Lithium battery low temperature pyrolysis system and pyrolysis method

Abstract

The present invention relates to the field of recycling of waste lithium batteries, and provides a lithium battery low-temperature pyrolysis system and a pyrolysis method thereof. The lithium battery low-temperature pyrolysis system comprises a pyrolysis chamber, a spiral is arranged in the pyrolysis chamber, and the two ends of the spiral are connected to two electrodes of a power source. The pyrolysis method comprises the following steps: processing the battery into battery fragments; the battery fragments enter the pyrolysis chamber, and the battery fragments are continuously transmitted by the spiral, and the two ends of the spiral are energized so that the temperature inside the pyrolysis chamber rises to 222°C2222°C, and the battery fragments are pyrolyzed. In the present application, heating is performed by heating in a manner of resistance principle, so that the pyrolysis chamber is heated rapidly in a short time, and has the advantages of being clean, environmentally friendly and pollution-free. By adjusting the rotation frequency of the spiral, the resistance of the battery fragments in the pyrolysis chamber is changed, and then the temperature inside the pyrolysis chamber is adjusted, so that the battery fragments are evenly heated, the pyrolysis temperature can be accurately controlled, the pyrolysis effect can be ensured, and the resource utilization of the battery is effectively realized.

Description

Technical Field

[0001] The invention relates to the field of waste lithium battery recycling, and in particular to a lithium battery low-temperature pyrolysis system and a pyrolysis method thereof. Background Art

[0002] Lithium-ion batteries have been widely used in 3C electronic products, power vehicles, military industry and other fields due to their advantages such as high energy density, long cycle life, wide operating temperature range, safety and reliability.

[0003] With the growing development of the electric vehicle industry, a large number of retired lithium-ion power batteries have entered the treatment and disposal stage as an emerging solid waste. As a kind of energy storage facility, the internal materials of waste lithium batteries are a mixture of metal and non-metal substances. From the structural point of view, they are divided into battery shell, battery collector, positive electrode material, negative electrode material, electrolyte, isolation membrane and other auxiliary parts. Waste lithium batteries are both an industrial hazardous waste and an urban mineral resource, and can be integrated and processed from the perspective of environmental protection and resource utilization.

[0004] Traditional lithium battery recycling mainly adopts pyrolysis or wet method for recycling. The pyrolysis method realizes material separation through high-temperature heat treatment process, but it has high energy consumption and can easily cause sintering transition of battery materials, affecting the quality of product recycling. The wet method mainly separates and purifies metals through processes such as acid leaching. This method can achieve high-purity separation of materials, but it also produces waste liquid containing heavy metals, which can easily cause secondary pollution to the environment.

[0005] In order to solve the above problems, the prior art uses low temperature heat treatment to treat the organic components of lithium battery materials, wherein a rotary kiln or a rotary pyrolysis chamber is mainly used to heat the lithium battery mixture internally or externally.

[0006] The internal heating type is mainly based on a rotary kiln, which uses external fuel and air to mix and burn to produce high-temperature flue gas, and the high-temperature flue gas is in direct contact with the material. In order to ensure the full combustion of the fuel and reduce the blackness and CO content in the flue gas, the air excess coefficient is usually 1.2 to 2.0, and the combustion reaction equipment is a dynamic equipment with poor sealing effect, so the oxygen content and the rotary kiln temperature cannot be accurately controlled. The external heating type is mainly indirect heating. The high-temperature flue gas generated by the fuel and air does not contact the material. The high-temperature flue gas is usually operated under negative pressure. The negative pressure is subject to the fluctuations of the incineration and flue gas purification system, resulting in changes in the amount of oxygen supplementation. The temperature is also difficult to control, which affects the pyrolysis effect. Both of them use combustion methods, which are prone to produce polluted gases. Summary of the invention

[0007] In order to solve the above technical problems or at least partially solve the above technical problems, the present invention provides a lithium battery low-temperature pyrolysis system and a pyrolysis method thereof.

[0008] The above-mentioned lithium battery low-temperature pyrolysis system includes a pyrolysis chamber, which is provided with a first feed channel for battery fragments to enter. A spiral is provided inside the pyrolysis chamber for rotation, and the feed end of the spiral is connected to the first feed channel. The spiral is used to continuously transport the battery fragments. The pyrolysis chamber is provided with a first discharge channel connected to the discharge end of the spiral. The feed end and the discharge end of the spiral are respectively connected to two electrodes of a power source, and the spiral is made of conductive material.

