A lithium battery pretreatment device and method under a supercritical carbon dioxide system

Abstract

The application discloses a lithium battery pretreatment device and method under a supercritical carbon dioxide system. The device comprises a feeding system, an air inlet system, a reaction kettle and a vertical centrifuge. The lithium battery enters the reaction kettle through the feeding system, and first completes charged crushing under an inert atmosphere in a crushing area of the reaction kettle. Then, the lithium battery enters a reaction area, and simultaneously completes supercritical carbon dioxide extraction of electrolyte and dimethyl sulfoxide dissolution of a binder. The carbon dioxide mixed with the electrolyte enters a separation kettle to complete separation and recovery, the dimethyl sulfoxide with the binder is separated through pressure filtration and enters a precipitation separation area at the same time, and positive and negative electrode powders are recovered. Finally, the separation and recovery of the solid-phase binder and the liquid-phase dimethyl sulfoxide are completed in the centrifuge. The device can simultaneously crush the battery and separate and recover high-purity electrolyte, the binder and the positive and negative electrode powders. The recycled dimethyl sulfoxide and carbon dioxide can be recycled and reused, safe lithium ion battery pretreatment is realized, pollution is avoided, the device is simple, efficient, low in energy consumption and cost, and large-batch mechanical pretreatment is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium battery precious metal recovery, and particularly relates to a lithium battery pretreatment device and method under a supercritical carbon dioxide system. BACKGROUND

[0002] In terms of quantity, with the rapid development of the new energy automobile industry in recent years, the demand and scrap quantity of power lithium ion batteries are increasing year by year, and resource management and recycling of the batteries are very beneficial to balance the supply and demand relationship and greatly promote the sustainable development of resources and the development of circular economy. In terms of structure, the positive and negative electrode materials of the battery include metal resources such as cobalt (Co), lithium (Li), nickel (Ni), manganese (Mn), copper (Cu) and iron (Fe). The component content is relatively certain, and even exceeds the resource content in natural ore. Among them, cobalt is a scarce strategic metal. Therefore, it is necessary to recycle lithium batteries.

[0003] The recycling process of waste lithium ion batteries mainly includes pretreatment, secondary treatment and deep treatment. The pretreatment steps include deep discharge, battery disassembly and crushing, electrolyte recovery, positive material and binder separation and the like. First, the waste lithium ion battery must be discharged before recycling to minimize the safety hazards in the recycling process, but the current discharge method has the disadvantages of long discharge time and serious pollution in the discharge process. After discharge treatment, the lithium battery structure can be destroyed by manual disassembly or mechanical crushing to facilitate the subsequent recycling of lithium batteries. Although manual disassembly has the characteristics of good separation effect, high product purity and good recycling effect, it has low production efficiency and certain danger. The electrolyte is the most dangerous and polluting substance in the waste lithium ion battery. The fluorine-containing electrolyte is a deliquescent and oxidizable substance, which is easy to decompose to produce HF, organic phosphate and alkyl fluorophosphoric acid compounds when exposed to the natural environment. Therefore, to avoid the reaction of the electrolyte in the battery with water, the battery is placed in an inert gas filled with argon and carbon dioxide for crushing, which can effectively avoid the contact of lithium and electrolyte with water and generate HF.

[0004] The electrolyte not only produces dangerous and polluting substances in the battery pretreatment crushing process, but also causes great pollution in the subsequent secondary treatment process. When the electrolyte LiPF6 is exposed to air and heated in the fire treatment, it will rapidly decompose PF5 gas, and finally form fluorine-containing flue gas and smoke dust for external discharge; the wet treatment can dissolve the electrolyte lithium salt in the solution, and the HF and PF5 are easily generated in the alkali dissolution process to form soluble fluorides, causing fluorine pollution of water bodies, which will directly or indirectly harm the human body. And the conventional electrolyte contains a large amount of organic solvent to dissolve lithium salt, so it is necessary to establish a recycling technology of electrolyte. Among them, supercritical CO2 is particularly suitable for extracting volatile and heat-sensitive substances, especially in the extraction of lithium ion battery electrolyte, which can effectively prevent the decomposition of heat-sensitive lithium salt (LiPF6), maximize the retention of functional components of the electrolyte and prevent the escape of volatile organic solvents.

