Method for heat treatment of battery and recovery of valuable material

Abstract

To heat-treat a battery at an optimal temperature, and efficiently recover valuable materials in a high-quality state by suppressing temperature rise due to thermal runaway of the battery during a heat treatment process.SOLUTION: A battery heat treatment method is a heat treatment method for recovering a valuable material from a battery 1, and includes a thermal runaway inducing step of inducing thermal runaway in the battery 1, and a heat treatment step of heat treating the pretreated battery treated in the thermal runaway inducing step to form a heat-treated battery, and the pretreated battery in which thermal runaway has been forcibly induced in the thermal runaway inducing step is heat-treated in the heat treatment step.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for heat treating a battery and a method for recovering valuable materials by heat treating a battery. [Background technology]

[0002] Valuable materials can be recovered from batteries by heat treatment. Heat treatment vaporizes and removes the battery's electrolyte. Batteries with the electrolyte removed have the advantage that valuable materials can be safely recovered. This recovery method makes it possible to recover non-ferrous valuable materials such as lithium, cobalt, nickel, copper foil, and aluminum foil from, for example, lithium-ion secondary batteries. Valuable materials can be recovered by heat treating the batteries, then crushing, pulverizing, and sorting to separate each valuable material. The recovered valuable materials can be effectively reused as raw materials for batteries, so technology to recover valuable materials from batteries is extremely important in resource-poor Japan.

[0003] The batteries are placed in a heat treatment furnace and heated to a preset temperature for heat treatment. In the heat treatment of the batteries, the batteries are heated to a preset temperature and baked to a state in which valuables can be efficiently recovered from the heat-treated batteries. If the heat treatment temperature of the batteries is too high or too low, it will be a factor that hinders efficient recovery of valuables in a high-quality state. In the heat treatment of the batteries, the temperature of the heated batteries is controlled to a set value by controlling the thermal energy supplied to the heat treatment furnace. However, if a battery that has been heated and has a high temperature for the heat treatment goes into thermal runaway, the battery temperature will rise suddenly and exceed the preferred temperature range, which will hinder the preferred heat treatment. Furthermore, a battery that has gone into thermal runaway will instantly emit high-temperature exhaust gas, and the high-temperature exhaust gas emitted from the battery will suddenly increase the internal temperature of the heat treatment furnace, hindering heat treatment even at the preferred temperature of other batteries. A sudden temperature rise in the battery will melt the valuables to be recovered or oxidize them, lowering the quality of the valuables to be recovered, and hindering efficient recovery of high-quality valuables. In particular, batteries that are not completely discharged, i.e., batteries with a large remaining capacity (SOC), have the problem that if the positive and negative electrodes are shorted, an excessively large short-circuit current flows, and the Joule heat of this short-circuit current generates heat, making them susceptible to thermal runaway.

[0004] Patent Document 1 discloses a technology in which, in a process of heat treating a lithium-ion secondary battery having a voltage of 80% or more of its rated voltage, the lithium-ion secondary battery is heated to 350°C or more and 430°C or less, and if the lithium-ion secondary battery ignites during this heat treatment process, the thermal energy supplied to the heat treatment furnace is changed to 50% or less of the amount of heat supplied before the lithium-ion secondary battery ignited. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-150282 Summary of the Invention [Problem to be solved by the invention]

[0006] In the method described in Patent Document 1, when a lithium-ion secondary battery undergoes heat treatment and ignites, the heat treatment temperature is limited by supplying 50% or less of heat energy. However, although this method can limit the gradual temperature rise of the battery, it cannot control the sudden temperature rise caused by the instantaneous generation of heat energy due to thermal runaway of the battery, and the temperature inside the furnace rises instantaneously and cannot be maintained at the set temperature, which becomes a factor that hinders the effective recovery of valuable materials from the heat-treated battery. The battery is heat-treated by heating, but since the battery may go into thermal runaway due to heating during the heat treatment, it is not possible to completely eliminate irregular thermal runaway of unspecified batteries in this heat treatment process, and it is extremely difficult to prevent a sudden rise in the internal temperature of the heat treatment furnace due to thermal runaway. The probability of the battery going into thermal runaway can be reduced by lowering the set temperature in the heat treatment process, but the low temperature range in which all batteries are heat-treated without going into thermal runaway does not allow efficient recovery of valuable materials. For this reason, in the heat treatment process, the adverse effect of random thermal runaway of unspecified batteries cannot be eliminated, and it is extremely difficult to prevent an abnormal rise in the temperature inside the furnace due to thermal runaway of batteries in the heat treatment process. Furthermore, since the heat treatment of batteries is carried out simultaneously by putting multiple batteries into a heat treatment furnace in order to efficiently heat treat a large number of discarded batteries, the thermal runaway of a specific battery also adversely affects other batteries being heat treated at the same time, becoming a factor that hinders the effective recovery of valuable materials.

[0007] The present disclosure has been developed with the aim of eliminating the above-mentioned disadvantages, and one of the objects of the present disclosure is to provide a method for heat-treating a battery within an optimal temperature range by suppressing the temperature rise due to thermal runaway of the battery during the heat treatment process, and a valuables recovery method that can efficiently recover valuables in a high-quality state by heat-treating the battery using this heat treatment method. [Means for solving the problem]

[0008] A battery heat treatment method according to one embodiment of the present disclosure is a heat treatment method for recovering valuables from a battery, and includes a thermal runaway induction step of inducing thermal runaway in a battery, and a heat treatment step of heat treating a pretreated battery treated in the thermal runaway induction step to produce a heat-treated battery, in which the pretreated battery in which thermal runaway has been forcibly induced in the thermal runaway induction step is heat-treated in the heat treatment step.

[0009] A method for recovering valuables from a battery according to one embodiment of the present disclosure is a method for recovering valuables from a battery, and includes a thermal runaway inducing step of inducing thermal runaway in a battery, a heat treatment step of heat-treating the pretreated battery treated in the thermal runaway inducing step to form a heat-treated battery, and a recovery step of crushing the heat-treated battery obtained in the heat treatment step to separate and recover valuables, and the valuables are recovered in the recovery step from the heat-treated battery obtained by heat-treating the pretreated battery in which thermal runaway has been forcibly induced in the thermal runaway inducing step. Effect of the Invention

[0010] The above method has the advantage that it can suppress temperature rise due to thermal runaway of the battery during the heat treatment process, heat treat the battery within an optimal temperature range, and efficiently recover valuable materials from the battery in a high-quality state. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram of a method for recovering valuable materials from a battery according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram showing an example of a thermal runaway inducing step (thermal runaway chamber). [Diagram 3] FIG. 2 is a schematic diagram showing an example of a heat treatment process (heat treatment chamber). [Figure 4] FIG. 2 is a schematic diagram showing a state in which a pretreated battery is heat-treated in a heat treatment step. [Diagram 5] FIG. 2 is a schematic perspective view showing an example of a heat treatment case. [Figure 6] FIG. 2 is a schematic side view showing an example of a heat treatment case. [Figure 7] FIG. 4 is a schematic cross-sectional view showing another embodiment of a heat treatment case. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present disclosure will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper", "lower", and other terms including these terms) are used as necessary, but the use of these terms is for the purpose of facilitating understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. In addition, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or members. Furthermore, the embodiments shown below are specific examples of the technical ideas of the present invention, and do not limit the present invention to the following. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative and not to limit the scope of the present invention. Furthermore, the contents described in one embodiment or example can be applied to other embodiments or examples. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation.

[0013] A battery heat treatment method according to one embodiment of the present disclosure is a heat treatment method for recovering valuables from a battery, and includes a thermal runaway induction step of inducing thermal runaway in a battery, and a heat treatment step of heat-treating a pretreated battery treated in the thermal runaway induction step to form a heat-treated battery, and the pretreated battery in which thermal runaway has been forcibly induced in the thermal runaway induction step is heat-treated in the heat treatment step to form a heat-treated battery.

[0014] The above-mentioned battery heat treatment method has the advantage that it can prevent the adverse effects of thermal runaway of the battery in the heat treatment process and heat treat the battery in a preferred temperature range. This is because by inducing thermal runaway in the battery in advance in the thermal runaway induction process to make it a pre-treated battery, it is possible to prevent an abnormal temperature rise due to thermal runaway of the battery in the next heat treatment process and heat treat the battery in a set preferred temperature range. Furthermore, the above-mentioned heat treatment method does not require measures to prevent thermal runaway of the battery in the heat treatment process, and it also realizes the advantage that all batteries, including batteries that are heated in the heat treatment process and have a high probability of thermal runaway, can be heat treated at an optimal temperature and valuable materials can be recovered in high quality from the heat-treated batteries.

