Lithium battery electrolyte front-end pretreatment and efficient recovery device and method

Abstract

The invention discloses a lithium battery electrolyte front-end pretreatment and efficient recovery device, which comprises a front-end pretreatment unit, an electrolyte recovery unit and a gas purification and discharge unit, and is characterized in that the front-end pretreatment unit comprises a battery crushing device, a heating device and a primary condensing device; the electrolyte recovery unit comprises a cracking device and a multi-stage condensation separation device, the multi-stage condensation separation device comprises a pre-condenser, a first-stage condenser, a second-stage condenser and a third-stage condenser, and the gas purification and emission unit comprises a filtering device and a waste gas treatment device; the invention further discloses a lithium battery electrolyte front-end pretreatment and efficient recovery method. According to the invention, after the battery is crushed, the battery is evaporated and condensed, the solid part is cracked, and the cracked gas-phase product is subjected to multi-stage condensation, so that the waste battery is subjected to multi-layer solid, liquid and gas three-phase treatment, the recovery efficiency and purity of the electrolyte are improved, the emission of harmful gas in the recovery process is reduced, and environment-friendly and efficient electrolyte recovery is realized.

Description

Technical Field

[0001] This invention relates to the field of waste battery recycling technology, and in particular to a device and method for pretreatment and efficient recycling of lithium battery electrolyte. Background Technology

[0002] With the rapid development of the new energy industry, lithium batteries are widely used as important energy storage devices. However, waste lithium batteries contain large amounts of heavy metals and organic solvents, which can cause serious environmental pollution if discarded directly. Currently, the recycling process of lithium battery electrolyte faces problems such as electrolyte adhering to battery components, making complete recovery difficult, low recycling efficiency, low purity, and the potential generation of harmful gases during the recycling process.

[0003] For example, Chinese patent CN114024051A provides a method for treating waste lithium battery electrolyte by pyrolysis. The method involves recovering the electrolyte by evaporation and pyrolyzing the remaining solids at high temperature. The pyrolysis residue is used as building material, and the pyrolysis gas is recycled after catalytic reforming and harmless treatment. However, this method results in a large loss of the recovered electrolyte and low purity. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a lithium battery electrolyte pretreatment and high-efficiency recycling device and method. By performing pretreatment on waste lithium batteries, the recycling efficiency and purity of electrolyte are improved, while reducing the emission of harmful gases during the recycling process, thus achieving environmentally friendly and efficient electrolyte recycling.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A lithium battery electrolyte pretreatment and high-efficiency recovery device is disclosed, comprising a pretreatment unit, an electrolyte recovery unit, and a gas purification and emission unit. The front-end pretreatment unit includes a battery crushing device, a heating device, and a primary condensation device. The battery crushing device is used to crush the waste lithium batteries to release the electrolyte from the inside of the batteries. The heating device is used to heat the product after crushing the waste lithium batteries. The primary condensation device is used to condense the first gas generated after heating by the heating device, and the condensation temperature is -20℃ to 20℃. The electrolyte recovery unit includes a pyrolysis device and a multi-stage condensation separation device. The pyrolysis device is used to pyrolyze the solid products after heating by the heating device. The multi-stage condensation separation device includes a pre-condenser, a primary condenser, a secondary condenser, and a tertiary condenser. The pre-condenser is used to condense a third gas, which is a gaseous product generated by the pyrolysis device, with a condensation temperature of 5℃ to 15℃. The primary condenser is used to condense a fourth gas, which is a gaseous residue after condensation of the third gas, with a condensation temperature of -5℃ to 15℃. The secondary condenser is used to condense a fifth gas and a second gas after mixing them, where the fifth gas is a gaseous residue after condensation of the fourth gas, and the second gas is a gaseous residue after condensation of the first gas, with a condensation temperature of -84℃ to -40℃. The tertiary condenser is used to condense a sixth gas, which is a gaseous residue after condensation of the mixture of the fifth gas and the second gas, with a condensation temperature of -196℃ to -85℃. The gas purification and emission unit includes a filtration device and an exhaust gas treatment device. The filtration device is used to filter out the gaseous residues after the sixth gas has been condensed and to remove solid impurities. The exhaust gas treatment device is used to render the sixth gas treated by the filtration device harmless, and the harmless treatment includes absorbing harmful substances with sodium hydroxide solution.

