CN109888370B

CN109888370B - Pyrolysis method and system for waste lithium ion batteries

Info

Publication number: CN109888370B
Application number: CN201910291009.5A
Authority: CN
Inventors: 刘诚; 苟海鹏; 余跃; 陈学刚; 裴忠冶; 杜士帽
Original assignee: China ENFI Engineering Corp
Current assignee: China ENFI Engineering Corp
Priority date: 2019-04-11
Filing date: 2019-04-11
Publication date: 2024-08-09
Anticipated expiration: 2039-04-11
Also published as: CN109888370A

Abstract

The invention provides a pyrolysis method and a pyrolysis system for waste lithium ion batteries. The method comprises the following steps: step S1, cooling the waste lithium ion batteries; step S2, removing the outer packaging shell of the cooled waste lithium ion battery under the protection of nitrogen or inert gas to obtain a battery cell; step S3, under the protection of nitrogen or inert gas, carrying out pyrolysis reaction on the battery cell to obtain solid residues and pyrolysis gas; and S4, sequentially carrying out physical adsorption and alkali absorption on the pyrolysis gas. By the method provided by the invention, the electrolyte in the waste lithium ion battery can be subjected to harmless treatment more effectively.

Description

Pyrolysis method and system for waste lithium ion batteries

Technical Field

The invention relates to the technical field of waste lithium ion battery treatment, in particular to a waste lithium ion battery pyrolysis method and system.

Background

The lithium ion battery has the advantages of high voltage, small volume, high specific energy, small self-discharge, high safety and the like, and is widely applied to the fields of consumer electronic products, electric vehicles, industrial energy storage and the like. Researches show that the charging cycle period of the lithium ion battery is about 500 times, the service life is generally 3-5 years, and along with the rapid increase of the production quantity and the use quantity of the lithium ion batteries, the quantity of the waste lithium ion batteries is also increased.

The lithium ion battery mainly comprises a positive electrode, a negative electrode, a diaphragm, electrolyte and an outer package, and the technology for recovering the waste lithium ion battery at home and abroad can be divided into a physical separation method, a pyrometallurgy method and a hydrometallurgy method, and the research is mainly focused on discharge treatment, disassembly and comprehensive recovery of positive and negative electrode materials. At present, the treatment and recovery process of the anode and cathode materials of the waste lithium ion battery is perfect, but the treatment and recovery of electrolyte in the battery are also very problematic.

The electrolyte of the waste lithium ion battery mainly comprises an organic solvent and an electrolyte LiPF ₆, is easy to volatilize in the recovery treatment process, and can generate toxic VOCs gas and HF gas after being contacted with air or baked. Patent CN104282962a and patent CN104009269a respectively disclose a method for recovering electrolyte of waste lithium ion battery, and the electrolyte is separated from the battery and recovered by high-speed centrifugation under the protection of inert gas. Patent CN104600392a discloses a method for recovering waste lithium ion battery electrolyte, which comprises the steps of putting battery cells into a centrifuge for separation to obtain waste electrolyte, filtering, decolorizing and dehydrating the waste electrolyte, and supplementing electrolyte and organic solvent to prepare electrolyte products. All three patents adopt a high-speed centrifugation method to treat electrolyte in waste batteries, the electrolyte in the waste batteries is required not to be subjected to quality change, and if organic solvent or electrolyte in the electrolyte is degraded, the process flow cannot reform the waste electrolyte into a new electrolyte product. Patent CN103943911A discloses a comprehensive recycling method of waste lithium ion batteries, wherein the waste lithium ion batteries are crushed into pieces with the diameter of 10-20 mm in a closed shearing crusher, spraying is carried out during crushing, and LiPF ₆ in the waste batteries is dissolved in spraying liquid. Although the spraying can effectively adsorb LiPF ₆ in the electrolyte, the organic solvent in the electrolyte cannot be degraded or adsorbed by the spraying.

In order to reduce the environmental pollution caused by the electrolyte in the recovery treatment process of the waste lithium ion batteries, it is necessary to provide a harmless treatment process for the electrolyte of the waste lithium ion batteries more effectively.

Disclosure of Invention

The invention mainly aims to provide a pyrolysis method and a pyrolysis system for waste lithium ion batteries, so as to provide a harmless treatment process for waste lithium ion battery electrolyte more effectively.