[0015] In the above method, a specific battery goes into thermal runaway in the thermal runaway induction step, but the external environment of the battery in the thermal runaway induction step is different from that in the heat treatment step. The battery in the heat treatment step is heated to an optimal temperature for recovering valuables, but the battery in the thermal runaway induction step does not need to be heated to a preferred temperature for recovering valuables. A battery that goes into thermal runaway in the heat treatment step goes into thermal runaway in a state where it is heated to an optimal temperature for heat treatment and instantly emits high-temperature, high-pressure exhaust gas, so that the heat treatment temperature rises rapidly and becomes abnormally high. In contrast, the thermal runaway in the thermal runaway induction step can be induced by shorting the positive and negative electrodes without heating the battery, or by partially heating the battery in a short time, so that the battery temperature can be limited to cause thermal runaway. The thermal runaway induction step does not need to heat the entire battery to a preset temperature range in order to recover valuables in a high-quality state. Therefore, the thermal runaway induction step can suppress thermal damage to a battery that goes into thermal runaway in this step. The heat treatment process can bake the pretreated batteries at an optimal temperature to prevent thermal runaway, so valuable materials can be efficiently recovered in high quality by crushing, pulverizing, and classifying the heat-treated batteries.

[0016] A method for heat-treating a battery according to another embodiment of the present disclosure can convert a used battery into a lithium-ion secondary battery. The above method has the advantage that heat treatment can be performed at an optimal temperature to efficiently recover high-quality valuable materials from the lithium-ion secondary battery of the heat-treated battery.

[0017] In another embodiment of the present disclosure, the battery heat treatment method includes a fire extinguishing step in which a thermal runaway battery that has gone into thermal runaway in the thermal runaway induction step is immersed in water or water is sprayed on the thermal runaway battery to extinguish or prevent ignition caused by thermal runaway, and the battery is heat treated in the heat treatment step after the fire extinguishing step. The above method can quickly extinguish a thermal runaway battery that has ignited in the thermal runaway induction step. Therefore, the time loss required to extinguish a thermal runaway battery that has ignited in the thermal runaway induction step can be reduced. In addition, the time loss can be reduced by preventing ignition in advance. In a battery that has gone into thermal runaway in the thermal runaway induction step, the thermal energy of the thermal runaway heats the constituent materials of the battery, causing flammable materials such as plastics to ignite, and the ignited battery continues to burn for several hours, which is a problem in that the battery cannot be moved to the next heat treatment step. The above method has the advantage that the time for the thermal runaway induction step can be significantly shortened and the next heat treatment step can be performed efficiently, since the battery that has gone into thermal runaway and caught fire can be quickly extinguished by immersing it in water or spraying it with water. In particular, the battery that has been extinguished by immersing it in water or spraying it with water contains a large amount of moisture, but this moisture is quickly vaporized and removed in the next heat treatment step. Therefore, the battery that has been immersed in water in the extinguishing step can be quickly transferred to the next heat treatment step for heat treatment without drying.

[0018] In another embodiment of the present disclosure, a thermal runaway chamber of a closed structure that contains a battery and induces thermal runaway in a thermal runaway inducing step and a heat treatment chamber of a closed structure that contains a battery and heat treats the battery in a heat treatment step are independent of each other, and the battery can be moved from the thermal runaway chamber to the heat treatment chamber for heat treatment after inducing thermal runaway in the thermal runaway chamber. The above method induces thermal runaway in the battery in a thermal runaway chamber of a closed structure in the thermal runaway inducing step, and in the subsequent heat treatment step, the battery is moved to a closed heat treatment chamber that is closed and independent from the thermal runaway chamber and heat treated therein. Therefore, in the thermal runaway inducing step, thermal runaway in the battery is induced in a preferred environment, and then the battery is moved from the thermal runaway chamber to the heat treatment chamber and heat treated in a preferred temperature environment, resulting in a heat-treated battery from which valuables can be efficiently recovered.

[0019] In the thermal runaway inducing step of the battery heat treatment method according to another embodiment of the present disclosure, a short-circuit rod is inserted into the battery, and the electrodes are forcibly short-circuited internally by the short-circuit rod to induce thermal runaway. The above method is characterized in that it can induce thermal runaway without heating the battery, and therefore can reduce the thermal damage of the battery caused by thermal runaway and can be heat-treated in the next heat treatment step.

[0020] In the thermal runaway inducing step of the thermal runaway in the thermal treatment method for a battery according to another embodiment of the present disclosure, the output of the battery can be short-circuited to induce thermal runaway. In a battery that is equipped with a protection circuit on the output side that cuts off current with a short-circuit current, the protection circuit can be bypassed to short-circuit the output to induce thermal runaway. The above method has the advantage that thermal runaway can be induced without heating the battery, so that the battery can be heat-treated in the next heat treatment step with less thermal damage caused by thermal runaway.

[0021] In another embodiment of the present disclosure, the battery heat treatment method can induce thermal runaway by partially heating the battery in the thermal runaway inducing step. Since the above method induces thermal runaway by partially heating the battery, it has an advantage that the battery can be heat-treated in the next heat treatment step with less thermal damage caused by thermal runaway compared to a method of heating the entire battery.

[0022] In the thermal runaway inducing step of the thermal runaway in the thermal treatment method for a battery according to another embodiment of the present disclosure, a laser beam is irradiated onto the battery to induce thermal runaway. The above method induces thermal runaway by irradiating the battery with a laser beam without physical contact, and therefore has the advantage that the battery can be heat-treated in the next heat treatment step with less thermal damage caused by thermal runaway.

[0023] A method for recovering valuables from batteries according to another embodiment of the present disclosure includes a thermal runaway inducing step of inducing thermal runaway in a battery, a heat treatment step of heat-treating the pretreated battery treated in the thermal runaway inducing step to form a heat-treated battery, and a recovery step of crushing the heat-treated battery obtained in the heat treatment step to separate and recover valuables, and valuables are recovered in the recovery step from the heat-treated battery obtained by heat-treating the pretreated battery in which thermal runaway has been forcibly induced in the thermal runaway inducing step.

[0024] The above method for recovering valuable materials from batteries has the advantage that it can prevent thermal runaway of the battery in the heat treatment process and heat treat the battery at a preferred temperature. This is because by inducing thermal runaway in the battery in advance in the thermal runaway inducing process to make it a pretreated battery, it is possible to prevent abnormal temperature rise due to thermal runaway of the battery in the next heat treatment process and heat treat it. Furthermore, the above method for recovering valuable materials from batteries has the advantage that it does not require measures to prevent thermal runaway of the battery in the heat treatment process and can heat treat the battery in an ideal state by performing heat treatment at an optimal temperature for heat treatment.

[0025] In the above method, the external conditions of the battery that goes into thermal runaway in the thermal runaway induction process, especially the temperature environment, are different from those of the battery that goes into thermal runaway in the heat treatment process. The battery that goes into thermal runaway in the heat treatment process goes into thermal runaway in a state of continuous heating, in other words, the temperature of the entire battery is raised, so the high-temperature, high-pressure exhaust gas that is ejected becomes a heat source that rapidly raises the temperature inside the heat treatment furnace. In contrast, the thermal runaway in the thermal runaway induction process causes the battery to go into thermal runaway by shorting the positive and negative electrodes of the battery or by partially heating it, so that the temperature rise in the thermal runaway chamber caused by the exhaust gas from the battery that has gone into thermal runaway can be limited. Unlike the heat treatment process, this thermal runaway induction process does not require the entire battery to be heated to a high temperature for the purpose of recovering valuables. Therefore, the thermal runaway induction process limits the temperature rise in the thermal runaway chamber caused by the heating of the battery that has gone into thermal runaway in this process, and can reduce thermal damage caused by heating the battery. In the heat treatment process, the pretreated batteries treated in the thermal runaway induction process can be baked at an optimal temperature, so that thermal runaway of the batteries can be prevented and the heat treatment can be performed at a preferred temperature, allowing high-quality valuable materials to be efficiently recovered from the heat-treated batteries.

[0026] A method for recovering valuable materials from a battery according to another embodiment of the present disclosure can recover valuable materials from a lithium-ion secondary battery. The above method has the advantage that valuable materials can be efficiently recovered with high quality from the lithium-ion secondary battery.

