Battery immersion method

Abstract

To provide battery immersion solution enabling thermal runaway of a battery to be suppressed.SOLUTION: Battery immersion solution is obtained by soaking chitosan in water, and a battery is immersed in the solution.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a battery soaking solution and a battery soaking method. [Background technology]

[0002] Electric vehicles, including hybrid electric vehicles, are equipped with batteries, such as lithium-ion batteries, nickel-metal hydride batteries, and all-solid-state batteries, to supply power for driving the wheels. When the original charging and discharging function of such batteries deteriorates due to the end of their life, they need to be replaced. As electric vehicles become more widespread, more and more used batteries are produced.

[0003] Patent Document 1 discloses a method for quickly discharging a used battery. This method includes an immersion step in which the battery is immersed in water containing a polypeptide. When the battery is immersed in water, the terminals of the battery are short-circuited by the water, and the battery is discharged through the water. In addition, valuable materials contained in the battery are precipitated in the water and collected by the polypeptide contained in the water. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-086753 Summary of the Invention [Problem to be solved by the invention]

[0005] Lithium-ion batteries are known to suffer from a phenomenon known as "thermal runaway," which can cause abnormal heat generation and fire. Thermal runaway occurs when a certain component inside the battery heats up due to some trigger, which then causes other components to heat up, causing the battery temperature to continue to rise. The main trigger for thermal runaway is an internal short circuit. An internal short circuit is caused, for example, when an external force or impact is applied to a battery during storage or transportation of a charged battery, causing the battery to deform or break. When an internal short circuit occurs, electricity flows suddenly to the negative electrode, causing the negative electrode to heat up. The heated negative electrode heats the positive electrode, which then causes an exothermic reaction in the positive electrode.

[0006] For this reason, measures such as using fireproof storage containers are used to store and transport batteries that contain electricity, but this method requires a large cost for storing and transporting the batteries. In the method disclosed in Patent Document 1, the battery is discharged through water, so electricity flows suddenly to the negative electrode, which may heat up the negative electrode and cause thermal runaway.

[0007] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a solution for immersing a battery that can suppress thermal runaway of the battery. [Means for solving the problem]

[0008] The battery immersion solution according to the present invention is made of water containing chitosan, and the battery is immersed in the solution.

[0009] In addition, the battery immersion method according to the present invention involves immersing a battery in a solution containing chitosan in water. Effect of the Invention

[0010] According to the present invention, it is possible to provide a battery immersion solution capable of suppressing thermal runaway of a battery. [Brief description of the drawings]

[0011] [Figure 1]1 is a flowchart illustrating a flow of a separation and extraction method including a battery immersion method according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram conceptually explaining the process from the salt water step to the separated extract obtaining step in the separation and extraction method, where FIG. 2(A) shows the salt water step, FIG. 2(B) shows the stable discharge solvent introduction step, FIG. 2(C) shows the battery introduction step, and FIG. 2(D) shows the separated extract obtaining step. [Diagram 3] FIG. 1 shows an example of the voltage progression of a battery infiltrated with water containing sodium chloride, chitosan, and citric acid. [Figure 4] FIG. 13 is a graph showing an example of the voltage progression of a battery infiltrated with water containing chitosan and citric acid but not sodium chloride. [Diagram 5] 10 is a flowchart illustrating the flow of a battery storage and transportation method including a battery immersion method according to a second embodiment of the present invention. [Figure 6] 6A and 6B are diagrams conceptually explaining the steps from the discharge prevention solvent injection step to the battery removal step in a battery storage and transportation method, where FIG. 6A shows the discharge prevention solvent injection step, FIG. 6B shows the battery injection step and the battery storage and transportation step, and FIG. 6C shows the battery removal step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a battery immersion solution according to an embodiment of the present invention will be described with reference to the drawings.

[0013] First Embodiment First, a battery immersion method according to a first embodiment will be described with reference to Figures 1 to 4. Figure 1 is a flow chart illustrating the flow of a separation and extraction method including a battery immersion method according to this embodiment.

[0014] As shown in Fig. 1, in the separation and extraction method, the salt water step (S110), the stable discharge solvent introduction step (S120), the battery introduction step (S130), and the separated extract acquisition step (S140) are performed in this order. Then, depending on the scale of the embodiment, the crushing step (S150) or the decomposition step (S160), the metal sorting step (S170), the re-infiltration step (S180), and the separated extract re-acquisition step (S190) are performed in this order (S180 and S190 are only S150), and the series of processes is completed. In the separation and extraction method, the stable discharge solvent introduction step (S120) and the battery introduction step (S130) may be collectively referred to as the infiltration step.