In order to achieve the above object, according to one aspect of the present invention, there is provided a pyrolysis method of a waste lithium ion battery, comprising the steps of: step S1, cooling the waste lithium ion batteries; step S2, removing the outer packaging shell of the cooled waste lithium ion battery under the protection of nitrogen or inert gas to obtain a battery cell; step S3, under the protection of nitrogen or inert gas, carrying out pyrolysis reaction on the battery cell to obtain solid residues and pyrolysis gas; and S4, sequentially carrying out physical adsorption and alkali absorption on the pyrolysis gas.

Further, in the step S1, the temperature is reduced to-80 to-20 ℃ in the process of temperature reduction treatment, and the temperature reduction time is longer than 3 hours.

Further, in step S3, the conditions of the pyrolysis reaction are as follows: heating the battery cell to 500-650 ℃ at a heating rate of 5-20 ℃/min, and preserving heat for 1-6 hours.

Further, in step S3, the pyrolysis reaction is performed in a tube furnace, and the flow rate of nitrogen or inert gas in the tube furnace is 0.2-2L/min.

Further, in step S4, activated carbon is used as an adsorbent in the physical adsorption process, and the weight ratio of the battery cell to the activated carbon is 1:0.2-2.

Further, in the step S4, the alkali solution adopted in the alkali absorption process is one or more aqueous solutions of Ca (OH) ₂、NaOH、KOH、NaHCO₃ and KHCO ₃, and the concentration of the alkali solution is preferably 1-5 mol/L.

Further, in the alkali absorption process, the pyrolysis gas after physical absorption is introduced into alkali liquor, or the alkali liquor is contacted with the pyrolysis gas after physical absorption in a spraying mode.

Further, before the cooling treatment process of the waste lithium ion battery, the step S1 further includes a process of discharging the waste lithium ion battery.

Further, the discharging treatment step includes: placing the waste lithium ion battery into neutral or alkaline conductive salt solution to be soaked for 12-24 hours; preferably, the conductive salt solution is NaCl aqueous solution or NaHCO ₃ aqueous solution, and more preferably the concentration of the conductive salt solution is 1-5 mol/L.

Further, after obtaining the solid residue, the method further comprises: s5, crushing the solid residues; and S6, carrying out reselection or floatation on the crushed solid residues to obtain metal copper, metal aluminum and anode and cathode powder.

According to another aspect of the present invention, there is also provided a pyrolysis system for waste lithium ion batteries, comprising: the cooling device is used for cooling the waste lithium ion batteries so as to reduce volatilization of the electrolyte in the subsequent process; the cutting device is connected with the cooling device and is used for cutting the cooled waste lithium ion batteries to separate battery cells; the pyrolysis device is connected with the cutting device and is used for carrying out pyrolysis reaction on the battery cells and is provided with a solid residue discharge port and a pyrolysis gas discharge port; the gas supply device is respectively connected with the cutting device and the pyrolysis device and is used for supplying nitrogen or inert gas to the inside of the cutting device and the pyrolysis device; the physical adsorption device is connected with the pyrolysis gas exhaust port and is used for carrying out physical adsorption on the pyrolysis gas exhausted from the pyrolysis gas exhaust port, and the physical adsorption device is also provided with a secondary exhaust port; and the alkali absorption device is connected with the secondary exhaust port and is used for absorbing alkali in the gas exhausted from the secondary exhaust port.

Further, the cooling device is a cryogenic refrigerator.

Further, the pyrolysis device is a tubular pyrolysis furnace.

Further, the physical adsorption device is an activated carbon adsorption device.

Further, the alkali absorbing device is a static alkaline liquid absorbing device or a spraying alkaline liquid device.

Further, the device also comprises a discharging device which is connected with the cooling device and is used for discharging the waste lithium ion batteries before cooling treatment.

Further, the device also comprises a crushing device which is connected with the solid residue discharge outlet of the pyrolysis device and is used for crushing the solid residue discharged from the solid residue discharge outlet.

Further, the crushing device is a ball mill or a rod mill.

Further, the device also comprises a mineral separation device which is connected with the crushing device and is used for carrying out gravity separation or floatation on the crushed solid residues.

Further, the device also comprises an air extracting device which is connected with the alkali absorbing device and is used for carrying out vacuumizing treatment on the alkali absorbing device.

