to make electrolyte can extract more fully, with improvement electrolyte recovery rate. Specifically, subcritical fluid with the flow rate of 100L/h-300L/h is introduced into 500 g-1200 g of the crushed material, and the crushed material is stirred at the rotation speed of 15 rpm-30 rpm for 10 min-60 min to obtain extract. Under such conditions, the recovery rate of the electrolyte can be improved.

Further, in the operation of S120, the flow rate of the subcritical fluid is 150L/h-250L/h, the rotation speed is 20 rpm-25 rpm, the stirring time is 20 min-40 min, the extraction pressure is 0.4 MPa-0.6 MPa, and the extraction temperature is 25 ℃ to 35 ℃. Preferably, in the operation of S120, the flow rate of the subcritical fluid is 200L/h, the rotation speed is 23rpm, the stirring time is 35min, the extraction pressure is 0.5MPa, and the extraction temperature is 30 ℃.

In one embodiment, the mass ratio of the subcritical fluid to the pulverized material is 5:2, and the extraction time is 10 to 60 min.

And S130, carrying out reduced pressure treatment on the extract to obtain electrolyte.

The method adopts a decompression mode to discharge n-butane in a gas form so as to ensure the purity of the electrolyte, and the discharged n-butane gas can be recovered and further prepared into subcritical fluid for recycling, so that the environment pollution caused by the emission of waste gas is avoided, and the recovery cost of the electrolyte is reduced.

In one embodiment, the operation of S130 is specifically: decompressing the extract liquor to 0 MPa-0.05 MPa at 20-40 ℃ to obtain electrolyte and gaseous n-butane.

In one embodiment, the operation of S130 is followed by compressing and condensing gaseous n-butane to sub-critical n-butane. Gaseous n-butane compression, the condensation become the normal butane of subcritical state can mix with smashing the thing again to subcritical extraction electrolyte makes gaseous n-butane can recycle, does not have waste gas discharge in the recovery process of the electrolyte that makes the battery, avoids the influence of waste gas to the environment, is favorable to reducing the recovery cost of electrolyte simultaneously. Specifically, gaseous n-butane is compressed to 0.3MPa to 0.8MPa at 20 ℃ to 40 ℃, namely, becomes sub-critical n-butane.

In one embodiment, after the operation of S130, the method further includes hermetically packaging the electrolyte, and introducing a protective gas for pressure protection. Preferably, the electrolyte is protected under pressure with nitrogen.

In one embodiment, after S120 and before S130, the method further includes filtering the extract. And solid impurities in the extract liquor are removed through filtering treatment, so that the purity of the electrolyte is further ensured. Specifically, the extraction liquid is filtered by a screen mesh of 50-150 meshes to obtain residue and filtered extraction liquid. The residue is solid impurity, and the residue can be further separated by magnetic separation, vortex battery separation and the like. The operation of filtering the extract may be omitted. When the operation of filtering the extraction liquid is omitted, the electrolyte may be filtered after S130 to remove solid impurities in the electrolyte.

In the method for recovering the electrolyte of the battery, the battery is crushed in the protective gas atmosphere, so that the electrolyte can flow out by crushing the battery, and the reaction of oxygen or water vapor with the electrolyte can be avoided, so that the stability of the electrolyte is ensured; the subcritical n-butane is adopted to quickly extract the electrolyte from the battery, the n-butane has stable property and cannot react with the electrolyte to ensure the purity of the electrolyte, the subcritical extraction has good extraction effect on the electrolyte, so that the recovery rate of the electrolyte is high, and meanwhile, the subcritical extraction is environment-friendly and does not pollute the environment; the method adopts a decompression mode to discharge n-butane in a gas form so as to ensure the purity of the electrolyte, and the discharged gaseous n-butane can be recovered and reproduced into subcritical fluid for recycling, so that the environment pollution caused by the discharge of waste gas is avoided, and the recovery cost of the electrolyte is reduced. Tests prove that by adopting the recovery mode, the recovery rate of the electrolyte is over 95 percent, and the recovered electrolyte is approximately consistent with the components and the proportion of the original electrolyte in the battery, and can be directly added into a battery cell for cyclic utilization. The recovery method is simple to operate, environment-friendly, high in recovery rate of the electrolyte, high in purity of the recovered electrolyte and beneficial to large-scale industrial application.