[0015] Figure 2 conceptually explains the process from the saltwater step to the separated extract obtaining step in the separation and extraction method. Figure 2(A) shows the saltwater step, Figure 2(B) shows the stable discharge solvent introduction step, Figure 2(C) shows the battery introduction step, and Figure 2(D) shows the separated extract obtaining step. In Figures 2(A) to 2(D), sodium chloride is written as "NaCl" and the stable discharge solvent is written as "solvent."

[0016] As shown in Fig. 2(A), before the saltwater step, water is stored in separation and extraction tank 10. In the saltwater step, sodium chloride is added to the water in separation and extraction tank 10. After the saltwater step is performed, the water in separation and extraction tank 10 contains sodium chloride.

[0017] As shown in Fig. 2(B), in the stable discharge solvent introduction step, chitosan, which functions as a stable discharge solvent, is introduced into the water in the separation and extraction tank 10. When the stable discharge solvent introduction step is carried out, chitosan is contained in the water in the separation and extraction tank 10. In other words, by carrying out both the salt water step and the stable discharge solvent introduction step, a solution containing both sodium chloride and chitosan in the water is produced.

[0018] In this example, the stable discharge solvent injection process is performed after the salt water process. However, the salt water process may be performed at least before the battery injection process, and may be performed after the stable discharge solvent injection process or in parallel with the stable discharge solvent injection process. The salt water process may also be omitted.

[0019] In addition, in the stable discharge solvent introduction step, acetic acid, citric acid, quaternary ammonium salt, and polypeptide may be introduced. In this case, when the stable discharge solvent introduction step is performed, the water in the separation and extraction tank 10 contains chitosan, acetic acid, citric acid, quaternary ammonium salt, and polypeptide. In other words, when both the salt water step and the stable discharge solvent introduction step are performed, the water contains sodium chloride, chitosan, acetic acid, citric acid, quaternary ammonium salt, and polypeptide. As the polypeptide, for example, polyglutamic acid can be used. Not limited to polyglutamic acid, other polypeptides having a flocculating effect may be used.

[0020] As shown in FIG. 2(C), in the battery introduction step, the battery 40 is introduced into the water after the stable discharge solvent introduction step. That is, in the soaking step including the stable discharge solvent introduction step and the battery introduction step, the battery 40 is soaked into water containing at least chitosan. The battery 40 is, for example, a vehicle battery mounted on a vehicle such as an electric vehicle. However, the battery 40 is not limited to a vehicle battery, and may be, for example, an electronic device battery that operates an electronic device. The battery 40 may be a lithium ion battery, a nickel metal hydride battery, or another type of battery.

[0021] The battery 40 is immersed in the water after the stable discharge solvent introduction step so that the terminals (not shown) of the battery 40 are immersed in the water. Here, since the salt water step is performed before the battery introduction step, when the battery introduction step is performed, the battery 40 is immersed in water containing both chitosan and sodium chloride.

[0022] Chitosan causes a chelating effect that retains electric charge. Therefore, even if the battery 40 is put into the water after the stable discharge solvent introduction process, the chelating effect of chitosan limits the discharge of the battery 40 through the water. Therefore, even if the battery 40 is immersed in the water after the stable discharge solvent introduction process, it is possible to prevent electricity from flowing suddenly to the negative electrode of the battery 40, and to suppress thermal runaway.

[0023] The strength of the chelating effect varies depending on the concentration of chitosan, so that the discharge of the battery 40 through water can be controlled by adjusting the concentration of chitosan.

[0024] Water in which citric acid is dissolved has a higher electrical conductivity than water in which citric acid is not dissolved. Therefore, when citric acid is added in the stable discharge solvent addition step, the amount of electricity flowing to the negative electrode of the battery 40 in the battery addition step can be adjusted by adjusting the concentrations of chitosan and citric acid, and the battery can be discharged early while suppressing thermal runaway.

[0025] The concentration of citric acid may be, for example, a saturated concentration. However, the concentration of citric acid is not limited to the saturated concentration, and may be, for example, about the salinity concentration of seawater. However, the higher the concentration of citric acid, the more quickly the battery 40 can be discharged.

