A method for recycling lithium battery electrolyte

Abstract

The present invention provides a method for recycling and recovering a lithium battery electrolyte, which includes the following steps: recycling and collecting the electrolyte in the lithium battery; putting the collected electrode liquid into an electrolyte storage tank for heating and stirring to reach the boiling point of the solvent of the electrolyte, and evaporating the electrolyte solvent within the temperature range of 80°C to 150°C; collecting the volatilized solvent into a first recovery container after condensation and reflux to obtain a distillate, which contains ethylene carbonate; opening the closing plate at the bottom of the first recovery container, and moving a lifting scraper along the inner wall of the first recovery container to scrape the crystals on the inner wall and move them downward to the crystal storage container at the bottom. A method for continuous distillate collection, continuous crystal collection without interruption of electrode liquid recovery and treatment is formed.

Description

Technical Field

[0001] The present invention relates to a method for recycling lithium battery electrolyte, and more specifically to a technology for better recycling and utilization of substances that can crystallize in the electrolyte. Background Art

[0002] With the continuous development of new energy technologies, lithium batteries have been widely used and are very important. After a certain period of use, the functions of lithium batteries will decline until they are phased out and recycled. In the structure of lithium batteries, they usually have an outer shell and an internal electrode liquid, and the electrolyte is an important component for the normal operation of lithium batteries.

[0003] In the electrolyte of lithium batteries, there are various solvent components and metal elements. How to recycle and utilize the useful components in these electrolytes has very important uses. On the one hand, it can reduce damage to the environment, and on the other hand, it can turn waste into treasure, thereby reducing the production costs of enterprises. Among the components recovered from the electrolyte, some components are prone to form crystals. For example, one of the components is ethylene carbonate (molecular formula: C3H4O3). This substance has special properties, with a melting point of 35 - 38°C, and is an excellent solvent for lithium battery electrolytes. The recycling and utilization of this substance has a very important position. However, in the prior art, the recycling and utilization of this substance usually have insufficient efficiency, especially the technical effects of continuous rapid crystallization, separation, and recovery cannot be achieved. Therefore, in the prior art, if it is possible to achieve rapid crystallization, separation, and recovery of ethylene carbonate, it has very important significance and will also make the recycling of lithium battery electrolyte more efficient. Summary of the Invention

[0004] To solve the problems existing in the above technologies, the present invention provides a technology for facilitating the continuous crystallization and recovery of ethylene carbonate in the electrolyte.

[0005] A method for recycling lithium battery electrolyte provided by the present invention includes the following steps:

[0006] S1: Recover and collect the electrolyte in the lithium battery;

[0007] S2: Put the recovered electrode liquid into an electrolyte storage tank and heat and stir it to reach the boiling point of the solvent of the electrolyte, and evaporate the electrolyte solvent within the temperature range of 80°C to 150°C;

[0008] S3: After the volatilized solvent is condensed and refluxed, it is collected in a first recovery container to obtain a distillate, and this distillate contains ethylene carbonate;

[0009] S4: After the electrolyte recovered in the first recovery container reaches a certain amount, replace it with the second recovery container to recover the electrolyte solvent;

[0010] S5: The ethylene carbonate in the first recovery container forms crystals after standing still and adheres to the inner wall of the first recovery container; the lifting straw moves in the first recovery container to contact the uncrystallized solvent part, and then the lifting straw sucks away the uncrystallized solvent part into the solvent storage container, leaving crystals in the first recovery container;

[0011] S6: Open the closing plate at the bottom of the first recovery container, and the lifting scraper 19 moves along the inner wall of the first recovery container to scrape off the crystals on the inner wall and move them down to the crystal storage container at the bottom.

[0012] The beneficial effects of the above solution are as follows: The recovered electrolyte is evaporated and condensed, and the fractions are selectively collected, which can be respectively introduced into multiple recovery containers at different positions, and then crystallization treatment is carried out in the recovery containers. Then, the liquid layer is recovered through stratification, and the crystals are scraped and collected, so that continuous operation can be achieved, and continuous treatment of the crystals can be realized, thus forming a method for continuous fraction collection, continuous crystal collection and uninterrupted electrode liquid recovery treatment.

[0013] It should be noted that the above implementation mode sets the crystallization temperature according to the properties of ethylene carbonate. If there are other suitable substances according to actual needs, through temperature setting, other types of crystals can also be recovered, or multiple solvent substances can be collected successively or simultaneously.