[0009] Optionally, it also includes a crushing device, which includes a shell, a second feed channel for batteries to enter is provided on the shell, a tool assembly for crushing the batteries into battery fragments is provided in the shell, and a second discharge channel for discharging the battery fragments is provided on the shell, and the battery fragments discharged through the second discharge channel enter the first feed channel.

[0010] Optionally, the second feed channel is provided with a first gate and a second gate in sequence along the feeding direction of the battery, and a cavity for stacking the batteries is formed between the first gate and the second gate.

[0011] Optionally, a first conveying device for conveying battery fragments is provided between the second discharge channel and the first feed channel.

[0012] Optionally, a nitrogen system for preparing nitrogen is provided on the shell, and an exhaust port is provided on the side wall of the shell.

[0013] Optionally, a separation device is also included, and the separation device includes:

[0014] A combustion chamber, used for burning the mixed gas generated by pyrolysis of the battery fragments, the combustion chamber is connected to the first discharge channel pipeline, and the combustion chamber is connected to a flue gas purification system;

[0015] Material separation system: the mixed material produced by thermal decomposition separation of battery fragments enters the material separation system.

[0016] Optionally, a second conveying device for conveying the mixed material is provided between the first discharge channel and the material separation system.

[0017] The above-mentioned low-temperature pyrolysis method of a lithium battery comprises the following steps:

[0018] Processing batteries into battery fragments;

[0019] The battery fragments enter the pyrolysis chamber and are continuously transported by the spiral inside the pyrolysis chamber. Both ends of the spiral are energized. After the battery fragments are energized, they release heat, causing the temperature inside the pyrolysis chamber to rise to 200°C to 300°C, and the battery fragments are pyrolyzed.

[0020] The mixed gas and mixed substances produced by pyrolysis enter the flue gas treatment system and the material separation system respectively.

[0021] Optionally, the battery is crushed in a nitrogen environment at -20°C to -40°C, and the particle size of the battery fragments is less than 5 cm.

[0022] Optionally, the rotation speed of the spiral is 5 to 50 Hz, and the volume of the battery fragments in the pyrolysis chamber is adjusted by adjusting the rotation speed of the spiral, thereby changing the resistance value of the battery fragments.

[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0024] In this application, the pyrolysis temperature is controlled at 200℃~300℃ to ensure the pyrolysis and volatilization of organic components contained in the battery materials, while avoiding the phenomenon that the battery materials burn and lose their activity at high temperature and cause excessive sintering. The heating is heated by the principle of resistance, so that the pyrolysis chamber can be heated quickly in a short time, which has the advantages of being clean, environmentally friendly and pollution-free. By adjusting the rotation frequency of the spiral, the resistance of the battery fragments in the pyrolysis chamber is changed, and then the temperature inside the pyrolysis chamber is adjusted, so that the battery fragments are heated evenly, the pyrolysis temperature can be accurately controlled, the pyrolysis effect can be ensured, and the resource utilization of the battery can be effectively realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a lithium battery low-temperature pyrolysis system in one embodiment of the present invention.

[0026] Reference numerals:

[0027] 1. Pyrolysis chamber; 11. First feed channel; 12. First discharge channel; 2. Screw; 3. Power supply; 4. Crushing device; 41. Shell; 42. Second feed channel; 43. Second discharge channel; 44. Primary crushing tool; 45. Secondary crushing tool; 46. First gate; 47. Second gate; 5. First conveying device; 6. Nitrogen system; 7. Combustion chamber; 71. Flue gas purification system; 72. Material separation system; 8. Second conveying device; 9. Elevator. DETAILED DESCRIPTION

[0028] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0029] like Figure 1As shown, the lithium battery low-temperature pyrolysis system provided in the embodiment of the present application includes a pyrolysis chamber 1, and the pyrolysis chamber 1 is provided with a first feed channel 11 for battery fragments to enter. A spiral 2 is provided inside the pyrolysis chamber 1 for rotation, and the feed end of the spiral 2 is connected to the first feed channel 11. The spiral 2 is used to continuously convey the battery fragments to ensure that the battery fragments are evenly accumulated in the spiral 2. The pyrolysis chamber 1 is provided with a first discharge channel 12 connected to the discharge end of the spiral 2, and the feed end and the discharge end of the spiral 2 are respectively connected to the two electrodes of the power supply 3. Specifically, the spiral 2 is made of conductive material, and the two electrodes of the power supply 3 are connected to the feed end and the discharge end of the spiral 2 through brushes, and the brushes are used to realize the conduction of current between the rotating parts and the stationary parts, and the connecting wires are made of high-temperature resistant materials to avoid damage during use.