[0005] In addition, the high stability of PVDF and its strong binding ability seriously hinder the separation of aluminum foil and waste lithium battery positive materials, so it is necessary to separate the positive material from the aluminum foil in the lithium battery pretreatment process, and the commonly used method is organic solvent dissolution method and calcination method. However, N-methyl-2-pyrrolidone and acetone can be used as solvents to dissolve the binder, but the organic solvent is low in toxicity and high in price, which increases the environmental risk and recycling cost, limits its industrial application. And heating is easy to cause volatilization and destroy the crystal structure of active substances. Therefore, there is an urgent need for a pollution-free and low-energy consumption method for separating the positive active material in lithium battery. SUMMARY

[0006] To solve the problems existing in the prior art, the purpose of the present application is to provide a lithium battery pretreatment device and method under a supercritical carbon dioxide system, which can realize safe, pollution-free, simple and efficient, low-energy consumption, low cost and large-scale mechanical pretreatment of lithium ion batteries.

[0007] The technical scheme adopted by the present application is as follows:

[0008] A lithium battery pretreatment device under a supercritical carbon dioxide system includes a feeding system, an air intake system, a solvent supply system, a reactor, and a centrifuge. The feeding system is a sealed system, and its outlet is connected to the reactor inlet. The reactor includes a crushing zone, a reaction zone, and a precipitation separation zone connected sequentially from top to bottom. The reactor inlet is located at the upper end of the crushing zone, and a carbon dioxide outlet is located on the side wall of the crushing zone. A pulverizing device is installed inside the crushing zone, located below the carbon dioxide outlet. The reaction zone is equipped with a heating device and a stirring device. A screen is located at the bottom of the reaction zone, and a carbon dioxide inlet and a solvent inlet are located above the screen at the bottom of the reaction zone. The outlet of the air intake system and the solvent outlet of the solvent supply system are connected to the carbon dioxide inlet and the solvent inlet, respectively. The precipitation separation zone has a reactor outlet, which is connected to the centrifuge inlet.

[0009] Preferably, the feeding system includes a sealed conveyor belt and a feed displacement chamber connected to the sealed conveyor belt, the bottom of which is connected to the reactor inlet of the reactor.

[0010] Preferably, the air intake system includes a carbon dioxide cylinder, a cryogenic circulator, and a carbon dioxide booster pump connected in sequence, with the carbon dioxide booster pump connected to the carbon dioxide inlet.

[0011] Preferably, the heating device is an electric heating jacket, which covers the outer wall of the reaction zone.

[0012] Preferably, the screen is an electric screen.

[0013] Preferably, the carbon dioxide inlet and the solvent inlet are positioned opposite each other, and the carbon dioxide outlet is connected to the separation vessel.

[0014] Preferably, the centrifuge is a vertical centrifuge, with the centrifuge inlet located at the top and the liquid phase outlet and residue bin located at the bottom.

[0015] Preferably, the liquid phase outlet is connected to the solvent supply system.

[0016] The present invention also provides a lithium battery pretreatment method under a supercritical carbon dioxide system. This method uses the lithium battery pretreatment apparatus under a supercritical carbon dioxide system described above, and includes the following steps:

[0017] 1) Close the screen and the discharge port of the reactor, and open the feed port of the reactor. The lithium-ion batteries with the plastic shell removed are sealed and transported into the crushing zone of the reactor through the feed system from the feed port of the reactor. After the lithium-ion batteries in the crushing zone reach the preset amount, close the feed port of the reactor.

[0018] 2) The intake system introduces inert carbon dioxide gas through the carbon dioxide inlet, while the lithium-ion battery with its plastic casing removed is crushed by the crushing device.

