JP2021015795A - Stabilization processing method of used lithium ion battery - Google Patents

Abstract

To provide a stabilization processing method of waste lithium ion battery performing discharge treatment safely.SOLUTION: In a stabilization processing method of waste lithium ion battery performing heating treatment of the waste lithium ion battery between a temperature (upper limit temperature) lower than both the decomposition temperature of the separator of the waste lithium ion battery and the SEI breaking temperature, and the gasification start temperature (lower limit temperature) of the electrolyte of the waste lithium ion battery, and causing internal short circuit of an electrode in the waste lithium ion battery, the upper limit temperature is about 280°C, the lower limit temperature is about 90°C, the waste lithium ion battery is heat treated in a substance which is liquid at the lower limit temperature, and having a boiling point or a demarcation point below the upper limit temperature, the substance is water (H2O) or triacyl glycerine, and after the heat treatment, plastics of the waste lithium ion battery are subjected to carbonization or decomposition processing in a roasting device or a super heat steam device while being placed in the substance.SELECTED DRAWING: Figure 1

Description

The present invention relates to a stabilization process in the recycling of used lithium ion batteries.

In mobile devices such as smart phones and electric vehicles, secondary batteries for storing electric power are used to store electricity. The demand for these is rapidly increasing, and the amount of secondary batteries discarded is also increasing rapidly, and the demand for disposal and recycling of storage batteries is also increasing. As these secondary batteries, secondary batteries having performance according to the equipment to be used are required, but lithium ion batteries are mainly used. A lithium ion battery is mounted in a metal (for example, aluminum) housing with a negative electrode material such as graphite fixed to a negative electrode substrate, which is a mounting substrate with copper foil or the like, or an aluminum foil. Positive electrode material which is a substrate, a positive electrode material in which a positive electrode active material such as lithium cobaltate or lithium nickelate is fixed, a current collector made of aluminum or copper, or a resin film such as polyolene fin (for example, polypropylene or polyethylene). It contains a separator, an electrolytic solution such as lithium hexafluorophosphate (LiPF ₆ ), an electrolyte, and the like. Used lithium-ion batteries (also referred to as waste lithium-ion batteries, or abbreviated as waste LiB) cannot be discarded or buried as they are because they contain the above-mentioned harmful substances such as fluoride and phosphoric acid. .. Further, since it contains a large number of rare valuable metals such as lithium (Li), cobalt (Co) and nickel (Ni), it is required to recover these valuable metals for resource conservation. For this purpose, many methods for treating harmful substances contained in waste lithium ion batteries and methods for recovering valuable metals have been proposed so far.

JP 2017-131795 JP 2016-22395

In the recycling of used lithium-ion batteries, active lithium exists in a charged or semi-charged lithium-ion battery in a high-energy state, and the high-energy state is released (discharged) in the recycling process. It causes heat generation, ignition or explosion of flammable electric field substances contained in the battery, and it is generally difficult to safely process the battery. For this reason, some manual discharges and electrolyte cleaning are performed as a preliminary step to the recycling process, but safe processing is still difficult and the cost of the recycling process is high. .. Therefore, if it is necessary to process in a high-temperature furnace where there is no problem even if it ignites, metal components such as aluminum and compound components such as cobalt acid are mixed at high temperature, which is a heavy burden on the subsequent extraction process. I'm wearing it. It has also been proposed to heat-treat at a temperature below the melting point of aluminum, but since there is still a problem due to electric discharge, a used lithium-ion battery is enclosed in a heat-resistant container and placed in a heat treatment furnace to generate heat due to electric discharge during heat treatment. It has also been proposed that the heat treatment furnace should not be damaged even if the above occurs. (Patent Document 1)

The method according to Patent Document 1 requires an expensive heat-resistant container, and it is unclear whether the problem will disappear even if it is actually used. That is, in order to carry out the recycling treatment effectively and inexpensively, there is a need for a method for safely discharging the used lithium ion battery at a low cost. In addition, based on the patent documents and information so far, in the treatment before the used lithium-ion battery is subjected to metal extraction, (A) a separable state in a process such as carbonization or combustion of organic components such as plastics or subsequent crushing. It is required to bring it to (B) to stabilize lithium such as oxides, which has a large energy storage. Further, it is also known that (C) by carrying out the reaction below the melting point of aluminum, the subsequent metal extraction becomes easy. (Patent Document 2)

Above all, the condition (B) above corresponds to the chemically accumulated electric energy held by the lithium ion battery, and it is required that this Li can be converted into a stable state. Li exists as lithium carbonate (LiC ₆ ) at the negative electrode and as a composite oxide such as Li (NiMnCo) O ₂ at the positive electrode. The positive electrode material is a stable composite oxide, but the positive electrode material must be stabilized at 4LiC ₆ + O ₂ → 2Li ₂ O + 24C, which requires an oxidizing atmosphere with oxygen potential. is there. Patent Document 2 has a "reducing or non-oxidizing" atmosphere, and does not fall under this. However, if the oxygen potential is high, an exothermic reaction of carbon combustion of C + O ₂ → CO ₂ occurs, and it becomes difficult to suppress the reaction below the melting point (about 660 ° C.) of aluminum in (C) above. That is, it is necessary to treat in a weakly oxidizing atmosphere that oxidizes Li and does not cause carbon combustion of C + O ₂ → CO ₂ .

The present invention provides a safe and secure stabilization treatment method for a waste lithium ion battery satisfying the above requirements (A), (B) and (C), and an accompanying stabilization treatment method for a waste lithium ion battery. The present invention provides a method for stabilizing a waste lithium ion battery, which is particularly safely discharged, and has the following features.
(1) The present invention is below a temperature (upper limit temperature) lower than both the decomposition temperature of the separator of a used lithium ion battery and the SEI (Solid Electrolyte interface) decay temperature, and gasification of the electrolyte of the used lithium ion battery. The used lithium ion is heat-treated at a temperature equal to or higher than the start temperature (lower limit temperature), and the used lithium ion battery is inactivated (for example, causes an internal short circuit of the electrode). A method for stabilizing a battery, the upper limit temperature is about 280 ° C., the lower limit temperature is about 90 ° C., and the lithium ion battery is a liquid at the lower limit temperature and has a boiling point or a boiling point below the upper limit temperature. heat treated at substance having a demarcation point, the material is characterized in that water (H 2 _O) or triacylglycerol.

(2) In the present invention, in addition to (1), the electrode layer of the used lithium ion battery is perforated before the heat treatment, and after the heat treatment, it is put in the substance. Carrying or decomposing the plastics of the used lithium-ion battery in the roasting device or superheated steam device, or in the roasting device or superheated steam device with the used lithium-ion battery in the substance. After the heat treatment is performed, the plastics of the used lithium-ion battery are carbonized or decomposed, or the used lithium-ion battery is placed in the substance and placed in a superheated steam device. , The used lithium-ion battery is characterized by carbonizing or disassembling the plastics, or the used lithium-ion battery is placed in a superheated steam device to carbonize or disassemble the plastics of the used lithium-ion battery. It is characterized in that the heat treatment according to (1) is realized by performing the decomposition treatment.