The system 10 for recovering an electrolyte of a battery according to an embodiment includes a pretreatment device 100, a charging device 200, a protective gas storage device 300, a subcritical extraction device 400, a decompression separation device 500, and a compression device 600. The recovery system 10 can recover the electrolyte of the battery.

The pretreatment device 100 is used for pulverizing the battery in a protective gas atmosphere to obtain a pulverized material, and the particle size of the pulverized material is 0.2mm to 5 mm.

The pretreatment apparatus 100 includes a displacer (not shown), a crusher (not shown), and a conveyor (not shown).

The displacer is used for displacing the protective gas of the battery. In the illustrated embodiment, the displacer is a nitrogen displacer. Further, when the displacer is a nitrogen displacer, the displacer can supply nitrogen gas with a purity of 99.999%.

The crusher is hermetically connected with the displacer so that the battery displaced by the protective gas can enter the crusher to be coarsely crushed, and coarsely crushed objects with the diameter of 5 mm-20 mm are obtained. In the illustrated embodiment, the crusher is a sealed twin shaft crusher. The crusher is provided with a first gas conveying pipeline to convey protective gas into the crusher, so that the battery subjected to protective gas replacement is coarsely crushed in a protective gas atmosphere, and the stability of electrolyte is guaranteed.

The crusher is communicated with the crusher so that the coarsely crushed material can enter the crusher to be crushed to obtain the crushed material. The crusher is provided with a second gas conveying pipeline to convey protective gas into the crusher, so that coarsely crushed objects are crushed in the protective gas atmosphere, and the stability of the electrolyte is guaranteed. In the illustrated embodiment, the shredder is sealably connected to the shredder.

The conveyor is communicated with the crusher and the crusher to convey the coarse crushed materials obtained in the crusher to the crusher for crushing. The conveyor is provided with a third gas delivery line for delivering protective gas into the conveyor. In the illustrated embodiment, the conveyor is a screw conveyor. The conveyor is hermetically connected with the crusher and the crusher.

The loading device 200 is used to automatically feed the batteries into the pretreatment device 100 to improve the automation of the recycling system 10. The loading device 200 includes a bucket elevator and a dumper.

The bucket elevator is connected with the displacer in a sealing way. The bucket elevator can convey the battery to the displacer. In the illustrated embodiment, the bucket elevator is a sealed bucket elevator. The bucket elevator is provided with a fourth gas conveying pipeline for introducing protective gas into the bucket elevator.

The tipper is used for conveying batteries to the bucket elevator. The tipping machine is provided with a storage hopper, and the battery can be placed in the storage hopper. The storage hopper can be in communication with the bucket elevator to transport the batteries into the bucket elevator. In the illustrated embodiment, the tipper is a hoist tipper. The tipper is equipped with the fifth gas conveying pipeline, and the fifth gas conveying pipeline communicates with the storage hopper to make the storage hopper carry protective gas.

The protective gas storage device 300 is communicated with the crusher, the conveyor, the bucket elevator, and the dumper to convey the protective gas to the crusher, the conveyor, the bucket elevator, and the dumper. Further, the protective gas storage device 300 is communicated with the first gas delivery pipeline, the second gas delivery pipeline, the third gas delivery pipeline, the fourth gas delivery pipeline and the fifth gas delivery pipeline. In the illustrated embodiment, the protective gas storage device 300 is a nitrogen storage tank. Further, the protective gas storage apparatus 300 is capable of providing nitrogen gas having a purity of 99.999%.

The subcritical extraction device 400 is communicated with the pretreatment device 100, and is used for performing subcritical extraction on the crushed object to obtain an extraction liquid, wherein an extraction solvent is n-butane in a subcritical state, the extraction temperature is 20-40 ℃, and the extraction pressure is 0.3-0.8 MPa.