[0019] 3) Carbon dioxide gas and solvent are injected into the reaction zone of the reactor through the carbon dioxide inlet and solvent inlet, respectively, using the gas intake system and solvent supply system. The pressure is continuously increased and the carbon dioxide pressure in the reactor is kept above the supercritical carbon dioxide pressure and kept stable. The heating device is turned on to keep the temperature in the reactor above the supercritical temperature and kept stable. As the pulverized lithium battery decreases in the reaction zone, the supercritical carbon dioxide extracts the electrolyte in the lithium battery and the solvent dissolves the binder in the lithium battery.

[0020] 4) After the extraction reaction has been carried out for a preset time, the sieve is opened and the solvent is forced through the sieve into the precipitation separation zone by carbon dioxide above the sieve. The filtered lithium battery positive and negative electrode powder is collected in the precipitation separation zone.

[0021] 5) Open the carbon dioxide outlet to extract the carbon dioxide containing the electrolyte and leave the reactor. Then separate the carbon dioxide and electrolyte. Turn off the heating device and cool the solvent to room temperature and pressure to allow the binder dissolved in the solvent to complete the precipitation reaction.

[0022] 6) Open the discharge port of the reactor. The solid binder and liquid solvent in the sedimentation separation zone enter the centrifuge through the centrifuge inlet for centrifugal separation. The separated solid binder enters the residue bin for collection.

[0023] Preferably, the solvent is dimethyl sulfoxide (DMSO), the reaction temperature in the reaction zone is 60-90℃, the pressure is 75-180 bar, the reaction duration is 10-30 min, and the solid-liquid ratio of DMSO to the lithium battery is 20-100 ml / g.

[0024] The present invention has the following beneficial effects:

[0025] In this invention, a lithium battery pretreatment device using a supercritical carbon dioxide system incorporates a sealed feeding system. This prevents the lithium-ion batteries, after their plastic casings have been removed, from contacting air during transport, thus preventing potential combustion or explosion. The air intake system supplies inert carbon dioxide to the entire device, ensuring the pretreatment of lithium-sulfur batteries takes place in a carbon dioxide atmosphere, preventing oxidation, combustion, and other unsafe phenomena. The reactor comprises a crushing zone, a reaction zone, and a precipitation separation zone, connected sequentially from top to bottom. The crushing zone pulverizes the lithium-ion batteries after their plastic casings have been removed. In the reaction zone, supercritical carbon dioxide, combined with a solvent, simultaneously extracts the electrolyte and dissolves the binder. High-purity, high-value electrolytes, binders, and positive and negative electrode powders can then be separated and recovered. The recovered dimethyl sulfoxide and carbon dioxide can be recycled. This invention achieves safe, pollution-free, simple, efficient, low-energy-consumption, low-cost, and large-scale mechanized pretreatment of lithium-ion batteries. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the lithium battery pretreatment device under the supercritical carbon dioxide system of the present invention.

[0027] In the diagram, 1-feeding system; 11-sealed conveyor belt; 12-feeding replacement chamber; 2-reactor; 3-vertical centrifuge; 31-centrifuge inlet; 32-liquid phase outlet; 33-residue bin; 4-crushing zone; 41-crushing device; 42-carbon dioxide outlet; 43-reactor inlet; 5-reaction zone; 51-electric heating jacket; 52-carbon dioxide inlet; 53-electric screen; 54-stirring device; 55-dimethyl sulfoxide solvent inlet; 6-precipitation separation zone; 61-reactor outlet; 7-gas inlet system; 71-carbon dioxide cylinder; 72-low temperature circulator; 73-carbon dioxide booster pump. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. These descriptions are intended to explain the invention and not to limit it.