(3) The present invention comprises stabilizing a used lithium ion battery, which comprises a step of arranging the used lithium ion battery in a charcoal weakly oxidizing environment to carry out a carbonization treatment or a decomposition treatment of plastics. In the treatment method, the weakly oxidizing environment is a combination of atmosphere and temperature having an oxygen potential capable of oxidizing lithium without causing the reaction of C + O2 → CO2 to proceed. This is a stabilization processing method.

(4) In the present invention, in addition to (1), the atmosphere of the weakly oxidizing environment is MxO (M is an element or a reactive group), and the temperature of the weakly oxidizing environment is 2XM + O ₂ = 2MxO. The oxygen potential is higher than the oxygen potential for oxidation of lithium (Li), lower than the oxygen potential for C + O ₂ = CO ₂ , and higher than the decomposition temperature for plastics, and the atmosphere of the weakly oxidizing environment. Is water vapor, and the temperature condition of the weakly oxidizing environment is about 650 ° C or lower, which is the temperature at the intersection of the oxygen potential diagrams of 2H ₂ O + O ₂ = 2H ₂ O and C + O ₂ = CO ₂ based on the Eringham diagram. It is characterized by being above the decomposition temperature of plastics.
(5) The present invention stabilizes the used lithium ion battery according to (3) or (4) after performing the method for stabilizing the used lithium ion battery according to (1) or (2). It is characterized by performing a processing method.

(6) In the present invention, a used lithium ion battery which has been discharged with a conductive aqueous solution of a salt having an anion which is decomposed by a carbide reaction with a cation which fixes fluorine and sulfur is treated with a superheated steam at 650 ° C. or lower to obtain a metal component. It is a method for stabilizing a used lithium ion battery that can be separated into a compound component and a carbide component, and further, after the used lithium ion battery is discharged with the conductive aqueous solution, the used lithium ion battery is subjected to the above. A superheated steam treatment is performed in a state of being placed in a conductive aqueous solution, and the conductive aqueous solution is an aqueous solution of calcium carbonate.

(7) In the present invention, in addition to (6), in the discharge treatment, the used lithium ion battery is cut by using ultrasonic ceramics cutting in a conductive aqueous solution, and the conductive aqueous solution is used from the cut portion. The lithium ion battery is leached into the lithium ion battery, or the discharge treatment is performed by drilling a hole in the used lithium ion battery using a cutting tool (tool) in the conductive aqueous solution, and the conductive aqueous solution is discharged from the perforated portion. The cutting tool (tool) is a good electric conductor and is characterized by passing an electric good conductor wire through the perforated portion by leaching into a used lithium ion battery, or the discharge treatment is performed in a conductive aqueous solution. The used lithium-ion battery is distorted by applying deformation from the outside, the conductive aqueous solution is leached into the used lithium-ion battery from the strain, and the used lithium-ion battery is deformed from the outside. The method of applying strain is characterized in that it is a method of applying deformation from the outside using a rotary press roller or a press machine to give strain to a used lithium ion battery.

(8) In the present invention, in addition to (6) or (7), a conductive filler or a conductive powder is mixed with the conductive aqueous solution, and the conductive filler or the conductive powder is a conductive carbon black. , Conductive tin oxide, conductive titanium oxide, or various metal powders, and the temperature of the superheated steam treatment is about 300 ° C. to about 650 ° C.

The present invention can relate to a method for stabilizing a used lithium ion battery, which is lower than both the decomposition temperature of the separator of the used lithium ion battery and the SEI (Solid Electrolyte interface) decay temperature (upper limit temperature). Since the used lithium-ion battery is heat-treated below and above the gasification start temperature (lower limit temperature) of the electrolyte of the used lithium-ion battery, the separator is deformed without being decomposed or carbonized to form a positive electrode. A partial short circuit of the negative electrode occurs, the internal electrolyte or the like changes, or the electrical system such as the electrode or wiring is damaged so that sudden discharge does not occur (this is an inactivated state in the present invention). It is possible to generate a gradual discharge without generating sudden heat generation or the like. In addition to this, the present invention heat-treats a used lithium-ion battery in a substance that is liquid at a lower limit temperature and has a boiling point or a demarcation point below the upper limit temperature, and heats generated during discharge treatment with a large heat capacity. Since it is absorbed by a substance, it is possible to completely prevent problems caused by heat generation and the like, for example, damage to the device due to ignition or explosion. When this liquid is water, it is inexpensive and does not burden the environment. Since the present invention is also a method for stabilizing a used lithium ion battery, which comprises a step of arranging the used lithium ion battery in a weakly oxidizing environment such as superheated steam at 650 ° C. or lower and performing a carbonization treatment, rapid heat generation is generated. It is possible to easily separate valuable metal components contained in a lithium ion battery by carbonizing only organic substances such as plastics.

FIG. 1 is a diagram showing a superheated steam device that heat-treats the waste lithium ion battery of the present invention. FIG. 2 is an Ellingham diagram. FIG. 3 is a graph showing the decomposition temperature of the plastic. FIG. 4 is a graph showing the experimental results of boiling water treatment of a used storage battery. FIG. 5 is a diagram showing a flow of the processing method of the present invention. FIG. 6 is a diagram showing a method of damaging a lithium ion battery in a conductive aqueous solution in a small container containing a conductive aqueous solution. FIG. 7 is a diagram showing another method of damaging a lithium ion battery. FIG. 8 is a diagram showing a state in which a lithium ion battery immersed in a large container containing a conductive aqueous solution and a small container containing the conductive aqueous solution are arranged. FIG. 9 is a diagram showing a superheated steam device in which a small container containing a waste lithium ion battery and a conductive aqueous solution is arranged in the device. FIG. 10 is a table showing the evaluation results of the deactivated state due to the heat treatment of the lithium battery.

The present invention is a stabilization process for a used (waste) lithium-ion battery, and is a safe method for facilitating component separation of a lithium-ion battery prior to metal extraction. That is, in a carbonized, weakly oxidizing environment, as a preliminary step for metal extraction from a waste lithium ion battery (LiB), organic substances such as plastics are carbonized or decomposed to facilitate separation from valuable metal components, and highly reactive lithium. This is a process for stabilizing (Li). Here, the carbonized or degradable weakly oxidizing atmosphere refers to a combination of an atmosphere and a temperature having an oxygen potential that does not allow the reaction of C + O ₂ → CO ₂ to proceed and can oxidize Li.

In the treatment before applying used LiB to metal extraction, (A) bring it to a separable state in processes such as carbonization and combustion separation of organic components such as plastics or subsequent crushing, and (B) large energy storage. It is required to put Li in a stable state such as oxide. Further, it is also known that (C) by carrying out the reaction below the melting point of aluminum, the subsequent metal extraction becomes easy. Above all, (B) corresponds to the chemically accumulated electrical energy held by LiB, and it is required that this Li can be converted into a stable state. Li exists as LiC ₆ at the negative electrode and as a composite oxide such as Li (NiMnCo) O ₂ at the positive electrode. The positive electrode material is a stable composite oxide, but the positive electrode material must be stabilized at 4LiC ₆ + O ₂ → 2Li ₂ O + 24C, which requires an oxidizing atmosphere with oxygen potential. is there. Patent Document 2 has a "reducing or non-oxidizing" atmosphere, and does not fall under this. However, if the oxygen potential is high, an exothermic reaction of carbon combustion of C + O ₂ → CO ₂ occurs, and it becomes difficult to suppress the reaction below the melting point of aluminum in (C). That is, it is necessary to treat in a weakly oxidizing atmosphere that oxidizes Li and does not cause carbon combustion of C + O ₂ → CO ₂ .