Referring to fig. 2, the subcritical extraction apparatus 400 includes an extraction kettle 410, a pressure controller (not shown), and a temperature controller.

The extraction kettle 410 is used for performing subcritical extraction on the crushed material to obtain an extraction liquid. The extraction tank 410 is in communication with a crusher so that the crushed material in the crusher can be conveyed to the extraction tank 410. The extraction kettle 410 is provided with a reaction chamber (not shown) which is communicated with the crusher so that crushed materials in the crusher can be conveyed into the reaction chamber.

The extraction kettle 410 is provided with a feed inlet 412, and the feed inlet 412 is communicated with the reaction cavity. The pulverized material can enter the reaction chamber through the feed inlet 412. Further, the subcritical extraction apparatus 400 further comprises a material conveyor (not shown). The material conveyer is communicated with the feeding hole 412 and the crusher to convey crushed materials in the crusher to the reaction cavity. In the illustrated embodiment, the conveyor is a screw conveyor.

The extraction kettle 410 is provided with a liquid inlet 414, and the liquid inlet 414 is communicated with the reaction cavity. N-butane in a subcritical state can enter the reaction chamber from the liquid inlet 414. In the illustrated embodiment, the inlet port 414 is disposed proximate the inlet port 412. Further, the subcritical extraction apparatus 400 further comprises a solvent transfer tank 420. The solvent transfer tank 420 is used to store n-butane in a subcritical state. The solvent transfer tank 420 is in communication with the inlet port 414 to deliver n-butane in a subcritical state to the reaction chamber. Further, the subcritical extraction apparatus 400 further includes a solvent pump 430, and the solvent pump 430 is communicated with both the solvent transfer tank 420 and the reaction chamber, so that n-butane in a subcritical state of the solvent transfer tank 420 can be conveyed into the reaction chamber through the solvent pump 430.

The extraction kettle 410 is provided with a storage chamber (not shown) which is communicated with the reaction chamber. The extraction liquid in the reaction chamber can flow into the storage chamber. Further, the extraction kettle 410 is provided with a screen (not shown), and the screen is accommodated in the storage cavity, so that the extract can be filtered by the screen to obtain solid waste and filtered extract. By providing a screen in the extraction tank 410, the extraction liquid can be directly filtered in the extraction tank 410, so as to avoid the operation of taking out the extraction liquid for separate filtration, and the above-mentioned recovery system 10 is more compact. In the illustrated embodiment, the mesh has a mesh opening size of 50 to 150 mesh.

The extraction kettle 410 is provided with a discharge port 416, and the discharge port 416 is communicated with the storage cavity. Filtrate in the storage chamber can be discharged from the discharge port 416. Further, the extraction vessel 410 is provided with a tap hole 418 communicating with the storage chamber. The solid waste slag in the storage chamber can be discharged from the slag outlet 418.

The extraction kettle 410 is provided with a stirrer (not shown) which is accommodated in the reaction cavity to mix the crushed material and the n-butane subcritical fluid in the reaction cavity, so that the crushed material and the n-butane subcritical fluid can be fully mixed.

The pressure controller is used to control the pressure in the extraction tank 410. In the illustrated embodiment, the pressure controller can control the pressure in the reaction chamber to 0.3 to 0.8 MPa. The temperature controller is used to control the temperature in the extraction tank 410. Further, a temperature controller is connected with the extraction kettle 410, and the temperature controller can control the temperature in the reaction cavity to be 20-40 ℃. In the illustrated embodiment, the temperature controller is a hot water circulator that controls the temperature in the reaction chamber by circulating hot water. The temperature controller is provided with a hot water inlet 442 and a hot water outlet 444 spaced apart from each other, and hot water flows from the hot water inlet 442 to the hot water outlet 444 to control the temperature of the extraction tank 410.

The reduced pressure separation apparatus 500 is in communication with the subcritical extraction apparatus 400. The decompression separation device 500 is used for decompressing the extraction liquid to obtain the electrolyte and the gaseous n-butane.

The decompression separation apparatus 500 includes a decompression evaporation kettle 510, a material delivery pump (not shown), a temperature controller (not shown), and a collector 530.

