JP2018147838A - Methods for discharging and processing wasted lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide methods for discharging and processing a wasted lithium ion battery, which can reduce an environmental load and suppress the rapid change in voltage in discharge, and thus enable the achievement of a safe work operation.SOLUTION: A method for discharging a wasted lithium ion battery comprises immersing the lithium ion battery in an aqueous solution containing a surfactant and then discharging the battery. The concentration of the surfactant in the aqueous solution may be made 0.5% or more and 1.5% or less. The electric conductivity of the aqueous solution may be made 500 ms/m or more and 5000 ms/m or less. A method for processing a wasted lithium ion battery comprises : immersing the lithium ion battery in an aqueous solution containing a surfactant and then discharging the battery; roasting the lithium ion battery thus discharged; and smashing the lithium ion battery thus roasted, followed by classification.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for discharging and treating a waste lithium ion battery used as a power source for a hybrid vehicle or an electric vehicle.

  A lithium ion battery used as a power source for an electric vehicle such as a hybrid vehicle or an electric vehicle is arranged in a plurality of battery modules as lithium ion battery cells, and the vehicle is a battery pack in which a plurality of battery modules are housed in a resin-made box-shaped housing. Mounted on. In this battery pack, a plurality of battery modules are electrically connected by a wire harness or the like, and the battery pack is further mounted with a circuit, a switch, and the like for cutting off the battery control system and the high-power circuit.

  A lithium ion battery is composed of a positive electrode material in which lithium, cobalt, nickel, etc. are applied to an aluminum foil, a negative electrode material in which graphite, etc. is applied to a copper foil, an electrolytic solution, a separator, etc., so that lithium, cobalt, nickel, copper Including valuable materials such as aluminum. Therefore, recovering these valuable materials from discarded lithium batteries is extremely beneficial for Japan, which is scarce of resources.

  In order to recover the valuable materials from the waste lithium ion battery, separation and recovery are performed by roasting, crushing or crushing, sieving, sorting, and the like. The purpose of the roasting treatment is to thermally decompose and remove an organic solvent such as propylene carbonate and ethylene carbonate, a supporting salt of lithium hexafluorophosphate, and a separator such as polyethylene and polypropylene contained in the electrolytic solution.

  However, when a charged lithium ion battery is roasted, the internal organic electrolyte solution evaporates, and the internal volume rapidly expands. Therefore, it is preferable to discharge the lithium ion battery prior to roasting.

  As a general battery discharging method, there is a method of discharging a battery by connecting it to an electric circuit. However, when a lithium ion battery is discharged by this method, it takes a long time to complete the discharge, and it is difficult to employ this method for discharging a lithium ion battery.

  Therefore, as a discharge method other than the discharge by the electric circuit, which can be adopted for the lithium ion battery, the lithium ion battery is discharged by being immersed in the same electrolyte as the organic electrolyte contained therein ( And a method of discharging by immersing in an aqueous solution of chloride such as sodium chloride (see Patent Document 2).

Japanese Patent Laid-Open No. 10-255861 JP-A-10-223264

  However, when using a method in which a lithium ion battery is immersed and discharged in an organic electrolyte, it is necessary to use a high-concentration organic electrolyte, which increases the environmental load due to drainage after discharge.

  Moreover, when using the method of immersing in chloride aqueous solution and discharging, there exists a possibility that the furnace used by the heat processing which is a post process may corrode with chlorine. In addition, since the aqueous chloride solution has high conductivity, there is a risk that the lithium ion battery will short-circuit and the voltage will change abruptly, causing problems such as sudden boiling of the aqueous solution.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and reduces the environmental load and suppresses a rapid voltage change during discharge, thereby discharging and treating a waste lithium ion battery. The purpose is to safely perform the work involved.

  In order to achieve the above object, the present invention is a method for discharging a lithium ion battery, wherein the lithium ion battery is immersed in an aqueous solution containing a surfactant and discharged.

  According to the present invention, by performing discharge using a surfactant, it is possible to reduce the environmental load, suppress a sudden change in voltage during discharge, and perform discharge safely.