The pyrolysis method of the waste lithium ion battery provided by the invention comprises the following steps: step S1, cooling the waste lithium ion batteries; step S2, removing the outer packaging shell of the cooled waste lithium ion battery under the protection of nitrogen or inert gas to obtain a battery cell; step S3, under the protection of nitrogen or inert gas, carrying out pyrolysis reaction on the battery cell to obtain solid residues and pyrolysis gas; and S4, sequentially carrying out physical adsorption and alkali absorption on the pyrolysis gas. According to the invention, before the battery cells are split, the waste lithium ion batteries are subjected to cooling treatment, so that the activity of the electrolyte can be reduced, the volatilization of the electrolyte in the splitting process is reduced, and the atmospheric pollution caused by the volatilization in the splitting stage is avoided. When the battery cell is subjected to pyrolysis reaction under the protection of nitrogen or inert gas, the electrolyte can undergo degradation reaction to generate HF gas and VOCs gas, and the HF gas and the VOCs gas and the nitrogen or the inert gas form pyrolysis gas. After physical adsorption, VOCs gas in the pyrolysis gas is adsorbed and removed, and HF gas is absorbed and removed in the alkali absorption process. Therefore, by the method provided by the invention, the electrolyte in the waste lithium ion battery can be subjected to harmless treatment more effectively.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

fig. 1 shows a schematic flow chart of a pyrolysis method of a waste lithium ion battery according to an embodiment of the invention;

FIG. 2 shows a block diagram of a pyrolysis system for spent lithium-ion batteries according to one embodiment of the invention; and

Fig. 3 shows a scanning electron microscope photograph of positive and negative electrode powder obtained by treatment of the pyrolysis method of the waste lithium ion battery according to the invention.

Wherein the above figures include the following reference numerals:

10. a cooling device; 20. a cutting device; 30. a pyrolysis device; 40. a gas supply device; 50. a physical adsorption device; 60. an alkali absorption device; 70. a discharge device; 80. a crushing device; 90. mineral separation equipment; 100. and an air extracting device.

Detailed Description

It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.

In order to more effectively carry out innocent treatment on the electrolyte of the waste lithium ion battery, the invention provides a pyrolysis method of the waste lithium ion battery, which is shown in figure 1 and comprises the following steps: step S1, cooling the waste lithium ion batteries; step S2, removing the outer packaging shell of the cooled waste lithium ion battery under the protection of nitrogen or inert gas to obtain a battery cell; step S3, under the protection of nitrogen or inert gas, carrying out pyrolysis reaction on the battery cell to obtain solid residues and pyrolysis gas; and S4, sequentially carrying out physical adsorption and alkali absorption on the pyrolysis gas.

Before the battery cells are split, the waste lithium ion batteries are subjected to cooling treatment, so that the activity of the electrolyte can be reduced, volatilization of the electrolyte in the splitting process is reduced, and atmospheric pollution caused by volatilization in the splitting stage is avoided. When the battery cell is subjected to pyrolysis reaction under the protection of nitrogen or inert gas, the electrolyte can undergo degradation reaction to generate HF gas and VOCs gas, and the HF gas and the VOCs gas and the nitrogen or the inert gas form pyrolysis gas. After physical adsorption, VOCs gas in the pyrolysis gas is adsorbed and removed, and HF gas is absorbed and removed in the alkali absorption process. Therefore, by the method provided by the invention, the electrolyte in the waste lithium ion battery can be subjected to harmless treatment more effectively.

In order to achieve the purpose of better reducing the activity of the electrolyte and inhibiting the volatilization of the electrolyte in the splitting process, in a preferred embodiment, in the step S1, the temperature is reduced to-80 to-20 ℃ in the process of temperature reduction treatment, and the temperature reduction time is longer than 3 hours. By adopting the cooling process, on one hand, the electrolyte is lower in activity and not easy to volatilize, and on the other hand, the energy consumption at lower temperature is avoided.

In a preferred embodiment, in step S3, the conditions of the pyrolysis reaction are as follows: heating the battery cell to 500-650 ℃ at a heating rate of 5-20 ℃/min, and preserving heat for 1-6 hours. Under this condition, the electrolytic reaction of the electrolyte is more complete. The apparatus used for the above pyrolysis reaction may be a conventional pyrolysis apparatus, and in a preferred embodiment, the pyrolysis reaction is performed in a tube furnace in which a flow rate of nitrogen or inert gas is 0.2 to 2L/min in step S3. The flow rate of nitrogen or inert gas is controlled within the above range, which is favorable for providing inert atmosphere for pyrolysis reaction, and on the one hand, HF gas and VOCs gas generated by pyrolysis reaction can be more stably conveyed to the subsequent physical adsorption and alkali absorption stages under the condition that the nitrogen or inert gas is carried.