The reduced-pressure evaporation kettle 510 is communicated with the extraction kettle 410, so that the extraction liquid can enter the reduced-pressure evaporation kettle 510 for reduced-pressure treatment. In the illustrated embodiment, reduced pressure evaporator 510 is in communication with outlet port 416 such that filtrate exiting outlet port 416 can enter reduced pressure evaporator 510. The reduced pressure evaporation kettle 510 can reduce the pressure of the filtrate to 0 MPa-0.05 MPa. The material delivery pump is connected with the reduced pressure evaporation kettle 510 and the discharge hole 416 so as to deliver the filtrate flowing out of the discharge hole 416 to the reduced pressure evaporation kettle 510.

The temperature controller is connected to the reduced-pressure evaporator 510 to control the temperature of the reduced-pressure evaporator 510. In the illustrated embodiment, the temperature controller is a hot water circulator that controls the temperature in the reduced-pressure evaporation kettle 510 by circulating hot water. The temperature controller has a water inlet 522 and a water outlet 524 which are spaced apart, and hot water flows from the water inlet 522 to the water outlet 524 to control the temperature of the reduced pressure evaporation kettle 510. The temperature controller can control the temperature of the reduced-pressure evaporation kettle 510 to be 20-40 ℃. The collector 530 is communicated with the reduced-pressure evaporation kettle 510, so that the electrolyte in the reduced-pressure evaporation kettle 510 can flow into the collector 530 for storage. Further, the decompression separation device 500 further comprises a delivery pump 540, and the delivery pump 540 is connected with both the decompression evaporation kettle 510 and the collector 530, so as to deliver the electrolyte in the decompression evaporation kettle 510 to the collector 530.

The compression device 600 is communicated with the decompression separation device 500 and the subcritical extraction device 400. The compression unit 600 is used to convert gaseous n-butane to sub-critical n-butane and deliver the sub-critical n-butane to the sub-critical extraction unit 400.

The compressing device 600 includes an air tank 610, a vacuum pump 620, a compressor 630, and a condenser 640.

The gas holder 610 is used for storing gaseous n-butane. The gas storage tank 610 is communicated with the reduced-pressure evaporation vessel 510 so that gaseous n-butane in the reduced-pressure evaporation vessel 510 can flow into the gas storage tank 610. It should be noted that the gas holder 610 is not limited to storing gaseous n-butane in the reduced-pressure evaporator 510, and can store fresh gaseous n-butane.

The compressor 630 is in communication with the storage tank 610 to enable the gaseous n-butane in the storage tank 610 to enter the compressor 630 for compression. In the illustrated embodiment, gaseous n-butane can be compressed in the compressor 630 to a pressure of 0.3MPa to 0.8 MPa. Further, the compressing device 600 further comprises a vacuum pump 620, and the vacuum pump 620 is connected with both the compressor 630 and the air storage tank 610. The vacuum pump 620 not only pumps air in the compression device 600 to ensure that the air is free of impurities, but also has a certain pressurization effect.

The condenser 640 is in communication with both the compressor 630 and the solvent transfer tank 420, such that gaseous n-butane compressed in the compressor 630 can be condensed into a subcritical state via the condenser 640, and the subcritical n-butane is delivered to the solvent transfer tank 420 for subcritical extraction. In the illustrated embodiment, the condenser 640 is a cold water circulator. The condenser 640 has a spaced cold water inlet 642 and a cold water outlet 644. Cold water can flow from the cold water inlet 642 to the cold water outlet 644 to condense the n-butane gas.

The recycling system 10 of the electrolyte of the battery is used as follows:

(1) the method comprises the steps of fully discharging and cleaning batteries, then pouring the cleaned batteries into a storage hopper of a tipper, turning over the tipper to pour the cleaned batteries into a bucket elevator, transferring the cleaned batteries into a replacement machine by the bucket elevator for protective gas replacement, transferring the replaced batteries into a crusher for coarse crushing into coarse crushed materials, conveying the coarse crushed materials into a crusher by a conveyor to be crushed into crushed materials, and introducing protective gas into a pretreatment device 100 and a feeding device 200 by a protective gas storage device 300 in the transferring, crushing and crushing processes.