[0030] The two ends of spiral 2 are energized, and spiral 2 and battery fragments form a conductive resistor. Since the resistance of battery fragments is small, during the power-on process, the battery fragments can release a large amount of heat while their own temperature rises, causing the pyrolysis chamber 1 to heat up, and then pyrolyze from the inside and outside of the battery fragments at the same time, increasing the pyrolysis efficiency. Spiral 2 is preferably an axisless spiral 2, and the driving device of spiral 2 extends out of the pyrolysis chamber 1 to avoid the temperature inside the pyrolysis chamber 1 being too high, causing the driving device to be damaged. The rotation speed of spiral 2 is adjusted by the driving device to change the time the battery fragments stay in the pyrolysis chamber 1 and the volume of the battery fragments in the pyrolysis chamber 1, thereby changing the resistance value of the conductive resistor between the two electrodes, increasing or reducing the heat released by the battery fragments per unit time, and effectively controlling the temperature inside the pyrolysis chamber 1. For further optimization, a temperature sensor can be arranged in the pyrolysis chamber 1. The temperature in the pyrolysis chamber 1 is detected in real time by the temperature sensor and fed back to the control system. The control system sends a work instruction to the driving device to increase or decrease the rotation speed of the spiral 2 according to the fed-back temperature information, thereby controlling the temperature in the pyrolysis chamber 1 within a certain range, and automatically adjusting it in real time to ensure the stability of the pyrolysis temperature.

[0031] The pyrolysis chamber 1 is a hollow cylinder, and the spiral 2 is arranged along the length direction of the pyrolysis chamber 1, so that the battery chip is transported along the length direction of the pyrolysis chamber 1. The pyrolysis chamber 1 and the spiral 2 are arranged concentrically to reduce the space occupied by the spiral 2, and the diameter of the pyrolysis chamber 1 is adapted to the outer diameter of the spiral 2. The adaptation here means that the diameter ratio of the pyrolysis chamber 1 is greater than the outer diameter of the spiral 2, so that the spiral 2 can rotate in the pyrolysis chamber 1. At the same time, the inner wall of the pyrolysis chamber 1 plays the role of supporting the battery fragments, so that the spiral 2 can continuously drive the battery fragments to move.

[0032] When used in this application, the battery fragments enter the pyrolysis chamber 1 in a continuous phase through the first feed channel 11, and enter the first end of the spiral 2. The spiral 2 rotates, thereby driving the battery fragments to be transmitted along the length direction of the spiral 2. In this process, the frequency and flow rate of the battery fragments entering the pyrolysis chamber 1 are fixed, and the rotation speed of the spiral 2 is fixed, so that the volume and cross-sectional area of ​​the battery fragments in the pyrolysis chamber 1 always remain the same. Due to the conductive properties of the spiral 2 and the battery material, the spiral 2 forms a conductive resistor with the battery fragments. When the power supply 3 is energized, the internal temperature of the battery fragments increases, and at the same time, the battery fragments and the spiral 2 release heat, so that the pyrolysis chamber 1 heats up in a short time, thereby effectively decomposing the isolation film, plastic and other substances in the battery fragments, and the pyrolyzed mixed material and mixed gas are discharged through the first discharge channel 12 for separation and purification.

[0033] like Figure 1 As shown, the lithium battery low-temperature pyrolysis system of the present application also includes a crushing device 4, a feeding device and a separation device.

[0034] The crushing device 4 includes a shell 41, and a second feed channel 42 for the battery to enter is provided on the shell 41. Preferably, the second feed channel 42 is vertically arranged so that the battery entering the second feed channel 42 enters the shell 41 under the action of its own gravity, which is convenient for operation. Further optimized, the end of the second feed channel 42 is open to facilitate the entry of the battery. In other embodiments, the second feed channel 42 can also be arranged horizontally or inclined. When the second feed channel 42 is arranged horizontally, other conveying tools such as a conveyor belt or a pushing device are required; when the second feed channel 42 is arranged at an angle, no other tools are required, and the battery can enter the shell 41 by its own weight, and the inclined arrangement can provide a certain buffering effect to avoid direct collision between the battery and the equipment in the shell 41.