[0027] The method for recovering valuable materials from a battery according to another embodiment of the present disclosure may include a fire-extinguishing step in which a battery that has gone into thermal runaway in the thermal runaway induction step is immersed in water or water is sprayed on the battery that has gone into thermal runaway. This method has the advantage that a battery that has gone into thermal runaway and ignited in the thermal runaway induction step can be quickly extinguished and moved to the next heat treatment step. A battery that has gone into thermal runaway in the thermal runaway induction step may ignite by heating the constituent materials of the battery with the thermal energy of the thermal runaway, and combustible materials such as electrolyte and plastic may continue to burn. A battery that has ignited may continue to burn for several hours and may not be able to be moved to the next heat treatment step, but the above method has the advantage that a battery that has gone into thermal runaway and ignited can be extinguished in a short time by immersing it in water or spraying water, thereby significantly shortening the time for the thermal runaway induction step and moving to the next heat treatment step for efficient heat treatment. In particular, a battery that has gone into water and extinguished contains a large amount of moisture, but the contained moisture is quickly vaporized and removed in the next heat treatment step. Therefore, this method has the advantage that the batteries immersed in water in the fire-extinguishing step can be quickly transferred to the next heat treatment step for heat treatment without being dried.

[0028] In a method for recovering valuables from a battery according to another embodiment of the present disclosure, a thermal runaway chamber having a closed structure in which a battery is stored in a thermal runaway inducing step and thermal runaway is induced, and a heat treatment chamber having a closed structure in which a battery is stored in a heat treatment step and thermally treated are independent of each other, and after inducing thermal runaway in the thermal runaway chamber, the battery is moved from the thermal runaway chamber to the heat treatment chamber for heat treatment. The above method induces thermal runaway in the battery in a thermal runaway chamber having a closed structure in the thermal runaway inducing step, and in the subsequent heat treatment step, the battery is moved to a closed heat treatment chamber having a closed structure and independent from the thermal runaway chamber for heat treatment, so that in the thermal runaway inducing step, thermal runaway in the battery is induced in a preferred environment, and then the battery is moved from the thermal runaway chamber to the heat treatment chamber and heat treated in a preferred temperature environment, thereby enabling efficient recovery of valuables.

[0029] In a method for recovering valuable materials from a battery according to another embodiment of the present disclosure, a short-circuiting rod is inserted into the battery in a thermal runaway inducing step, and the electrodes are forcibly short-circuited internally with the short-circuiting rod to induce thermal runaway. The above method is characterized in that thermal runaway can be induced without heating the battery, thereby reducing thermal damage to the battery due to thermal runaway, and valuable materials can be efficiently recovered by heat treatment in the next heat treatment step.

[0030] In the method for recovering valuable materials from a battery according to another embodiment of the present disclosure, in the thermal runaway inducing step, the output of the battery can be short-circuited to induce thermal runaway. The above method has the advantage that thermal damage to the battery caused by thermal runaway can be reduced and valuable materials can be efficiently recovered by heat treatment in the subsequent heat treatment step, since thermal runaway can be induced without heating the battery.

[0031] In the method for recovering valuable materials from a battery according to another embodiment of the present disclosure, the battery can be partially heated to induce thermal runaway in the thermal runaway inducing step. Since the above method induces thermal runaway by partially heating the battery, it has an advantage that the thermal damage to the battery caused by thermal runaway is reduced compared to a method in which the entire battery is heated, and valuable materials can be efficiently recovered by heat treatment in the subsequent heat treatment step.

[0032] In a method for recovering valuable materials from a battery according to another embodiment of the present disclosure, a laser beam can be irradiated onto the battery in a thermal runaway inducing step to induce thermal runaway. The above method induces thermal runaway by irradiating a laser beam onto the battery without physical contact, and thus has the advantage of being able to reduce thermal damage to the battery caused by thermal runaway and to efficiently recover valuable materials by heat treatment in the subsequent heat treatment step.

[0033] In the method for recovering valuables from batteries according to another embodiment of the present disclosure, the heat-treated battery product is crushed in the recovery step, and black mass containing valuables can be separated from the crushed product. The above method has the advantage that the valuables can be efficiently recovered by separating black mass containing valuables from the crushed product of the heat-treated battery.

[0034] A method for recovering valuables from batteries according to another embodiment of the present disclosure includes a recovery step of crushing heat-treated batteries and separating black mass containing valuables from the crushed material, the black mass containing any of cobalt, nickel, lithium, and aluminum. The above method has the feature that valuables containing any of cobalt, nickel, lithium, and aluminum can be efficiently recovered by separating black mass containing valuables from crushed heat-treated batteries.

[0035] In the method for recovering valuable materials from a battery according to another embodiment of the present disclosure, the battery can be a battery having an aluminum foil as a core body of an electrode. The above method has a feature that valuable materials can be efficiently recovered from a battery having an aluminum foil as a core body of an electrode.

[0036] In the method for recovering valuable materials from batteries according to another embodiment of the present disclosure, the batteries can be continuously heat-treated in a continuous furnace in the heat treatment step. The above method has the advantage that valuable materials can be efficiently recovered. (Embodiment 1)

[0037] The present disclosure relates to a method for heat-treating a battery to produce a heat-treated battery, and then crushing, pulverizing, classifying, and otherwise recovering valuable materials from the heat-treated battery. In particular, the present disclosure is characterized in that the heat-treatment method for a battery is performed in a thermal runaway induction step and a heat treatment step. As a method for recovering valuable materials from a battery that has been heat-treated by the heat treatment method, not only currently used methods but also methods to be developed in the future can be used. Therefore, the present disclosure does not limit the method for recovering valuable materials from a heat-treated battery to the method described below, and all other methods that can recover valuable materials from a heat-treated battery can be used.

[0038] The battery is a battery that contains at least valuable materials to be recovered. The battery is, for example, a used or discarded battery, and includes a battery that has been used due to its lifespan, a defective battery that has a defect during manufacture or subsequent use, a battery that has been discarded during use, a battery in an equipment that has been used due to its lifespan, a battery in a defective equipment that has a defect during manufacture or subsequent use, and a battery in an equipment that has been discarded during use. Since the present disclosure recovers valuable materials of the constituent materials by heat treating the battery, the structure, shape, size, capacity, mode, type, etc. of the battery to be heat treated are not specified, but for example, the structure of the battery includes a positive electrode, a negative electrode, a separator, an electrolyte, and a battery case, cover, film, or other container that contains these. In addition, the present disclosure does not specify the type of battery, but since valuable materials can be recovered by heat treating the battery, the battery is suitable for use with a battery with excellent characteristics that is currently widely used, particularly a lithium ion secondary battery with a large charge / discharge capacity relative to its weight and volume. However, the present disclosure does not limit the battery to a lithium ion secondary battery, since valuable materials can be recovered from any battery that can be subjected to heat treatment to recover valuable materials.

[0039] Furthermore, the present disclosure does not specify a battery as a single battery cell, but includes, for example, a battery unit used as a power source for driving a motor for driving an electric vehicle. The battery unit is a battery in which, for example, multiple secondary batteries such as lithium ion secondary batteries are placed in a metal exterior case and used as a power source device. Valuables can be recovered from the battery unit by heat treatment without disassembling it into battery cells. Therefore, in the method of the present disclosure, the battery from which valuables are recovered by heat treatment is used in a broad sense to include not only a single battery but also a battery unit consisting of multiple batteries. Since it requires cost, effort, and time to disassemble a battery unit into single battery cells, valuables are recovered by heat treatment without disassembling the battery unit into single battery cells. For this reason, the present disclosure does not specify a battery from which valuables are recovered by heat treatment as a single battery, but includes a battery unit consisting of multiple batteries. Furthermore, since a battery unit has multiple batteries built in a metal exterior case, the method of recovering valuables by heat treatment of a battery unit has the feature that in addition to the constituent materials of the batteries, the metal material of the exterior case can also be recovered together. In addition, the heat treatment method and recovery method disclosed herein perform heat treatment and recover valuable materials without disassembling the battery unit, thereby preventing accidents caused by disassembling the battery and enabling valuable materials to be recovered safely.

[0040] Furthermore, the present disclosure relates to a method for recovering valuables by heat treating a battery, but the valuables recovered are specified by the constituent materials of the battery, and for example, valuables recovered from a lithium-ion secondary battery include the constituent materials of the electrodes, such as copper foil, aluminum foil, cobalt, nickel, and lithium, as well as the metal material of the case, etc. Since the valuables recovered by heat treatment vary depending on the constituent materials of the battery, the present disclosure does not specify the valuables recovered from the battery, and the valuables contained in the battery are specified by the constituent materials of the battery.