(2) The n-butane gas is charged into the gas container 610, and the vacuum pump 620, the compressor 630 and the condenser 640 are turned on to convert the gaseous n-butane into a subcritical state to be stored in the solvent transfer tank 420. The material conveyer conveys the pulverized material to the reaction cavity of the extraction kettle 410, and conveys the subcritical n-butane in the solvent transfer tank 420 to the reaction cavity of the extraction kettle 410 through the solvent pump 430. And starting a pressure controller and a temperature controller to control the pressure and the temperature, and starting a stirrer to stir the crushed material and the subcritical n-butane so as to extract the electrolyte. N-butane in a subcritical state may be charged into the solvent transfer tank 420 in advance.

(3) After extraction is finished, the extract is transferred to a storage cavity, and the extract is separated into filter residue and filtered extract under the action of a screen. And further separating filter residues by magnetic separation, vortex battery separation and the like. The filtered extract liquid flows into a decompression evaporation kettle 510 under the action of a delivery pump for decompression treatment to obtain n-butane gas and electrolyte, the n-butane gas flows into a gas storage tank 610 for circulation, the electrolyte flows into a collector 530 for sealed storage under the action of a delivery pump 540, and nitrogen is introduced into the collector 530 for pressurization protection.

The above-mentioned recovery system 10 of the electrolyte of the battery has at least the following advantages:

in the recovery system 10, the battery is crushed into crushed materials with the particle size of 0.2 mm-5 mm in the protective gas atmosphere through the pretreatment device 100, so that the battery can be crushed to enable the electrolyte to flow out, and oxygen or water vapor can be prevented from reacting with the electrolyte to ensure the stability of the electrolyte; the subcritical extraction device 400 is adopted, so that the electrolyte can be quickly extracted from the battery, the recovery rate of the electrolyte is high, and the environment is protected; decompressing the extraction liquid by using a decompression separation device 500 to discharge n-butane in a gas manner so as to obtain electrolyte with higher purity; n-butane gas is converted into subcritical fluid by the compression device 600, and the subcritical fluid is sent to the subcritical extraction device 400, so that the n-butane gas is recovered and recycled, thereby avoiding environmental pollution caused by emission of waste gas, and reducing the recovery cost of electrolyte. The recovery system 10 is simple in structure, high in recovery rate of the electrolyte, high in purity of the recovered electrolyte, environment-friendly and capable of being applied to industrial recovery of the electrolyte of the battery.

It is understood that the loading device 200 may be omitted. When the loading device 200 is omitted, the battery may be directly placed in the displacer.

It will be appreciated that the crusher may be omitted. When the crusher is omitted, the conveyor is communicated with the replacement machine and the crusher so as to transfer the batteries replaced in the replacement machine into the crusher to be directly crushed into crushed materials with the particle size of 0.2 mm-5 mm.

The following are specific examples.

Example 1

The electrolyte recovery process of the battery of this example was as follows:

(1) fully discharging and cleaning the waste lithium battery, and crushing the waste lithium battery in a nitrogen atmosphere to obtain a crushed material with the particle size of 0.2mm, wherein the purity of nitrogen in the nitrogen atmosphere is 99.999%.

(2) And (3) introducing subcritical fluid with the flow rate of 100L/h into 500g of crushed material, and stirring at the rotation speed of 15rpm for 10min to obtain extraction liquid, wherein the extraction temperature is 20 ℃, the extraction pressure is 0.3MPa, and the subcritical fluid is subcritical n-butane.

(3) And (3) sieving the extract liquor by a 50-mesh sieve to obtain filtrate and residues, decompressing the filtrate to 0MPa at 20 ℃ to obtain electrolyte, and sealing the electrolyte to ensure the electrolyte and performing nitrogen pressurization protection.

Example 2

The electrolyte recovery process of the battery of this example was as follows:

(1) fully discharging and cleaning waste lithium batteries, and crushing the waste lithium batteries in a nitrogen atmosphere to obtain crushed materials with the particle size of 0.5mm, wherein the purity of nitrogen in the nitrogen atmosphere of the crushed materials is 99.999%.