[0006] Furthermore, the condensation temperature of the primary condenser is -10℃ to 10℃, the condensation temperature of the secondary condenser is -70℃ to -50℃, and the condensation temperature of the tertiary condenser is -130℃ to -100℃.

[0007] Furthermore, the heating temperature of the heating device is 100℃~150℃.

[0008] Furthermore, the pyrolysis apparatus includes a temperature sensor for real-time monitoring of the pyrolysis temperature and a gas analyzer for real-time analysis of the gas composition.

[0009] Furthermore, the outer surface of the heating device is coated with a thermal phase change material.

[0010] This invention also provides a method for front-end pretreatment and efficient recycling of lithium battery electrolyte, the method comprising the following steps: Step S1, Battery pretreatment: The waste lithium batteries are crushed and then heated at 100℃~150℃. Step S2, initial condensation: The first gas generated after the heating treatment in step S1 is condensed into a second gas at -10℃ to 10℃, and the second gas is delivered to the subsequent process for use. Step S3, pyrolysis: The solid after heat treatment in step S1 is pyrolyzed under inert gas protection, and the third gas produced by pyrolysis is collected. Step S4, Pre-condensation: The third gas is condensed into the fourth gas at 5℃~15℃, and the fourth gas is sent to the next process; Step S5, primary condensation: The fourth gas in step S4 is condensed into the fifth gas at -5℃ to 15℃, and the fifth gas is then sent to the next process. Step S6, Secondary condensation: The second gas in step S2 and the fifth gas in step S5 are mixed and condensed into a sixth gas at -84℃ to -40℃. Step S7, three-stage condensation: The sixth gas from step S6 is condensed at -196℃ to -85℃, and the remaining gas after condensation is treated and then discharged.

[0011] Furthermore, in step S7, the treatment process of the remaining gas includes the following steps: first, filtering the remaining gas to remove solid impurities; then, treating the filtered remaining gas to render it harmless, wherein the harmless treatment includes absorbing harmful substances with sodium hydroxide solution.

[0012] Furthermore, in step S3, the pyrolysis is divided into two stages. The pyrolysis temperature in the first stage is 350℃~450℃, and the temperature in the second stage is increased to 450℃~550℃. The reaction time for each stage is 30~60 minutes.

[0013] Based on the above technical solutions, this invention has the following advantages compared with the prior art: by using inert gas protection, low temperature cooling and other technical means, waste lithium batteries are disassembled and electrolyte is pretreated to ensure that the electrolyte is separated under safe and stable conditions, providing a guarantee for subsequent recycling; the recycling efficiency and purity of the electrolyte are improved, while reducing the emission of harmful gases during the recycling process, achieving environmentally friendly and efficient electrolyte recycling. Attached Figure Description

[0014] Figure 1 This is a structural and flowchart embodiment of the present invention.

