Organic carbonate recovery method and recovery device

Abstract

To effectively collect a plurality of organic carbonates contained in an electrolyte of a lithium-ion battery.SOLUTION: There is provided a method for collecting organic carbonate contained in an electrolyte of a waste lithium-ion battery. The organic carbonate contains: a first carbonate; and a second carbonate having a melting point and a boiling point higher than those of the first carbonate. The method comprises the steps of: performing temperature adjustment processing that an internal temperature of a drying device in which the waste lithium-ion battery is housed is held in a first temperature region, each pipe extended to below the drying device is held in a second temperature region, and each condenser connected to the drying device via the pipe is held in a third temperature region; and performing correction processing that an internal pressure of the drying device, the pipe, and the condenser is reduced in pressure from a normal pressure to the first pressure and the first carbonate is collected in the condenser.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method and apparatus for recovering organic carbonate, which is a main component of the electrolyte of used lithium ion batteries. [Background technology]

[0002] JP 11-167936 A discloses a method for recovering diethyl carbonate, which is a main component of the electrolyte contained in used lithium ion batteries. In this conventional method, used lithium ion batteries are crushed in a freezer, and the resulting crushed pieces are heated in diethyl carbonate as an extraction solvent. This extraction is performed at a temperature condition lower than 25°C and higher than -43°C. The extraction solvent is separated from the solid content of the crushed pieces. The diethyl carbonate contained in the electrolyte is recovered together with the diethyl carbonate as the extraction solvent by distillation of the separated extraction solvent.

[0003] In addition to JP-A No. 11-167936, JP-A No. 2012-59564 can be cited as examples of documents showing the state of the art in the technical field related to the present disclosure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-167936 [Patent Document 2] JP 2012-59564 A Summary of the Invention [Problem to be solved by the invention]

[0005] The main components of the electrolyte in lithium-ion batteries are organic carbonates such as diethyl carbonate (DEC), ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). Conventional methods use DEC as an extraction solvent, which is considered to be suitable for recovering DEC. However, on the other hand, there is a possibility that the recovery of other organic carbonates such as EC may be insufficient. In addition, the state of the DEC for extraction when it is brought into contact with the crushed pieces is liquid. Therefore, the DEC for extraction that adheres to the solid part of the crushed pieces cannot be separated from this solid part, and the recovery rate of DEC, the main component of the electrolyte, may be low.

[0006] One object of the present disclosure is to provide a technique capable of efficiently recovering a plurality of organic carbonates contained in an electrolyte solution of a lithium ion battery. [Means for solving the problem]

[0007] A first aspect of the present disclosure is a method for recovering an organic carbonate contained in an electrolyte of a used lithium ion battery. The organic carbonate includes a first carbonate and a second carbonate having a higher melting point and boiling point than the first carbonate. The method comprises: A step of performing a temperature adjustment process in which an internal temperature of a dryer in which waste lithium-ion batteries are accommodated is maintained in a first temperature range, an internal temperature of a pipe extending below the dryer is maintained in a second temperature range, and a condenser connected to the dryer via the pipe is maintained in a third temperature range; A recovery process is performed in which the internal pressure of the dryer, the pipe, and the condenser is reduced from normal pressure to a first pressure to recover the first carbonate in the condenser; Includes. The first temperature range includes a temperature range in which only the first carbonate vaporizes under the first pressure and both the first and second carbonates vaporize under a second pressure lower than the first pressure. The second temperature range includes a temperature range that is equal to or higher than the melting point of the second carbonate under the first pressure and equal to or lower than the thermal decomposition temperature of the electrolyte of the waste lithium ion batteries under the second pressure. The third temperature range includes a temperature range in which the first carbonate liquefies under the first pressure.

[0008] In a first aspect, the third temperature range may include a temperature range in which a first carbonate liquefies under the first pressure, a second carbonate liquefies under the second pressure, and the first carbonate condensed under the first pressure does not re-vaporize. In this case, the method may further include, after the step of recovering the first carbonate, a step of performing a recovery process in which the internal pressure of the dryer, the piping, and the condenser is reduced from the first pressure to the second pressure to recover the second carbonate in the condenser.

[0009] A second aspect of the present disclosure is an apparatus for recovering organic carbonate contained in an electrolyte of a used lithium ion battery. The device includes a dryer, a pipe, a condenser, a pressure pump, a dryer heater, a pipe heater, and a condenser heater. The dryer accommodates waste lithium ion batteries. The pipe extends below the dryer. The condenser is connected to the dryer via the pipe. The pressure pump adjusts the internal pressure of the dryer, the pipe, and the condenser. The dryer heater adjusts the internal temperature of the dryer. The pipe heater adjusts the internal temperature of the pipe. The condenser heater adjusts the internal temperature of the condenser. The organic carbonate includes a first carbonate and a second carbonate having a higher melting point and boiling point than the first carbonate. When the first carbonate recovery process is performed, the dryer heater maintains the internal temperature of the dryer in a first temperature range, the piping heater maintains the internal temperature of the piping in a second temperature range, and the condenser heater maintains the internal temperature of the condenser in a third temperature range. In the process of recovering the first carbonate, the pressure pump reduces the internal pressure of the dryer, the piping, and the condenser from normal pressure to a first pressure. The first temperature range includes a temperature range in which only the first carbonate vaporizes under the first pressure and both the first and second carbonates vaporize under a second pressure lower than the first pressure. The second temperature range includes a temperature range that is equal to or higher than the melting point of the second carbonate under the first pressure and equal to or lower than the thermal decomposition temperature of the electrolyte of the waste lithium ion batteries under the second pressure. The third temperature range includes a temperature range in which the first carbonate liquefies under the first pressure.