[0035] A tool assembly for crushing the battery into battery fragments is provided in the shell 41. Among them, the tool assembly includes a primary crushing tool 44 and a secondary crushing tool 45 which are arranged in sequence along the entry direction of the battery. Specifically, the tool assembly adopts a four-axis shear crushing method, the shell 41 is arranged vertically, two primary crushing tools 44 are arranged in the upper part of the shell 41 for primary crushing, and two secondary crushing tools 45 are arranged in the lower part for secondary crushing. When the battery enters the shell 41 through the second feed channel 42, it falls between the two primary crushing tools 44. The battery fragments crushed by the primary crushing tool 44 enter between the two secondary crushing tools 45. After two stages of crushing, the particle diameter of the battery fragments is less than 5 cm, which is convenient for thermal decomposition. The tool assembly can also adopt other settings, as long as the particle diameter of the crushed battery fragments is less than 5 cm.

[0036] The housing 41 is provided with a second discharge channel 43 for discharging battery fragments. The battery fragments crushed by the secondary crushing tool 45 enter the second discharge channel 43, and the battery fragments discharged through the second discharge channel 43 enter the first feed channel 11 for subsequent pyrolysis. Further optimized, a first conveying device 5 for conveying battery fragments is provided between the second discharge channel 43 and the first feed channel 11. Preferably, the first conveying device 5 is an inclined screw conveyor, the first end of the screw conveyor is connected to the second discharge channel 43, the second end of the screw conveyor is connected to the first feed channel 11, and the height of the second end of the screw conveyor is higher than the height of the first end of the screw conveyor. The battery fragments will move toward the first end of the screw conveyor under the action of their own gravity. At this time, the battery fragments in the screw conveyor are pushed by the battery fragments that continuously enter the first end of the screw conveyor to move toward the second end of the screw conveyor, thereby continuously conveying the battery fragments in the screw conveyor, ensuring that the battery fragments continuously enter the pyrolysis chamber 1, and ensuring the pyrolysis effect. Further optimized, a valve is provided at the first feed channel 11 to effectively control the flow of battery fragments and facilitate use.

[0037] When in use, the battery fragments discharged through the second discharge channel 43 enter the first end of the screw conveyor and are transported toward the second end thereof by the screw conveyor. The battery fragments are continuously discharged through the second end of the screw conveyor and enter the first feed channel 11. The first feed channel 11 of the pyrolysis chamber 1 is vertically arranged upward, so that the battery fragments enter the screw 2 under the action of their own gravity.

[0038] Further optimized, the second feed channel 42 is provided with a first gate 46 and a second gate 47 in sequence along the feeding direction of the battery, and a cavity for battery stacking is formed between the first gate 46 and the second gate 47. The double gate control method can effectively ensure the sealing of the shell 41, and is used to block the outside air from entering the shell 41. A nitrogen system 6 for preparing nitrogen is provided on the shell 41, and an exhaust port is provided on the side wall of the shell 41.

[0039] During use, the first gate 46 is opened, the second gate 47 is closed, and the battery enters the cavity between the first gate 46 and the second gate 47. At this time, the exhaust port is opened, and nitrogen is filled into the shell 41 through the nitrogen system 6 to exhaust the air in the shell 41. When the air in the shell 41 is exhausted, the exhaust port is closed so that the shell 41 is filled with nitrogen. The first gate 46 is closed, the second gate 47 is opened, and the battery enters the shell 41 for crushing. Since the discharge of the battery may not be absolutely complete before crushing, the oxygen in the shell 41 is isolated by filling nitrogen, and the moisture content is reduced, so that the battery is crushed in an oxygen-free environment, reducing the fire rate and increasing the safety of the use process. Preferably, the temperature of the nitrogen is -20 to -40°C.

[0040] The feeding device includes a turnover box and an elevator 9. Used lithium batteries are placed in the turnover box, and the turnover box is moved to the bottom of the elevator 9. The staff can introduce the batteries in the turnover box into the elevator 9, and the elevator 9 drives the batteries to move upward. The batteries are discharged from the discharge port of the elevator 9 and enter the second feeding channel 42. It is easy to use and increases the degree of automation. Among them, self-propelled rollers can be set at the bottom of the turnover box, and the turnover box itself moves to the bottom of the elevator 9; or a conveyor belt can be set to transport the turnover box through the conveyor belt.