(2) And introducing subcritical fluid with the flow rate of 300L/h into 1200g of the crushed material, and stirring at the rotation speed of 30rpm for 60min to obtain an extraction liquid, wherein the extraction temperature is 40 ℃, the extraction pressure is 0.8MPa, and the subcritical fluid is subcritical n-butane.

(3) And (3) sieving the extract liquor by a 150-mesh sieve to obtain filtrate and residues, decompressing the filtrate to 0.05MPa at 40 ℃ to obtain electrolyte, and sealing the electrolyte to ensure the electrolyte and pressurizing and protecting the electrolyte by nitrogen.

Example 3

The electrolyte recovery process of the battery of this example was as follows:

(1) fully discharging and cleaning the waste lithium battery, and replacing for 10min in nitrogen with the purity of 99.999%; and (3) crushing the waste lithium battery subjected to nitrogen conversion in a nitrogen atmosphere to obtain a crushed material, wherein the particle size of the crushed material is 0.2mm, and the purity of nitrogen in the nitrogen atmosphere is 99.999%.

Example 4

The electrolyte recovery process of the battery of this example was as follows:

(1) fully discharging and cleaning the waste lithium battery, and replacing for 20min in nitrogen with the purity of 99.999%; crushing the waste lithium battery subjected to nitrogen conversion in a nitrogen atmosphere to obtain a crushed material with the diameter of 5mm, crushing the crushed material in the nitrogen atmosphere to obtain a crushed material with the particle size of 0.2mm, wherein the purity of nitrogen in the nitrogen atmosphere is 99.999%.

Example 5

The electrolyte recovery process of the battery of this example was as follows:

(1) fully discharging and cleaning the waste lithium battery, and replacing for 60min in nitrogen with the purity of 99.999%; crushing the waste lithium battery subjected to nitrogen conversion in a nitrogen atmosphere to obtain a crushed material with the diameter of 20mm, crushing the crushed material in the nitrogen atmosphere to obtain a crushed material with the particle size of 5mm, wherein the purity of nitrogen in the nitrogen atmosphere is 99.999%.

Example 6

The electrolyte recovery process of the battery of this example was as follows:

(1) fully discharging and cleaning the waste lithium battery, and replacing for 30min in nitrogen with the purity of 99.999%; crushing the waste lithium battery subjected to nitrogen conversion in a nitrogen atmosphere to obtain a crushed material with the diameter of 13mm, crushing the crushed material in the nitrogen atmosphere to obtain a crushed material with the particle size of 2.5mm, wherein the purity of nitrogen in the nitrogen atmosphere is 99.999%.

(2) And introducing subcritical fluid with the flow rate of 200L/h into 900g of the crushed material, and stirring at the rotation speed of 30rpm for 35min to obtain an extraction liquid, wherein the extraction temperature is 30 ℃, the extraction pressure is 0.5MPa, and the subcritical fluid is subcritical n-butane.

(3) And (3) sieving the extract liquor by a 100-mesh sieve, collecting filtrate, decompressing the filtrate to 0.03MPa at 30 ℃ to obtain electrolyte, and sealing the electrolyte to ensure the electrolyte and performing nitrogen pressurization protection.

Example 7

The electrolyte recovery process of the battery of this example was as follows:

(1) fully discharging and cleaning the waste lithium battery, and crushing the waste lithium battery in a nitrogen atmosphere to obtain a crushed material with the particle size of 0.1mm, wherein the purity of nitrogen in the nitrogen atmosphere is 99.999%.

Example 8

The electrolyte recovery process of the battery of this example was as follows:

(1) fully discharging and cleaning waste lithium batteries, and crushing the waste lithium batteries in a nitrogen atmosphere to obtain crushed materials with the particle size of 0.8mm, wherein the purity of nitrogen in the nitrogen atmosphere of the crushed materials is 99.999%.