[0010] In a second aspect, the third temperature range may include a temperature range in which the first carbonate liquefies under the first pressure, the second carbonate liquefies under the second pressure, and the first carbonate condensed under the first pressure does not re-vaporize. In addition, the recovery process of the second carbonate may be performed after the recovery process of the first carbonate. In this case, in the recovery process of the second carbonate, the pressure pump may reduce the internal pressure of the dryer, the piping, and the condenser from the first pressure to the second pressure. Effect of the Invention

[0011] According to the present disclosure, it is possible to separate and recover the first carbonate contained in the electrolyte of a used lithium ion battery from the second carbonate contained in the electrolyte. In addition, by performing a recovery process of the second carbonate after a recovery process of the first carbonate, it is possible to recover the second carbonate in addition to the first carbonate. [Brief description of the drawings]

[0012] [Figure 1]FIG. 2 is a diagram illustrating an example of the configuration of a recovery device according to the first embodiment. [Diagram 2] 4 is a flowchart showing an example of processing by a control device that is particularly related to the first embodiment. [Diagram 3] FIG. 11 is a diagram illustrating an example of the configuration of a recovery device according to a second embodiment. [Figure 4] 10 is a flowchart showing an example of processing by a control device that is particularly related to the second embodiment. [Diagram 5] FIG. 13 is a diagram illustrating an example of the configuration of a recovery device according to a third embodiment. [Figure 6] 13 is a flowchart showing an example of processing by a control device that is particularly related to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

[0014] 1. Overview of the embodiment 1-1. Organic carbonates As already explained, the main components of the electrolyte of a lithium ion battery include organic carbonates such as ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), etc. In the present disclosure, these organic carbonates are recovered from used lithium ion batteries (hereinafter also referred to as "waste lithium ion batteries").

[0015] The melting points and boiling points at room temperature and pressure of the organic carbonates to be recovered in this disclosure are as shown in Table 1 below.

[0016] [Table 1]

[0017] As can be seen from Table 1, EC has the highest boiling point and melting point among the organic carbonates to be recovered. In particular, the boiling point of EC is more than 100° C. higher than DEC, which has the second highest boiling point. In light of this, in the present disclosure, the recovery process of organic carbonates other than EC (i.e., DMC, EMC, DEC) and the recovery process of EC are performed separately. Hereinafter, the organic carbonates other than EC will also be referred to as the "first carbonate" or "first CN", and EC will also be referred to as the "second carbonate" or "second CN".

[0018] 1-2. Overview of collection process In the present disclosure, the recovery process of the first and second carbonates is performed under heating and reduced pressure conditions. The reason for performing the process under heating and reduced pressure conditions is to vaporize the first and second carbonates in a short time. However, as is clear from the boiling point, the second CN is more difficult to vaporize than the first CN. Therefore, in the present disclosure, the degree of reduced pressure when the recovery process of the second CN is performed is set higher than that when the recovery process of the first CN is performed. For example, the recovery process of the first CN is performed under a pressure of about 50 hPa (e.g., 45 to 55 hPa), and the recovery process of the second CN is performed under a pressure of less than 3 hPa (e.g., 1 to 2 hPa). Hereinafter, the pressure of about 50 hPa is also referred to as the "first pressure", and the pressure of less than 3 hPa is also referred to as the "second pressure".

[0019] Thus, in the present disclosure, the pressure when the recovery process of the first and second CNs is performed is lower than that when the recovery process of the first CN is performed. Therefore, in the present disclosure, the recovery process of the first CN is performed before the recovery process of the second CN. By performing the recovery processes of the first and second carbonates in this order, it becomes possible to recover the first CN from the waste lithium-ion batteries in the recovery process of the first CN, and to recover the second CN from the waste lithium-ion batteries from which the first CN has been removed in the recovery process of the second CN.

[0020] In the present disclosure, the temperature conditions of the vaporization system and the condensation system are set based on the pressure conditions when the first CN recovery process is performed so that only the first CN is recovered in the first CN recovery process (i.e., the second CN is not recovered in the first CN recovery process). The temperature conditions of the vaporization system are set to conditions under which the first CN vaporizes under the pressure when the first CN recovery process is performed and the first CN does not thermally decompose. On the other hand, the temperature conditions of the condensation system are set to conditions under which the first CN liquefies under the pressure when the first CN recovery process is performed.

[0021] In the present disclosure, the temperature conditions of the vaporization system and the condensation system are set based on the pressure conditions when the recovery process of the second CN is performed so that the second CN is recovered in the recovery process of the second CN. The temperature conditions of the vaporization system are set to conditions under which the second CN vaporizes under the pressure when the recovery process of the second CN is performed and the first CN does not thermally decompose. The reason for the "conditions under which the first CN does not thermally decompose" is that EC is less susceptible to thermal decomposition than organic carbonates other than EC, so if the "conditions under which the first CN does not thermally decompose" are set, the second CN can be prevented from thermally decomposing. On the other hand, the temperature conditions of the condensation system are set to conditions under which the second CN liquefies under the pressure when the recovery process of the second CN is performed.