[0026] Polypeptides have the effect of flocculating impurities in water. Therefore, when the polypeptide is added to water in the stable discharge solvent adding step, the battery 40 is immersed in water containing the polypeptide in the battery adding step. Then, the precipitates precipitated in the water from the battery 40 are captured by the polypeptide and precipitated.

[0027] The separated extract obtaining step is performed after a predetermined time has elapsed since the start of the battery charging step. The predetermined time is set based on the completion time of discharging the battery 40. In other words, the separated extract obtaining step is performed after the battery 40 is sufficiently discharged and the precipitate is deemed to have been sufficiently precipitated.

[0028] Here, used batteries may be collected in a charged (stored) state. For this reason, when valuable materials are collected from used batteries, it is necessary to discharge the battery until the voltage drops below a certain level at which electric shock from the battery can be avoided. This certain voltage corresponds to the criterion for determining whether or not discharging is complete. The certain voltage may be, for example, about the voltage of an auxiliary battery (e.g. For example, 13 V) or the voltage of a dry cell (for example, 2 V).

[0029] As shown in FIG. 2(D), in the separation and extraction obtaining step, the battery 40 is taken out from the water in the separation and extraction tank 10.

[0030] 3 is a diagram showing an example of the change in voltage of battery 40 soaked in water containing sodium chloride, chitosan, and citric acid. Battery 40 has a property of self-recovering its voltage when the environment changes from a soaked state to air, so the change in voltage of battery 40 is measured by repeating soaking and withdrawing.

[0031] 3, the voltage of the battery 40 soaked in water containing sodium chloride, chitosan, and citric acid falls below a predetermined voltage (the voltage at which discharging is considered complete) within 20 minutes. The time it takes for the voltage of the battery 40 to fall below the voltage at which discharging is considered complete also depends on the amount of stored electricity.

[0032] 4 is a diagram showing an example of the change in the voltage of the battery 40 immersed in water containing chitosan and citric acid but not sodium chloride. As in the case of obtaining the results shown in FIG. 3, the change in the voltage of the battery 40 was measured by repeating the immersion and withdrawal.

[0033] As shown in Fig. 4, chitosan is at a saturated concentration in the early stage of infiltration. Therefore, the voltage is maintained without dropping from the start of infiltration. After this, the chitosan is diluted to reduce the chitosan concentration, and the voltage of the battery 40 drops, that is, the battery 40 starts to discharge. Note that the chitosan concentration in the early stage of infiltration is not limited to the saturated concentration, and may be any concentration that can maintain the voltage of the battery 40.

[0034] When the concentration of chitosan is diluted, the amount of charge held by the chelating effect of chitosan is reduced. This causes a transfer of charge between the terminals of the battery 40 in the aqueous solution, i.e., a forced short circuit of the battery 40 occurs, and discharging begins. Even in this case, the diluted chitosan suppresses thermal runaway of the battery 40, so that ignition and steam explosion of the battery 40 can be prevented.

[0035] 4, the battery 40 soaked in water after diluting chitosan has a voltage below a predetermined voltage (a voltage considered to be discharged completely) within 20 minutes. The time it takes for the voltage of the battery 40 to fall below the voltage considered to be discharged completely depends on the amount of stored electricity.

[0036] Furthermore, in both cases where the battery 40 is immersed in water and where it is immersed in salt water, the voltage of the separation and extraction tank 10 when the battery 40 is immersed is very low. Therefore, even if a person touches the separation and extraction tank 10 when the battery 40 is immersed, the person will not receive an electric shock. In other words, the battery 40 can be discharged safely.

[0037] The temperature of the water in the separation and extraction tank 10 may be, for example, room temperature. However, the temperature of the water in the separation and extraction tank 10 is not limited to room temperature. The water in the separation and extraction tank 10 may be at least liquid, and may be, for example, higher than room temperature. The higher the temperature of the water in the separation and extraction tank 10, the more quickly the battery 40 can be discharged.

[0038] Although the present embodiment has been described above, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the claims, and it is understood that such examples also naturally fall within the technical scope of the present invention.

[0039] In the above embodiment, the battery 40 is treated as a used battery and is subjected to a crushing or disassembly process and a metal recovery process to recover valuable materials. However, since no voltage drop occurs in the battery 40 soaked in an aqueous solution with a high chitosan concentration, the battery 40 may be a used battery that is safely transported.