Example 9

The electrolyte recovery process of the battery of this example was as follows:

(2) And (3) introducing subcritical fluid with the flow rate of 80L/h into 500g of crushed material, and stirring at the rotation speed of 15rpm for 10min to obtain extraction liquid, wherein the extraction temperature is 20 ℃, the extraction pressure is 0.3MPa, and the subcritical fluid is subcritical n-butane.

Example 10

The electrolyte recovery process of the battery of this example was as follows:

(2) And introducing subcritical fluid with the flow rate of 350L/h into 1200g of crushed material, and stirring at the rotation speed of 30rpm for 60min to obtain extract, wherein the extraction temperature is 40 ℃, the extraction pressure is 0.8MPa, and the subcritical fluid is subcritical n-butane.

Example 11

The electrolyte recovery process of the battery of this example was as follows:

(2) And introducing subcritical carbon dioxide fluid with the flow rate of 100L/h into 500g of the crushed material, and stirring at the rotation speed of 15rpm for 10min to obtain an extraction liquid, wherein the extraction temperature is 26 ℃, and the extraction pressure is 6.5 MPa.

And (3) testing:

1. the recovery rates of the electrolytes obtained by the recovery methods of examples 1 to 11 were measured, and the results are shown in Table 1. Wherein the recovery rate is equal to the mass ratio of the electrolyte obtained by the recovery method of the embodiment 1-11 to the electrolyte of the uncrushed waste battery.

TABLE 1 recovery rates of the electrolytes recovered in examples 1 to 11

As can be seen from table 1, the recovery rate of the electrolytes obtained in examples 1 to 6 was at least 94.2%, which is significantly better than the recovery rate of the electrolyte obtained in example 11, indicating that the recovery rate of the electrolyte was high by the recovery method in the above embodiment.

Among these, the highest electrolyte recovery rate in example 6 indicates that the electrolyte in the cell can be recovered as much as possible by an appropriate cell disruption method, an appropriate subcritical fluid extraction method, and an appropriate pressure reduction separation method. The recovery rate of the electrolyte in example 11 is significantly lower than that in example 1, probably because part of the carbon dioxide subcritical fluid in example 11 is slightly soluble in the electrolyte, and ester substances in the electrolyte are hydrolyzed, thereby reducing the recovery rate of the electrolyte. The recovery rate of the electrolyte in the embodiment 3 is higher than that in the embodiment 1, which shows that after nitrogen replacement is carried out before the cell is crushed, air carried by the cell can be removed, so that impurities doped in the protective gas in the crushing process are less, and the recovery rate of the electrolyte is more favorably ensured. The electrolyte recovery rate of example 4 is higher than that of example 1, and the electrolyte recovery rate of example 5 is higher than that of example 2, which shows that the crushing effect of the battery is higher after two-step crushing, the particle sizes of crushed materials are appropriate and uniformly distributed, and the n-butane subcritical fluid can more easily and fully extract the electrolyte from the crushed materials.

The electrolyte recovery rate of the embodiment 7 is lower than that of the embodiment 1, probably because the particle size of the crushed material of the embodiment 7 is too small, a certain amount of electrolyte is carried in filter residue obtained after the extraction liquid is sieved, and the electrolyte recovery rate is further reduced; the recovery rate of the electrolyte in example 8 was lower than that in example 2, and it was likely that the particle size of the crushed product in example 8 was too large, and it was difficult to infiltrate the extract into the crushed product and to extract the electrolyte sufficiently. The electrolyte recovery rate of example 9 was lower than that of example 1, probably because the subcritical fluid flowing into the extraction vessel in example 9 was too small in flow rate, so that the electrolyte could not be sufficiently extracted; the electrolyte recovery rate of example 10 is lower than that of example 2, probably because the subcritical fluid is supersaturated due to the excessive flow rate of the subcritical fluid flowing into the extraction kettle in example 10, and the electrolyte is lost due to the fact that the n-butane gas can carry part of the electrolyte in the decompression separation process.