[0022] Examples of the vaporization system and the condensation system, and examples of the temperature conditions of the vaporization system and the condensation system will be described below with reference to examples of the configuration of the apparatus.

[0023] 2. First embodiment 2-1. Device configuration example FIG. 1 is a diagram showing a configuration example of a recovery device according to a first embodiment of the present disclosure. FIG. 1 shows a configuration example of a recovery device including a dryer 1, a condenser 2, a pipe 3, a pressure pump 4, and a control device 5. The dryer 1 and the pipe 3 correspond to a configuration corresponding to a "vaporization system," and the condenser 2 corresponds to a configuration corresponding to a "condensation system." Note that a heat insulating material (not shown) is provided at the connection between the dryer 1 and the pipe 3, suppressing heat transfer from the components of the dryer 1 to the pipe 3. Also, a heat insulating material (not shown) is provided at the connection between the condenser 2 and the pipe 3.

[0024] The dryer 1 contains crushed pieces BT of waste lithium ion batteries. The crushed pieces BT are obtained, for example, by crushing frozen waste lithium ion batteries outside the recovery device. The crushed pieces BT may be fed into the dryer 1 before or after heating the dryer 1, which will be described later. The dryer 1 is provided with a dryer heater 6 that adjusts the temperature of the gas inside.

[0025] The condenser 2 is a device for condensing the first or second carbonate in a gaseous state. The condenser 2 is disposed vertically below the dryer 1. The condenser 2 is provided with a condenser heater 7 for adjusting the temperature of the gas therein. The condenser 2 is connected to the dryer 1 via a pipe 3 having a straight shape. The pipe 3 is provided with a pipe heater 8 for adjusting the temperature of the gas therein.

[0026] The connection port of the pipe 3 on the condenser 2 side is located on the top surface of the condenser 2. On the other hand, the connection port of the pipe 3 on the dryer 1 side is located on the side surface of the dryer 1. The reason for this is that under heating and decompression conditions, the first or second carbonate vaporized in the dryer 1 may liquefy midway through the pipe 3, and if this occurs, the first or second carbonate will not be able to move to the condenser 2.

[0027] In this regard, by disposing the condenser 2 below the dryer 1 and making the pipe 3 connecting the dryer 1 and the condenser 2 straight, it becomes possible to introduce the first or second carbonate vaporized in the dryer 1 into the condenser 2. Note that the shape of the pipe 3 does not necessarily have to be straight, and any shape can be adopted as long as the shape of the pipe 3 does not point upward halfway.

[0028] The pressure pump 4 simultaneously adjusts the pressure of the gas inside the dryer 1, the condenser 2, and the piping 3. The pressure pump 4 is a so-called pressure reducing pump, and operates according to a control signal from the control device 5. When the pressure pump 4 operates, the pressure of the gas inside the dryer 1, the condenser 2, and the piping 3 decreases. The assumed pressures of the gas inside the dryer 1, the condenser 2, and the piping 3 due to the operation of the pressure pump 4 are a pressure of around 50 hPa (i.e., a first pressure) and a pressure of less than 3 hPa (i.e., a second pressure).

[0029] The control device 5 is typically a computer having at least one processor and at least one memory. The control device 5 controls the operation of the dryer heater 6, the condenser heater 7, and the piping heater 8. The control device 5 also controls the operation of the pressure pump 4. To control the operation of these three types of heaters and the pressure pump, the temperature T1 and pressure P1 of the gas inside the dryer 1, the temperature T2 and pressure P2 of the gas inside the condenser 2, and the temperature T3 of the gas inside the piping 3 are input to the control device 5. These physical quantities can be acquired, for example, from temperature sensors and pressure sensors attached to each component of the dryer 1, etc.

[0030] The control device 5 also controls the operation of the three types of heaters based on temperatures T1 to T3 so that the temperature of the gas inside the dryer 1 is maintained in a "first temperature range", that of the pipe 3 is maintained in a "second temperature range", and that of the condenser 2 is maintained in a "third temperature range".

[0031] Here, the first temperature range is a temperature range in which only the first CN vaporizes (evaporates) under the first pressure, and both the first and second CN vaporize under the second pressure. The second temperature range is a temperature range that is equal to or higher than the melting point of the second CN under the first pressure and equal to or lower than the thermal decomposition temperature of the electrolyte (e.g., LiPF6) of the waste lithium ion battery under the second pressure. The third temperature range is a temperature range in which the first CN liquefies (condenses) under the first pressure, the second CN liquefies under the second pressure, and the first CN condensed under the first pressure does not re-vaporize. In order to prevent the condenser 2 and the piping 3 from being clogged when the liquefied first and second CN are solidified, it is preferable that the lower limit of the third temperature range is a temperature at which the first CN condensed under the first pressure and the second CN condensed under the second pressure do not solidify. The first to third temperature ranges can be set in advance, for example, based on the first and second pressures and the melting point and boiling point of the organic carbonate to be recovered.

[0032] 2-2. Examples of organic carbonate recovery Fig. 2 is a flow chart showing an example of processing by the control device 5 that is particularly related to the first embodiment. The processing flow shown in Fig. 2 is executed, for example, after the introduction of the crushed pieces BT into the dryer 1 is completed. The introduction of the crushed pieces BT into the dryer 1 can also be performed between steps S12 and S13. In this case, the processing flow shown in Fig. 2 is executed, for example, when the recovery device is started.