FIG. 1 is a diagram showing a roasting apparatus for heat-treating the waste lithium ion battery of the present invention, and shows a superheated steam apparatus 100 as an example of the roasting apparatus. The waste lithium ion battery 107 is arranged on the support shelf plate 106 in the superheated steam device 100. A superheated steam generator 102 is attached to the superheated steam device 100, and the temperature-controlled superheated steam is introduced into the superheated steam device 100. A temperature sensor 103 that detects the temperature inside the superheated steam device 100 is attached, and the temperature inside the superheated steam device 100 is sent to the controller 104, and the steam is heated to an appropriate temperature by the boiler 101 and sent to the superheated steam generator 102. Then, superheated steam having a predetermined temperature is introduced into the superheated steam device 100. Therefore, the temperature inside the superheated steam device 100 is always controlled to a predetermined temperature. The superheated steam introduced into the superheated steam device 100 and the gas (waste gas, pyrolysis gas, etc.) generated by the heat treatment of the waste lithium ion battery 107 are discharged to the outside from the exhaust line 105.

When the waste lithium ion battery 107 is arranged in the superheated steam device 100, air or the like is contained in the superheated steam device 100. Therefore, before the superheated steam is put into the superheated steam device 100, a pump or the like (for example, It may be attached to another line or exhaust line 105) and discharged to the outside. Normally, air or the like is discharged from the exhaust line 105 together with superheated steam at the initial stage, so that the superheated steam device 100 is filled with superheated steam at the stage where the actual heat treatment is performed, and the waste lithium ion battery 107 Is heated by superheated steam.

The superheated steam device gives a weakly oxidizing atmosphere because the atmosphere is superheated steam (H ₂ O). That is, water vapor gives an oxygen potential that equilibrates in the reaction of 2H ₂ O → 2H ₂ + O ₂ . As can be seen from the Ellingham diagram shown in FIG. 2, this oxygen potential causes an oxidation reaction of Li over the entire temperature range of several thousand degrees or less for lithium (Li). However, in the low temperature range, it does not give the oxygen potential to proceed the reaction of C + O ₂ → CO ₂ , but in the high temperature range, it gives the oxygen potential sufficient to proceed the carbon combustion reaction. Its transition temperature is known to be a temperature _{that 2H 2 + O 2 = 2H 2} O and _{C +} O 2 = oxygen potential diagram of CO ₂ intersect on the diagram Ellingham, about 650 ° C. from Ellingham diagram of FIG. 2 Is. If the temperature rises above this temperature, an exothermic reaction of carbon combustion of C + O ₂ → CO ₂ occurs, so it is difficult to suppress the reaction below the melting point (660 ° C) of aluminum as the temperature rises steadily.

That is, if the temperature of the superheated steam is set to about 650 ° C. or lower, a weakly oxidizing environment that oxidizes lithium (Li) and does not cause carbon combustion of C + O ₂ → CO ₂ is obtained. Further, since plastics are decomposed by high temperature heat treatment, it is necessary that the temperature is equal to or higher than the decomposition start temperature of the plastic. For example, FIG. 3 is a graph showing the decomposition temperature of plastic. For example, since the decomposition start temperature of polyethylene is about 350 ° C., if the target plastic is polyethylene, it should be about 350 ° C. or higher and about 650 ° C. or lower. For example, it is the above-mentioned weakly oxidizing environment and is an environment in which plastic is decomposed or carbonized. In the present invention, the term <decomposition> may be used instead of the term <carbonization>, but it should be noted that these terms have different contents. That is, carbonization can be considered to be included in the decomposition. Further, as described above, the weakly oxidizing environment (atmosphere) is a combination of an atmosphere and a temperature having an oxygen potential capable of oxidizing lithium without proceeding with the reaction of C + O2 → CO2.

MxO (M is an element or reactive group) is also generally used to provide a weakly oxidizing atmosphere. When MxO is used, the oxygen potential according to the 2XM + O2 = 2MxO Ellingham diagram is higher than the oxygen potential of Li oxidation, and the treatment is performed in a temperature range lower than the oxygen potential of C + O ₂ → CO ₂ , so that (A) and ( Achieve the purpose of B). The above-mentioned water (H ₂ O) is also a kind of MxO, but other examples include CsO ₂ , N ₂ O, and NO ₂ .

When a waste lithium-ion battery is directly decomposed or carbonized by a superheated steam device or a roasting device, the separator is decomposed or carbonized and discharge occurs between the positive and negative electrodes, causing heat generation or, in the worst case, explosion. It may be damaged. Further, when the discharge process is performed by such partial contact, it is difficult to control the partial contact, so that the short-circuit current may become large and a chain of heat generation may occur, and the temperature rise due to the heat generation melts the metal such as aluminum and is valuable. It may be difficult to recover metals. The weakly oxidizing environment of the present invention may not be maintained due to heat generation.

In a lithium ion battery, a separator is inserted between the positive electrode and the negative electrode, and this separator hinders discharge. Therefore, if the separator is removed, discharge will occur. However, if the separator is completely eliminated by carbonization, a sudden discharge will occur and the device will be damaged due to sudden heat generation or explosion. Therefore, partial damage or partial destruction of the separator that causes a quiet discharge is required. It may be raised to realize a partial short circuit between the positive electrode and the negative electrode.

Decomposition of polyolefin, which is the main component of the separator, begins, for example, at about 350 ° C. for polyethylene, about 320 ° C. for polypropylene, and about 320 ° C. for polystyrene (not shown in FIG. 3), as shown in FIG. If this temperature is exceeded, the separator decomposes or carbonizes and has electrical conductivity, but rather becomes a conductor and short-circuits, causing rapid ignition. In order to achieve safe energy release, it is necessary to realize discharge by partial short circuit below this temperature. Further, at 280 ° C. just below that temperature, the SEI (Solid Electrolyte Interphase) (coating) formed by the partial reduction reaction between Li of the LiB negative electrode and the electrolytic solution collapses, and heat is generated by the direct reaction between Li and the electrolyte. It has been reported that the heat generated causes a separator decomposition reaction, so the SEI (Solid Electrolyte Interphase) (coating) collapses and the discharge treatment at a temperature (280 ° C or less) that does not generate heat due to the direct reaction between Li and the electrolyte. Is required. Alternatively, heat treatment at a temperature within this range may chemically change the electrolyte or damage the electrical system such as electrodes and wiring, so that sudden discharge does not occur. In chemical terms, deactivation means that the activity of a chemical substance or the like is lost and the reaction does not occur, that is, inactivation, but in the present invention, deactivation means that a sudden discharge does not occur. Call. Further, the deactivated state is called an deactivated state, and the process of deactivating the deactivated state (for example, the above-mentioned heat treatment) is called an deactivated process.

In order to realize a partial short circuit, it is necessary to deform the separator without disassembling or carbonizing it to locally realize a state in which the positive electrode and the negative electrode are in contact with each other. In order to deform the separator, it is necessary that the separator is softened or melted so that it can be deformed, and that a force for deforming is applied. Examples of the polyolefin used for the separator include PE (polyethylene), PS (polystyrene), and PP (polypropylene). The melting point of PE is 95 ° C. to 140 ° C., the melting point of PS is 100 ° C., the glass transition temperature of PS is 90 ° C., and the glass transition temperature of PP is as low as 0 ° C. Therefore, the separator can be easily deformed if a force is applied at a temperature of around 100 ° C.