2. The contents of the components in the electrolyte recovered in examples 1 to 11 were measured by gas chromatography-mass spectrometer analysis and atomic absorption spectrometer, and the contents of the components in the electrolyte of the uncrushed cell were measured as a control, and the measurement results are shown in table 2. Wherein, the content is mass percent (%) and the following components in the electrolyte are mainly determined: lithium hexafluorophosphate (LiPF)₆) Methyl ethyl carbonate (EMC), Propylene Carbonate (PC) and dimethyl carbonate (DMC). Table 2 shows the contents of the components in the electrolyte of the uncracked battery and the electrolyte obtained by the recovery methods of examples 1 to 11.

TABLE 2 contents of respective components in the electrolyte obtained by the recovery methods of examples 1 to 11

	LiPF₆(％)	EMC(％)	PC(％)	DMC(％)
					Example 1	14.13	32.97	18.84	28.26
Example 2	14.31	33.39	19.08	28.62
					Example 3	14.295	33.355	19.06	28.59
Example 4	14.43	33.07	19.24	28.86
					Example 5	14.325	33.425	19.10	28.65
Example 6	14.55	33.95	19.40	29.10
					Example 7	14.175	33.075	18.90	28.35
Example 8	14.295	33.355	19.06	28.59
					Example 9	13.905	32.445	18.54	27.81
Example 10	14.22	33.18	18.96	28.44
					Example 11	13.38	31.22	17.84	26.76
Control group	15	35	20	30

As can be seen from table 2, the content of each component in the electrolytes of examples 1 to 6 is approximately equal to that of the electrolyte of the control group, and the content of each component in the electrolytes of examples 1 to 6 is in direct proportion to the recovery rate of the electrolyte, which illustrates that the recovery method of the above embodiment can better ensure the purity of the recovered electrolyte, so that the recovered electrolyte can be directly added into the battery cell for recycling.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The method for recovering the electrolyte of the battery is characterized by comprising the following steps of:

2. The method of claim 1, wherein the protective gas is at least one selected from the group consisting of nitrogen and argon.

3. The method for recovering an electrolyte solution for a battery according to claim 1, wherein the step of pulverizing the battery in a protective gas atmosphere further comprises the steps of: and replacing the battery by using the protective gas to remove air carried by the battery, wherein the replacement time is 10-60 min.

4. The method of claim 1, wherein the step of pulverizing the battery in a protective gas atmosphere comprises: roughly crushing the battery into roughly crushed objects in the protective gas atmosphere, wherein the diameter of the roughly crushed objects is 5-20 mm; and

5. The method for recovering the battery electrolyte according to claim 1, wherein the operation of performing the subcritical extraction on the pulverized material with the subcritical fluid to obtain the extract specifically comprises: and introducing the subcritical fluid with the flow speed of 100-300L/h into 500-1200 g of the crushed material, and stirring at the rotation speed of 15-30 rpm for 10-60 min to obtain the extract.

6. The method for recovering the electrolyte of the battery according to claim 1, wherein the operation of subjecting the extract to the pressure reduction treatment to obtain the electrolyte is specifically: and decompressing the extract liquid to 0MPa to 0.05MPa at the temperature of 20-40 ℃ to obtain the electrolyte and the gaseous n-butane.

7. The method for recovering the electrolyte solution of the battery according to claim 6, further comprising, after the operation of subjecting the extract solution to the pressure reduction treatment to obtain the electrolyte solution: compressing and condensing the n-butane in a gaseous state into the n-butane in a subcritical state.

8. The method for recovering battery electrolyte according to claim 1, further comprising filtering the extract after the operation of subcritical extracting the pulverized material with the subcritical fluid to obtain the extract and before the operation of depressurizing the extract to obtain the electrolyte.

9. The method for recovering the electrolyte of the battery according to claim 1, wherein the operation of filtering the extract solution is specifically: and filtering the extract liquor by adopting a screen with 50-150 meshes to obtain the filtered extract liquor.

10. A system for recovering electrolyte from a battery, comprising:

a compression device in communication with both the reduced pressure separation device and the subcritical extraction device, the compression device for converting the n-butane in the gaseous state to the n-butane in the subcritical state and delivering the n-butane in the subcritical state to the subcritical extraction device.