[0033] In the process flow shown in Fig. 2, a temperature adjustment process is first performed (step S11). In this temperature adjustment process, for example, a heater drive control process is performed so that the temperature of the gas inside the dryer 1 is kept in a first temperature range, that of the pipe 3 is kept in a second temperature range, and that of the condenser 2 is kept in a third temperature range. An example of this drive control process is a feedback control process based on temperatures T1 to T3. Note that the temperature adjustment process continues to be executed even after the process of step S11 is finished, until the process of step S15 is started.

[0034] Following the process of step S11, it is determined whether the temperature has stabilized (step S12). If it is determined that the temperatures T1 to T3 are within the respective target temperature ranges (i.e., the first to third temperature ranges) as a result of the temperature adjustment process of step S11, the determination result of step S12 is positive. The process of step S12 is repeatedly executed until a positive determination result is obtained.

[0035] If a positive determination result is obtained in step S12, a recovery process of the first CN (i.e., DMC, EMC, and DEC) is performed (step S13). In the recovery process of the first CN, the operation of the pressure pump is controlled so that the gas pressure inside the dryer 1, the condenser 2, and the pipe 3 is reduced from normal pressure to a pressure of about 50 hPa (i.e., the first pressure). The recovery process of the first CN is continuously performed for a time that is preset as a time that allows sufficient recovery of the first CN, based on the amount of crushed pieces BT input into the dryer 1, for example.

[0036] When the pressure of the gas inside the dryer 1, the condenser 2, and the pipe 3 drops to the first pressure while the temperature adjustment process is being performed, the first CN is vaporized in the dryer 1, and this first CN flows into the condenser 2 through the pipe 3. The temperature of the gas inside the pipe 3 is maintained in the second temperature range. Therefore, a part of the first CN may be liquefied in the pipe 3. In this case, this part of the first CN flows into the condenser 2 in a liquid state. And the temperature of the gas inside the condenser 2 is maintained in the third temperature range. Therefore, the first CN that flows into the condenser 2 in a gaseous state is cooled and liquefied here. In this way, the first CN is recovered.

[0037] Following the process of step S13, a recovery process of the second CN (i.e., EC) is performed (step S14). In the recovery process of the second CN, the operation of the pressure pump is controlled so that the pressure of the gas inside the dryer 1, the condenser 2, and the pipe 3 is reduced from a pressure of about 50 hPa (i.e., the first pressure) to a pressure of less than 3 hPa (i.e., the second pressure). The recovery process of the second CN is continuously performed for a time that is preset as a time for which the second CN can be sufficiently recovered based on, for example, the amount of crushed pieces BT input into the dryer 1.

[0038] When the pressure of the gas inside the dryer 1, the condenser 2, and the pipe 3 drops to the second pressure while the temperature adjustment process is being performed, the second CN is vaporized in the dryer 1, and this second CN flows into the condenser 2 through the pipe 3. The temperature of the gas inside the pipe 3 is maintained in the second temperature range. Therefore, a part of the second CN may be liquefied in the pipe 3. In this case, this part of the second CN flows into the condenser 2 in a liquid state. The temperature of the gas inside the condenser 2 is maintained in a third temperature range. Therefore, the second CN that flows into the condenser 2 in a gaseous state is cooled and liquefied here. In this way, the second CN is recovered.

[0039] Incidentally, it is preferable that the first CN and the second CN are recovered using separate condensers 2 so that the first CN recovered in the first CN recovery process and the second CN recovered in the second CN recovery process are not mixed in the condenser 2. This recovery example will be described in the second and third embodiments.

[0040] Following the process of step S14, a pressure increase and temperature decrease process is performed (step S15). The pressure increase and temperature decrease process is a process for returning the temperature and pressure of the gas inside the dryer 1, the condenser 2, and the pipe 3 to normal temperature and normal pressure.

[0041] 3. Second embodiment 3-1.Example of device configuration Fig. 3 is a diagram showing a configuration example of a recovery device according to a second embodiment of the present disclosure. Unlike the configuration example shown in Fig. 1, Fig. 3 shows a configuration example including two types of condensers. Specifically, Fig. 3 shows a configuration example of a recovery device including a first condenser 21 and a second condenser 22, a first pipe 31 and a second pipe 32, a first condenser heater 71 and a second condenser heater 72, and a first pipe heater 81 and a second pipe heater 82.

[0042] The first condenser 21 is provided to recover the first CN. The first condenser 21 is disposed below the second condenser 22. The first condenser heater 71 is provided to adjust the temperature of the gas inside the first condenser 21. The first piping 31 has a straight shape, and connects the dryer 1 and the first condenser 21 via the second piping 32 and the second condenser 22.

[0043] The connection port of the first pipe 31 on the first condenser 21 side is located on the top surface of the first condenser 21. On the other hand, the connection port of the first pipe 31 on the second condenser 22 side is located on the side surface of the second condenser 22. The reason for adopting such a shape and arrangement of the first pipe 31 is basically the same as the reason for adopting the shape and arrangement of the pipe 3 described in the first embodiment.

[0044] The second condenser 22 is provided to recover the second CN. The second condenser heater 72 is provided to adjust the temperature of the gas inside the second condenser 22. The second piping 32 has a straight shape, and connects the dryer 1 and the second condenser 22.