[0014] The method for cyclic recovery of the lithium battery electrolyte of the present invention includes the following steps: while the lifting scraper descends, the flexible brush on the outer edge of the lifting scraper performs a cleaning action on the inner wall;

[0015] The first recovery container is provided with a blanking pipe and a lifting straw. The lifting scraper has a first through hole and a second through hole. The blanking pipe movably passes through the first through hole, and the lifting straw movably passes through the second through hole.

[0016] In the actual application process, crystals generally condense at the inner wall position of the container because the temperature on the inner wall is lower, especially on the lower inner wall. The flexible brush scrapes or contacts and presses the inner wall position to make these crystals move down quickly and finally be collected into the recovery container at the bottom.

[0017] In addition, there are two perforations on the lifting scraper. One is for the insertion of the discharge pipe, and the other is for the insertion of the lifting suction pipe. The aperture of the perforation is relatively large, so when the lifting scraper moves up and down, it will not interfere with these two pipes, that is, they can move relatively independently. Through the action of the discharge pipe, the fraction can be directly discharged to the lower position of the lifting scraper, that is, the position close to the lower side, so as to avoid waste caused by the residue on the upper side of the lifting scraper when the fraction is discharged into the upper layer. Because if a part of the fraction is sprayed on the upper side of the inner wall or the upper part of the lifting scraper, crystallization will occur in these places and it is not easy to scrape off. In addition, for the lifting suction pipe to move up and down, the upper side of the lifting suction pipe is connected to a flexible pipe, so it can move up and down. In this way, according to the actual stratification height, that is, the height of the liquid layer inside the container, the height of the suction pipe can be adjusted appropriately, so that the liquid layer can be sucked away more accurately and thoroughly, and then the crystalline solid is moved down subsequently.

[0018] In the method for recycling the lithium battery electrolyte of the present invention, after the electrolyte solvent enters the first recovery container, a gradient temperature decrease trend is formed. The gradient temperature trend decreases from top to bottom. The upper layer temperature in the first recovery container is above 40°C, and the lower layer temperature in the first recovery container is below 20°C; when the electrolyte solvent flows or is stored in the first recovery container, crystallization does not occur at the upper layer position, while crystallization occurs at the lower layer position.

[0019] In the method for recycling the lithium battery electrolyte of the present invention, the following steps are included. During the process of forming crystals at the lower layer position, the lifting scraper moves up and down repeatedly at intervals, so that the lifting scraper scrapes the crystals on the inner wall at the lower layer position to avoid the formation of crystals with too thick a structure on the inner wall.

[0020] In practical applications, if crystallization occurs for a long time or the crystals are relatively thick, it is easy to form a relatively firm adhesion on the inner wall of the container, which is not conducive to subsequent scraping. Therefore, a liftable lifting scraper is provided here. Whenever crystallization reaches a certain time or a certain amount, the lifting scraper moves up and down to clean the crystals on the inner wall of the container, thus realizing multiple repeated cleaning and scraping. And when it is finally necessary to press and clean these crystals into the lower recovery container, that is, when the bottom closing plate is opened, these crystals can move down relatively quickly, and there will be relatively few crystals remaining inside. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the method for recycling the lithium battery electrolyte of the present invention.

[0022] Figure 2It is a schematic diagram of some application components for the cyclic recovery of lithium battery electrolyte.

[0023] Figure 3 It is a schematic diagram of some application components for the cyclic recovery of lithium battery electrolyte.

[0024] Figure 4 It is a schematic diagram of the lifting scraper with a hollow channel for the cyclic recovery of lithium battery electrolyte. Detailed implementation mode

[0025] First embodiment:

[0026] As Figure 1 and Figure 2 shown, a method for the cyclic recovery of a lithium battery electrolyte in this embodiment includes the following steps:

[0027] S1: Recover and collect the electrolyte in the lithium battery.

[0028] S2: Put the recovered and collected electrode liquid into the electrolyte storage tank 10 for heating and stirring to reach the boiling point of the solvent of the electrolyte, and evaporate the electrolyte solvent within the temperature range of 80°C to 150°C.

[0029] S3: The volatilized solvent is condensed and refluxed through the condensation structure 11 and then collected in the first recovery container 12 to obtain a fraction, which contains ethylene carbonate.