[0041] The separation device includes a combustion chamber 7 and a material separation system 72. The combustion chamber 7 is used to burn the mixed gas generated by pyrolysis of battery fragments, wherein the mixed gas includes CO2, HF, LiF, etc. The combustion chamber 7 is connected to the first discharge channel 12 pipeline, and the connection is arranged above the first discharge channel 12 to prevent the mixed material from entering the pipeline and causing pipeline blockage. The mixed gas enters the combustion chamber 7 through the pipeline for premixed combustion, and the combustion temperature should be greater than 850°C to achieve the incineration of toxic and harmful substances. The combustion chamber 7 is connected to a flue gas purification system 71, and the flue gas generated by the combustion enters the flue gas purification system 71 through the flue. After the flue gas purification system 71 is cooled by a waste heat boiler, it enters the bag filter for dust removal, and then enters the deacidification tower for wet washing to remove major pollutants such as HCl, HF, SO2, and finally discharged through the chimney.

[0042] The mixed material generated by the pyrolysis separation of the battery fragments enters the material separation system 72. The mixed material includes components such as nickel, cobalt, manganese, aluminum, and unseparated negative electrode graphite, copper foil, and aluminum foil. After magnetic separation, the materials can be recycled to increase economic benefits.

[0043] Further optimized, a second conveying device 8 for conveying the mixed material is provided between the first discharge channel 12 and the material separation system 72. Preferably, the second conveying device 8 is an inclined screw conveyor, the first end of the screw conveyor is connected to the first discharge channel 12, the second end of the screw conveyor is connected to the material separation system 72, and the height of the second end of the screw conveyor is higher than the height of the first end of the screw conveyor. The separated mixed material is uniformly entered into the material separation system 72 for magnetic separation, and the speed at which the mixed material enters the material separation system 72 is effectively controlled. A valve for controlling the circulation of the mixed material is provided on the first discharge channel 12, which is convenient for controlling the flow of materials and increasing the convenience of use.

[0044] The present application also provides a method for low-temperature pyrolysis of a lithium battery, comprising the following steps:

[0045] Step 1: Process the battery into battery fragments. There are many methods for processing the motor, such as the method of crushing with a tool assembly disclosed in the above-mentioned pyrolysis device, or the method of cutting. The specific method is not limited as long as the particle size of the processed battery fragments is less than 5 cm. Since the battery is not necessarily discharged completely before being crushed, in order to increase the safety of the use process, the battery is crushed under a protective gas. Specifically, the protective gas is preferably nitrogen, and the temperature of the nitrogen is -20°C to -40°C.

[0046] In step 2, the battery fragments enter the pyrolysis chamber 1, and are continuously transported by the spiral 2 inside the pyrolysis chamber 1. The spiral 2 is made of conductive material, and both ends of the spiral 2 are energized. After the battery fragments are energized, they release heat, causing the temperature inside the pyrolysis chamber 1 to rise to 200°C to 300°C, and the battery fragments are pyrolyzed.

[0047] Specifically, spiral 2 and battery fragments form a conductive resistor. Since the resistance of battery fragments is small, during the power-on process, the battery fragments can release a large amount of heat while their own temperature rises, causing the pyrolysis chamber 1 to heat up, thereby pyrolyzing the battery fragments. The speed of spiral 2 is 5 to 50 Hz. If the speed is too slow, heat energy will be wasted. If the speed is too fast, the battery fragments are prone to over-sintering. The volume of the battery fragments in the pyrolysis chamber 1 can be adjusted by adjusting the speed of spiral 2, thereby changing the resistance value of the battery fragments.

[0048] The spiral 2 is rotated by a driving device. The driving device is preferably a variable frequency motor. The speed of the spiral 2 can be controlled by adjusting the frequency of the motor, thereby adjusting the time the battery fragments stay in the pyrolysis chamber 1 and the amount of battery fragments accumulated per unit volume, thereby changing the resistance of the conductive resistor between the two electrodes to achieve temperature regulation. Specifically, when the motor speed is fast, the speed of the spiral 2 increases, the battery fragments stay in the pyrolysis chamber 1 for a short time, and the amount of battery fragments accumulated per unit volume inside the pyrolysis chamber 1 is small, the resistance of the battery fragments decreases, the heat released increases, and the temperature inside the pyrolysis chamber 1 is increased; conversely, the temperature inside the pyrolysis chamber 1 is reduced. A temperature sensor can be set in the pyrolysis chamber 1 to detect the temperature inside the pyrolysis chamber 1. When the temperature sensor detects that the temperature is between 200 and 300°C, the spiral 2 rotates normally; when the temperature sensor detects that the temperature is lower than 200°C, the speed of the spiral 2 is increased; when the temperature sensor detects that the temperature is higher than 300°C, the speed of the spiral 2 is reduced to achieve automatic control, maintain the stability of the temperature in the pyrolysis chamber 1, and increase the pyrolysis effect.