[0015] The components are as follows: 1-front-end pretreatment unit; 2-electrolyte recovery unit; 3-gas purification and emission unit; 4-battery crushing device; 5-heating device; 6-primary condensing device; 7-pyrolysis device; 8-pre-condenser; 9-first-stage condenser; 10-second-stage condenser; 11-third-stage condenser; 12-filtration device; 13-exhaust gas treatment device; 14-first gas; 15-second gas; 16-third gas; 17-fourth gas; 18-fifth gas; 19-sixth gas. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments are described below. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0017] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0018] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0019] In the description of this application, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical connection or internal connection between two components. They can be direct connection or indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0020] like Figure 1 As shown, a lithium battery electrolyte front-end pretreatment and high-efficiency recovery device is disclosed. The device includes a front-end pretreatment unit 1, an electrolyte recovery unit 2, and a gas purification and emission unit 3. The front-end pretreatment unit 1 includes a battery crushing device 4, a heating device 5, and a primary condensation device 6. The battery crushing device 4 crushes the waste lithium batteries, making it easier to release the electrolyte from the battery. This device uses a high-strength crushing blade, capable of effectively crushing lithium batteries of different types and packaging forms. The heating device 5 heats the crushed batteries under inert gas protection, causing at least some of the solvent in the electrolyte to evaporate. The heating temperature is controlled between 100℃ and 150℃. Precise temperature control ensures effective evaporation of the electrolyte solvent while avoiding unnecessary thermal decomposition of the battery materials. The heating device is coated with a thermal phase change material to reduce heat loss and store energy. The primary condensation device 6 performs primary condensation on the first gas 14 generated during heating, removing at least some of the solvent. The condensation temperature of the primary condensation is -20℃ to 20℃, preferably -10℃ to 10℃. This condensation condenses the evaporated solvent into a liquid, facilitating subsequent processing. The electrolyte recovery unit 2 includes a pyrolysis device 7 and a multi-stage condensation separation device. The pyrolysis device 7 is used to pyrolyze the solid product after heating by the heating device 5. The pre-treated solid is pyrolyzed under inert gas protection and at the pyrolysis temperature of lithium salt, and the tail gas generated by pyrolysis is collected. To further improve the pyrolysis effect and recovery efficiency, a segmented temperature control method can be adopted, dividing the pyrolysis into two stages. The first stage pyrolysis temperature is 350℃~450℃, allowing the lithium salt to decompose initially and release most of the target gas and organic solvent. The second stage temperature is increased to 450℃~550℃ to ensure complete decomposition of the lithium salt and further remove any remaining impurities. The reaction time of each stage can be adjusted according to factors such as the specific lithium salt type, solid content, and equipment performance, generally 30~60 minutes. The pyrolysis temperature is higher than the solvent heating temperature, allowing the lithium salt to fully decompose and produce a third gas containing organic solvents, nitrogen, moisture, phosphorus pentafluoride (PF5), hydrogen fluoride (HF), phosphorus trifluoride (POF3), etc. This temperature setting is also because lithium salts in common lithium battery electrolytes, such as lithium hexafluorophosphate (LiPF6), decompose more slowly at lower temperatures. At around 350℃, lithium salt begins to decompose significantly, producing a third gas containing organic solvents, nitrogen, moisture, PF5, HF, POF3, etc. If the temperature is below 350℃, lithium salt decomposition is incomplete, leading to a decrease in the yield of the target product (such as PF5) and affecting the efficiency of electrolyte recovery. In the pretreatment stage, the heating device 5 causes some solvent in the electrolyte to evaporate, but some solvent still adheres to the solid. The temperature of 350℃ ensures that while lithium salt decomposes, this residual organic solvent can also evaporate well and enter the subsequent condensation and separation stage, thereby improving the overall recovery rate of the electrolyte. By setting the temperature in two stages, excessive solvent residue can be effectively avoided. When the temperature is too high, the gas produced by lithium salt decomposition may undergo a series of side reactions. For example, PF5 may further decompose or react with other substances at high temperatures to generate new impurities, which will not only reduce the yield of the target product PF5. The purity of the material will increase the difficulty of subsequent separation and purification. 550℃ is a relatively safe upper limit temperature. At this temperature, the occurrence of side reactions can be effectively reduced. The pyrolysis unit 7 needs to operate stably within a certain temperature range. Excessively high temperatures place higher demands on the materials and structure of the equipment. In the temperature range below 550℃, the commonly available high-temperature resistant materials (such as stainless steel, nickel-based alloys, etc.) can better meet the usage requirements of the equipment, ensure the long-term stable operation of the equipment, and reduce the equipment failure rate and maintenance costs.

[0021] By installing a temperature sensor for real-time monitoring of the pyrolysis temperature and a gas analyzer for real-time analysis of gas composition in the pyrolysis device 7, parameters such as heating power and gas flow rate can be adjusted in a timely manner based on the monitoring results, ensuring that the pyrolysis temperature is always kept within a suitable range, thereby achieving the best pyrolysis effect and electrolyte recovery efficiency.