  In the above discharge method, the electrical conductivity of the aqueous solution can be 500 ms / m or more and 5000 ms / m or less. When the electric conductivity of the aqueous solution is less than 500 ms / m, the time required for discharge becomes extremely long, which is not practical. In addition, it is difficult for an aqueous solution containing a surfactant to have an electrical conductivity exceeding 5000 ms / m, and even if the surfactant is excessively added, only the cost is increased, and the discharge promoting effect is saturated.

  In the above discharge method, the concentration of the surfactant in the aqueous solution can be 0.5% or more and 1.5% or less. Thereby, it is possible to suppress the consumption of the surfactant and reduce the environmental load while exhibiting a sufficient discharge effect.

  Further, the present invention is a method for treating a lithium ion battery, the step of immersing the lithium ion battery in an aqueous solution containing a surfactant and discharging, and the step of roasting the lithium ion battery after discharge, And crushing and classifying the lithium ion battery after roasting.

  According to the present invention, the lithium ion battery can be discharged safely while reducing the environmental load, and the lithium ion battery can be roasted safely after the discharge treatment.

  In the treatment method, the electrical conductivity of the aqueous solution can be 500 ms / m or more and 5000 ms / m or less. When the electric conductivity of the aqueous solution is less than 500 ms / m, the time required for discharge becomes extremely long, which is not practical. In addition, it is difficult for an aqueous solution containing a surfactant to have an electric conductivity exceeding 5000 ms / m. Even if an excessive amount of a surfactant is added, only an increase in cost is caused and the effect of promoting discharge is saturated.

  In the treatment method, the concentration of the surfactant in the aqueous solution can be 0.5% or more and 1.5% or less. Thereby, it is possible to suppress the consumption of the surfactant and reduce the environmental load while exhibiting a sufficient discharge effect.

  As described above, according to the present invention, the environmental load is reduced, the rapid voltage change during discharge is suppressed, the environmental load is reduced, and the rapid voltage change during discharge is suppressed. It is possible to provide a discharge method and a treatment method for a waste lithium ion battery that can be safely performed.

It is a whole block diagram which shows the discharge experiment apparatus of a lithium ion battery. It is a graph which shows the experimental result using the experimental apparatus of FIG. It is the graph which extracted the result to 120 minutes among the results shown in the graph of FIG.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  During the lithium ion battery recycling process, in discharging the lithium ion battery before roasting, in the present embodiment, the lithium ion battery is immersed in an aqueous solution containing a surfactant.

  An anionic surfactant is used as the surfactant. Specifically, sulfonic acid type anionic surfactants such as sodium linear alkylbenzene sulfonate, sodium alkylbenzene sulfonate, sodium naphthalene sulfonate, and disodium naphthalene disulfonate, alpha sulfo fatty acid methyl ester salt, sodium octanoate Carboxylic acid type anionic surfactants such as sulfate ester type anionic surfactants such as sodium lauryl sulfate and sodium laureth sulfate can be used.

  Most of the cationic surfactants and amphoteric surfactants are unsuitable because they contain chlorine and there is a risk that chlorine is generated by discharge. In addition, the nonionic surfactant is inappropriate because it has a non-electrolyte hydrophilic portion and has no effect of promoting discharge.

  Only one type of surfactant may be used, or a plurality of types of surfactants may be mixed and used. Since the surfactant has extremely low toxicity, the environmental load due to the waste liquid containing the surfactant can be reduced as compared with the case of using a conventional organic electrolyte or the like.

  The aqueous solution containing the surfactant is prepared by dissolving the surfactant in industrial water (engineering water). The aqueous solution containing the surfactant may be one in which only the surfactant is dissolved, or one in which components other than the surfactant are also dissolved. However, this aqueous solution needs to be free from chlorides such as sodium chloride.

  The electric conductivity of the aqueous solution containing the surfactant is set to 500 ms / m or more and 5000 ms / m or less. When the electric conductivity of the aqueous solution is less than 500 ms / m, the time required for discharge becomes extremely long, which is not practical. In addition, it is difficult for an aqueous solution containing a surfactant to have an electric conductivity exceeding 5000 ms / m. Even if an excessive amount of a surfactant is added, only an increase in cost is caused and the effect of promoting discharge is saturated.