[0040] The solution in which the battery 40 is immersed may be water containing the following combinations of solvents: (1) Chitosan (2) Chitosan, sodium chloride (3) Chitosan, acetic acid (4) Chitosan, citric acid (5) Chitosan, quaternary ammonium salt (6) Chitosan, acetic acid, quaternary ammonium salt (7) Chitosan, citric acid, quaternary ammonium salt (8) Chitosan, sodium chloride, acetic acid (9) Chitosan, sodium chloride, citric acid (10) Chitosan, sodium chloride, quaternary ammonium salt (11) Chitosan, sodium chloride, acetic acid, quaternary ammonium salt (12) Chitosan, sodium chloride, citric acid, quaternary ammonium salt (13) Chitosan, Polypeptide (14) Chitosan, sodium chloride, polypeptide (15) Chitosan, acetic acid, polypeptide (16) Chitosan, citric acid, polypeptide (17) Chitosan, quaternary ammonium salts, polypeptides (18) Chitosan, acetic acid, quaternary ammonium salt, polypeptide (19) Chitosan, citric acid, quaternary ammonium salt, polypeptide (20) Chitosan, sodium chloride, acetic acid, polypeptide (21) Chitosan, sodium chloride, citric acid, polypeptide (22) Chitosan, sodium chloride, quaternary ammonium salts, polypeptides (23) Chitosan, sodium chloride, acetic acid, quaternary ammonium salt, polypeptide (24) Chitosan, sodium chloride, citric acid, quaternary ammonium salt, polypeptide

[0041] <Second embodiment> Next, a battery immersion method according to a second embodiment of the present invention will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a flowchart illustrating the flow of a battery storage and transportation method including the battery immersion method according to this embodiment.

[0042] 5, in the battery storage and transportation method, a series of processes are performed in the order of a discharge prevention solvent injection process (S210), a battery insertion process (S220), a battery storage and transportation process (S230), and a battery removal process (S240), and then the series of processes are completed. In the battery storage and transportation method, the discharge prevention solvent injection process (S210), the battery insertion process (S220), and the battery storage and transportation process (S230) may be collectively referred to as a soaking process.

[0043] Fig. 6 is a diagram conceptually explaining the steps from the discharge prevention solvent injection step to the battery removal step in the battery storage and transportation method. Fig. 6(A) shows the discharge prevention solvent injection step, Fig. 6(B) shows the battery insertion step and the battery storage and transportation step, and Fig. 6(C) shows the battery removal step. Note that in Figs. 6(A) to 6(C), the discharge prevention solvent is referred to as solvent.

[0044] As shown in Fig. 6(A), before the discharge prevention solvent introduction step, water is stored in the storage and transport tank 210. In the discharge prevention solvent introduction step, the discharge prevention solvent is introduced into the water in the storage and transport tank 210. The discharge prevention solvent contains chitosan and citric acid. After the solvent introduction step is performed, the water in the storage and transport tank 210 contains the discharge prevention solvent, chitosan, and citric acid.

[0045] The discharge prevention solvent may contain sodium chloride. In this case, the water in the storage / transport tank 210 contains all of chitosan, citric acid, and sodium chloride.

[0046] In this example, the discharge prevention solvent introduction step is performed by introducing a solvent in which chitosan, citric acid, and sodium chloride are mixed in their respective combinations. However, in the discharge prevention solvent introduction step, it is sufficient that the water in the storage / transport tank 210 is an aqueous solution in which chitosan, citric acid, and sodium chloride are dissolved in their respective combinations at least before the battery introduction step, and chitosan, citric acid, and sodium chloride may be introduced in order (in no particular order), or the introduction steps for each solvent may be performed in parallel. Also, sodium chloride does not have to be introduced. The solvent introduced in the discharge prevention solvent introduction step may be a high-concentration aqueous solution that is adjusted to a predetermined concentration when dissolved in the water in the storage / transport tank 210.

[0047] 6(B), in the battery introduction step, the battery 40 is introduced into the water after the discharge prevention solvent introduction step. That is, in the soaking step including the discharge prevention solvent introduction step, the battery introduction step, and the battery storage and transportation step, the battery 40 is soaked into water containing at least chitosan and citric acid. Here, because sodium chloride is introduced in the discharge prevention solvent introduction step, when the battery introduction step is performed, the battery 40 is soaked into water containing chitosan, citric acid, and sodium chloride.