[0030] S4: When the recovered electrolyte in the first recovery container 12 reaches a certain amount, replace it with the second recovery container 13 for the recovery of the electrolyte solvent; preferably, there are a main pipeline 15 and multiple branch pipelines 16 on the pipeline. The branch pipelines 16 are connected to the first recovery container 12 and the second recovery container 13, and a three-way control valve 17 is provided at the connection position of the main pipeline 15 and the branch pipelines 16. By controlling the three-way control valve 17, the fluid can selectively flow into the first recovery container 12, the second recovery container 13, or other recovery containers 14.

[0031] S5: The ethylene carbonate in the first recovery container 12 forms crystals and adheres to the inner wall of the first recovery container 12; the lifting straw 21 moves in the first recovery container 12 to contact the uncrystallized solvent part, and then the lifting straw 21 sucks away the uncrystallized solvent part into the solvent storage container 22, and the crystals are left in the first recovery container 12.

[0032] S6: Open the closing plate 18 at the bottom of the first recovery container 12, and the lifting scraper 19 moves along the inner wall of the first recovery container 12 to scrape off the crystals on the inner wall and move them downward into the bottom crystal storage container 20.

[0033] The recycled electrolyte is subjected to evaporation and condensation, and the fractions are selectively collected and can be introduced into multiple recovery containers at different positions respectively. Then, crystallization treatment is carried out in the recovery containers. Then, the liquid layer is recovered by stratification, and the crystallized substances are scraped and collected. In this way, continuous operation can be achieved, and continuous treatment of the crystallized substances can be realized, thus forming a method for continuous fraction collection, continuous crystallized substance collection without interruption of the electrolyte recovery treatment.

[0034] Second Embodiment:

[0035] The method for recycling the lithium battery electrolyte of the present invention includes the following steps: while the lifting scraper 19 descends, the flexible brush 31 at the outer edge of the lifting scraper 19 performs a cleaning action on the inner wall.

[0036] A blanking pipe 32 and a lifting suction pipe 21 are provided on the first recovery container 12. The upper end of the blanking pipe 32 is connected to the branch pipe 16. The lifting scraper 19 has a first through hole 33 and a second through hole 34. The blanking pipe 21 movably passes through the first through hole 33, and the lifting suction pipe 21 movably passes through the second through hole 34.

[0037] In the method for recycling the lithium battery electrolyte of the present invention, after the electrolyte solvent enters the first recovery container 12, a gradient temperature drop trend is formed. The gradient temperature trend decreases from top to bottom. The upper layer temperature in the first recovery container is above 40°C or 50°C, while the lower layer temperature in the first recovery container is below 20°C. When the electrolyte solvent flows or is stored in the first recovery container, no crystallization is formed at the upper layer position, while crystallized substances are formed at the lower layer position.

[0038] In the actual application process, the crystallized substances generally condense on the inner wall of the container because the temperature on the inner wall is lower, especially on the lower inner wall. By scraping or contacting and pressing the inner wall position with the flexible brush, these crystallized substances can be quickly moved downward and finally collected into the bottom recovery container.

[0039] In addition, there are two perforations on the lifting scraper. One is for the insertion of the discharge pipe, and the other is for the insertion of the lifting suction pipe. The aperture of the perforation is relatively large, so when the lifting scraper moves up and down, it will not interfere with these two pipes, that is, they can move relatively independently. Through the action of the discharge pipe, the fraction can be directly discharged to the lower position below the lifting scraper, that is, the position close to the lower side, so as to avoid waste caused by the fraction remaining on the upper side of the lifting scraper when discharged into the upper layer. Because if a part of the fraction is sprayed on the upper side of the inner wall or the upper part of the lifting scraper, crystallization will occur in these places and it is not easy to scrape off. In addition, the lifting suction pipe moves up and down. The upper side of the lifting suction pipe is connected to a flexible pipe, so it can move up and down. In this way, according to the actual stratification height, that is, the height of the liquid layer inside the container, the height of the suction pipe can be adjusted appropriately, so that the liquid layer can be sucked away more accurately and thoroughly, and then the crystalline solid is moved down subsequently.

[0040] The method for recycling the lithium battery electrolyte of the present invention includes the following steps. During the process of forming crystalline substances at the lower layer position, the lifting scraper moves up and down repeatedly at intervals to scrape the crystalline substances on the inner wall at the lower layer position, so as to avoid the formation of crystalline substances with too thick a structure on the inner wall.