[0029] Reference Figure 1This invention provides a lithium battery pretreatment device under a supercritical carbon dioxide system, comprising a feeding system 1, an air intake system 7, a solvent supply system, a reactor 2, and a vertical centrifuge 3. The feeding system 1 includes a sealed conveyor belt 11 and a feeding displacement chamber 12 connected to the sealed conveyor belt 11. The bottom of the feeding displacement chamber 12 is connected to the reactor inlet 43 at the top of the reactor 2. The air intake system 7 includes a carbon dioxide cylinder 71, a cryogenic circulator 72, and a carbon dioxide booster pump 73 connected in sequence. The carbon dioxide booster pump 73 is connected to the carbon dioxide inlet 52 of the reactor. The reactor 2 includes a crushing zone 4, a reaction zone 5, and a precipitation separation zone connected vertically from top to bottom. Zone 6; The upper part of the side wall of the crushing zone 4 has a carbon dioxide outlet 42. The crushing zone 4 is equipped with a pulverizing device 43, which is located below the carbon dioxide outlet 42. The carbon dioxide outlet 42 is connected to the separation vessel. The outer wall of the reaction zone 5 is covered with an electric heating jacket 51. The reaction zone 5 is equipped with a stirring device 54. The lower side of the reaction zone 5 has a carbon dioxide inlet 52. The dimethyl sulfoxide solvent inlet 55 is symmetrically located to the carbon dioxide inlet 52. An electric screen 53 is installed at the bottom of the reaction zone 5. The outlet of the carbon dioxide booster pump 73 is connected to the carbon dioxide inlet 52. The solvent outlet of the solvent supply system is connected to the inlet of the dimethyl sulfoxide solvent inlet 55. The discharge port 61 of the reaction vessel at the bottom of the precipitation separation zone 6 is connected to the centrifuge inlet 31 at the top of the vertical centrifuge 3. The vertical centrifuge 3 has a centrifuge inlet 31 at the top, a liquid phase outlet 32 ​​at the lower side, and a residue bin 33 at the bottom.

[0030] The working process of the lithium battery pretreatment device under the supercritical carbon dioxide system of the present invention includes the following steps:

[0031] 1) Close the electric screen 53 at the bottom of the reaction zone 5 and the discharge port 61 of the reactor, and open the feed port 43 of the reactor. The lithium-ion batteries with the plastic shell removed are sequentially transported into the crushing zone 4 of the reactor 2 through the sealed conveyor belt 11, the feed replacement chamber 12 and the feed port 43 of the feed system 1. After the feeding is completed, close the feed port 43 of the reactor.

[0032] 2) Inert carbon dioxide gas is introduced into the carbon dioxide inlet 52 of the reactor 2, while the lithium battery is crushed by the crushing device 41 in the crushing zone 4.

[0033] 3) Carbon dioxide gas and dimethyl sulfoxide solvent are injected into the reactor 2 through carbon dioxide inlet 52 and dimethyl sulfoxide solvent inlet 55, respectively. The pressure is continuously increased and the carbon dioxide pressure in the reactor 2 is maintained above the supercritical pressure (75-180 bar) and kept stable. The electric heating jacket 51 is turned on to maintain the temperature in the reactor above the supercritical temperature (60-90℃) and kept stable. The pulverized lithium battery completes supercritical carbon dioxide extraction of electrolyte and dimethyl sulfoxide solvent dissolution of binder in the reaction zone 5. Dimethyl sulfoxide solvent is added to the lithium battery at a solid-liquid ratio of 20-100 ml / g.

[0034] 4) After the extraction reaction has been going on for 10-30 minutes, open the electric screen 53 at the bottom of the reaction zone 5. The dimethyl sulfoxide solvent in the reaction zone 5 is filtered through the electric screen 53 by the high pressure carbon dioxide in the reaction zone 5 and then filtered into the precipitation separation zone 6 to obtain the positive and negative electrode powders.

[0035] 5) Then open the carbon dioxide outlet 42 at the top of the reactor 2, and the carbon dioxide containing the electrolyte leaves the reactor 2 and enters the separation vessel to complete the separation process of carbon dioxide and electrolyte; close the electric heating jacket, and cool the dimethyl sulfoxide solvent to room temperature and pressure, so that the binder dissolved in the dimethyl sulfoxide solvent can complete the precipitation reaction.

[0036] 6) Open the bottom outlet 61 of the reactor 2. The solid binder and liquid dimethyl sulfoxide in the sedimentation separation zone 6 enter the vertical centrifuge 3 through the feed inlet 31 of the vertical centrifuge for centrifugal separation. The liquid dimethyl sulfoxide solvent enters the liquid outlet 32 ​​for recovery and can be re-entered into the dimethyl sulfoxide solvent inlet 55 of the reactor for reuse. The solid binder enters the residue bin 33 for collection.