[0041] The block diagram in Figure 1 shows a method for recovering valuable materials from batteries and a heat treatment method for recovery. The recovery method shown in this figure includes a thermal runaway induction process in which the battery is forced into thermal runaway as a pre-process of the heat treatment process in order to prevent an abnormal temperature rise caused by thermal runaway of the battery in the heat treatment process, and the pre-treated battery in which thermal runaway has been forcibly induced in the thermal runaway induction process is heat-treated in the heat treatment process. The recovery process recovers valuable materials from the heat-treated battery that has been heat-treated in the heat treatment process. [Thermal runaway induction process]

[0042] The thermal runaway inducing step forces the battery 1, which is heat-treated in the heat treatment step, to go into thermal runaway. In the thermal runaway inducing step, the battery 1 is induced to go into thermal runaway to become a pre-treated battery. The pre-treated battery is a battery in which thermal runaway is induced in the thermal runaway inducing step. The method of inducing thermal runaway in the thermal runaway inducing step is not particularly limited and can be appropriately selected according to the purpose. For example, the battery goes into thermal runaway by forcibly short-circuiting the positive and negative electrodes or by heating, so this step can preferably cause thermal runaway by short-circuiting the positive and negative electrodes or by heating. The method of short-circuiting the positive and negative electrodes to cause thermal runaway includes a method of short-circuiting the positive and negative electrodes inside the battery and a method of short-circuiting outside the battery. The method of short-circuiting the electrodes inside the battery can be realized, for example, by penetrating a conductive nail so as to penetrate the battery and causing an internal short circuit. The thermal runaway inducing step ensures safety by storing the battery 1 in a thermal runaway chamber 10 having a closed structure and inducing thermal runaway. The thermal runaway chamber 10 can be provided with a mechanism for inducing thermal runaway in the battery 1, and can efficiently induce thermal runaway in the battery 1. The mechanism for inducing thermal runaway is not particularly limited and can be appropriately selected according to the purpose. For example, as shown in FIG. 2, a penetration mechanism 11 for penetrating the battery 1 with a metal nail 11a, an external short circuit mechanism 12 for short-circuiting the outside of the battery 1, and a flame blowing mechanism 13 such as a burner for partially blowing a flame onto the battery 1 can be provided. One or more mechanisms for inducing thermal runaway can be provided. The thermal runaway chamber 10 can be provided with an exhaust processing unit 14 for exhausting the air inside the thermal runaway chamber 10 and discharging the thermal energy of the battery undergoing thermal runaway, thereby limiting the temperature rise inside the thermal runaway chamber 10.

[0043] The battery 1 can be efficiently heat-treated without disassembling a battery module consisting of multiple battery cells connected in series or parallel, and valuable materials can be recovered. Therefore, the thermal runaway inducing step can efficiently induce thermal runaway in the battery module state, preferably without disassembling the battery 1 into battery cells. This method involves, for example, penetrating a battery module with a pointed metal nail 11a. The metal nail 11a penetrating the battery cell penetrates and short-circuits the positive and negative electrodes inside the battery cell. An excessive short-circuit current flows in a battery cell in which the positive and negative electrodes are short-circuited. The short-circuit current instantaneously generates Joule heat and causes the battery cell to go into thermal runaway. This method has the characteristic of being able to reliably cause thermal runaway in battery cells that are not completely discharged. This is because the metal nail 11a penetrating the battery cell short-circuits the positive and negative electrodes, causing an excessive current to flow partially and causing intensive heating inside the battery cell. In particular, lithium-ion secondary batteries have the characteristic that they can reliably experience thermal runaway because the solvent-based electrolyte is heated and ignited by Joule heat caused by a short circuit current.

[0044] The method of inserting metal nails 11a into battery cells to induce thermal runaway requires that metal nails 11a penetrate the battery cells of a battery module, because metal nails 11a penetrating the battery cells short out the electrodes internally, causing thermal runaway. Batteries 1 come in various forms, and for example, the battery modules of batteries mounted on electric vehicles have a structure in which multiple battery cells are housed in a sturdy exterior case. For example, by removing the exterior case of this battery module, metal nails 11a can be smoothly inserted into the battery cells to induce thermal runaway.

[0045] The method of inserting the metal nail 11a into the battery may cause a battery cell that is internally shorted by the metal nail 11a to go into thermal runaway, and the thermal runaway battery cell may induce thermal runaway in other battery cells. This is because the high-temperature, high-pressure ejection from the thermal runaway battery cell heats the other battery cells and induces thermal runaway. If thermal runaway is induced in other battery cells, the thermal runaway battery cell also ejects high-temperature, high-pressure ejection, causing a sudden increase in the total thermal energy ejected from the battery cell, and further increasing the probability of inducing thermal runaway in other battery cells. Therefore, in this state, multiple battery cells go into thermal runaway, and the occurrence of thermal runaway in battery cells can be more effectively prevented in the next heat treatment process.

[0046] In a battery 1 consisting of multiple battery cells, multiple metal nails 11a can be inserted into the battery module at the same time to cause multiple battery cells to go into thermal runaway at the same time. When multiple battery cells go into thermal runaway, each battery cell emits high-temperature, high-pressure ejection material, and the thermal energy emitted from the battery cells increases. Therefore, this method has the advantage that a battery cell that has gone into thermal runaway can cause other battery cells to go into thermal runaway, causing a larger number of battery cells to go into thermal runaway. The method of inserting multiple metal nails 11a into the battery module is suitable for inducing thermal runaway in large batteries.

[0047] The battery 1 can induce thermal runaway by shorting the output side, regardless of internal short circuit. In the method of inducing thermal runaway by providing an external short circuit mechanism 12 and shorting the output side, in a battery not equipped with a protection circuit, thermal runaway can be induced by shorting the output terminal and passing an excessive short current, but in a battery equipped with a protection circuit that cuts off the current when the output current exceeds a threshold, thermal runaway can be induced by shorting the output terminal, for example, by bypassing the fuse or switching element of the protection circuit. The thermal runaway induction step of shorting the output terminal to induce thermal runaway can easily cause thermal runaway in a battery module compared to the method of inserting a metal nail 11a. This is because thermal runaway can be induced by shorting the output terminal. In this method, the output terminal is shorted and an excessive short current flows in all battery cells. A large short current flows in all battery cells, and each battery cell generates heat due to Joule heat. The same short current flows in battery cells connected in series, causing heat generation. Battery modules with multiple battery cells, especially battery modules with many battery cells, may be connected in series and parallel, but even in parallel-connected battery cells, they are connected to reduce current imbalance, so that an approximately equal short-circuit current flows through each battery cell. Therefore, the method of shorting the output terminals allows an approximately equal short-circuit current to flow through multiple battery cells, making the thermal energy of heat generated by Joule heat in each battery cell approximately equal, and inducing thermal runaway in each battery cell.

[0048] The thermal runaway inducing step can also induce thermal runaway by heating the battery 1. In the thermal runaway inducing step, the battery 1 is stored in a thermal runaway chamber 10 having a closed structure to induce thermal runaway, thereby ensuring and improving safety. The thermal runaway inducing step can induce thermal runaway by heating the battery 1, but the thermal runaway inducing step heats the battery in an environment that limits the temperature rise caused by the thermal energy of the thermal runaway battery 1. For example, as shown in FIG. 2, the thermal runaway inducing step of heating the battery 1 to induce thermal runaway can be induced by a flame blowing mechanism 13 that blows flames partially onto the surface of the battery 1 placed in the thermal runaway chamber 10 without heating the entire battery 1, and further, the thermal energy of the thermal runaway battery 1 is exhausted from the thermal runaway chamber 10 by an exhaust processing unit 14, thereby limiting the temperature rise in the thermal runaway chamber 10.

[0049] The thermal runaway inducing step of heating the battery 1 heats the battery 1 in the same manner as the heat treatment step, but the battery 1 can be heated in a heating environment different from that of the heat treatment step. The heating in the thermal runaway inducing step is forcibly inducing thermal runaway in the battery 1 before the heat treatment step, while the heat treatment step heats the battery 1 at a predetermined heat treatment temperature to make the battery 1 in a favorable state for recovering valuables. For example, in the thermal runaway inducing step of FIG. 2, the flame blowing mechanism 13 partially blows a flame toward the surface of the battery 1 placed in the thermal runaway chamber 10 to induce thermal runaway, thereby limiting the temperature rise in the thermal runaway chamber 10 without heating the entire battery 1, and the exhaust treatment unit 14 exhausts the thermal energy of the battery 1 undergoing thermal runaway from the thermal runaway chamber 10 to the outside, thereby limiting the temperature rise in the thermal runaway chamber 10. The thermal runaway inducing step intentionally induces thermal runaway in the battery 1 in advance, thereby limiting the temperature rise in the battery 1 due to thermal runaway in the subsequent heat treatment step, thereby preventing a decrease in the recovery efficiency and quality of valuables due to an abnormal temperature rise in the battery 1 in the heat treatment step, and enabling the recovery of valuables in a high-quality state or efficient recovery of valuables. In the heat treatment step described below, as shown in Figures 3 and 4, the battery 1 (pre-treated battery) is placed in a heat treatment chamber 20 in which the furnace temperature is set to a predetermined heat treatment temperature and heat treated.