[0041] It includes an electrolyte storage tank, a reflux pipe and a recovery container; the electrolyte storage tank is used to store the recycled and collected electrolyte. There is a stirrer and a heater inside the electrolyte storage tank. A reflux pipe is arranged at the top of the electrolyte storage tank, and the recovery container is arranged on one side at the bottom of the reflux pipe;

[0042] Among them, the recovery container has a lifting rod and a lifting plate connected to each other. The outer edge of the lifting plate is a flexible brush, and the flexible brush is arranged in contact with the inner wall of the recovery container; there is a through hole on the lifting plate, and a discharge pipe is arranged on the through hole. The top of the discharge pipe passes through the top wall of the recovery container and is detachably connected to the reflux pipe.

[0043] In practical applications, if crystallization occurs for a long time or the crystalline substances are relatively thick, it is easy to form a relatively firm adhesion on the inner wall of the container, which is not conducive to subsequent scraping. Therefore, a liftable lifting scraper is provided here. Whenever crystallization reaches a certain time or a certain amount, the lifting scraper moves up and down to clean the crystalline substances on the inner wall of the container, thus realizing multiple repeated cleaning and scraping. When finally these crystalline substances need to be pressed and cleaned into the lower recovery container, that is, when the bottom closing plate is opened, these crystalline substances can move down relatively quickly, and there will be relatively few crystalline substances remaining inside.

[0044] Such as Figure 4As shown in the figure, in a further preferred embodiment, a lifting rod 35 is connected to the lifting scraper 19. The lifting rod 35 realizes the lifting movement through a lifting structure. One side of the lifting rod 35 has an inlet part 36, and the inlet part 36 is connected to a hollow channel 37 inside the lifting rod 35. The hollow channel 37 penetrates through the lifting scraper 19. In some cases, in order to accelerate the formation of crystals or when it is not easy to form crystals, crystal seeds are added into the inlet part. The crystal seeds come out of the lifting scraper along the hollow channel and then fall into the liquid below, and then accelerate the precipitation of ethylene carbonate. In addition, the lifting scraper can also be first moved downward to a suitable position so that the crystal seeds are slowly added to the lower side position, so that the crystalline substance is formed at the lower side position of the container, which is more convenient for scraping the crystalline substance and stratifying in the later stage.

Claims

1. A method for recycling lithium battery electrolyte, characterized in that, Including the following steps: S1: Recover and collect the electrolyte in the lithium battery; S2: Put the recovered and collected electrolyte into an electrolyte storage tank for heating and stirring to reach the boiling point of the solvent of the electrolyte, and evaporate the electrolyte solvent within the temperature range of 80°C to 150°C; S3: The volatilized solvent is collected in a first recovery container after condensation and reflux to obtain a distillate, which contains ethylene carbonate; S4: When a certain amount of electrolyte is recovered in the first recovery container, replace it with a second recovery container for recovering the electrolyte solvent; S5: The ethylene carbonate in the first recovery container forms crystals and adheres to the inner wall of the first recovery container; the lifting suction pipe moves in the first recovery container to contact the uncrystallized solvent part, and then the lifting suction pipe sucks away the uncrystallized solvent part into the solvent storage container, leaving crystals in the first recovery container; S6: Open the closing plate at the bottom of the first recovery container, and the lifting scraper moves along the inner wall of the first recovery container to scrape off the crystals on the inner wall and move them downward into the crystal storage container at the bottom; 2. The recycling method of the lithium battery electrolyte according to claim 1, characterized in that Including the following steps: while the lifting scraper is descending, the flexible brush on the outer edge of the lifting scraper performs a cleaning action on the inner wall; A discharge pipe and a lifting suction pipe are provided on the first recovery container, the lifting scraper has a first through hole and a second through hole, the discharge pipe movably passes through the first through hole, and the lifting suction pipe movably passes through the second through hole; 3. The recycling method of the lithium battery electrolyte according to claim 1, characterized in that, After the electrolyte solvent enters the first recovery container, a gradient temperature drop trend is formed, and the gradient temperature trend decreases from top to bottom. The upper layer temperature in the first recovery container is above 40°C, and the lower layer temperature in the first recovery container is below 20°C; when the electrolyte solvent flows or is stored in the first recovery container, no crystals are formed at the upper layer position, while crystals are formed at the lower layer position; 4. The method for cyclic recycling of the lithium battery electrolyte according to claim 3, characterized in that, Including the following steps, during the process of forming crystals at the lower layer position, the lifting scraper moves up and down repeatedly at intervals to scrape off the crystals on the inner wall at the lower layer position to prevent the formation of overly thick crystal structures on the inner wall.

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