[0037] As can be seen, the lithium battery pretreatment device under the supercritical carbon dioxide system of the present invention can simultaneously crush the battery and separate and recover high-purity electrolyte, binder and positive and negative electrode powders, and can recycle the recovered dimethyl sulfoxide and carbon dioxide, thus achieving safe, pollution-free, simple, efficient, low-energy consumption, low-cost, and large-scale mechanized pretreatment of lithium-ion batteries.

[0038] The following embodiments of the present invention all employ the lithium battery pretreatment device under the supercritical carbon dioxide system described above.

[0039] Example 1:

[0040] 1)Reference Figure 1Close the electric screen 53 at the bottom of the reaction zone 5 and the discharge port 61 of the reactor, and open the feed port 43 of the reactor. The lithium-ion batteries with the plastic shell removed are conveyed into the crushing zone 4 of the reactor 2 through the sealed conveyor belt 11, the feed replacement chamber 12 and the feed port 43 of the feed system 1. After the feeding is completed, close the feed port 43 of the reactor to keep the entire reactor in a sealed state.

[0041] 2) Inert carbon dioxide gas is introduced into the carbon dioxide inlet 52 of the reactor 2 to fill the entire reactor 2 with inert carbon dioxide gas. At the same time, the lithium battery is crushed by the crushing device 41 in the crushing zone 4 of the reactor 2.

[0042] 3) Carbon dioxide gas and dimethyl sulfoxide solvent are pressurized into reactor 2 through carbon dioxide inlet 52 and dimethyl sulfoxide solvent inlet 55, respectively. The added dimethyl sulfoxide content and the liquid-solid ratio of the lithium battery powder are maintained at 20 ml / g. The pressure is continuously increased and the carbon dioxide pressure in reactor 2 is maintained at 75 bar and kept stable. The electric heating jacket 51 is turned on to maintain the temperature in the reactor at 60°C and keep it stable. The pulverized lithium battery reacts in reaction zone 5 for 10 minutes, simultaneously completing the supercritical carbon dioxide extraction of the electrolyte and the dimethyl sulfoxide dissolution of the binder.

[0043] 4) After the extraction reaction for 10 minutes, the electric screen 53 at the bottom of the reaction zone 5 is opened. The dimethyl sulfoxide solvent in the reaction zone 5 is filtered through the electric screen into the precipitation separation zone 6 by the high pressure carbon dioxide in the reaction zone 5. The positive and negative electrode solid materials are recovered by the electric screen 53.

[0044] 5) Then open the carbon dioxide outlet 42 at the top of the reactor 2, and the carbon dioxide containing the electrolyte leaves the reactor 2 and enters the subsequent separation vessel to complete the separation process of electrolyte and carbon dioxide; at the same time, close the electric heating jacket and cool the dimethyl sulfoxide solvent to room temperature and pressure, so that the binder dissolved in the dimethyl sulfoxide solvent can complete the precipitation reaction.

[0045] 6) Open the bottom outlet 61 of the reactor 2. The solid-liquid mixture in the sedimentation separation zone 6 is a mixture of liquid dimethyl sulfoxide and solid binder. The solid-liquid mixture enters the vertical centrifuge 3 through the feed inlet 31 of the vertical centrifuge for centrifugal separation. The liquid dimethyl sulfoxide solvent enters the liquid outlet 32 ​​for recovery and can be reintroduced into the dimethyl sulfoxide solvent inlet 55 for reuse. The solid binder enters the residue bin 33 for recovery.

[0046] Example 2:

[0047] 1)Reference Figure 1Close the electric screen 53 at the bottom of the reaction zone 5 and the discharge port 61 of the reactor, and open the feed port 43 of the reactor. The lithium-ion batteries with the plastic shell removed are conveyed into the crushing zone 4 of the reactor 2 through the sealed conveyor belt 11, the feed replacement chamber 12 and the feed port 43 of the feed system 1. After the feeding is completed, close the feed port 43 of the reactor to keep the entire reactor in a sealed state.