[0050] The thermal runaway induction step can also be performed by irradiating the battery 1 with a laser beam to forcibly induce thermal runaway without physical contact. This can be achieved by concentrating the energy of the laser on the irradiated area to melt it, open a hole, and cause an internal short circuit. The size and depth of the hole to be opened are set to be sufficient to cause an internal short circuit in the battery 1. The size of the hole to be opened is, for example, 3 mm to 40 mm, preferably 5 mm to 30 mm. The method and configuration of the laser beam irradiation are not specified, and all lasers that are currently commercially available or will be developed in the future that can forcibly induce thermal runaway in the battery 1 can be used. The laser can penetrate a specified thickness with a fixed focus, and the focus and depth positions can be changed. In addition, a short circuit can be reliably caused by irradiating multiple laser beams.

[0051] The atmosphere used to induce thermal runaway is not particularly limited and can be appropriately selected depending on the purpose, for example, air atmosphere, inert atmosphere, reducing atmosphere, low-oxygen atmosphere, etc. [Extinguishing process]

[0052] In the fire-extinguishing process, the battery that has gone into thermal runaway and caught fire in the thermal runaway induction process is immersed in water or sprayed with water to extinguish and deactivate it. In the fire-extinguishing process, the battery is immersed in water or sprayed with water to prevent the battery from catching fire. The battery 1 (pre-treatment battery) in which thermal runaway has been induced in the thermal runaway induction process emits high-temperature exhaust gas, which may ignite if the high-temperature exhaust gas comes into contact with air. The battery that has ignited continues to burn for a long time until the combustible material is burned out. The battery that has ignited moves to the next heat treatment process and cannot be heat-treated in a normal state. If the battery that has ignited burns for a long time, the fire will not go out for several hours. The battery that has ignited moves to the next heat treatment process after the fire goes out, which requires unnecessary fire-extinguishing time, and there is a problem that the total time for heat-treating the battery 1 is long. In the extinguishing step, for example, the battery 1 that has gone into thermal runaway and caught fire in the thermal runaway induction step is immersed in water or water is sprayed on the battery 1 that has gone into thermal runaway to quickly extinguish the fire. The extinguishing step for quickly extinguishing the battery 1 that has gone into thermal runaway and caught fire shortens the total time for heat-treating the battery 1. In the battery 1 that has gone into thermal runaway in the thermal runaway induction step, the sudden rise in temperature can cause, for example, plastic, which is a constituent material of the battery, to ignite, and the burning can continue for a long time. If the battery in a burning state is heat-treated in the next heat treatment step without extinguishing the fire, it cannot be fired in a desirable state. This is because the battery is heated to a temperature higher than the set temperature. Since it can take an extremely long time, such as several hours, for the burning battery to extinguish and go out of fire, if the battery 1 goes into thermal runaway in the thermal runaway induction step, a considerably long time is required for the fire to be extinguished before moving from the thermal runaway induction step to the next heat treatment step. This significantly reduces the treatment efficiency of the battery 1. In the extinguishing process, the battery 1 in a burning state is immersed in water or sprayed with water, which can extinguish the fire instantly or in a short time. The extinguished battery 1 contains a large amount of moisture, but the contained moisture is vaporized and removed in the next heat treatment process. Therefore, the battery 1 containing a large amount of moisture in the extinguishing process can be quickly transferred to the next heat treatment process and heat treated without drying. [Heat treatment process]

[0053] The heat treatment process is a process in which the pretreated batteries treated in the thermal runaway induction process are heat-treated and fired to a state from which valuables can be recovered, to produce heat-treated batteries. In the subsequent recovery process, valuables are recovered from the heat-treated batteries by methods such as crushing, pulverization, sorting, separation, and further classification. Since the pretreated batteries pretreated in the thermal runaway induction process are heat-treated in the heat treatment process, thermal runaway of the batteries 1 in this heat treatment process can be prevented and an abnormal temperature rise in the batteries 1 due to thermal runaway can be limited. Since an abnormal temperature rise in the batteries 1 can cause a decrease in the recovery efficiency of high-quality valuables, the heat-treated batteries that have been heat-treated to prevent thermal runaway in the heat treatment process can efficiently recover valuables in a high-quality state in the subsequent recovery process.

[0054] In the heat treatment process, the pretreated battery is placed in a heat treatment furnace (heat treatment chamber 20) heated to a set temperature and heat-treated. In the heat treatment process, as shown in FIG. 3, for example, the battery 1 (pretreated battery) is placed in a heat treatment chamber 10 in which the temperature inside the furnace is set to the heat treatment temperature and heat-treated. The heat treatment furnace (heat treatment chamber 10) is a firing furnace with a closed structure that is separated from and independent of the thermal runaway chamber 10 that induces thermal runaway in the battery 1. In the heat treatment process, the heat-treated battery in which thermal runaway has been induced in the thermal runaway induction process is moved from the thermal runaway chamber 10 to the heat treatment furnace (heat treatment chamber 10) and heat-treated. The pretreated battery that is heat-treated in the heat treatment furnace (heat treatment chamber 10) that is independent from the thermal runaway chamber 10 can prevent thermal runaway in the heat treatment furnace, efficiently recover high-quality valuables, and improve work safety.

[0055] The heat treatment furnace (heat treatment chamber 10) is not particularly limited as long as it has a heat source and can heat-treat the pretreated batteries, and can be appropriately selected according to the purpose. For example, all heat treatment furnaces currently in use or to be developed in the future can be used. A continuous furnace capable of efficiently heat-treating the pretreated batteries is suitable as the heat treatment furnace. The continuous furnace can heat-treat the pretreated batteries by, for example, heating them while transporting them on a heat-resistant belt conveyor. This continuous furnace has a closed structure through which the pretreated batteries can pass through the inlet and outlet, and can continuously heat-treat the pretreated batteries by maintaining the internal temperature at a set temperature. Furthermore, the continuous furnace can also heat-treat one or more pretreated batteries while being placed in a container such as a pallet or tray and transported. The pallet can be structured so that the upper part is open and the pretreated batteries can be exposed and heated and fired in the heat treatment furnace. This continuous furnace can heat-treat the pretreated batteries by pushing the pallet and moving it into the continuous furnace. Furthermore, the heat treatment step can also involve placing one or more pretreated batteries in a heat treatment case 30 that is closed but not sealed, and heating this heat treatment case 30 in a heat treatment furnace to heat and heat treat the pretreated batteries. The pallet or heat treatment case 30 can be moved, for example, by placing it on a dolly 25, and providing heat-resistant wheels 26 on the bottom surface of the pallet or heat treatment case 30, or by arranging multiple heat-resistant rollers 26 in a parallel position to allow smooth movement.

[0056] The heat treatment step does not specify the atmosphere in which the pretreated battery is heat treated, but can be, for example, air or a low-oxygen atmosphere. A low-oxygen atmosphere can be achieved by discharging the internal gas with a gas that does not contain oxygen, such as an inert gas or water vapor. Heat treatment in a low-oxygen atmosphere has the advantage that valuable resources can be recovered in a higher quality state because the pretreated battery can be heat treated while suppressing oxidation.

[0057] The heat treatment temperature and heat treatment time can be set to optimal values ​​taking into consideration the type of battery 1 to be heat-treated and the material of the valuables, and further the state of the valuables recovered from the heat-treated battery 1. For example, the heat treatment of a lithium-ion secondary battery can be set preferably to 250°C or higher and 550°C or lower. If the heat treatment temperature is too low or too high, it becomes difficult to efficiently recover high-quality valuables. Therefore, the heat treatment temperature of the battery 1 in the heat treatment process is set to an optimal temperature and time based on the state of the valuables recovered from the heat-treated battery.