Deformation forces include stress due to the difference in the coefficient of thermal expansion, and pressure due to vaporization and gas generation due to chemical reactions. The difference in thermal expansion coefficient between metal and plastic is about 0.01% / ° C, and the higher the temperature, the more effective it is. The greater effect is the generation of pressure due to vaporization and gas generation, which has also been observed in cases such as the swelling of deteriorated lithium-ion batteries.

As the LiB electrolyte, a lithium salt 1M such as LiPF ₆ dissolved in an organic solvent is used. As the organic solvent, a volatile solvent such as EC (ethylene carbonate), PC (propylene carbonate), DMC (dimethyl carbonate), and EMC (ethyl methyl carbonate) is mixed and used. In particular, DMC is used in many LiBs, but its boiling point is 90 ° C., and higher heating causes evaporation, which can cause deformation.

PC (boiling point 242 ° C) is sometimes used without mixing with DMC, but it is known that it decomposes into acetone and propanal as a deterioration mechanism during use, and acetone is present in used LiB. The boiling point of this acetone is 56 ° C, which is lower than the boiling point of DMC of 90 ° C. That is, if the temperature is higher than the boiling point of DMC, this acetone will evaporate. In addition, there are cases where EMC (boiling point 107 ° C) is also used without mixing with DMC, but it is known that a 2EMC → DMC + DEC reaction occurs as a deterioration reaction during use, and it has also been used in this case. LiB contains DMC with a boiling point of 90 ° C. By heating to 90 ° C. or higher, which is the boiling point of DMC contained in the organic solvent, it is possible to apply a pressure to give deformation to the softened separator, and a local short circuit can be realized.

As described above, at a temperature below the temperature at which the internal short circuit occurs due to the decomposition or carbonization of the separator, the separator in LiB is deformed by the pressure due to the gasification of the volatile electrolyte and the alteration of the separator, resulting in a partial short circuit between the positive electrode and the negative electrode. In order to wake up and gradually release the energy of LiB, the temperature is below the decomposition temperature or carbonization temperature of the separator and below the temperature at which the SEI film does not generate heat due to the direct reaction between Li and the electrolyte, and the gasification start temperature of the electrolyte. Above. Specifically, the present invention is an energy release method capable of heat-treating a waste lithium ion battery at a temperature of 90 ° C. or higher and 280 ° C. or lower to gradually generate an electric discharge. In this method, the same superheated steam device (furnace) or roasting device (furnace) can be continuously (continuously or continuously after the discharge treatment), and the same device can be used for decomposition treatment or carbonization treatment. That is, continuous treatment of discharge treatment and decomposition treatment or carbonization treatment is also possible.

However, even with the above-mentioned partial discharge treatment, the discharge treatment may proceed rapidly. That is, when the discharge process by partial contact is performed, the short-circuit current becomes large because the partial contact portion is difficult to control, which may cause a chain of heat generation. Therefore, in consideration of the worst, the present invention further absorbs such rapid heat generation with a substance having a large heat capacity. Since liquids often have a large heat capacity, the object of the present invention is a liquid. That is, the waste lithium ion battery is immersed in a liquid to perform a discharge treatment. Since the liquid is in a liquid state, the discharge treatment is performed below the boiling point or the decomposition point (temperature) of the liquid, and the heat generated by the discharge is absorbed by the liquid. That is, the above object can be achieved by treating in a substance which is liquid at the above-mentioned temperature of 90 ° C. and has a boiling point or a decomposition point between 100 ° C. and 280 ° C. Further, it is desirable that this liquid does not generate composite oxides or sulfides in the subsequent decomposition, carbonization or roasting treatment. Liquids that satisfy these conditions are, for example, triacylglycerol and water. That is, the waste lithium ion battery is immersed in boiling water of about 90 ° C. or higher (in water of about 90 ° C. to about 100 ° C.) or immersed in triacylglycerol at about 90 ° C. to about 280 ° C. and discharged. Wake up. Triacylglycerol is, for example, various edible oils, and the decomposition point of peanut oil is 220 ° C., and the decomposition point of olive oil is 210 ° C.

This discharge treatment may be performed independently, or may be performed using a superheated steam device or a roasting furnace, and the same device may be continuously used to perform decomposition treatment, carbonization treatment, or conventional roasting treatment. .. When the discharge treatment is performed using the superheated steam device, naturally, the superheated steam is not introduced and the heat treatment is performed under the above-mentioned conditions. In addition, a container containing a waste lithium battery is placed in the above-mentioned treatment solution (for example, triacylglycerol or water) in a carbonization treatment or roasting apparatus, and discharge treatment is performed in the temperature raising process to continuously perform the discharge treatment. It can also be carbonized or roasted. In this case, the container can be recycled if the container is made of a material that does not deform or chemically react during heat treatment. For example, it is made of stainless steel or titanium. The treatment solution in the container evaporates and is exhausted by decomposition treatment, carbonization treatment, and roasting treatment. If the container is not recycled, if the container is made of plastic, this container will also be decomposed or carbonized, so there is no problem. In addition, the conditions for this discharge treatment may differ depending on the size and type of the waste lithium battery, so the conditions for the waste lithium battery to be treated are completely deactivated (a state in which the deactivated state is not restored) (for example, heat treatment). It is also possible to check the temperature and heat treatment time in advance and perform the deactivation treatment under those conditions. For example, there is a method of performing one long-time heat treatment or a plurality of (two or more times) heat treatment. In this case as well, it may be carried out independently, or it may be carried out by using a superheated steam device or a roasting furnace, and the decomposition treatment or carbonization treatment or the conventional roasting treatment may be carried out continuously by using the same device.

When this treatment is performed in the process of decomposition or carbonization by superheated steam, a water film (which may be called a boundary film) covering LiB formed on the surface of LiB is formed at the initial stage, so that it is automatically performed. The above-mentioned conditions (LiB is in a state of 90 ° C to 100 ° C) are satisfied. That is, superheated steam is a condition for realizing a weakly oxidizing environment, and if the temperature is set to a temperature equal to or higher than the decomposition or carbonization temperature of the plastic, the discharge treatment is automatically performed. Alternatively, if LiB is simply discharged, superheated steam treatment at 100 ° C. or higher may be applied to LiB. That is, even if LiB is not immersed in water and treated at 90 ° C. to 100 ° C., it is a condition to realize a weakly oxidizing environment with superheated steam in a superheated steam device, and the temperature is higher than the decomposition or carbonization temperature of plastic. If the superheated steam treatment is performed at the above temperature, the LiB is discharged at the initial stage. In order to perform the above-mentioned discharge treatment more effectively, the electrode layer of the waste lithium battery may be perforated in advance, and the perforation treatment damages the separator (for example, holes are formed), so that the discharge is performed. The process works effectively.