  The concentration of the surfactant in the aqueous solution containing the surfactant is adjusted to 0.5% or more and 1.5% or less. If the concentration of the surfactant is less than 0.5%, the electric conductivity of the aqueous solution becomes extremely low, and the lithium ion battery cannot be discharged, or it takes a long time to discharge, which is not practical. On the other hand, when the concentration of the surfactant exceeds 1.5%, the discharge of the lithium ion battery may be abrupt and may cause bumping, and the environmental load increases when the aqueous solution is discarded.

  The immersion of the lithium ion battery in the aqueous solution containing the surfactant having the above concentration is performed until the voltage of the lithium ion battery starts to rapidly decrease as will be described later. Thereby, it becomes possible to reduce the charge amount of a lithium ion battery to the grade which can be safely roasted.

  The discharged lithium ion battery is then roasted, and after the roasted lithium ion battery is pulverized and classified, valuable materials such as lithium, cobalt, nickel, copper, and aluminum are recovered. By treating the waste lithium ion battery in this way, valuable materials can be recycled.

  Next, an experimental example regarding discharge of a lithium ion battery using an aqueous solution containing a surfactant will be described. In this experiment, an in-vehicle lithium ion battery having an average voltage of 39.4 V was used as the lithium ion battery LB.

  FIG. 1 is an overall configuration diagram showing a discharge experiment apparatus for a lithium ion battery.

  The experimental apparatus 1 mainly includes a measurement container 2, a storage container 4, a waste liquid container 9, a measuring machine 13, and a camera 14.

  The measuring container 2 has a capacity of 50 L, and immerses the lithium ion battery LB in an aqueous solution containing industrial water, saline, or a surfactant, and measures voltage and the like. A ground wire is provided in the measurement container 2.

  The storage container 4 has a capacity of 250 L, and stores industrial water, saline, or an aqueous solution containing a surfactant supplied to the measurement container 2. The storage container 4 is connected to the measurement container 2 via the pipe 3. Supply of the industrial water, the salt solution, or the aqueous solution containing the surfactant from the storage container 4 to the measurement container 2 is performed by an air driven pump 5 provided in the pipe 3. The air drive pump 5 is driven by using the compressed air supplied from the compressed air cylinder 7 through the pipe 6 as a power source.

  The waste liquid container 9 is a container having a capacity of 250 L, and stores the waste liquid discharged from the measurement container 2. The waste liquid container 9 is connected to the measurement container 2 via the pipe 8. The transfer of the waste liquid from the measurement container 2 to the waste liquid container 9 is performed by a pump 10 provided in the pipe 8. The pump 10 is driven by using electricity supplied from the AC power supply 11 as a power source. The driving of the pump 10 is on / off controlled by a switch 12.

  The measuring device 13 measures the voltage of the lithium ion battery LB in the measurement container 2 and measures the water temperature in the measurement container 2. Data obtained by the measuring instrument 13 is displayed on a display device (not shown) and stored in a storage device (not shown).

  The camera 14 is a camera for observing the inside of the measurement container 2 from the outside. An image photographed by the camera 14 is displayed on the display device described above and stored in a storage device.

  In an experiment using the experimental apparatus 1 having the above-described configuration, first, the lithium ion battery LB is disposed in the measurement container 2 and an aqueous solution containing industrial water, saline, or a surfactant is stored in the storage container 4. did.

  As the saline, industrial water was used as a solvent, sodium chloride was used as a solute, and 1% and 3% concentrations were prepared.

  In addition, as an aqueous solution containing a surfactant, an industrial water was used as a solvent, and an aqueous solution was prepared by diluting a commercial clothing detergent containing a surfactant. This laundry detergent contains 22% sodium linear alkylbenzene sulfonate, an anionic surfactant. And the density | concentration of this washing | cleaning detergent was 3% and 5%, ie, the aqueous solution whose surfactant concentration is 0.66% and 1.1% was prepared.

  Electrical conductivity was 10 mS / m for industrial water, 1400 mS / m for 1% saline, 5000 mS / m for 3% saline, 1000 mS / m for 3% detergent solution, and 1500 mS / m for 5% detergent solution. .

  Next, one end of the voltage connection wiring was connected to the lithium ion battery LB, and the other end was connected to the measuring instrument 13. In addition, a thermometer for water temperature measurement was disposed in the storage container 4. The thermometer was also connected to the measuring device 13 through wiring.