In a preferred embodiment, in step S4, activated carbon is used as an adsorbent in the physical adsorption process, and the weight ratio of the battery cell to the activated carbon is 1:0.2-2. This allows the VOCs in the pyrolysis gas to be more fully adsorbed.

In a preferred embodiment, in step S4, the alkali solution used in the alkali absorption process is an aqueous solution of one or more of Ca (OH) ₂、NaOH、KOH、NaHCO₃ and KHCO ₃, and preferably the concentration of the alkali solution is 1-5 mol/L. In a specific implementation process, the adsorbed pyrolysis gas can be directly introduced into alkali liquor to react with the alkali liquor, or can be contacted and reacted with the adsorbed pyrolysis gas in an alkali liquor spraying mode.

In order to improve the operation safety, in a preferred embodiment, before the cooling treatment process of the waste lithium ion battery, the step S1 further includes a process of discharging the waste lithium ion battery. The discharge treatment may be performed by a method commonly used in the art, and in a preferred embodiment, the discharge treatment step includes: and (3) placing the waste lithium ion battery in neutral or alkaline conductive salt solution for soaking for 12-24 hours. Thus, the discharge treatment is more sufficient. Preferably, the conductive salt solution is NaCl aqueous solution or NaHCO ₃ aqueous solution, and more preferably the concentration of the conductive salt solution is 1-5 mol/L.

After the battery cell undergoes pyrolysis reaction, besides the electrolyte is degraded, the anode and cathode materials also react, specifically as follows: the carbon of the cathode material in the battery cell can react with the LiNi _1-x-yCo_xMn_yO₂ of the anode material to generate anode and cathode pyrolyzate, and the main components of the pyrolyzate are C, coO, mnO, niO, li ₂CO₃ and Ni. Besides the anode and cathode powders, the solid residue after pyrolysis also contains Cu, al sheets and the like in the anode and cathode sheets. In a preferred embodiment, after obtaining the solid residue, the above method further comprises: s5, crushing the solid residues; and S6, carrying out reselection or floatation on the crushed solid residues to obtain metal copper, metal aluminum and anode and cathode powder (a scanning electron microscope photograph of the anode and cathode powder is shown in figure 3). During the crushing process, a ball mill or a rod mill can be adopted, and the rotating speed is preferably 100-300 r/min.

For the anode and cathode powder, the valuable metal elements such as Li, ni, co and Mn in the anode and cathode powder can be extracted by adopting a hydrometallurgy method commonly used in the art, and the specific methods are known to the skilled in the art and are not repeated here.

The waste lithium ion battery is preferably a waste ternary lithium ion battery.

According to another aspect of the present invention, there is also provided a pyrolysis system for waste lithium ion batteries, as shown in fig. 2, which includes a cooling device 10, a cutting device 20, a pyrolysis device 30, a gas supply device 40, a physical adsorption device 50, and an alkali absorption device 60; the cooling device 10 is used for cooling the waste lithium ion batteries to reduce volatilization of the electrolyte in the subsequent process; the cutting device 20 is connected with the cooling device 10 and is used for cutting the cooled waste lithium ion batteries to separate battery cells; the pyrolysis device 30 is connected with the cutting device 20 and is used for carrying out pyrolysis reaction on the battery cells, and the pyrolysis device 30 is provided with a solid residue discharge port and a pyrolysis gas discharge port; the gas supply device 40 is connected to the cutting device 20 and the pyrolysis device 30, respectively, for supplying nitrogen or inert gas to the insides thereof; the physical adsorption device 50 is connected with the pyrolysis gas exhaust port and is used for physically adsorbing the pyrolysis gas exhausted from the pyrolysis gas exhaust port, and the physical adsorption device 50 is also provided with a secondary exhaust port; the alkali absorbing device 60 is connected to the secondary exhaust port, and is used for absorbing alkali from the gas discharged from the secondary exhaust port.