[0048] 2) Inert carbon dioxide gas is introduced into the carbon dioxide inlet 52 of the reactor 2 to fill the entire reactor 2 with inert carbon dioxide gas. At the same time, the lithium battery is crushed by the crushing device 41 in the crushing zone 4 of the reactor 2.

[0049] 3) Carbon dioxide gas and dimethyl sulfoxide solvent are pressurized into reactor 2 through carbon dioxide inlet 52 and dimethyl sulfoxide solvent inlet 55, respectively. The added dimethyl sulfoxide content and the liquid-solid ratio of the lithium battery powder are maintained at 60 ml / g. The pressure is continuously increased and the carbon dioxide pressure in reactor 2 is maintained at 120 bar and kept stable. The electric heating jacket 51 is turned on to maintain the temperature in the reactor at 75°C and keep it stable. The pulverized lithium battery reacts in reaction zone 5 for 20 minutes, simultaneously completing the supercritical carbon dioxide extraction of the electrolyte and the dimethyl sulfoxide dissolution of the binder.

[0050] 4) After the extraction reaction for 20 minutes, the electric screen 53 at the bottom of the reaction zone 5 is opened. The solvent dimethyl sulfoxide in the reaction zone 5 is filtered through the electric screen into the precipitation separation zone 6 by the high pressure carbon dioxide in the reaction zone 5. The positive and negative electrode solid materials are recovered by the electric screen 53.

[0051] 5) Then open the carbon dioxide outlet 42 at the top of the reactor 2, and the carbon dioxide containing the electrolyte leaves the reactor 2 and enters the subsequent separation vessel to complete the separation process of electrolyte and carbon dioxide; at the same time, close the electric heating jacket and cool the dimethyl sulfoxide solvent to room temperature and pressure, so that the binder dissolved in the dimethyl sulfoxide solvent can complete the precipitation reaction.

[0052] 6) Open the bottom outlet 61 of the reactor 2. The solid-liquid mixture in the sedimentation separation zone 6 is a mixture of liquid dimethyl sulfoxide and solid binder. The solid-liquid mixture enters the vertical centrifuge 3 through the feed inlet 31 of the vertical centrifuge for centrifugal separation. The liquid dimethyl sulfoxide solvent enters the liquid outlet 32 ​​for recovery and can be reintroduced into the dimethyl sulfoxide solvent inlet 55 for reuse. The solid binder enters the residue bin 33 for recovery.

[0053] Example 3:

[0054] 1)Reference Figure 1Close the electric screen 53 at the bottom of the reaction zone 5 and the discharge port 61 of the reactor, and open the feed port 43 of the reactor. The lithium-ion batteries with the plastic shell removed are conveyed into the crushing zone 4 of the reactor 2 through the sealed conveyor belt 11, the feed replacement chamber 12 and the feed port 43 of the feed system 1. After the feeding is completed, close the feed port 43 of the reactor to keep the entire reactor in a sealed state.

[0055] 2) Inert carbon dioxide gas is introduced into the carbon dioxide inlet 52 of the reactor 2 to fill the entire reactor 2 with inert carbon dioxide gas. At the same time, the lithium battery is crushed by the crushing device 41 in the crushing zone 4 of the reactor 2.

[0056] 3) Carbon dioxide gas and dimethyl sulfoxide solvent are pressurized into reactor 2 through carbon dioxide inlet 52 and dimethyl sulfoxide solvent inlet 55, respectively. The added dimethyl sulfoxide content and the liquid-solid ratio of the lithium battery powder are maintained at 100 ml / g. The pressure is continuously increased and the carbon dioxide pressure in reactor 2 is maintained at 180 bar and kept stable. The electric heating jacket 51 is turned on to maintain the temperature in the reactor at 90°C and keep it stable. The pulverized lithium battery reacts in reaction zone 5 for 30 minutes, simultaneously completing the supercritical carbon dioxide extraction of the electrolyte and the dimethyl sulfoxide dissolution of the binder.