<Example 1>
FIG. 4 is a graph showing the experimental results of boiling water treatment of a used storage battery. The voltage of the used LiB as it was charged was measured by putting it in boiling tap water and taking it out 1 minute later, and then putting it in boiling tap water for 30 minutes and taking it out. In addition, in order to verify the effect of the difference in electrolyte, KOH is used as the electrolyte, and the nickel-metal hydride battery (Ni-HM) battery that does not react in this temperature range is charged and after 30 minutes of boiling tap water treatment. The voltage of was compared. The voltage of LiB was reduced to less than half after 1 minute of processing, and it became almost zero after 30 minutes of processing, confirming the effect of discharge. On the other hand, with Ni-HM, which has a stable electrolyte, there was no change even after 30 minutes.
<Example 2>
FIG. 10 shows a potential difference between a positive electrode (+ electrode) and a negative electrode (-pole) at room temperature after immersing a coin-type lithium battery (LiB) CR1616 in a salad oil bath held at 120 ° C. and holding the battery for a predetermined time. It is a table which shows the measurement result of (electromotive force), that is, the evaluation result of the deactivated state by the heat treatment of a lithium battery. When the electromotive force becomes almost 0V (about 0.2V or less), it can be determined that LiB is inactive. The data of 170 min in the first time (holding at 120 ° C.) is the result of measuring by holding LiB immersed in 150 min for 20 min at room temperature. The second data is the measurement result after the first 170 min-treated LiB was held at room temperature for 21 hours and then immersed in the salad oil bath again for a predetermined time. The second 130 min data is the measurement result when the 120 min treated LiB was held at room temperature for 10 min. The data of 360 min and 1000 min are also the electromotive force of LiB when kept at room temperature. According to this, it can be seen that even LiB, which seems to have been deactivated by one long-time (about 150 min) heat treatment, is restored (returned to the original state) by being left at room temperature for a short time. In addition, the second long-term heat treatment (about 60 min to 120 min) completely deactivates the product. From this, it is effective to carry out the waste heat treatment twice. Alternatively, it indicates that it is necessary to continuously perform a heat treatment longer than the above heat treatment time (for example, about +60 min to 120 min), and if such a long heat treatment (for example, about 210 min to 270 min) is performed once. A completely deactivated state can be obtained by heat treatment. From the results shown in FIG. 10, if the heat treatment (for example, temperature and time) is insufficient and the battery separator is not completely destroyed, the state of the separator may be restored to some extent by leaving it at room temperature or it may be restored. Alternatively, even if the electrolyte inside the battery changes due to heat treatment and the electromotive force disappears once, some of the electrolyte that has deteriorated due to being left at room temperature returns to its original state, or the electrodes and wiring are heat-treated. Even if the electromotive force is once lost due to damage, the electrodes and wiring damaged by leaving at room temperature may be partially repaired and restored by heat treatment. However, the above state becomes an irreversible state and becomes a completely deactivated state by a heat treatment of multiple times (two times or more) or a continuous long-time heat treatment (one time).

The present invention is a treatment method for recovering rare elements (Li, Co, Ni, etc.) used in lithium ion batteries used in mobile phones and automobiles, that is, a treatment method for recycling used (waste) lithium ion batteries. Next, another method (second invention) capable of performing the discharge treatment before the decomposition treatment or the carbonization treatment of the plastics of the waste lithium ion battery will be described. In the recycling of used lithium-ion batteries, active lithium (Li) exists in a high-energy state in a charged lithium-ion battery, which causes heat generation and ignition of flammable electrolyte substances when the high-energy state is released. Generally, safe processing is difficult. Therefore, although some manual discharges and electrolyte cleaning have been attempted, most of them have to be processed in a high-temperature furnace where there is no problem even if they ignite. Therefore, metal components such as aluminum and compound components such as cobalt acid are mixed at a high temperature, which imposes a heavy burden on the subsequent extraction process. Therefore, the present invention is characterized in that superheated steam treatment at 650 ° C. or lower, in which metals and compounds are physically easily separated, is performed as a pre-stage of metal extraction, and there is a high risk of reaction with steam for that purpose. Li in the energy state is discharged by an aqueous solution of an electrolytic salt. At that time, instead of using a salt containing halogen as an anion, an organic anion consisting of carbon, hydrogen, and oxygen that is decomposed and carbonized by superheated steam treatment is used, and calcium (Ca) that adsorbs fluorine and the like contained in a lithium ion battery, etc. By using the above-mentioned cation, the release of harmful substances in the superheated steam treatment stage is prevented.

The second invention makes it possible to separate a lithium ion battery discharged by an aqueous electrolyte solution of a salt having an anion that decomposes by a carbonization reaction and a cation that fixes fluorine and sulfur into metal components, compound components, and carbides by superheated steam treatment. It is a processing method to be performed. During the discharge process, ultrasonic ceramic cutting is used to damage the lithium-ion battery to cause discharge between the electrodes, and during the discharge process, a good conductor drill that is potentially insulated from the earth, etc. A short-time discharge is promoted by using the cutting risk of the above, or the cell package is distorted by external deformation during the discharge treatment, and the electrolyte aqueous solution is leached from the strain.

FIG. 5 is a diagram showing an example of the flow of the processing method of the present invention. A used lithium-ion battery (sometimes referred to as LiB) is immersed in a container containing a conductive aqueous solution (also referred to as an electrolytic aqueous solution or an electrolyte aqueous solution). Alternatively, a used lithium ion battery is placed in a container, a conductive aqueous solution is put therein, and the lithium ion battery is immersed in the conductive aqueous solution. A conductive aqueous solution is a salt having a cation that fixes and adsorbs fluorine and sulfur and an anion that decomposes by a carbonization reaction. For example, the cation is a calcium (Ca) ion, the anion is an organic anion such as carbonic acid, acetic acid, oxalic acid, or formic acid, and the salt is, for example, a calcium carbonate salt. Conventionally, the discharge treatment of a used lithium ion battery is generally performed from the viewpoint of safety, but a method of immersing in an inexpensive salt water or a chloride aqueous solution such as sodium chloride to discharge the battery is used. However, the anion of salt water and the like is chlorine, and when it is treated with superheated steam, it is converted to hydrochloric acid and damages the furnace and the environment. Alternatively, the heating furnace may be corroded by chlorine or released as outside air in the subsequent roasting treatment or superheated steam treatment, which may damage the heating furnace and the environment. Further, since the aqueous chloride solution has high conductivity, there is a possibility that the lithium ion battery is short-circuited and the voltage suddenly changes, causing a problem that the aqueous solution suddenly bursts.

On the other hand, the organic anion such as carbonic acid used in the present invention is damaged to the heating furnace and the environment because it is decomposed and carbonized in the heat treatment (superheated steam treatment) in the subsequent process and does not contain chlorine at all. The risk of giving is small. On the other hand, the conductive aqueous solution (organic acid-based salt) such as calcium carbonate used in the present invention has a problem that the dissociation constant is low and the discharge treatment is not effectively performed. Therefore, since it is necessary to shorten the distance between the discharge electrodes, in the present invention, the housing of the lithium ion battery is damaged by cutting or perforation, and the distance between the output electrodes inside the lithium ion battery (separate) is short. (Between the positive electrode and the cathode) that sandwiches the That is, the conductive aqueous solution invades the lithium ion battery due to damage such as cuts and perforations, causing a short circuit (discharge) between the positive electrode and the cathode.