[0058] The heat treatment step can preferably involve placing one or more pretreated batteries in a heat treatment case 30 that is closed but not sealed, for heat treatment. The heat treatment case 30 can heat treat the pretreated batteries in a state where the flame of the heat treatment furnace does not directly heat the batteries 1 and locally increase the temperature. This is because the heat treatment case 30 is heated by the flame of the heat treatment furnace, and the pretreated batteries inside are heated and heat treated. The heat treatment case 30 that is heated by the flame of the heat treatment furnace can be made of a metal plate with excellent heat resistance, such as a heat-resistant stainless steel plate. The heat treatment furnace heats the outer periphery case part 31 that covers the outer periphery of the heat treatment case 30 with the flame, and the heated heat treatment case 30 heats the batteries 1.

[0059] The heat treatment furnace (heat treatment chamber 20) that heats the heat treatment case 30 to heat the pre-treated battery can be either a continuous furnace or a batch type furnace, but a continuous furnace capable of efficient heat treatment is preferable. In a continuous furnace, for example, the heat treatment case 30 is moved on a cart 25, or the heat treatment case 30 is moved on a heat-resistant conveyor arranged at the bottom, and the heat treatment case 30 is heated one after another to heat the battery. The heat treatment furnace (heat treatment chamber 20) shown in FIG. 4 is equipped with a burner 23 that sprays a flame toward the outer casing part 31 of the heat treatment case 30. The burner 23 sprays a flame toward the heat treatment case 30 to heat the surface of the outer casing part 31. In FIG. 4, the flame is sprayed horizontally to heat the outer casing part 31 of the heat treatment case 30. The flame directly heats the outer casing part 31, and the heat of the heated outer casing part 31 and the internal gas indirectly heats the battery 1. The outer casing portion 31 is located between the burner 23 and the battery 1, and blocks the flame of the burner 23, preventing the flame from being blown directly onto the battery 1, thereby preventing a local temperature rise in the battery 1.

[0060] The heat treatment case 30 is heated by blowing the flame of the heat treatment furnace onto the surface of the outer casing part 31. The heat treatment case 30 has a unique structure that can heat the battery 1 evenly and efficiently recover valuable materials. The heat treatment case 30 shown in the cross-sectional view of FIG. 4, the perspective view of FIG. 5, and the side view of FIG. 6 is a square tube whose outer periphery is covered by the outer casing part 31. The outer casing part 31 is closed at the bottom by a bottom plate 31a and closed at the top by a top plate 31b to form the heat treatment case 30. The outer casing part 31 made of a metal plate can be connected in a thermally conductive state to the outer periphery of one of the bottom plate 31a or top plate 31b made of a metal plate, and closed at the other. The heat treatment case 30 has an exhaust part 33 in the outer casing part 31 that exhausts the internal gas and the exhaust gas of the battery to the outside, and has a closed chamber inside that is closed but not sealed. The heat treatment case 30 has the exhaust section 33 located at a position where it can prevent flames from entering through the exhaust section 33 and directly heating the battery 1, thereby preventing localized temperature increases, or has a structure that can prevent direct heating and localized temperature increases of the battery 1. The exhaust section 33 has a structure in which the heat treatment case 30 is closed but not sealed, and the internal gas is stirred by convection, reducing temperature unevenness of the battery 1 and heating it evenly.

[0061] The heat treatment case 30 has an outer casing 31 heated from the surface by the flame of the heat treatment furnace, and the internal temperature rises. The outer casing 31, which has risen in temperature, heats the internal gas of the heat treatment case 30. The heated internal gas becomes lighter and becomes an upward flow that rises along the inner surface of the outer casing 31. The upward flow that flows along the inner surface of the outer casing 31 hits the inner surface of the top plate 31b of the heat treatment case 30 and changes direction to become a downward flow. The internal gas of the heat treatment case 30 becomes an upward flow that rises along the inner surface of the outer casing 31, collides with the inner surface of the top plate, and becomes a downward flow, convecting up and down. The internal gas that convects up and down is agitated to reduce the temperature difference between the top and bottom, and reduces the temperature unevenness of the battery 1 to be heated. Furthermore, the internal gas that convects up and down flows along the surface of the battery 1 to heat the battery 1 surface evenly and efficiently, thereby performing heat treatment.

[0062] The cross-sectional view of Fig. 4 shows the state of internal gas convection in heat treatment case 30. In this figure, arrow A indicates the flow direction of the upward flow that rises as a result of being heated on the inner surface of outer casing portion 31, and arrow B indicates the flow direction of the internal gas that changes direction when the upward flow hits the top plate and becomes a downward flow. As shown by arrows A and B, the convection action of the internal gas in heat treatment case 30 accelerates the flow rate on the surface of battery 1, suppresses local temperature rise of battery 1, and is effective in efficiently and evenly heating and heat-treating the entire battery 1.

[0063] The heat treatment case 30 in Figs. 4 to 6 has support legs 34 provided under the bottom plate 31a, and a hot air flow gap 35 provided under the bottom plate 31a. The flow gap 35 can be adjusted by the height of the support legs 34. The height of the support legs 34 is, for example, 5 cm or more and 50 cm or less, preferably 10 cm or more and 30 cm or less, so that hot air can flow through the flow gap 35. The hot air flowing through the flow gap 35 heats the bottom plate 31a, heating both the internal gas in the heat treatment case 30 and the batteries 1. The heated bottom plate 31a heats the internal gas at the bottom of the heat treatment case 30 to make it an upward flow, and also makes the internal gas that collides with the top plate 31b and descends upward again, thereby stirring the internal gas in the heat treatment case 30 overall and equalizing the internal temperature. This structure has the advantage that a large number of batteries 1 can be more efficiently and evenly heat-treated in an apparatus that efficiently heat-treats a plurality of batteries 1 placed in a large-volume heat treatment case 30. A flow gap 35 is formed between the multiple support legs 34. The support legs 34 have both heat resistance and strength, and their shape, thickness, size, material, posture, arrangement, etc. are not specified, but they can support the heat treatment case 30 in a dot-like, linear, or planar shape. The support legs 34 can efficiently heat the heat treatment case 30 from the bottom by taking a shape, posture, and arrangement that do not hinder the hot air flow in the flow gap 35. For example, when flames are ejected horizontally from the burners 23 provided on both sides of the incinerator 20 as shown in FIG. 4 to heat the heat treatment case 30, the support legs 34 can be made plate-like extending in the same direction as the direction of travel of the flames and hot air as shown in FIG. 5 and FIG. 6, so that the support legs 34 do not block the hot air, and the hot air can smoothly flow through the flow gap 35 to efficiently heat the heat treatment case 30 from the bottom.

[0064] The heat treatment case 30 preferably has an internal volume larger than 1 cubic meter, and is large enough to put multiple batteries 1 in and heat treat them together. As shown in FIG. 4, this heat treatment case 30 can heat treat multiple batteries 1 simultaneously. When the batteries 1 are heated in a heat treatment furnace in this state, the bottom plate 31a is heated by hot air entering the flow gap 35, and the internal gas and the batteries 1 can be efficiently heated and heat treated. In addition to directly heating the batteries 1, the heated bottom plate 31a also heats the internal gas that is redirected and descends at the top plate 31b, turning it into an ascending current, and efficiently agitating the internal gas overall. The ascending current also flows along the surface of the batteries 1, and can heat the batteries 1. By heating from the bottom plate 31a (the bottom surface in FIG. 4), which is different from the outer periphery case part 31 (both side surfaces in FIG. 4), which is heated by the ejection of flames, multiple batteries 1 can be efficiently heated and heat treated.

[0065] When the battery 1 is heated inside the heat treatment case 30, the electrolyte vaporizes, and the vaporized gas is discharged to the outside through the exhaust section 33. The exhaust section 33 can be a through hole 33a provided in the outer circumferential case section 31 of the heat treatment case 30 as shown in Figs. 4 to 6, or an exhaust duct 36 as shown in Fig. 7. In the heat treatment case 30 of Fig. 6, the exhaust section 33 of the through hole 33a opens above the upper end of the battery 1 to be heat-treated inside. This heat treatment case 30 can heat-treat the battery 1 in a preferable temperature environment by preventing the adverse effect of flames penetrating the inside through the through hole 33a of the exhaust section 33 and locally heating the battery 1. Furthermore, the heat treatment case 30 in which the through hole 33a opens above the battery 1 can heat the entire battery 1 through the outer circumferential case section 31 by preventing the adverse effect of flames penetrating the inside through the through hole 33a and locally heating the surface of the battery 1. Furthermore, in this heat treatment case 30, the battery 1 surface is heated by an upward flow of internal gas rising through the heating gap (S) between the battery 1 and the inner surface of the outer case portion 31. The upward flow flowing over the battery 1 surface heats the battery 1 surface evenly and efficiently with a small temperature difference, thereby performing heat treatment.