[0057] 4) After the extraction reaction for 30 minutes, the electric screen 53 at the bottom of the reaction zone 5 is opened. The dimethyl sulfoxide solvent in the reaction zone 5 is filtered through the electric screen into the precipitation separation zone 6 by the high pressure carbon dioxide in the reaction zone 5. The positive and negative electrode solid materials are recovered by the electric screen 53.

[0058] 5) Then open the carbon dioxide outlet 42 at the top of the reactor 2, and the carbon dioxide containing the electrolyte leaves the reactor 2 and enters the subsequent separation vessel to complete the separation process of electrolyte and carbon dioxide; at the same time, close the electric heating jacket and cool the dimethyl sulfoxide solvent to room temperature and pressure, so that the binder dissolved in the dimethyl sulfoxide solvent can complete the precipitation reaction.

[0059] 6) Open the bottom outlet 61 of the reactor 2. The solid-liquid mixture in the sedimentation separation zone 6 is a mixture of liquid dimethyl sulfoxide and solid binder. The solid-liquid mixture enters the vertical centrifuge 3 through the feed inlet 31 of the vertical centrifuge for centrifugal separation. The liquid dimethyl sulfoxide solvent enters the liquid outlet 32 ​​for recovery and can be reintroduced into the dimethyl sulfoxide solvent inlet 55 for reuse. The solid binder enters the residue bin 33 for recovery.

[0060] As can be seen from the above solution, the present invention has at least the following advantages:

[0061] 1. This device can mechanically break lithium batteries under an inert gas atmosphere, avoiding the safety hazards of prolonged high-pollution discharge and manual disassembly. It is simple to operate and has the potential for large-scale industrial applications.

[0062] 2. The entire recycling process is non-toxic and pollution-free, with high environmental benefits: The device uses supercritical carbon dioxide to efficiently and cleanly separate and extract the electrolyte, avoiding environmental pollution and human toxicity caused by solvent extraction of electrolytes; The device uses a dimethyl sulfoxide system to recover and regenerate the binder PVDF, avoiding the use of highly polluting NMP and acetone to dissolve the binder or the generation of highly polluting gases from pyrolysis of PVDF.

[0063] 3. The device is simple and efficient to operate and is expected to be applied on a large scale: the operating temperature and pressure conditions are mild and easy to control; the device can realize the crushing of lithium batteries, dissolution of binders, extraction of electrolytes and subsequent separation and recycling in one integrated process, without complicated post-processing, and with higher resource utilization.

[0064] 4. The device has significant economic benefits: it uses inexpensive and recyclable carbon dioxide and dimethyl sulfoxide as extraction fluids, reducing operating costs; it can separate and recover high-purity, high-value electrolytes, binders, and positive and negative electrode powders, and the recovered dimethyl sulfoxide and carbon dioxide can be recycled.