[0048] 6(B), when the battery 40 is immersed in the water during the battery introduction step, the chelating effect of the chitosan contained in the water prevents the battery 40 from discharging. Therefore, even if the battery 40 is immersed in water after the discharge prevention solvent introduction step, it is possible to prevent electricity from flowing suddenly to the negative electrode of the battery 40, and to suppress thermal runaway.

[0049] The strength of the chelating effect varies depending on the concentration of chitosan. By making the concentration of chitosan a saturated concentration, it is possible to prevent the battery 40 from discharging, and it is possible to maintain the voltage of the battery 40.

[0050] The water in the storage / transport tank 210 contains citric acid. That is, the water is an aqueous solution in which citric acid is dissolved. The concentration of the aqueous citric acid solution can be, for example, a saturated concentration.

[0051] The battery insertion step is followed by a battery storage and transportation step, after which a battery removal step is carried out.

[0052] As shown in FIG. 6(C), in the battery removal step, the battery 40 is removed from the water in the storage and transport tank 210.

[0053] In the battery 40 stored and transported in this manner, the chitosan suppresses discharge and maintains the voltage of the battery 40. Therefore, when the battery 40 is taken out of the water in the storage and transport tank 210, it is in a charged state and can be used immediately.

[0054] It should be noted that the voltage transition of the battery 40 soaked in water containing chitosan, citric acid, and sodium chloride is not shown here.

[0055] Although not shown in the drawings, before the battery removal step, the chitosan may be diluted to reduce the chitosan concentration and the battery 40 may be discharged.

[0056] When the chitosan concentration decreases, the amount of charge held by the chelating effect of chitosan decreases. This causes charge to move between the terminals of the battery 40 in the aqueous solution, i.e., a forced short circuit of the battery 40 occurs, and discharging begins. Even in this case, the diluted chitosan suppresses thermal runaway of the battery 40, so that ignition and steam explosion of the battery 40 can be prevented.

[0057] When the battery 40 is discharged by diluting chitosan, the voltage of the infiltrated battery 40 can be reduced to a predetermined voltage (the voltage at which discharging is considered complete) or lower within, for example, 20 minutes, depending on the chitosan concentration and the amount of stored charge.

[0058] This predetermined voltage is a voltage that can prevent electric shock from the battery 40 that is retrieved in a charged state, and corresponds to a criterion for determining completion of discharge. The predetermined voltage may be, for example, about the voltage of the auxiliary battery 40 (e.g., 13 V) or about the voltage of a dry cell (e.g., 2 V).

[0059] Furthermore, when the battery 40 is immersed in the discharge prevention solvent aqueous solution, the voltage of the storage / transport tank 210 when the battery 40 is immersed is very low. Therefore, even if a person touches the storage / transport tank 210 when the battery 40 is immersed, the person will not receive an electric shock. In other words, the battery 40 can be stored and transported safely.

[0060] Although the present embodiment has been described above, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the claims, and it is understood that such examples also naturally fall within the technical scope of the present invention.

[0061] For example, in each of the above embodiments, the temperature of the water in the storage / transport tank 210 is room temperature. However, the temperature of the water in the storage / transport tank 210 is not limited to room temperature. As long as at least liquid is maintained inside the storage / transport tank 210, the temperature may be higher than room temperature, for example.

[0062] The solution in which the battery 40 is immersed may be water containing the following combinations of solvents: (25) Chitosan (26) Chitosan, Acetic Acid (27) Chitosan, citric acid (28) Chitosan, quaternary ammonium salt (29) Chitosan, acetic acid, quaternary ammonium salt (30) Chitosan, citric acid, quaternary ammonium salt [Explanation of symbols]

[0063] 40 Battery

Claims

1. A battery immersion solution in which a battery is immersed, the battery immersed in the water containing chitosan.

2. 10. The battery soaking solution of claim 1 further comprising sodium chloride.

3. 10. The battery soaking solution of claim 1 further comprising acetic acid.

4. 10. The battery soaking solution of claim 1 further comprising citric acid.

5. 2. The battery soaking solution according to claim 1, further comprising a quaternary ammonium salt.

6. 10. The battery soaking solution of claim 1 further comprising a polypeptide.

7. 1. A method for immersing a battery, comprising the steps of: A battery immersion method comprising immersing the battery in a solution containing chitosan in water.

8. 8. The battery soaking method of claim 7, further comprising diluting the chitosan after soaking the battery.

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