[0066] Furthermore, the heat treatment case 30 shown in the perspective view of FIG. 6 has a through hole 33a of the exhaust section 33, which is located downward from the upper end edge of the side wall of the outer casing section 31. This structure prevents the rising internal gas from flowing along the lower surface of the top plate 31b and being discharged to the outside through the through hole 33a, and the internal gas can be efficiently convected by changing the direction from an upward flow to a downward flow. Furthermore, the exhaust section 33, which is opened downward from the upper edge, does not allow the internal gas to be discharged to the outside due to the action of the air curtain of the upward flow flowing along the inner surface of the outer casing section 31 when the battery 1 is not discharging exhaust gas, i.e., the opening area of ​​the exhaust section 33 is substantially small. Therefore, when the battery 1 is not discharging exhaust gas, the heat treatment case 30 becomes a heat treatment case 30 that is closed but not sealed in a preferable state, and has the characteristic that the temperature difference of the internal gas can be reduced by effective convection action to heat the battery 1. When a lithium-ion secondary battery is heated and goes into thermal runaway, it instantly emits high-temperature, high-pressure exhaust gas, and in this state the exhaust gas is quickly discharged to the outside from the exhaust section 33. This is because the exhaust gas instantaneously increases the internal pressure of the heat treatment case 30, and the internal gas is discharged from the exhaust section 33.

[0067] In the heat treatment case 30, the exhaust section 33 can be an exhaust duct 36. The exhaust duct 36 can be a tall hollow cylinder with the intake opening 36a and the exhaust opening 36b disposed at different positions, away from each other. In the heat treatment case 30 of FIG. 7, the exhaust section 33 is an exhaust duct 36 penetrating the heat treatment case 30, with the intake opening 36a of the exhaust duct 36 disposed inside the heat treatment case 30 and the exhaust opening 36b opened to the outside. The exhaust duct 36 of the heat treatment case 30 can exhaust the exhaust gas of the battery 1 from inside the heat treatment case 30, so that the battery 1 can be heated evenly without the exhaust gas of the battery 1 suppressing the convection action of the internal gas. This is because the exhausted internal gas can effectively stir the internal gas by the convection action of the internal gas without impeding the upward flow in the heat treatment case 30. In particular, it is possible to quickly exhaust to the outside the high-temperature exhaust gas that is discharged into the heat treatment case 30 when the battery 1 experiences thermal runaway, while suppressing an abnormal increase in internal temperature caused by the exhaust gas, thereby achieving the characteristic of heat treating the battery 1.

[0068] Furthermore, the exhaust duct 36 has the intake opening 36a disposed inside the heat treatment case 30 and away from the inner surface of the outer casing portion 31, so that the exhaust gas can be exhausted without impeding the convection action of the internal gas caused by the exhaust gas. In particular, exhausting the exhaust gas of the battery 1 from inside the heat treatment case 30 can prevent the harmful effect of the exhaust gas impeding the upward flow of the exhaust gas rising along the inner surface of the heat treatment case 30. Furthermore, the heat treatment case 30 of FIG. 7 has the intake opening 36a of the exhaust duct 36 disposed at the opening of the lower part inside and away from the inner surface of the outer casing portion 31. The heat treatment case 30 of this structure can exhaust the downward flow of the internal gas from the lower part, so that the exhaust gas flows in a direction that accelerates the downward flow. Therefore, the above heat treatment case 30 allows the exhaust gas to act in a direction that accelerates the downward flow without impeding the upward flow, making the convection action of the internal gas more effective. For this reason, the above-described heat treatment case 30 has the advantage that even when the battery 1 is emitting exhaust gas, the internal temperature can be equalized by the effective convection action of the gas inside the heat treatment case 30, and the battery 1 can be heated evenly to perform heat treatment.

[0069] The outer casing part 31 of the heat treatment case 30 can have a main case 32A that is partially open, and a top cover 32B that can open and close the partial opening. In the heat treatment case 30 of FIG. 7, the top end opening of the main case 32A, which is open at the top, is closed by a top cover 32B that can be opened and closed, and an exhaust duct 36 is fixed to the top cover 32B. The exhaust duct 36 is fixed through the top cover 32B and exhausts the exhaust gas inside to the outside of the heat treatment case 30. The exhaust duct 36 has an intake opening 36a disposed inside the heat treatment case 30 and an exhaust opening 36b that opens to the outside of the heat treatment case 30. With this structure, the top cover 32B can be removed and the exhaust duct 36 can be moved to a position where it does not get in the way, making it convenient to insert and remove the battery 1. Furthermore, the intake opening 36a of the exhaust duct 36 can be disposed in a preferred position.

[0070] The heat treatment case 30 in FIG. 4 and FIG. 5 has a plurality of through holes 33a as the exhaust section 33. As shown in FIG. 4, the plurality of through holes 33a are arranged in a distributed manner in both the vertical direction and the width direction, and exhaust gas is exhausted from each of the through holes 33a. The heat treatment case 30 can be provided with a required number of through holes 33a at appropriate positions, and the plurality of through holes 33a can be arranged in one or more rows, or in one or more rows. The heat treatment case 30 in FIG. 4 has the exhaust sections 33 arranged in multiple rows and multiple rows. Furthermore, the heat treatment case 30 in FIG. 4 is a rectangular parallelepiped, and the exhaust sections 33 are provided on both side surfaces of the heat treatment case 30. The heat treatment case 30 can be provided with the exhaust sections 33 on both side surfaces and both end surfaces, or can be provided with the exhaust sections 33 only on both end surfaces.

[0071] The heat treatment case 30 in Fig. 4 is provided with an exhaust section 33 consisting of a plurality of through holes 33a to form a heat treatment case 30 that is closed but not sealed, but the exhaust section 33 has a total opening area of ​​the plurality of through holes 33a that is preferably 10% or less of the total surface area of ​​the heat treatment case 30, and the internal gas of the heat treatment case 30 can be stirred by convection. The heat treatment case 30 that can stir the internal gas by convection can heat the battery 1 without temperature unevenness, and can perform heat treatment in a state in which valuable materials can be efficiently recovered. The heat treatment case 30 provided with the exhaust section 33 consisting of a plurality of through holes 33a has a total opening area of ​​the plurality of exhaust sections 33 that is 10% or less of the total surface area of ​​the heat treatment case 30, but the heat treatment case 30 provided with a single exhaust section 33 has an opening area of ​​the single exhaust section 33 that is 10% or less of the total surface area of ​​the heat treatment case 30.

[0072] The exhaust section 33 is made up of a plurality of through holes 33a, and the opening area of ​​each through hole 33a is preferably 80 cm 2The opening area of ​​each through hole 33a is limited to the above range, and the total opening area of ​​the multiple through holes 33a is set to 10% or less. Through holes 33a with too large an opening area will allow an excessive amount of exhaust gas to flow out, which will hinder the convection action of the internal gas. Therefore, the opening area of ​​each through hole 33a is limited to the above range, preventing excessive outflow of internal gas and achieving a favorable convection action. If the opening area of ​​each through hole 33a is too small, exhaust gas from the battery 1 cannot be quickly discharged, so the opening area of ​​each through hole 33a is preferably 3cm or less. 2 Furthermore, if the total opening area of ​​the multiple through holes 33a of the exhaust section 33 is too small, the exhaust gas cannot be quickly discharged to the outside of the heat treatment case 30 when multiple batteries 1 are simultaneously discharging exhaust gas, so the total opening area of ​​the multiple through holes 33a is set to 1% or more of the total surface area of ​​the heat treatment case 30, and the exhaust section 33 is structured to be able to quickly discharge the exhaust gas to the outside of the heat treatment case 30 even when a large amount of exhaust gas is being discharged from the batteries 1.

[0073] The heat treatment furnace detects the battery temperature in the heat treatment case 30 and controls the battery temperature to a set temperature to perform heat treatment. The heat treatment furnace controls the thermal energy to control the battery 1 to a set temperature so that the detected battery temperature is within a preset temperature range. The set temperature for heating the battery 1 to heat treatment is set to a temperature at which valuables can be efficiently recovered by crushing, sorting, separating, classifying, or the like after the battery 1 is heated and heat treated. If the set temperature is too low, the heat-treated battery 1 cannot be crushed or pulverized to separate it into a state suitable for recovering valuables, and conversely, if the set temperature is too high, valuables cannot be recovered in a high-quality state. Therefore, as described above, for example, for lithium-ion secondary batteries, the set temperature for heat treatment is preferably 250°C or higher and 550°C or lower. The heat treatment furnace is provided with an exhaust treatment unit 24 to exhaust the internal air in the furnace and discharge the thermal energy of the battery 1, thereby adjusting the temperature inside the heat treatment furnace and limiting the temperature rise.