Claims

1. A pretreatment method for lithium batteries in a supercritical carbon dioxide system, characterized in that, The treatment method uses a lithium battery pretreatment device under a supercritical carbon dioxide system. The lithium battery pretreatment device under a supercritical carbon dioxide system includes a feeding system (1), an air intake system (7), a solvent supply system, a reactor (2), and a centrifuge. The feeding system (1) is a sealed system, and the outlet of the feeding system (1) is connected to the reactor inlet (43) of the reactor (2). The reactor (2) includes a crushing zone (4), a reaction zone (5), and a precipitation separation zone (6) connected from top to bottom. The reactor inlet (43) is set at the upper end of the crushing zone (4), and a carbon dioxide outlet is opened on the side wall of the crushing zone (4). (42) The crushing zone (4) is equipped with a crushing device (41) located below the carbon dioxide outlet (42); the reaction zone (5) is equipped with a heating device and a stirring device (54), the bottom of the reaction zone (5) is equipped with a screen, and the bottom of the reaction zone (5) is equipped with a carbon dioxide inlet (52) and a solvent inlet above the screen. The outlet of the gas inlet system (7) and the solvent outlet of the solvent supply system are respectively connected to the carbon dioxide inlet (52) and the solvent inlet; the precipitation separation zone (6) is equipped with a reactor outlet (61), and the reactor outlet (61) is connected to the centrifuge inlet (31) of the centrifuge; The method includes the following steps: 1) Close the screen and the reactor outlet (61), and open the reactor inlet (43). The lithium-ion batteries with the plastic shell removed are sealed and transported from the reactor inlet (43) into the crushing zone (4) of the reactor (2) through the feeding system (1). After the lithium-ion batteries in the crushing zone (4) reach the preset amount, close the reactor inlet (43). 2) The intake system (7) introduces inert carbon dioxide gas through the carbon dioxide inlet (52), while the lithium-ion battery with the plastic casing removed passes through the crushing device (41) for crushing. 3) The gas inlet system (7) and the solvent supply system respectively pressurize carbon dioxide gas and solvent into the reaction zone (5) of the reactor (2) through the carbon dioxide inlet (52) and the solvent inlet, respectively, continuously increasing the pressure and keeping the carbon dioxide pressure in the reactor (2) above the supercritical carbon dioxide pressure and maintaining stability; turn on the heating device to keep the temperature in the reactor above the supercritical temperature and maintain stability, and while the pulverized lithium battery decreases in the reaction zone (5), the supercritical carbon dioxide extracts the electrolyte in the lithium battery and the solvent dissolves the binder in the lithium battery; 4) After the extraction reaction has been carried out for a preset time, the sieve is opened and the solvent is filtered through the sieve (53) into the precipitation separation zone (6) by the carbon dioxide above the sieve. The filtered lithium battery positive and negative electrode powder is collected in the precipitation separation zone (6). 5) Open the carbon dioxide outlet (42) to extract the carbon dioxide containing the electrolyte and leave the reactor (2). Then separate the carbon dioxide and electrolyte. Turn off the heating device and cool the solvent to room temperature and pressure so that the binder dissolved in the solvent can complete the precipitation reaction. 6) Open the discharge port (61) of the reactor. The solid binder and liquid solvent in the sedimentation separation zone (6) enter the centrifuge through the centrifuge inlet (31) for centrifugal separation. The separated solid binder enters the residue bin (33) for collection.

2. The lithium battery pretreatment method under a supercritical carbon dioxide system according to claim 1, characterized in that, The solvent used is dimethyl sulfoxide (DMSO). The reaction temperature in the reaction zone (5) is 60-90℃, the pressure is 75-180 bar, the reaction duration is 10-30 min, and the solid-liquid ratio of the DMSO solvent to the lithium battery is 20-100 ml / g.

3. The lithium battery pretreatment method under a supercritical carbon dioxide system according to claim 1, characterized in that, The feeding system (1) includes a sealed conveyor belt (11) and a feed replacement chamber (12) connected to the sealed conveyor belt (11). The bottom of the feed replacement chamber (12) is connected to the reactor inlet (43) of the reactor (2).

4. The lithium battery pretreatment method under a supercritical carbon dioxide system according to claim 1, characterized in that, The air intake system (7) includes a carbon dioxide cylinder (71), a cryogenic circulator (72) and a carbon dioxide booster pump (73) connected in sequence, with the carbon dioxide booster pump (73) connected to the carbon dioxide inlet (52).

5. The lithium battery pretreatment method under a supercritical carbon dioxide system according to claim 1, characterized in that, The heating device uses an electric heating sleeve (51), which covers the outer wall of the reaction zone (5).

6. The lithium battery pretreatment method under a supercritical carbon dioxide system according to claim 1, characterized in that, The screen is an electric screen (53).

7. The lithium battery pretreatment method under a supercritical carbon dioxide system according to claim 1, characterized in that, The carbon dioxide inlet (52) and the solvent inlet are positioned opposite each other, and the carbon dioxide outlet (42) is connected to the separation vessel.

8. The lithium battery pretreatment method under a supercritical carbon dioxide system according to claim 1, characterized in that, The centrifuge is a vertical centrifuge (3). The top of the vertical centrifuge (3) is provided with the centrifuge inlet (31), and the bottom of the vertical centrifuge (3) is provided with the liquid phase outlet (32) and the residue bin (33).

9. A lithium battery pretreatment method under a supercritical carbon dioxide system according to claim 8, characterized in that, The liquid phase outlet (32) is connected to the solvent supply system.

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