  Next, the air drive pump 5 was driven, and 35 L of industrial water, 1% saline, 3% saline, 3% detergent solution or 5% detergent solution was charged from the storage container 4 to the measuring container 2. Then, the lithium ion battery LB was immersed in each liquid, the voltage and the water temperature were measured by the measuring device 13, and the state of the lithium ion battery LB was observed by the camera 14.

  After the immersion, the pump 10 was driven, the liquid in the measurement container 2 was discharged to the waste liquid container 9, and the test was completed. The test results are shown in FIGS.

  When the lithium ion battery LB was immersed in industrial water, the battery was hardly discharged and the voltage was hardly lowered. Moreover, generation | occurrence | production of the bubble from the lithium ion battery LB and generation | occurrence | production of the steam and smoke from industrial water were not seen.

  On the other hand, when the lithium ion battery LB was immersed in a 1% saline solution, the voltage began to drop rapidly in about 10 minutes from the start of immersion, and became 1 V in about 80 minutes. At this time, bubbles were generated in 1% saline solution, and generation of steam and smoke was also confirmed.

  In addition, when the lithium ion battery LB was immersed in 3% saline, the voltage started to decrease rapidly in about 30 minutes from the start of immersion, and became 1 V in about 50 minutes. At this time, bubbles were generated in 3% saline, and generation of steam and smoke was also confirmed.

  When the lithium ion battery LB was immersed in a 3% detergent solution, the voltage began to drop rapidly in about 60 minutes from the start of immersion, and became 1 V in about 700 minutes. Generation of bubbles, steam and smoke was not confirmed in the 3% detergent solution.

  In addition, when the lithium ion battery LB was immersed in a 5% detergent solution, the voltage started to drop sharply in about 50 minutes from the start of immersion, and became 1 V in about 400 minutes. Generation of bubbles, steam and smoke was not confirmed in the 5% detergent solution.

  From the experimental results described above, when the discharge treatment of the lithium ion battery LB is performed using a detergent solution (an aqueous solution containing a surfactant), the change in voltage at the time of discharge is smaller than when using a saline solution. It was found to be calm, free from bubbles, steam and smoke, and to discharge safely.

  In addition, when the lithium ion battery LB is discharged, the voltage that has been gradually decreased starts to decrease abruptly. However, further research by the inventor has revealed that the lithium ion battery LB after the sudden decrease in voltage has started. Then it was found that there was no risk of explosion during roasting.

  As described above, in the case of a 3% detergent solution (0.66% surfactant aqueous solution), the voltage starts to drop sharply at the point of 60 minutes from the start of immersion, and the 5% detergent solution (1.1% In the case of a surfactant aqueous solution), it is 50 minutes from the start of immersion. Therefore, if it is after these time points, the discharge of the lithium ion battery prior to roasting has been sufficiently performed, and the subsequent roasting can be performed safely.

DESCRIPTION OF SYMBOLS 1 Experimental apparatus 2 Measuring container 3 Piping 4 Storage container 5 Air drive pump 6 Piping 7 Compressed air cylinder 8 Piping 9 Waste liquid container 10 Pump 11 AC power supply 12 Switch 13 Measuring machine 14 Camera LB Lithium ion battery

Claims (6)

  A method for discharging a waste lithium ion battery, wherein the lithium ion battery is discharged by being immersed in an aqueous solution containing a surfactant.   The method for discharging a waste lithium ion battery according to claim 1, wherein the electrical conductivity of the aqueous solution is 500 ms / m or more and 5000 ms / m or less.   The method for discharging a waste lithium ion battery according to claim 1 or 2, wherein the concentration of the surfactant in the aqueous solution is 0.5% or more and 1.5% or less. A step of immersing a lithium ion battery in an aqueous solution containing a surfactant and discharging;
Roasting the lithium ion battery after discharge;
And a step of pulverizing and classifying the lithium ion battery after roasting.   The method for treating a waste lithium ion battery according to claim 4, wherein the electrical conductivity of the aqueous solution is 500 ms / m or more and 5000 ms / m or less.   The method for treating a waste lithium ion battery according to claim 4 or 5, wherein the concentration of the surfactant in the aqueous solution is 0.5% or more and 1.5% or less.

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