In the present invention, the lithium ion battery is damaged in a container (small container) containing a conductive aqueous solution. FIG. 6 is a diagram showing an example of a method of damaging a lithium ion battery in a conductive aqueous solution in a small container 11 containing a conductive aqueous solution. FIG. 6A is a diagram showing how the lithium ion battery 12 is damaged by being pushed by the presses 14 and 15 (in the direction of the arrow) from both side surfaces of the housing of the lithium ion battery 12. That is, the housing of the lithium ion battery 12 is deformed by pressing and crushing the lithium ion battery 12 with the presses 14 and 15, and the conductive aqueous solution is permeated into the housing through the gap generated by the deformation. This method may be called a lateral pressure method. The conductive aqueous solution inside the housing discharges the electrodes. The pressure to be deformed may be uniform on the side surface of the housing or may be concentrated on a part of the housing as long as it causes a gap in the housing. Since the press used for the lateral pressure method also enters the conductive aqueous solution, it is made of a material having strong resistance to deterioration with respect to the conductive aqueous solution. For example, it is made of stainless steel or ceramics.

FIG. 6B is a diagram showing a state in which the lithium ion battery 13 is deformed by the rotary rolling rolls 16 and 17 to form a gap. The rotary rolling rolls 16 and 17 are rotating in the direction of the arrow, and the lithium ion battery 13 is passed between the rotary rolling rolls 16 and 17 with a gap enough to damage the housing of the lithium ion battery 13 in the direction of the arrow. Carry. The conductive aqueous solution is permeated into the housing through the gap created by the damage, and the conductive aqueous solution that has entered the housing discharges the electrodes between the electrodes. The example of FIG. 6B deforms the housing of the lithium ion battery 12 by changing the pressure portion with time, and may be called a continuous roll method. Since the rotating (rolling) roll used in the continuous roll method is also contained in the conductive aqueous solution, it is made of a material having strong resistance to deterioration with respect to the conductive aqueous solution. For example, it is made of stainless steel or ceramics.

FIG. 7 is a diagram showing another method of damaging the lithium ion battery. The lithium ion battery 21 is immersed in a small container 11 containing a conductive aqueous solution, and the lithium ion battery 21 is dipped using a drill 22. A hole is made in the side surface of the housing to damage the lithium ion battery 21. The external electrodes of the lithium-ion battery are indicated by A and B so that the front side and the back side can be seen. In FIG. 7A, the tip of the drill 22 is brought into contact with the side surface of the lithium ion battery 21 on the front side of the housing. Since the positive electrode surface, the separate surface, and the negative electrode surface (collectively referred to as the electrode surface) are arranged substantially parallel to this side surface, a hole can be drilled in the center of the front side surface of the lithium ion battery 21. A hole penetrating the electrode surface is formed. FIG. 7B is a view showing a state in which the drill 22 penetrates the side surface of the housing of the lithium ion battery 21, and shows the back side of the side surface of the housing. Even in this state, if the drill 22 is made of a material having good electrical conductivity (for example, made of various metals), the electrodes (positive electrode and negative electrode) are short-circuited and an electric discharge is generated. And / or, it permeates into the inside of the lithium ion battery 21 through the hole in which the conductive aqueous solution is formed, and discharge starts. That is, the blade of the drill assists the discharge by the conductive aqueous solution as an external discharge body.

However, when the electrical conductivity of the drill 22 is low, electric discharge is unlikely to occur, when drilling with a drill, electric discharge is unlikely to occur, and when the conductivity of the conductive aqueous solution is low and the electric discharge gradually progresses, the figure is shown in FIG. As shown in 7 (c), the hole is passed through the housing of the lithium ion battery 21 with the drill 22, and after the tip of the drill 22 comes out on the back side of the side surface of the housing, the electric conductivity is provided near the tip of the drill 22. When an extremely good metal wire (which may be in the form of a string or tape) 23 is attached and then the drill 22 is pulled out as shown in FIG. 7 (d), the metal wire 23 is in a state of passing through the through hole. When the metal wire 23 is removed from the drill (blade) 22 after the metal wire 23 has passed through the through hole, the metal wire 23 is in the through hole as shown in FIG. 7 (e). FIG. 7 (e) is a view seen through a plan (upper surface) view of the lithium ion battery 21, and the positive electrode surface, the separate surface, and the negative electrode surface are arranged in multiple layers substantially parallel to the side surface of the housing. A hole made by a drill 22 penetrates a substantially central portion thereof, and a metal wire 23 passes through the hole. The metal wire 23 directly connects the electrodes (positive electrode and negative electrode) to discharge, and / or the conductive aqueous solution that has entered the pores causes the discharge to proceed rapidly. When the metal wire 23 is in direct contact with the electrodes (positive electrode-negative electrode), an electric discharge is generated immediately, but even if the metal wire 23 is not in direct contact, the distance between the electrode and the metal wire 22 is extremely small (distance between electrodes). Since it is much smaller than the above), it is possible to generate an electric discharge in a short time by the conductive aqueous solution in between. In addition, various electric good conductors (wires) other than metal wires may be used. For example, carbon wire, VDD and conductive plastic can be mentioned. Further, although it is described as a line, as long as it enters a through hole (including a perforation), it may be in the form of a string or a tape, and therefore, even if it is described as a line, these various types are included.

As a method of damaging the waste lithium ion battery using the above-mentioned drill or the like, putting a conductive aqueous solution inside the waste lithium ion battery and discharging it between the electrodes, there is also a method of cutting or drilling with an ultrasonic ceramic cutter. That is, similarly to the method shown in FIGS. 6 and 7, a waste lithium ion battery (housing) is placed in a conductive aqueous solution, and the housing is cut or perforated with an ultrasonic ceramic cutter to inside the housing. Allow the conductive aqueous solution to permeate into the. When the cutter is a good conductor, when the structure electrically separated by the separator inside the battery is cut at the time of drilling, the cutter penetrates the separator and partially short-circuits between the electrodes (positive electrode and negative electrode). As a result, an internal short circuit occurs and the generation of an external discharge current is impaired. On the other hand, when a ceramic cutter is used, since the ceramic cutter is an insulator, such a short-circuit phenomenon does not occur, and it is possible to avoid impairing the generation of an external discharge current. In addition, ultrasonic waves can not only increase perforation and machinability, but also promote the penetration of the conductive aqueous solution into the battery. When the discharge treatment is performed in a conductive aqueous solution having a large heat capacity as in the present invention, even if the discharge treatment occurs rapidly, the temperature does not rise sharply due to heat generation, and an explosion or sudden outbreak does not occur. Therefore, the discharge treatment is extremely safe. It can be said that it is a law.

If the conductivity of the conductive aqueous solution is not very high, discharge is less likely to occur. Therefore, in order to increase the conductivity of the conductive aqueous solution, the present invention mixes the conductive filler or the conductive fine powder with the conductive aqueous solution. Since the conductive filler or the conductive fine powder is dispersed and suspended in the conductive aqueous solution, when the conductive aqueous solution infiltrates the vicinity of the electrode of the battery cell from the damaged part of the waste lithium ion battery, the dispersed conductivity Discharge through a conductive aqueous solution whose conductivity has been increased with a conductive filler or the like. Examples of the conductive (dispersed) filler or the conductive (dispersed) fine powder include carbon black, graphite, various metal powders such as silver, nickel and copper, conductive tin oxide, and conductive titanium oxide. They are harmless and can be recovered as they remain as carbonized or metal compounds or elemental metals after superheated steam treatment or roasting.