[0049] Step 3: The mixed gas and mixed substance produced by pyrolysis enter the flue gas treatment system and the material separation system 72 respectively. The flue gas treatment system and the material separation system 72 are both relatively common existing technologies. At the same time, the treatment method is illustrated in the above-mentioned pyrolysis device, so no detailed description is given here.

[0050] In this application, the pyrolysis temperature is controlled at 200°C to 300°C to ensure that the organic components contained in the battery materials are pyrolyzed and volatilized, while avoiding the phenomenon that the battery materials burn and lose their activity at high temperatures and cause excessive sintering. The heating method adopts the principle of resistance to achieve rapid heating of the pyrolysis chamber 1 in a short time, which has the advantages of being clean, environmentally friendly and pollution-free. By adjusting the rotation frequency of the spiral 2, the resistance of the battery fragments in the pyrolysis chamber 1 is changed, and then the temperature inside the pyrolysis chamber 1 is adjusted, so that the battery fragments are heated evenly, the pyrolysis temperature can be accurately controlled, the pyrolysis effect can be ensured, and the resource utilization of the battery can be effectively realized.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lithium battery low temperature pyrolysis system, characterized in that: It comprises a pyrolysis chamber, the pyrolysis chamber is provided with a first feed channel for battery fragments to enter, the pyrolysis chamber is provided with a spiral for rotation inside, the feed end of the spiral is connected with the first feed channel, the spiral is used to continuously convey the battery fragments, the pyrolysis chamber is provided with a first discharge channel connected with the discharge end of the spiral, the feed end and the discharge end of the spiral are respectively connected with two electrodes of a power source, the spiral is made of conductive material, and the rotation speed of the spiral is adjusted by a driving device; Wherein, the pyrolysis temperature of the lithium battery low-temperature pyrolysis system is controlled at 200°C~300°C.

2. The lithium battery low temperature pyrolysis system according to claim 1, characterized in that: It also includes a crushing device, which includes a shell, a second feed channel for batteries to enter is provided on the shell, a tool assembly for crushing the batteries into battery fragments is provided in the shell, and a second discharge channel for discharging the battery fragments is provided on the shell, and the battery fragments discharged through the second discharge channel enter the first feed channel.

3. The lithium battery low temperature pyrolysis system according to claim 2, characterized in that: The second feeding channel is provided with a first gate and a second gate in sequence along the feeding direction of the battery, and a cavity for stacking the batteries is formed between the first gate and the second gate.

4. The lithium battery low temperature pyrolysis system according to claim 2, characterized in that: A first conveying device for conveying the battery fragments is provided between the second discharge channel and the first feed channel.

5. The lithium battery low temperature pyrolysis system according to claim 2, characterized in that: The shell is provided with a nitrogen system for preparing nitrogen, and the side wall of the shell is provided with an exhaust port.

6. The lithium battery low temperature pyrolysis system according to claim 2, characterized in that: Also included is a separation device, the separation device comprising: A combustion chamber, used for burning the mixed gas generated by pyrolysis of the battery fragments, the combustion chamber being connected to the first discharge channel pipeline, and the combustion chamber being connected to a flue gas purification system; A material separation system, wherein the mixed material generated by the thermal decomposition separation of the battery fragments enters into the material separation system.

7. The lithium battery low temperature pyrolysis system according to claim 6, characterized in that: A second conveying device for conveying the mixed material is provided between the first discharge channel and the material separation system.

8. A method for low-temperature pyrolysis of lithium batteries, characterized in that: The following steps are involved: Processing batteries into battery fragments; The battery fragments enter the pyrolysis chamber and are continuously transported by the spiral inside the pyrolysis chamber. Both ends of the spiral are energized. When the battery fragments are energized, they release heat, causing the temperature inside the pyrolysis chamber to rise to 200°C~300°C, and the battery fragments are pyrolyzed. The mixed gas and mixed substances produced by pyrolysis enter the flue gas treatment system and the material separation system respectively; The rotation speed of the spiral is 5~50HZ. By adjusting the rotation speed of the spiral, the volume of the battery fragments inside the pyrolysis chamber is adjusted, thereby changing the resistance value of the battery fragments.

9. The method for low-temperature pyrolysis of lithium batteries according to claim 8, characterized in that: The batteries are crushed in a nitrogen environment at -20℃~-40℃, and the particle size of the battery fragments is less than 5cm.

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