[0022] The multi-stage condensation separation device includes a pre-condenser 8, a primary condenser 9, a secondary condenser 10, and a tertiary condenser 11. The pre-condenser 8 is used to condense the third gas 16 to remove organic solvents. The third gas 16 is a gaseous product generated by the pyrolysis unit. The condensation temperature is set between 5℃ and 15℃. Because there are many types of organic solvents with different boiling points, most common organic solvents (such as ethanol (boiling point 78.3℃), acetone (boiling point 56.5℃), etc.) can be partially condensed at relatively low temperatures. Setting the temperature range of 5℃ to 15℃ effectively allows most organic solvents to reach their dew point and condense, separating them from the gas. On the other hand, this temperature is not too low, avoiding excessive energy consumption and unnecessary condensation of certain gas components. It also prevents significant thermal stress on the equipment due to sudden temperature drops. The liquid phase collected during the pre-condensation stage... The main products are various organic solvents, such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC). These organic solvents can be collected and further purified by distillation to meet the standards for use in lithium battery electrolytes, thus achieving solvent recycling and reducing production costs. The distillation purification process can separate various solvents one by one by controlling the distillation temperature and pressure according to the differences in boiling points of different solvents, removing trace impurities such as water and metal ions.

[0023] The primary condenser 9 is used to condense the fourth gas 17 to remove water and HF. The fourth gas 17 is the gaseous residue after the condensation of the third gas 16. The condensation temperature can be adjusted according to actual conditions to ensure effective removal of water and HF. It is typically set between 0℃ and 10℃. If the gas contains high levels of water and HF, or if more thorough removal is desired, the temperature can be appropriately lowered to -5℃ to 0℃. Considering energy consumption and subsequent process connections, the temperature can also be appropriately increased to 10℃ to 15℃, but it must be ensured that water and HF can be effectively condensed and removed. The liquid product obtained in the primary condensation stage contains water and hydrofluoric acid (HF). The water can be used in the cooling system of the device or other production processes with low water quality requirements after simple purification, achieving rational utilization of water resources. Hydrofluoric acid is an important chemical raw material that can be collected and used in the production of fluorides, metal surface treatment, glass etching, and other fields. Before further utilization, the hydrofluoric acid needs to be tested for purity and undergo necessary purification to meet the needs of different application scenarios.

[0024] The secondary condenser 10 is used to condense the mixture of the fifth gas 18 and the second gas 15 to remove gases other than PF5. The fifth gas 18 is the gaseous residue after the condensation of the fourth gas 17, and the second gas 15 is the gaseous residue after the condensation of the first gas 14. The condensation temperature is -84℃ to -40℃, preferably -70℃ to -50℃. The normal operating temperature can be set at -60℃, which is a commonly used value after comprehensively considering the separation effect and the stability of equipment operation. If the boiling points of other impurity gases besides PF5 in the gas are relatively high, the temperature can be adjusted accordingly. To reduce energy consumption, the temperature is increased to around -50℃. If the impurity gas has a low boiling point, the temperature can be lowered to -70℃ to ensure effective separation. Within this temperature range, PF5 remains gaseous, while most other common gaseous impurities (such as some low-boiling-point organic fluorides, nitrogen, oxygen, etc., whose boiling points are mostly above -70℃) will condense into liquid. -60℃ is a temperature point that has been proven in practice to achieve a good balance between separation effect and equipment cost and energy consumption. Depending on the composition and content of the impurity gas, the temperature can be flexibly adjusted to optimize the separation process and improve the purity of PF5. This stage of condensation is mainly for substances that are relatively easy to condense, except for PF5. However, under normal process design, most of the target substances have already been condensed and separated in the previous steps. The amount of liquid phase product collected in the secondary condensation is relatively small and may contain a small amount of water, HF, and some polar organic impurities that were not completely separated in the primary condensation. These liquid phase products can be returned to the product collection system of the primary condensation and processed and utilized together with the primary condensation products to avoid resource waste and environmental pollution.