Next, with the lithium ion battery immersed in the conductive aqueous solution of the small container, the small container is immersed in the large container containing the conductive aqueous solution. The conductive aqueous solution in the small container and the large container is the same. Although the lithium ion battery was damaged in the previous step to promote the discharge, it is desirable to discharge the lithium ion battery sufficiently, so it is better to leave it in the conductive aqueous solution for a certain period of time. For example, leave it for half a day to about a week. FIG. 8 is a diagram showing a state in which a lithium ion battery immersed in a large container 31 containing a conductive aqueous solution and a small container 11 containing the conductive aqueous solution are arranged. If a large number of small containers 11 can be arranged, the running cost can be reduced. In FIG. 8, the small containers 11 are only arranged in a row on the bottom surface of the large container 31, but if shelves are made or stacked and arranged in a plurality of stages, mass processing is possible.

Take out the small container containing the fully discharged waste lithium-ion battery from the large container, put the waste lithium-ion battery in the conductive aqueous solution, and in the state where the conductive aqueous solution has permeated, put the small container in the superheated steam device (furnace). ). FIG. 9 is a diagram showing a superheated steam device 100 in which a small container 108 containing a waste lithium ion battery and a conductive aqueous solution is arranged on a support shelf 106 provided in the device. The superheated steam device 100 includes a superheated steam generator 102, and a temperature sensor 103 for detecting the temperature inside the device is arranged. The signal from the temperature sensor 103 is sent to the controller 104, the controller 104 controls the operation of the boiler 101 in order to maintain the temperature inside the device at a predetermined temperature, and sends the superheated steam at an appropriate temperature to the superheated steam generator 102. A predetermined temperature and a predetermined amount of steam are sent from the superheated steam generator 102 into the superheated steam device 100 to bring the temperature and the amount of steam in the superheated steam device 100 into a predetermined state. In particular, make sure that the small container 108 and its surroundings are in a predetermined state. The pressure in the superheated steam device 100 may be set to a high pressure state of atmospheric pressure or higher. The gas in the superheated steam device is discharged to the outside through the exhaust line 105. At the stage when the small container 108 is arranged in the superheated steam device 100, air is contained in the device, but when the superheated steam enters the device, the air is discharged from the exhaust line 105 to the outside, so that the inside of the device is overheated. It is filled with water vapor and oxygen does not exist.

The conductive aqueous solution in the small container 108 is maintained at the evaporation temperature (around about 100 ° C., depending on the type of aqueous solution) until it evaporates, but after evaporation, it is at almost the same temperature as the superheated steam temperature (about 300 ° C. ~). At about 650 ° C.), the plastics constituting the waste lithium ion battery are carbonized or decomposed. In addition, rare metals contained in electrodes and the like are also oxidized to form oxidized compounds thereof. The small container 108 may be made of a metal (for example, stainless steel) that does not react even at this temperature, or may be made of a carbonized plastic (for example, polypropylene or polycarbonate). Metals can be used repeatedly, and plastics are carbonized or decomposed, so the trouble of collecting them can be saved. Exhaust line 105 may be provided with exclusion equipment. The waste lithium-ion battery is put in the small container 108 in the state of being in the housing, but if the metals such as screws fixing the housing and the attached metals are removed in advance, it will be superheated steam. Easy to recycle after carbonization. Since the temperature inside the superheater is a temperature equal to or lower than the melting point of Al (about 660 ° C) (preferably a temperature not exceeding 650 ° C) and is treated in an oxygen-free state, Al and various metals other than lithium are one of the surfaces and the like. Although the part is oxidized, it remains unoxidized as a whole, so that the recycling process is easy.

The reason why the waste lithium ion battery is placed in the superheated steam device in the state of being put in the conductive aqueous solution is to prevent sudden heat generation and explosion due to electric discharge during heat treatment in the superheated steam device. Since sufficient discharge has already been performed by processing in a large container, there is almost no need to worry, but just in case, a small container 108 containing a waste lithium ion battery in a conductive aqueous solution is used in the superheated steam device 100. It is placed in. Further, since the waste lithium ion battery contains fluorine (electrolyte LiPF _6, etc.), if fluorine is discharged in the form of hydrogen fluoride (HF) or the like, the device may be damaged or the environment may be polluted. Equipped with exhaust gas exclusion equipment as a measure against environmental pollution will increase equipment costs and running costs. However, harmless fluoride is formed by combining with HF and the like in which cations are generated in the conductive aqueous solution. For example, when the conductive aqueous solution is calcium carbonate, calcium fluoride (CaF ₂ ) is formed and can be detoxified. Since the anionic compounds are CO ₂ and H ₂ O, there is no problem even if they are discharged to the outside, so no special exclusion equipment is required. Since the temperature inside the superheated steam device is maintained at 300 ° C. to 650 ° C., the conductive aqueous solution also becomes a high temperature state, and the electric conductivity of the conductive aqueous solution also increases, so that the remaining discharge proceeds. Since the conductive aqueous solution will eventually completely evaporate and remain in the small container in the form of calcium (Ca) alone or in the form of a compound, it can be recovered by being sent to post-treatment together with the carbonized waste lithium ion battery. The method by superheated steam treatment used in the present invention is a heat treatment at 650 ° C. or lower, which is lower than the melting point of aluminum, so that there is no risk of aluminum melting, and plastics are decomposed or carbonized but CO2 is not emitted. Furthermore, since no chlorine-based substance is used, no chlorine-based compound is generated, and the load on the environment is small.

After the superheated steam treatment, treated products such as carbonized plastics and oxidized compounds of metals that have reacted with steam and unreacted metals remain. These processed products are taken out and used as raw materials for the extraction process after physical separation. If a small container exists, these processed products remain in the small container, so the small container is taken out from the superheated steam furnace. If the small container is also carbonized and does not remain, it is easier to recover the treatment residue if the medium container containing the small container is placed in the superheat heat furnace before the treatment with the superheated steam device. After crushing the residual processed material with a crusher, sorting is performed to separate metals and other substances, and metals (for example, lithium (Li), cobalt (Co), nickel (Ni), copper (for example) Cu), aluminum (Al), iron (Fe), etc. are recovered in an extraction step or the like. For the residue after the superheated steam treatment, various conventional methods for recovering valuable metals such as an extraction step after physical separation can be used. When performing the discharge treatment in the liquid described above, the above-mentioned long-term heat treatment (single heat treatment) or multiple heat treatment (for example, FIG. It is also possible to take out the waste lithium battery completely deactivated by the above heat treatment method) from the liquid and then put it in a superheated steam device to perform decomposition / carbonization treatment (process from the middle shown in FIG. 5). A liquid container in which a waste lithium battery is immersed can be placed in a superheated steam device and discharged (for example, long-term heat treatment (single heat treatment) or multiple heat treatments) in the superheated steam device, and then placed in the container. It is also possible to continuously decompose and carbonize the waste lithium battery that has been deactivated while it is in the battery while it is placed in the superheated steam device (similar to the method shown in FIG. 5).

As described in detail above, the present invention provides a method for stabilizing a waste (used) lithium ion battery that can be safely discharged. By using the present invention, the discharge treatment of the waste lithium ion battery can be safely performed, and the adverse effect on the treatment device and the environment can be significantly reduced. In addition, the stabilization processing cost of the present invention is small, and the recycling cost of the lithium ion battery can be reduced. It goes without saying that the content can be applied to the other part of the specification without any contradiction as to the fact that the content described and explained in the specification can be applied to the other part without contradiction. In addition, it is natural that the contents of the examples and embodiments described in the present application document can be used in combination with the contents of other examples and embodiments. Further, it goes without saying that the embodiment is an example and can be modified in various ways without departing from the gist, and the scope of rights of the present invention is not limited to the embodiment.