[0045] The connection port of the second pipe 32 on the second condenser 22 side is located on the upper surface of the second condenser 22. On the other hand, the connection port of the second pipe 32 on the dryer 1 side is located at the dryer 1. The reason for adopting such a shape and arrangement of the second pipe 32 is basically the same as the reason for adopting the shape and arrangement of the pipe 3 described in the second embodiment.

[0046] In the second embodiment, the control device 5 controls the driving of the dryer heater 6, the first condenser heater 71, the second condenser heater 72, the first piping heater 81, and the second piping heater 82. To control the driving of these five types of heaters, the control device 5 receives inputs of the gas temperature T1 and pressure P1 inside the dryer 1, the gas temperature T21 and pressure P21 inside the first condenser 21, the gas temperature T22 and pressure P22 inside the second condenser 22, the gas temperature T31 inside the first piping 31, and the gas temperature T32 inside the second piping 32.

[0047] During the first CN recovery process, the control device 5 controls the operation of five types of heaters based on temperatures T1, T21, T22, T31 and T32 so that the temperatures of the gas inside the dryer 1, the second condenser 22 and the second piping 32 are maintained in the first temperature range, that of the first piping 31 is maintained in the second temperature range, and that of the first condenser 21 is maintained in the third temperature range.

[0048] On the other hand, during the recovery process of the second CN, the control device 5 controls the operation of the three types of heaters based on the temperatures T1, T22 and T32 so that the temperature of the gas inside the dryer 1 is maintained in the first temperature range, that of the second piping 32 is maintained in the second temperature range, and that of the second condenser 22 is maintained in the third temperature range.

[0049] During the recovery process of the second CN, the control device 5 further controls the driving of the two types of heaters based on the temperatures T21 and T31 so that the temperature of the gas in the first condenser 21 is maintained in a temperature range (for example, the first temperature range) higher than the third temperature range and the temperature of the gas inside the first piping 31 is maintained in a temperature range (for example, the first temperature range) higher than the second temperature range. The reason for this is to prevent the second CN from liquefying midway through the first piping 31 or in the first condenser 21, and to reliably recover the second CN in the second condenser 22.

[0050] The drive control of the pressure pump 4 by the control device 5 is the same as that in the first embodiment.

[0051] 3-2. Examples of organic carbonate recovery Fig. 4 is a flowchart showing an example of processing by the control device 5 that is particularly related to the second embodiment. An example of the start timing of the processing flow shown in Fig. 4 is the same as that of the processing flow described with reference to Fig. 2.

[0052] In the process flow shown in Fig. 4, first, a first temperature adjustment process is performed (step S21). In this first temperature adjustment process, for example, a heater drive control process is performed so that the temperatures of the gases in the dryer 1, the second condenser 22, and the second pipe 32 are kept in a first temperature range, that of the first pipe 31 is kept in a second temperature range, and that of the first condenser 21 is kept in a third temperature range. An example of this drive control process is a feedback control process based on temperatures T1, T21, T22, T31, and T32. Note that the first temperature adjustment process is continuously executed even after the process of step S21 is finished, until the process of step S24 is started.

[0053] Following the process of step S21, it is determined whether the temperature has stabilized (step S22). If it is determined that the temperatures T1, T21, T22, T31, and T32 fall within the respective target temperature ranges (i.e., the first to third temperature ranges) as a result of the first temperature adjustment process of step S21, the determination result of step S22 is positive. The process of step S22 is repeatedly executed until a positive determination result is obtained.

[0054] If a positive determination result is obtained in step S22, a recovery process of the first CN (i.e., DMC, EMC, and DEC) is performed (step S23). The contents of the recovery process of the first CN performed in step S23 are the same as those performed in step S13 of FIG.

[0055] When the pressure of the gas inside the dryer 1 etc. drops to the first pressure while the first temperature adjustment process is being performed, the first CN is vaporized in the dryer 1, and this first CN flows into the second condenser 22 through the second piping 32. The first CN in a gaseous state that has flowed into the second condenser 22 flows into the first condenser 21 through the first piping 31. The reason why the first CN maintains its gaseous state in the second condenser 22 is because the temperature of the gas inside the second condenser 22 and the second piping 32 is maintained in the first temperature range.

[0056] On the other hand, the temperature of the gas inside the first piping 31 is maintained in the second temperature range. Therefore, a portion of the first CN that flows from the second condenser 22 into the first piping 31 may be liquefied here. In this case, this portion of the first CN flows into the first condenser 21 in a liquid state. And the temperature of the gas inside the first condenser 21 is maintained in the third temperature range. Therefore, the first CN that flows into the first condenser 21 in a gaseous state is cooled and liquefied here. As a result, the first CN is recovered in the first condenser 21.

[0057] Following the process of step S23, a second temperature adjustment process is performed (step S24). In this second temperature adjustment process, for example, a heater drive control process is performed so that the temperatures of the gases in the dryer 1, the first condenser 21, and the first pipe 31 are kept in the first temperature range, that of the second pipe 32 is kept in the second temperature range, and that of the second condenser 22 is kept in the third temperature range. An example of this drive control process is a feedback control process based on temperatures T1, T21, T22, T31, and T32. The second temperature adjustment process is continued even after the process of step S24 is finished, until the process of step S27 is started.