[0025] The three-stage condenser 11 is used to condense the sixth gas 19, which is the gaseous residue of the condensation of the fifth gas 18 and the second gas 15, collecting liquid PF5. The condensation temperature is -196℃ to -85℃, preferably -130℃ to -100℃, and generally -120℃ is chosen. If the purity requirement of PF5 is extremely high, or if it is desirable to recover PF5 as completely as possible, the temperature can be lowered to -130℃ or even lower. Considering equipment cost and operating energy consumption, the temperature can be appropriately increased to -110℃ while meeting the basic purity requirements of the product. The boiling point of PF5 is -84.6℃. At -120℃, PF5 can be fully condensed into liquid. At the same time, this temperature can further reduce the residue of possible trace impurities and improve the purity of the recovered PF5. Although lowering the temperature can improve purity and recovery rate, it will increase the cooling energy consumption and cost of the equipment. Raising the temperature may affect product quality. Therefore, it is necessary to choose the appropriate temperature based on actual conditions. By balancing production needs and economic benefits, precise condensation temperature control is used to effectively separate PF5 from other gases. The three-stage condensation stage focuses on deep condensation and recovery of PF5, ensuring that PF5 is fully condensed into liquid to improve recovery purity. This step focuses on the collection of PF5, and under normal circumstances, no other large amounts of liquid products are mixed in. The collected liquid PF5 can undergo further purification processes, such as distillation and crystallization, to remove any trace impurities it may contain. Then, it can be used as an important chemical raw material for the production of fluoropolymers, fluorinated surfactants, pharmaceutical intermediates, etc., and has high economic value.

[0026] The gas purification and emission unit 3 includes a filter device 12 and an exhaust gas treatment device 13. The filter device 12 is used to filter the gaseous residues of the sixth gas 19 after condensation, removing any dust or other small particulate matter or other solid impurities that may be present. The exhaust gas treatment device 13 is used to render the sixth gas 19 after filtration harmless. The harmless treatment includes using sodium hydroxide solution to absorb harmful substances, ensuring that the exhaust gas meets emission standards before being discharged, thereby reducing environmental pollution.

[0027] This invention also provides a method for front-end pretreatment and efficient recycling of lithium battery electrolyte, the method comprising the following steps: Step S1, Battery pretreatment: The waste lithium batteries are crushed and then heated at 100℃~150℃. Step S2, initial condensation: The first gas 14 generated after the heating treatment in step S1 is condensed into a second gas 15 under the condition of -10℃ to 10℃, and the second gas 15 is delivered to the subsequent process for use. Step S3, pyrolysis: The solid after heat treatment in step S1 is pyrolyzed under inert gas protection, and the third gas 16 produced by pyrolysis is collected. Step S4, Pre-condensation: The third gas 16 is condensed into the fourth gas 17 at 5℃~15℃, and the fourth gas 17 is sent to the next process. Step S5, primary condensation: The fourth gas 17 from step S4 is condensed into the fifth gas 18 at -5℃ to 15℃, and the fifth gas 18 is sent to the next process. Step S6, Secondary condensation: The second gas 15 from step S2 and the fifth gas 18 from step S5 are mixed and condensed into the sixth gas 19 under the condition of -84℃ to -40℃. Step S7, three-stage condensation: The sixth gas 19 from step S6 is condensed at -196℃ to -85℃. The remaining gas after condensation is treated and then discharged.

[0028] Furthermore, in step S7, the treatment process of the remaining gas includes the following steps: first, filtering the remaining gas to remove solid impurities; then, treating the filtered remaining gas to render it harmless, wherein the harmless treatment includes absorbing harmful substances with sodium hydroxide solution.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them; although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation methods of the application or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of this application, and all of them should be covered within the scope of the technical solutions claimed in this application.