The method for stabilizing a waste lithium ion battery of the present invention may be applicable to a recycling process for other ion batteries.

11 ... Small container, 12 ... Lithium-ion battery, 13 ... Lithium-ion battery,
14 ... press, 15 ... press, 16 ... rotary rolling roll, 17 ... rotary rolling roll,
21 ... Lithium-ion battery, 22 ... Drill, 23 ... Metal wire, 31 ... Large container,
100 ... Superheated steam device, 101 ... Boiler, 102 ... Superheated steam generator,
103 ... temperature sensor, 104 ... controller, 105 ... exhaust line,
106 ... Support shelf, 107 ... Lithium-ion battery, 108 ... Small container

Claims (25)

Below the decomposition temperature of the separator of the used lithium-ion battery and the SEI (Solid Electrolyte interface) decay temperature (upper limit temperature), and above the gasification start temperature (lower limit temperature) of the electrolyte of the used lithium-ion battery. A method for stabilizing a used lithium-ion battery, which comprises heat-treating the used lithium-ion battery between the two to deactivate the used lithium-ion battery. The method for stabilizing a used lithium ion battery according to claim 1, wherein the upper limit temperature is about 280 ° C. and the lower limit temperature is about 90 ° C. The used lithium ion battery according to claim 1 or 2, wherein the lithium ion battery is liquid at the lower limit temperature and is heat-treated in a substance having a boiling point or a demarcation point below the upper limit temperature. Stabilization processing method. The substance stabilization method of a spent lithium ion battery according to any one of the paragraphs, characterized, according to claim 1 to 3 that the water (H 2 _O) or triacylglycerol. The method for stabilizing a used lithium ion battery according to any one of claims 1 to 4, wherein the electrode layer of the used lithium ion battery is perforated before the heat treatment. The third to third aspect of the present invention, wherein after the heat treatment, the plastics of the used lithium ion battery are carbonized or decomposed in a roasting apparatus or a superheated steam apparatus in a state of being contained in the substance. 5. The method for stabilizing a used lithium ion battery according to any one of 5. A used lithium-ion battery is placed in a roasting device or a superheated steam device in a state of being contained in the substance to perform the heat treatment, and then carbonization treatment or decomposition treatment of plastics of the used lithium-ion battery is performed. The method for stabilizing a used lithium ion battery according to any one of claims 3 to 5, which comprises the method. A third to fifth aspect of the present invention, wherein the used lithium ion battery is placed in a superheated steam device in a state of being contained in the substance to carry out carbonization treatment or decomposition treatment of plastics of the used lithium ion battery. The method for stabilizing a used lithium ion battery according to any section. The heat treatment according to claim 1, wherein the used lithium ion battery is placed in a superheated steam device and carbonization treatment or decomposition treatment of plastics of the used lithium ion battery is performed to realize the heat treatment according to claim 1. The method for stabilizing a used lithium ion battery according to 1 or 2. A method for stabilizing a used lithium ion battery, which comprises a step of arranging the used lithium ion battery in a weakly oxidizing environment to carry out a carbonization treatment or a decomposition treatment of plastics, wherein the used lithium ion battery is weakly oxidizing. The environment is a method for stabilizing a used lithium ion battery, which is a combination of atmosphere and temperature having an oxygen potential capable of oxidizing lithium without proceeding with the reaction of C + O2 → CO2. The atmosphere of the weakly oxidizing environment is MxO (M is an element or a reactive group).
The temperature of the weakly oxidizing environment is such that the oxygen potential according to the Ellingham diagram of 2XM + O ₂ = 2MxO is higher than the oxygen potential for oxidation of lithium (Li) and lower than the oxygen potential for C + O ₂ = CO _2. The method for stabilizing a used lithium ion battery according to claim 10, wherein the temperature is equal to or higher than the decomposition temperature of plastics. The atmosphere of the weakly oxidizing environment is water vapor.
The temperature condition of the weakly oxidizing environment is about 650 ° C. or less, which is the temperature at the intersection of the oxygen potential diagrams of 2H ₂ O + O ₂ = 2H ₂ O and C + O ₂ = CO ₂ , based on the Ellingham diagram, and plastics. The method for stabilizing a used lithium ion battery according to claim 11, wherein the temperature is equal to or higher than the decomposition temperature of the above. Use, wherein the method for stabilizing the used lithium ion battery according to claims 1 to 5 is performed, and then the method for stabilizing the used lithium ion battery according to claims 10 to 12 is performed. Stabilization method for finished lithium-ion batteries. A used lithium-ion battery discharged by a conductive aqueous solution of a salt having an anion that decomposes by a carbonization reaction with a cation that fixes fluorine and sulfur is separated into a metal component, a compound component, and a carbide component by a superheated steam treatment at 650 ° C or lower. A method for stabilizing used lithium-ion batteries. 14. The 14th aspect of claim 14, wherein the used lithium ion battery is discharged with the conductive aqueous solution and then the superheated steam treatment is performed with the used lithium ion battery placed in the conductive aqueous solution. How to stabilize used lithium-ion batteries. The method for stabilizing a used lithium ion battery according to claim 14 or 15, wherein the conductive aqueous solution is an aqueous solution of calcium carbonate. The discharge treatment is characterized in that the used lithium ion battery is cut by ultrasonic ceramics cutting in a conductive aqueous solution, and the conductive aqueous solution is leached into the used lithium ion battery from the cut portion. The method for stabilizing a used lithium ion battery according to claim 15 or 16. The discharge treatment is performed by drilling a hole in a used lithium ion battery in a conductive aqueous solution using a cutting tool (tool) and leaching the conductive aqueous solution into the used lithium ion battery from the perforated portion. The method for stabilizing a used lithium ion battery according to claim 15 or 16, wherein the used lithium ion battery is characterized. The method for stabilizing a used lithium ion battery according to claim 18, wherein the cutting tool (tool) is an electrically good conductor. The method for stabilizing a used lithium ion battery according to claim 17 or 18, wherein an electrically good conductor wire is passed through the perforated portion. The discharge treatment is performed by externally deforming the used lithium ion battery in a conductive aqueous solution to give strain to the used lithium ion battery, and leaching the conductive aqueous solution into the used lithium ion battery from the strain. Alternatively, the method for stabilizing a used lithium ion battery according to 16. The method of applying deformation from the outside to distort the used lithium ion battery is characterized in that the method of applying deformation from the outside using a rotary press roller or a pressing machine to distort the used lithium ion battery. The method for stabilizing a used lithium ion battery according to claim 21. The method for stabilizing a used lithium ion battery according to any one of claims 15 to 22, wherein a conductive filler or a conductive powder is mixed with the conductive aqueous solution. The used lithium ion battery according to claim 23, wherein the conductive filler or the conductive powder is conductive carbon black, conductive tin oxide, conductive titanium oxide, or various metal powders. Stabilization processing method. The method for stabilizing a used lithium ion battery according to any one of claims 15 to 24, wherein the temperature of the superheated steam treatment is about 300 ° C. to about 650 ° C.