According to the system provided by the invention, the waste lithium ion battery is subjected to cooling treatment by using the cooling device 10 before the battery cells are split, so that the activity of the electrolyte can be reduced, the volatilization of the electrolyte in the splitting process is reduced, and the atmospheric pollution caused by the volatilization of the splitting stage is avoided. When the battery cell is subjected to pyrolysis reaction in the pyrolysis device 30 under the protection of nitrogen or inert gas, the electrolyte can undergo degradation reaction to generate HF gas and VOCs gas, and the HF gas and the VOCs gas and the nitrogen or inert gas form pyrolysis gas. After physical adsorption in the physical adsorption device 50, VOCs gas in the pyrolysis gas is adsorbed and removed, and HF gas is adsorbed and removed by alkali absorption in the alkali absorption device 60. Therefore, by the system provided by the invention, the electrolyte in the waste lithium ion battery can be subjected to harmless treatment more effectively.

In a preferred embodiment, the cooling device 10 is a cryogenic refrigerator. The equipment used for the pyrolysis reaction described above may be conventional pyrolysis equipment, and in a preferred embodiment, pyrolysis unit 30 is a tubular pyrolysis furnace.

In a preferred embodiment, physical adsorption device 50 is an activated carbon adsorption device. The activated carbon is adopted as an adsorbent in the activated carbon adsorption device, so that the specific surface area is large, the adsorption performance is good, and VOCs gas in the pyrolysis gas can be adsorbed more fully.

The purpose of the alkali absorption device is to absorb the absorbed pyrolysis gas and alkali liquor so as to enable the HF gas in the pyrolysis gas to react with the alkali liquor. In a preferred embodiment, the alkaline absorbing device 60 is a static alkaline liquid absorbing device or a spray alkaline liquid device. In this way, in the specific execution process, the adsorbed pyrolysis gas can be directly introduced into alkali liquor to react with the alkali liquor, or can be contacted and reacted with the adsorbed pyrolysis gas in an alkali liquor spraying mode.

In practical operation, the physical adsorption device 50 and the alkali absorption device 60 should increase the contact area of the gas with the adsorbent and the alkali liquor as much as possible, which is beneficial to the adsorption treatment of the VOCs gas and the HF gas.

In order to improve the operation safety, in a preferred embodiment, the device further comprises a discharging device 70, wherein the discharging device 70 is connected with the cooling device 10 and is used for discharging the waste lithium ion batteries before the cooling treatment. The discharge treatment process may be performed by a device commonly used in the art.

After the battery cell undergoes pyrolysis reaction, besides the electrolyte is degraded, the anode and cathode materials also react, specifically as follows: the carbon of the cathode material in the battery cell can react with the LiNi _1-x-yCo_xMn_yO₂ of the anode material to generate anode and cathode pyrolyzate, and the main components of the pyrolyzate are C, coO, mnO, niO, li ₂CO₃ and Ni. Besides the anode and cathode powders, the solid residue after pyrolysis also contains Cu, al sheets and the like in the anode and cathode sheets. In a preferred embodiment, the apparatus further comprises a crushing device 80, and the crushing device 80 is connected to the solid residue discharge outlet of the pyrolysis device 30, for crushing the solid residue discharged from the solid residue discharge outlet. More preferably, the apparatus further comprises a beneficiation device 90, the beneficiation device 90 being connected to the crushing apparatus 80 for re-selecting or flotation of the crushed solid residues. The copper metal, aluminum metal and the anode and cathode powders in the solid residue can be separated by the beneficiation apparatus 90. Preferably, the device further comprises a hydrometallurgical device for extracting valuable metal elements such as Li, ni, co and Mn from the anode powder and the cathode powder.

In order to increase the crushing efficiency, in a preferred embodiment, the crushing device 80 includes, but is not limited to, a ball mill or a rod mill.

In a preferred embodiment, the apparatus further comprises an air extraction device 100, wherein the air extraction device 100 is connected to the alkali absorption device 60 for performing a vacuum treatment on the alkali absorption device 60. The air extractor can accelerate the flow velocity of the gas in the path, so that the treatment efficiency is improved, and the air extractor can be of a common type such as a vacuum pump.

The application is described in further detail below in connection with specific examples which are not to be construed as limiting the scope of the application as claimed.