Claims

1. A lithium battery electrolyte pretreatment and high-efficiency recovery device, characterized in that, The device includes a front-end pretreatment unit, an electrolyte recovery unit, and a gas purification and emission unit. The front-end pretreatment unit includes a battery crushing device, a heating device, and a primary condensation device. The battery crushing device is used to crush the waste lithium batteries to release the electrolyte from the inside of the batteries. The heating device is used to heat the product after crushing the waste lithium batteries. The primary condensation device is used to condense the first gas generated after heating by the heating device, and the condensation temperature is -20℃ to 20℃. The electrolyte recovery unit includes a pyrolysis device and a multi-stage condensation separation device. The pyrolysis device is used to pyrolyze the solid products after heating by the heating device. The multi-stage condensation separation device includes a pre-condenser, a primary condenser, a secondary condenser, and a tertiary condenser. The pre-condenser is used to condense a third gas, which is a gaseous product generated by the pyrolysis device, with a condensation temperature of 5℃ to 15℃. The primary condenser is used to condense a fourth gas, which is a gaseous residue after condensation of the third gas, with a condensation temperature of -5℃ to 15℃. The secondary condenser is used to condense a fifth gas and a second gas after mixing them, where the fifth gas is a gaseous residue after condensation of the fourth gas, and the second gas is a gaseous residue after condensation of the first gas, with a condensation temperature of -84℃ to -40℃. The tertiary condenser is used to condense a sixth gas, which is a gaseous residue after condensation of the mixture of the fifth gas and the second gas, with a condensation temperature of -196℃ to -85℃. The gas purification and emission unit includes a filtration device and an exhaust gas treatment device. The filtration device is used to filter out the gaseous residues after the sixth gas has been condensed and to remove solid impurities. The exhaust gas treatment device is used to render the sixth gas treated by the filtration device harmless, and the harmless treatment includes absorbing harmful substances with sodium hydroxide solution.

2. The lithium battery electrolyte front-end pretreatment and high-efficiency recovery device according to claim 1, characterized in that, The condensing temperature of the primary condenser is -10℃ to 10℃, the condensing temperature of the secondary condenser is -70℃ to -50℃, and the condensing temperature of the tertiary condenser is -130℃ to -100℃.

3. The lithium battery electrolyte front-end pretreatment and high-efficiency recovery device according to claim 1, characterized in that, The heating temperature of the heating device is 100℃~150℃.

4. The lithium battery electrolyte front-end pretreatment and high-efficiency recovery device according to claim 1, characterized in that, The pyrolysis device includes a temperature sensor for real-time monitoring of the pyrolysis temperature and a gas analyzer for real-time analysis of the gas composition.

5. The lithium battery electrolyte front-end pretreatment and high-efficiency recovery device according to claim 1, characterized in that, The heating device is coated with a thermal phase change material.

6. A method for front-end pretreatment and efficient recovery of lithium battery electrolyte, characterized in that, The method includes the following steps: Step S1, Battery pretreatment: The waste lithium batteries are crushed and then heated at 100℃~150℃. Step S2, initial condensation: The first gas generated after the heating treatment in step S1 is condensed into a second gas at -10℃ to 10℃, and the second gas is delivered to the subsequent process for use. Step S3, pyrolysis: The solid after heat treatment in step S1 is pyrolyzed under inert gas protection, and the third gas produced by pyrolysis is collected. Step S4, Pre-condensation: The third gas is condensed into the fourth gas at 5℃~15℃, and the fourth gas is sent to the next process; Step S5, primary condensation: The fourth gas in step S4 is condensed into the fifth gas at -5℃ to 15℃, and the fifth gas is then sent to the next process. Step S6, Secondary condensation: The second gas in step S2 and the fifth gas in step S5 are mixed and condensed into a sixth gas at -84℃ to -40℃. Step S7, three-stage condensation: The sixth gas from step S6 is condensed at -196℃ to -85℃, and the remaining gas after condensation is treated and then discharged.

7. The method for front-end pretreatment and efficient recovery of lithium battery electrolyte according to claim 6, characterized in that, In step S7, the treatment of the remaining gas includes the following steps: First, the remaining gas is filtered to remove solid impurities; then, the filtered remaining gas is subjected to harmless treatment, which includes absorbing harmful substances with sodium hydroxide solution.

8. The method for front-end pretreatment and efficient recovery of lithium battery electrolyte according to claim 6, characterized in that, In step S3, the pyrolysis is divided into two stages. The pyrolysis temperature in the first stage is 350℃~450℃, and the temperature in the second stage is increased to 450℃~550℃. The reaction time for each stage is 30~60 minutes.

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