[0058] Following the process of step S24, it is determined whether the temperature has stabilized (step S25). The process of step S25 is basically the same as that of step S21. That is, if it is determined that the temperatures T1, T21, T22, T31, and T32 fall within the respective target temperature ranges (i.e., the first to third temperature ranges) as a result of the second temperature adjustment process, the determination result of step S25 is positive. The process of step S25 is repeatedly executed until a positive determination result is obtained.

[0059] If a positive determination result is obtained in step S25, a process of collecting the second CN (i.e., the EC) is performed (step S26). The contents of the process of collecting the second CN performed in step S26 are the same as those performed in step S14 in FIG.

[0060] When the pressure of the gas inside the dryer 1 etc. drops to the second pressure while the second temperature adjustment process is being performed, the second CN is vaporized in the dryer 1, and this second CN flows into the second condenser 22 through the second pipe 32. The temperature of the gas inside the second pipe 32 is maintained in the second temperature range. Therefore, a part of the first CN that flows into the second pipe 32 from the dryer 1 may be liquefied here. In this case, this part of the second CN flows into the second condenser 22 in a liquid state. And the temperature of the gas inside the second condenser 22 is maintained in the third temperature range. Therefore, the second CN that flows into the second condenser 22 in a gaseous state is cooled and liquefied here. As a result, the second CN is recovered in the second condenser 22.

[0061] Following the process of step S26, a pressure increase and temperature decrease process is carried out (step S27). The content of the process of step S27 is the same as that of step S15 in FIG.

[0062] 4. Third embodiment 4-1. Device configuration example FIG. 5 is a diagram showing a configuration example of a recovery device according to a third embodiment of the present disclosure. As with the configuration example shown in FIG. 3, FIG. 5 shows a configuration example having two types of condensers. Specifically, the difference between the configuration example shown in FIG. 3 and that shown in FIG. 5 is the connection form of the dryer 1 to the first condenser 21 and the second condenser 22. That is, in the configuration example shown in FIG. 3, the first condenser 21 and the second condenser 22 are connected in series to the dryer 1. In contrast, in the configuration example shown in FIG. 5, the first condenser 21 and the second condenser 22 are connected in parallel to the dryer 1.

[0063] 5, in order to connect the first condenser 21 and the second condenser 22 in parallel, the first pipe 31 branches off from the middle of the second pipe 32. In addition, a switching valve 9 is provided at the point where the first pipe 31 branches off from the second pipe 32. The switching valve 9 switches the connection destination of the dryer 1 between the first condenser 21 and the second condenser 22, based on a control signal from the control device 5.

[0064] In the configuration example shown in Fig. 3, the first condenser 21 is provided below the second condenser 22. In contrast, in the third embodiment, the positional relationship between these condensers is not particularly limited. That is, the positional relationship between the first condenser 21 and the second condenser 22 does not have to be the positional relationship shown in Fig. 5, and this positional relationship may be reversed, or the first condenser 21 and the second condenser 22 may be provided at the same height. However, the first condenser 21 and the second condenser 22 are disposed below the dryer 1 in the vertical direction.

[0065] In the third embodiment, the control device 5 controls the switching valve 9. Specifically, the control device 5 switches the connection destination of the dryer 1 to the first condenser 21 during the recovery process of the first CN. On the other hand, the control device 5 switches the connection destination of the dryer 1 to the second condenser 22 during the recovery process of the second CN.

[0066] The control device 5 also controls the operation of five types of heaters based on temperatures T1, T21, T22, T31 and T32 so that the temperature of the gas inside the dryer 1 is maintained in a first temperature range, that of the first piping 31 and the second piping 32 is maintained in a second temperature range, and that of the first condenser 21 and the second condenser 22 is maintained in a third temperature range.

[0067] The drive control of the pressure pump 4 by the control device 5 is the same as that in the first embodiment.

[0068] 4-2. Examples of organic carbonate recovery Fig. 6 is a flowchart showing an example of processing by the control device 5 that is particularly related to the third embodiment. An example of the start timing of the processing flow shown in Fig. 6 is the same as that of the processing flow described with reference to Fig. 2.

[0069] In the process flow shown in Fig. 6, a temperature adjustment process is first performed (step S31). In this temperature adjustment process, for example, a heater drive control process is performed so that the temperature of the gas inside the dryer 1 is kept in a first temperature range, that of the first pipe 31 and the second pipe 32 is kept in a second temperature range, and that of the first condenser 21 and the second condenser 22 is kept in a third temperature range. An example of this drive control process is a feedback control process based on temperatures T1, T21, T22, T31, and T32. Note that this temperature adjustment process continues to be executed even after the process of step S31 ends, until the process of step S37 starts.

[0070] Following the process of step S31, it is determined whether the temperatures have stabilized (step S32). If it is determined that the temperatures T1, T21, T22, T31, and T32 fall within the respective target temperature ranges (i.e., the first to third temperature ranges) as a result of the temperature adjustment process of step S31, the determination result of step S32 is positive. The process of step S32 is repeatedly executed until a positive determination result is obtained.

[0071] If a positive determination result is obtained in step S32, the switching valve 9 is controlled to connect the dryer 1 to the first condenser 21 (step S33). That is, in the process of step S33, the connection destination of the dryer 1 is switched to the first condenser 21.

[0072] Following the process of step S33, a recovery process of the first CN (that is, DMC, EMC, and DEC) is performed (step S34). The contents of the recovery process of the first CN performed in step S34 are the same as those performed in step S13 of FIG.