Example 1

The waste ternary lithium ion battery is treated by adopting the process and the device in the figures 1 and 2:

And (3) putting the waste ternary lithium ion battery into a NaCl solution with the concentration of 2mol/L to discharge for 24 hours, and taking out the battery after discharging and airing. And (3) putting the dried battery into a cryogenic refrigerator at the temperature of minus 80 ℃ to freeze for 3 hours, and reducing the activity of electrolyte. Taking out the frozen battery, cutting the outer packaging shell of the battery under the protection of nitrogen gas, and taking out the battery cell. 300g of battery cell is placed into a tube furnace, heated to 650 ℃ at a heating rate of 10 ℃/min under the protection of nitrogen gas of 0.8L/min, and naturally cooled to room temperature after heat preservation for 3 hours. The air outlet of the tube furnace is connected with an activated carbon adsorption device and an alkali absorption device, the mass of the activated carbon is 100g, and 2L of sodium hydroxide solution with the concentration of 2mol/L is filled in the alkali absorption device. Table 1 shows the concentrations of VOCs and HF gases measured at the crusher discharge port, the tube furnace discharge port and in the alkali absorber during the reaction. Taking out the pyrolyzed battery, putting the battery into a ball mill, ball-milling for 1h at a rotating speed of 100r/min, and obtaining Cu powder, al powder and black powder by floatation of the ball-milled material. The black powder has C, coO, mnO, niO, li ₂CO₃ and Ni as main components, and can be further used for extracting metals Li, ni, co and Mn by means of metallurgy.

TABLE 1 detection results of tube furnace gas outlet and alkali absorber

Example 2

And (3) putting the waste ternary lithium ion battery into a 4mol/L NaCl solution to discharge for 24 hours, and taking out the battery after discharging and airing. And (5) putting the dried battery into a cryogenic refrigerator at the temperature of minus 60 ℃ to freeze for 8 hours, and reducing the activity of electrolyte. Taking out the frozen battery, cutting the outer packaging shell of the battery under the protection of nitrogen gas, and taking out the battery cell. 300g of battery cell is placed into a tube furnace, the temperature is raised to 600 ℃ at a heating rate of 5 ℃/min under the protection of 1L/min nitrogen, and the battery cell is naturally cooled to room temperature after heat preservation for 5 hours. The air outlet of the tube furnace is connected with an activated carbon adsorption device and an alkali absorption device, the mass of the activated carbon is 200g, and 2L of sodium hydroxide solution with the concentration of 4mol/L is filled in the alkali absorption device. Table 2 shows the measured VOCs and HF gas concentrations at the crusher discharge port, the tube furnace discharge port and the alkali absorber during the reaction. And taking out the pyrolyzed battery, putting the battery into a ball mill, ball-milling for 1h at a rotating speed of 200r/min, and carrying out flotation on the ball-milled material to obtain Cu powder, al powder and black powder. The black powder has C, coO, mnO, niO, li ₂CO₃ and Ni as main components, and can be further used for extracting metals Li, ni, co and Mn by means of metallurgy.

Table 2 detection results of tube furnace gas outlet and alkali absorber

Example 3

And (3) putting the waste ternary lithium ion battery into a NaCl solution with the concentration of 1mol/L to discharge for 24 hours, and taking out the battery after discharging and airing. And (5) putting the dried battery into a cryogenic refrigerator at the temperature of minus 20 ℃ to freeze for 8 hours, and reducing the activity of electrolyte. Taking out the frozen battery, cutting the outer packaging shell of the battery under the protection of nitrogen gas, and taking out the battery cell. 300g of battery cell is placed into a tube furnace, heated to 650 ℃ at a heating rate of 20 ℃/min under the protection of nitrogen gas of 0.2L/min, and naturally cooled to room temperature after heat preservation for 1h. The gas outlet of the tube furnace is connected with an activated carbon adsorption device and an alkali absorption device, the mass of the activated carbon is 600g, and 2L of NaHCO ₃ solution with the concentration of 5mol/L is filled in the alkali absorption device. Table 3 shows the concentrations of VOCs and HF gases measured at the crusher discharge port, the tube furnace discharge port, and in the alkali absorber during the reaction. And taking out the pyrolyzed battery, putting the battery into a ball mill, ball-milling for 1h at a rotating speed of 200r/min, and carrying out flotation on the ball-milled material to obtain Cu powder, al powder and black powder. The black powder has C, coO, mnO, niO, li ₂CO₃ and Ni as main components, and can be further used for extracting metals Li, ni, co and Mn by means of metallurgy.