[0074] The temperature and time for heating and heat-treating the battery 1 vary depending on the type and structure of the battery 1, so the heat-treated battery 1 is crushed, pulverized, and sorted to confirm and identify a state in which valuable materials can be effectively recovered. For example, batteries with a plastic exterior film, such as lithium polymer secondary batteries, can be heat-treated with short heating times, while batteries with metal exterior cans can be heat-treated with longer heating times. Furthermore, the heat treatment time for the battery 1 separated into individual units differs from that for a battery unit in which multiple batteries 1 are housed in a metal exterior case; individual batteries 1 can be heat-treated in a short time because the battery 1 is heated directly, but batteries 1 housed in an exterior case require a longer heat treatment time because the battery 1 is heated via the exterior case.

[0075] The heat treatment furnace does not specify the atmosphere in which the battery 1 is heat-treated, but for example, the battery 1 is heat-treated in an air atmosphere or a low-oxygen atmosphere. In the air atmosphere, the heat treatment can be performed without controlling the atmosphere in the heat treatment chamber, reducing running costs, while in the low-oxygen atmosphere, the heat treatment can be performed while preventing oxidation of valuable materials. [Recovery process]

[0076] In the recovery process, valuable materials are recovered from treated batteries that have been heat-treated in a heat treatment furnace. In the present disclosure, the method and device for recovering valuable materials from treated batteries are not particularly limited, and can be appropriately selected according to the purpose, such as the configuration and mode of the battery, the state of the treated battery, and the valuable materials to be recovered. For example, the recovery of valuable materials can include any of crushing, pulverization, sorting, separation, and classification of the treated batteries, and can further include other steps as necessary. The method of each step can be a combination of multiple steps, or the steps can be carried out in stages. For example, in the sorting step, sorting can be performed using wind force, magnetic force, sieves, etc., and these can be combined depending on the valuable materials to be recovered. In the crushing step, the treated batteries are crushed to obtain crushed materials. In the crushing step, the batteries are crushed into finer pieces to obtain crushed materials. Valuable materials or materials containing valuable materials are sorted and separated using sieves, magnetic force, wind force, centrifugal force, suction force, etc. In the classification step, crushed materials such as coarse grain products and fine grain products are separated according to the size of the crushed materials and crushed materials. [Industrial Applicability]

[0077] The present disclosure can be suitably used as a method for heat-treating a battery at an optimal temperature by suppressing a temperature rise due to thermal runaway of the battery during a heat treatment process, and as a valuable resource recovery method that can efficiently recover valuable resources in a high-quality state by heat-treating a battery using this heat treatment method. [Explanation of symbols]

[0078] 1...Battery 10...Thermal runaway chamber 11...Penetration mechanism 11a...metal nail 12...External short circuit mechanism 13...Flame spray mechanism 14...Exhaust treatment section 20…Heat treatment room 23…Burner 24...Exhaust treatment section 25…Trolley 26...Wheels, rollers 30…Heat treatment case 31...Outer case part 31a…Bottom plate 31b…Tabletop 32A…Main body case 32B…Top lid 33…Exhaust section 33a...Through hole 34…Support leg 35...Flow gap 36…Exhaust duct 36a...Suction opening 36b…Discharge opening

Claims

1. A heat treatment method for recovering valuable materials from a battery, comprising: a thermal runaway inducing step of inducing thermal runaway in the battery; a heat treatment step of heating the pretreated battery treated in the thermal runaway induction step to form a heat-treated battery, The method for heat treating a battery includes heating and heat treating the pretreated battery in which thermal runaway has been forcibly induced in the thermal runaway inducing step in the heat treatment step.

2. A method for heat treating a battery according to claim 1, comprising the steps of: The method for heat treating a battery, wherein the battery is a lithium ion secondary battery.

3. The method for heat treating a battery according to claim 1, The thermal runaway battery that has gone into thermal runaway in the thermal runaway inducing step is immersed in water; or a fire extinguishing step of spraying water on the thermal runaway battery, After the extinguishing step, The battery heat treatment method comprises heat treating the battery in the heat treatment step.

4. A method for heat treating a battery according to claim 1, comprising the steps of: a thermal runaway chamber having a closed structure that houses the battery and induces thermal runaway in the thermal runaway inducing step; a heat treatment chamber having a closed structure in which the battery is housed and heat-treated in the heat treatment step is a closed chamber independent of each other; The battery, After inducing thermal runaway in the thermal runaway chamber, The method of heat treating a battery includes transferring the battery from the thermal runaway chamber to the heat treatment chamber and heat treating the battery.

5. A method for heat treating a battery according to claim 1, comprising the steps of: In the thermal runaway inducing step, Inserting a shorting rod through the battery; This is a heat treatment method for a battery in which the electrodes are forcibly shorted internally by the shorting rod to induce thermal runaway.

6. A method for heat treating a battery according to claim 1, comprising the steps of: In the thermal runaway inducing step, A method of heat treatment of batteries in which the battery output is short-circuited to induce thermal runaway.

7. A method for heat treating a battery according to claim 1, comprising the steps of: In the thermal runaway inducing step, A method of heat treatment of a battery in which a part of the battery is heated to induce thermal runaway.

8. A method for heat treating a battery according to claim 1, comprising the steps of: In the thermal runaway inducing step, A method of heat treatment of batteries in which a laser beam is irradiated onto the battery to induce thermal runaway.

9. A method for recovering valuable materials from a battery, comprising the steps of: a thermal runaway inducing step of inducing thermal runaway in the battery; a heat treatment step of heating the pretreated battery treated in the thermal runaway induction step to a set temperature to form a heat-treated battery; and a recovery step of crushing the heat-treated batteries obtained in the heat treatment step to separate and recover valuable materials, A method for recovering valuable materials from batteries.

10. A method for recovering valuable materials from the battery according to claim 9, comprising: The method for recovering valuable materials from a battery, wherein the battery is a lithium ion secondary battery.

11. A method for recovering valuable materials from a battery according to claim 9, comprising: The thermal runaway battery that has gone into thermal runaway and ignited in the thermal runaway inducing step is immersed in water; Or, a fire extinguishing process is included in which water is sprayed on the thermal runaway battery, After the extinguishing step, A method for recovering valuable materials from a battery, comprising heat-treating the battery in the heat treatment step.

12. A method for recovering valuable materials from the battery according to claim 9, comprising: a thermal runaway chamber having a closed structure that houses the battery and induces thermal runaway in the thermal runaway inducing step; In the heat treatment step, heat treatment chambers having a closed structure in which the batteries are housed and heat-treated are independent closed chambers, The battery, After inducing thermal runaway in the thermal runaway chamber, A method for recovering valuable materials from batteries which are moved from the thermal runaway chamber to the heat treatment chamber and subjected to heat treatment.

13. A method for recovering valuable materials from the battery according to claim 9, comprising: In the thermal runaway inducing step, A shorting rod is inserted through the battery, A method for recovering valuable materials from a battery in which thermal runaway is induced by forcibly shorting the electrodes internally using the shorting rod.

14. A method for recovering valuable materials from the battery according to claim 9, comprising: In the thermal runaway inducing step, A method for recovering valuable materials from batteries that induce thermal runaway by heating the batteries.

15. A method for recovering valuable materials from the battery according to claim 9, comprising: In the thermal runaway inducing step, A method of recovering valuable materials from batteries by irradiating them with a laser beam to induce thermal runaway.

16. A method for recovering valuable materials from the battery according to claim 9, comprising: In the recovery step, Crush the heat-treated batteries, A method for recovering valuable materials from batteries, comprising a separation step of separating black mass containing valuable materials from crushed material.

17. A method for recovering valuable materials from the battery according to claim 9, comprising: In the recovery step, Crush the heat-treated batteries, A separation step of separating black mass containing valuables from the crushed material, The black mass is A method for recovering valuable materials from batteries containing at least any one of non-ferrous metals, i.e., cobalt, nickel, lithium, copper, and aluminum.

18. A method for recovering valuable materials from the battery according to claim 9, comprising: The battery, A method for recovering valuable materials from batteries that have copper foil or aluminum foil as the electrode core.

19. A method for recovering valuable materials from the battery according to claim 9, comprising: The method for recovering valuable materials from batteries comprises continuously heat-treating the batteries in a continuous furnace in the heat treatment step.

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