[0073] When the pressure of the gas in the dryer 1, the first condenser 21, and the first pipe 31 drops to the first pressure while the temperature adjustment process is being performed, the first CN is vaporized in the dryer 1, and the first CN flows into the first condenser 21 through the first pipe 31. The temperature of the gas in the first pipe 31 and the second pipe 32 is maintained in the second temperature range. Therefore, in the second pipe 32 or the first pipe 31 upstream of the installation location of the switching valve 9, a part of the first CN may be liquefied. In this case, the part of the first CN flows into the first condenser 21 in a liquid state. The temperature of the gas in the first condenser 21 is maintained in the third temperature range. Therefore, the first CN that flows into the first condenser 21 in a gaseous state is cooled and liquefied here. As a result, the first CN is recovered in the first condenser 21.

[0074] Following the process of step S34, the switching valve 9 is controlled to connect the dryer 1 to the second condenser 22 (step S35). That is, in the process of step S35, the connection destination of the dryer 1 is switched to the second condenser 22.

[0075] Following the process of step S35, a collection process of the second CN (that is, the EC) is carried out (step S36). The contents of the collection process of the first CN carried out in step S36 are the same as those carried out in step S13 of FIG.

[0076] When the pressure of the gas inside the dryer 1, the second condenser 22, and the second pipe 32 drops to the second pressure while the temperature adjustment process is being performed, the second CN is vaporized in the dryer 1, and this second CN flows into the second condenser 22 through the second pipe 32. The temperature of the gas inside the second pipe 32 is maintained in the second temperature range. Therefore, a part of the second CN may be liquefied in the second pipe 32. In this case, this part of the second CN flows into the second condenser 22 in a liquid state. The temperature of the gas inside the second condenser 22 is maintained in the third temperature range. Therefore, the second CN that flows into the second condenser 22 in a gaseous state is cooled and liquefied here. As a result, the second CN is recovered in the second condenser 22.

[0077] Following the process of step S36, a pressure increase and temperature decrease process is carried out (step S37). The content of the process of step S37 is the same as that of step S15 in FIG. [Explanation of symbols]

[0078] 1 Dryer 2 Condenser 3 Piping 4 Pressure pump 5 Control device 6 Dryer heater 7 Condenser heater 8 Piping heater 9 Switching valve 21 First condenser 22 Second condenser 31 First piping 32 Second piping 71 First condenser heater 72 Second condenser heater 81 First piping heater 82 Second piping heater BT Debris T1, T2, T3, T21, T22, T31, T32 Temperature P1, P2, P21, P22 Pressure

Claims

1. A method for recovering organic carbonate contained in an electrolyte of a used lithium ion battery, comprising the steps of: The organic carbonate includes a first carbonate and a second carbonate having a higher melting point and a higher boiling point than the first carbonate, A step of performing a temperature adjustment process in which an internal temperature of a dryer in which waste lithium-ion batteries are accommodated is maintained in a first temperature range, an internal temperature of a pipe extending below the dryer is maintained in a second temperature range, and a temperature of a condenser connected to the dryer via the pipe is maintained in a third temperature range; A recovery process is performed in which the internal pressure of the dryer, the pipe, and the condenser is reduced from normal pressure to a first pressure to recover the first carbonate in the condenser; Including, The first temperature range includes a temperature range in which only the first carbonate vaporizes under the first pressure and both the first and second carbonates vaporize under a second pressure lower than the first pressure, the second temperature range includes a temperature range that is equal to or higher than the melting point of the second carbonate under the first pressure and equal to or lower than the thermal decomposition temperature of the electrolyte of the waste lithium ion batteries under the second pressure, and the third temperature range includes a temperature range in which the first carbonate liquefies under the first pressure. A method for recovering organic carbonates, comprising the steps of:

2. 2. The method of claim 1 , The third temperature range includes a temperature range in which the first carbonate liquefies under the first pressure, the second carbonate liquefies under the second pressure, and the first carbonate condensed under the first pressure does not re-vaporize; After the step of recovering the first carbonate, the method further includes a step of reducing the internal pressure of the dryer, the piping, and the condenser from the first pressure to the second pressure to recover the second carbonate in the condenser. A method for recovering organic carbonates, comprising the steps of:

3. 3. The method of claim 2, The condenser includes a first condenser that recovers the first carbonate, and a second condenser that is disposed below the first condenser and recovers the second carbonate, The piping includes a first piping that connects the dryer and the first condenser, and a second piping that connects the dryer and the second condenser, The first pipe is connected to the dryer via the second condenser and the second pipe, When the first carbonate recovery process is performed, in the temperature adjustment process, the internal temperatures of the dryer, the second pipe, and the second condenser are maintained in a first temperature range, the internal temperature of the first pipe is maintained in the second temperature range, and the internal temperature of the first condenser is maintained in the third temperature range; When the second carbonate recovery process is performed, in the temperature adjustment process, the internal temperatures of the dryer, the first pipe, and the first condenser are maintained in a first temperature range, the internal temperature of the second pipe is maintained in the second temperature range, and the internal temperature of the second condenser is maintained in the third temperature range. A method for recovering organic carbonates, comprising the steps of:

4. 3. The method of claim 2, The condenser includes a first condenser that recovers the first carbonate and a second condenser that recovers the second carbonate, The piping includes a first piping that connects the dryer and the first condenser, and a second piping that connects the dryer and the second condenser, The first pipe branches off from the middle of the second pipe, A step of switching the connection destination of the dryer between the first condenser and the second condenser is further provided, When the first carbonate recovery process is performed, in the temperature adjustment process, the internal temperatures of the first and second pipes are maintained in the second temperature range, and that of the first condenser is maintained in the third temperature range, and in the switching process, the connection destination of the dryer is switched to the first condenser, When the second carbonate recovery process is performed, in the temperature adjustment process, the internal temperature of the second pipe is maintained in the second temperature range, and that of the second condenser is maintained in the third temperature range, and in the switching process, the connection destination of the dryer is switched to the second condenser. A method for recovering organic carbonates, comprising the steps of:

5. An apparatus for recovering organic carbonate contained in an electrolyte of a used lithium ion battery, comprising: a dryer for accommodating waste lithium-ion batteries, a pipe extending below the dryer, a condenser connected to the dryer via the pipe, a pressure pump for adjusting the internal pressure of the dryer, the pipe, and the condenser, a dryer heater for adjusting the internal temperature of the dryer, a pipe heater for adjusting the internal temperature of the pipe, and a condenser heater for adjusting the internal temperature of the condenser, The organic carbonate includes a first carbonate and a second carbonate having a higher melting point and a higher boiling point than the first carbonate, When the first carbonate recovery process is performed, the dryer heater maintains the internal temperature of the dryer in a first temperature range, the piping heater maintains the internal temperature of the piping in a second temperature range, and the condenser heater maintains the internal temperature of the condenser in a third temperature range; In the recovery process of the first carbonate, the pressure pump reduces the internal pressure of the dryer, the piping, and the condenser from normal pressure to a first pressure, The first temperature range includes a temperature range in which only the first carbonate vaporizes under the first pressure and both the first and second carbonates vaporize under a second pressure lower than the first pressure, the second temperature range includes a temperature range that is equal to or higher than the melting point of the second carbonate under the first pressure and equal to or lower than the thermal decomposition temperature of the electrolyte of the waste lithium ion batteries under the second pressure, and the third temperature range includes a temperature range in which the first carbonate liquefies under the first pressure. An organic carbonate recovery apparatus comprising:

6. 6. The apparatus of claim 5, The third temperature range includes a temperature range in which the first carbonate liquefies under the first pressure, the second carbonate liquefies under the second pressure, and the first carbonate condensed under the first pressure does not re-vaporize; The recovery process of the second carbonate is carried out after the recovery process of the first carbonate, In the recovery process of the second carbonate, the pressure pump reduces the internal pressure of the dryer, the piping, and the condenser from the first pressure to the second pressure. An organic carbonate recovery apparatus comprising:

7. 7. The apparatus of claim 6, The condenser includes a first condenser that recovers the first carbonate, and a second condenser that is disposed below the first condenser and recovers the second carbonate, the condenser heater includes a first condenser heater that adjusts an internal temperature of the first condenser and a second condenser heater that adjusts an internal temperature of the second condenser; The piping includes a first piping that connects the dryer and the first condenser, and a second piping that connects the dryer and the second condenser, The first pipe is connected to the dryer via the second condenser and the second pipe, the piping heater includes a first piping heater that adjusts an internal temperature of the first piping and a second piping heater that adjusts an internal temperature of the second piping, When the first carbonate recovery process is performed, the dryer heater maintains the internal temperature of the dryer in a first temperature range, the second piping heater maintains the internal temperature of the second piping in the first temperature range, the second condenser heater maintains the internal temperature of the second condenser in the first temperature range, the first piping heater maintains the internal temperature of the first piping in the second temperature range, and the first condenser heater maintains the internal temperature of the first condenser in the third temperature range, When the second carbonate recovery process is performed, the dryer heater maintains the internal temperature of the dryer in a first temperature range, the first piping heater maintains the internal temperature of the first piping in the first temperature range, the first condenser heater maintains the internal temperature of the first condenser in the first temperature range, the second piping heater maintains the internal temperature of the second piping in the second temperature range, and the second condenser heater maintains the internal temperature of the second condenser in the third temperature range. An organic carbonate recovery apparatus comprising:

8. 7. The apparatus of claim 6, The condenser includes a first condenser that recovers the first carbonate and a second condenser that recovers the second carbonate, the condenser heater includes a first condenser heater that adjusts an internal temperature of the first condenser and a second condenser heater that adjusts an internal temperature of the second condenser, The piping includes a first piping that connects the dryer and the first condenser, and a second piping that connects the dryer and the second condenser, The first pipe branches off from the middle of the second pipe, The piping heater includes a first piping heater that adjusts an internal temperature of the first piping and a second piping heater that adjusts an internal temperature of the second piping, a switching valve provided at a branching portion where the first pipe branches into the second pipe and switches a connection destination of the dryer between the first condenser and the second condenser; When the first carbonate recovery process is performed, the first pipe heater maintains the internal temperatures of the first and second pipes in the second temperature range, the first condenser heater maintains the internal temperature of the first condenser in the third temperature range, and the switching valve switches the connection destination of the dryer to the first condenser, When the second carbonate recovery process is performed, the second pipe heater maintains the internal temperature of the second pipe in the second temperature range, the second condenser heater maintains the internal temperature of the second condenser in the third temperature range, and the switching valve switches the connection destination of the dryer to the second condenser. An organic carbonate recovery apparatus comprising:

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