TABLE 3 detection results of tube furnace gas outlet and alkali absorber

Example 4

And (3) putting the waste ternary lithium ion battery into 5mol/L NaCl solution to discharge for 12 hours, and taking out the battery after discharging and airing. And (5) putting the dried battery into a cryogenic refrigerator at the temperature of minus 60 ℃ to freeze for 5 hours, and reducing the activity of electrolyte. Taking out the frozen battery, cutting the outer packaging shell of the battery under the protection of nitrogen gas, and taking out the battery cell. 300g of battery cell is placed into a tube furnace, the temperature is raised to 500 ℃ at a heating rate of 5 ℃/min under the protection of 2L/min nitrogen, and the battery cell is naturally cooled to room temperature after heat preservation for 1 h. The air outlet of the tube furnace is connected with an activated carbon adsorption device and an alkali absorption device, the mass of the activated carbon is 60g, and 2L of Ca (OH) ₂ solution with the concentration of 1mol/L is filled in the alkali absorption device. Table 4 shows the measured VOCs and HF gas concentrations at the crusher discharge port, the tube furnace discharge port and the alkali absorber during the reaction. And taking out the pyrolyzed battery, putting the battery into a ball mill, ball-milling for 1h at a rotating speed of 200r/min, and carrying out flotation on the ball-milled material to obtain Cu powder, al powder and black powder. The black powder has C, coO, mnO, niO, li ₂CO₃ and Ni as main components, and can be further used for extracting metals Li, ni, co and Mn by means of metallurgy.

Table 4 results of tube furnace gas outlet and alkali absorber detection

Comparative example 1

And (3) putting the waste ternary lithium ion battery into a NaCl solution with the concentration of 0.8mol/L to discharge for 12 hours, and taking out the battery after discharging and airing. And cutting the outer packaging shell of the battery under the protection of nitrogen gas, and taking out the battery core. 300g of battery cell is placed into a tube furnace, heated to 480 ℃ at a heating rate of 5 ℃/min under the protection of 2L/min nitrogen, and naturally cooled to room temperature after heat preservation for 1h. The gas outlet of the tube furnace is connected with an activated carbon adsorption device and an alkali absorption device, the mass of the activated carbon is 50g, and 2L of Ca (OH) ₂ solution with the concentration of 1mol/L is filled in the alkali absorption device. Table 5 shows the measured VOCs and HF gas concentrations at the crusher discharge port, the tube furnace discharge port and the alkali absorber during the reaction. And taking out the pyrolyzed battery, putting the battery into a ball mill, ball-milling for 1h at a rotating speed of 200r/min, and carrying out flotation on the ball-milled material to obtain Cu powder, al powder and black powder. The black powder has C, coO, mnO, niO, li ₂CO₃ and Ni as main components, and can be further used for extracting metals Li, ni, co and Mn by means of metallurgy.

Table 5 tube furnace gas outlet and alkali absorber test results

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The pyrolysis method of the waste lithium ion battery is characterized by comprising the following steps of:

Step S1, adopting a cryogenic refrigerator to cool the waste lithium ion batteries; in the cooling treatment process, the cooling temperature is-80 to-20 ℃, and the cooling time is more than 3 hours;

step S2, removing the outer packaging shell of the cooled waste lithium ion battery under the protection of nitrogen or inert gas to obtain a battery cell;

Step S3, under the protection of nitrogen or inert gas, carrying out pyrolysis reaction on the battery cell to obtain solid residues and pyrolysis gas;

And S4, sequentially carrying out physical adsorption and alkali absorption on the pyrolysis gas.

2. The method for pyrolyzing a waste lithium ion battery according to claim 1, wherein in the step S3, the conditions of the pyrolysis reaction are as follows: and heating the battery cell to 500-650 ℃ at a heating rate of 5-20 ℃/min, and preserving heat for 1-6 hours.

3. The method for pyrolyzing waste lithium ion batteries according to claim 2, wherein in the step S3, the pyrolysis reaction is performed in a tube furnace, and the flow rate of nitrogen or inert gas in the tube furnace is 0.2-2L/min.

4. The method for pyrolyzing a waste lithium ion battery according to any one of claims 1 to 3, wherein in the step S4, activated carbon is used as an adsorbent in the physical adsorption process, and the weight ratio of the battery cell to the activated carbon is 1:0.2-2.

5. The method according to any one of claims 1 to 3, wherein in the step S4, the alkali solution used in the alkali absorption process is an aqueous solution of one or more of Ca (OH) ₂、NaOH、KOH、NaHCO₃ and KHCO ₃, and preferably the concentration of the alkali solution is 1-5 mol/L.

6. The method for pyrolyzing waste lithium ion batteries according to claim 5, wherein in the alkali absorption process, the pyrolysis gas after the physical absorption is introduced into the alkali liquor, or the alkali liquor is contacted with the pyrolysis gas after the physical absorption in a spraying manner.

7. The method according to any one of claims 1 to 3, wherein the step S1 further comprises a process of discharging the waste lithium ion battery before the cooling process of the waste lithium ion battery.

8. The method for pyrolyzing a waste lithium ion battery according to claim 7, wherein the discharging treatment step comprises: placing the waste lithium ion battery into neutral or alkaline conductive salt solution to be soaked for 12-24 hours; preferably, the conductive salt solution is NaCl aqueous solution or NaHCO ₃ aqueous solution, and more preferably the concentration of the conductive salt solution is 1-5 mol/L.

9. The method for pyrolysis of waste lithium ion batteries according to any one of claims 1 to 3, further comprising, after obtaining the solid residue:

s5, crushing the solid residues;

And S6, carrying out reselection or floatation on the crushed solid residues to obtain metal copper, metal aluminum and anode and cathode powder.

10. The utility model provides a old and useless lithium ion battery pyrolysis system which characterized in that includes:

the cooling device (10) is used for cooling the waste lithium ion batteries so as to reduce volatilization of the electrolyte in the subsequent process; the cooling device (10) is a cryogenic refrigerator, the cooling temperature is-80 to-20 ℃, the cooling time is longer than 3h, and the cutting device (20) is connected with the cooling device (10) and is used for cutting the cooled waste lithium ion batteries to separate battery cells;

The pyrolysis device (30) is connected with the cutting device (20) and is used for carrying out pyrolysis reaction on the battery cells, and the pyrolysis device (30) is provided with a solid residue discharge outlet and a pyrolysis gas discharge outlet;

A gas supply device (40) connected to the cutting device (20) and the pyrolysis device (30), respectively, for supplying nitrogen or inert gas to the inside of the two;

The physical adsorption device (50) is connected with the pyrolysis gas exhaust port and is used for carrying out physical adsorption on the pyrolysis gas exhausted from the pyrolysis gas exhaust port, and the physical adsorption device (50) is also provided with a secondary exhaust port; and

And the alkali absorption device (60) is connected with the secondary exhaust port and is used for absorbing alkali in the gas exhausted from the secondary exhaust port.

11. The waste lithium ion battery pyrolysis system according to claim 10, wherein the pyrolysis device (30) is a tubular pyrolysis furnace.

12. The waste lithium ion battery pyrolysis system according to claim 10, characterized in that the physical adsorption device (50) is an activated carbon adsorption device.

13. The waste lithium ion battery pyrolysis system according to claim 10, wherein the alkali absorbing device (60) is a static alkaline liquid absorbing device or a spray alkaline liquid device.

14. The waste lithium ion battery pyrolysis system of any one of claims 10 to 13, wherein the apparatus further comprises a discharge device (70), the discharge device (70) being connected to the cooling device (10) for discharging the waste lithium ion battery prior to the cooling treatment.

15. The waste lithium ion battery pyrolysis system of any one of claims 10 to 13, wherein the apparatus further comprises a crushing device (80), the crushing device (80) being connected to the solid remainder discharge outlet of the pyrolysis device (30) for crushing the solid remainder discharged from the solid remainder discharge outlet.

16. The waste lithium ion battery pyrolysis system according to claim 15, characterized in that the crushing device (80) is a ball mill or a rod mill.

17. The waste lithium ion battery pyrolysis system according to claim 15, characterized in that the device further comprises a beneficiation device (90), wherein the beneficiation device (90) is connected with the crushing device (80) for re-selecting or floating crushed solid residues.

18. The waste lithium ion battery pyrolysis system according to any one of claims 10 to 13, wherein the apparatus further comprises an air extraction device (100), wherein the air extraction device (100) is connected to the alkali absorption device (60) for performing a vacuuming treatment on the alkali absorption device (60).