Battery processing method

Abstract

The present invention relates to a battery processing method, and the method comprises the steps of: preparing waste batteries; measuring an average charging and discharging time of the waste batteries; measuring an average charging and discharging time of module-unit waste batteries among the waste batteries, and comparing the measured value with the average charging and discharging time of the waste batteries; and depending on whether an average charging and discharging time of pack-unit waste batteries and a charging and discharging time of a module-unit waste battery satisfy equation 1 according to the present specification, determining whether a corresponding module is normal.

Description

How to dispose of batteries

[0001] It is about waste batteries, and more specifically, about battery disposal methods.

[0002] Electric vehicles, the supply and demand of which are rapidly increasing due to environmental concerns, require battery technology as a key element. The disposal of these waste batteries, generated from these electric vehicles, is becoming a social issue. These waste batteries, which use lithium-ion batteries, contain organic solvents, explosive materials, and heavy metals such as nickel, cobalt, manganese, iron, and phosphorus (Ni), carbon, and other electrolyte materials. Among these, nickel, cobalt, manganese, iron, phosphorus, and lithium are rare and valuable metals, and the recovery and recycling processes for these discarded lithium secondary batteries are emerging as important research areas.

[0003] Specifically, a lithium secondary battery mainly consists of copper and aluminum used as a current collector, Li, Ni, Co, and Mn-containing oxides forming a positive electrode, and graphite forming a negative electrode, and includes a separator separating the positive electrode and the negative electrode, and an electrolyte injected into the separator. The solvent used as the solvent and salt forming the electrolyte are mainly a mixture of carbonate organic substances such as ethylene carbonate and propylene carbonate, and for example, LiPF6 is used.

[0004] Waste batteries, including the aforementioned lithium secondary batteries, face technical challenges in safely dismantling. These waste batteries can be produced as process scrap during battery manufacturing, or as waste from used electric vehicles or energy storage devices. These waste batteries exist in cell, module, or pack configurations, and voltage is typically monitored on a pack or module basis. While many waste batteries are discarded due to their end-of-life, some are generated due to short-circuiting of the electrodes.

[0005] Distinguishing between the electrodes of the above-mentioned battery is crucial, as electrical discharge is impossible when the electrodes are short-circuited. However, since a single pack consists of hundreds of cells connected in series or parallel, it is difficult to identify short-circuited cells in a parallel configuration, making electrical discharge difficult.

[0006] To solve these problems, a water discharge method is being utilized in which waste batteries are separated into cell units, the outer shell is cut open, and the batteries are immersed in water or salt water to discharge them. However, the sodium and chlorine in the waste water or salt water can cause various problems in the subsequent process.

[0007] The technical problem to be solved by the present invention is to provide a battery processing method that safely discharges a battery even if it contains short-circuited cells and reduces the risk of fire when crushing the discharged battery.

[0008] According to one embodiment of the present invention, a battery processing method may include the steps of preparing a pack unit including a plurality of modules or a spent battery having two or more modules, measuring a charge and discharge rate of the pack unit including the plurality of modules or a spent battery having two or more modules to determine an average charge and discharge time, measuring the charge and discharge rate of the module unit spent battery to determine an average charge and discharge time of the module unit spent battery and comparing the measured charge and discharge rate with the average charge and discharge time, and determining a normal module or a defective module based on whether the average charge and discharge time of the pack unit spent battery and the charge and discharge time of the module unit spent battery satisfy the following Equation 1.

[0009] <Formula 1>

[0010]

[0011] (In the above equation 1, t aver t means the average charge and discharge time / module unit of a waste battery having a pack unit containing multiple modules or two or more modules, and the number of waste batteries module refers to the charge and discharge time / cell count of the module unit waste battery)

[0012] In one embodiment, the method may include a step of electrically discharging a normal module satisfying the above equation 1 to 0.1 V or less. In one embodiment, after the electrically discharging step, the method may include a step of grounding the normal module.

[0013] In one embodiment, the step of crushing the normal module that has undergone the electric discharge may be included. In one embodiment, the step of crushing the normal module may be performed in an inert gas.

[0014] In one embodiment, the step of crushing the normal module may be performed in an atmosphere having an oxygen concentration of 3% or less. In one embodiment, after the step of crushing the normal module, the step of drying the crushed result at a temperature of 200° C. or less may be included. In one embodiment, the step of measuring the charging and discharging speed of the waste battery to determine the average charging and discharging speed may be performed by charging and discharging the waste battery at a constant voltage or constant current.

[0015] According to another embodiment of the present invention, a battery processing method may include a step of preparing a waste battery in a module unit including a plurality of cells, a step of measuring a charge and discharge rate of the waste battery, a step of evaluating a temperature of a cell unit within the module, and a step of determining a normal module or a defective module based on whether a temperature deviation of the cell unit satisfies 3°C or less.

[0016] In one embodiment, the method may include a step of electrically discharging the normal module to 0.1 V or less. In one embodiment, the method may include a step of crushing the normal module subjected to the electrical discharge in an atmosphere having an oxygen concentration of 0.5% or less. In one embodiment, after the step of crushing the normal module, the method may include a step of drying the crushed result at a temperature of 200° C. or less. In one embodiment, the method may include a step of freeze-crushing the defective module.

[0017] According to another embodiment of the present invention, a battery processing method includes the steps of preparing a pack unit including a plurality of modules or a spent battery having two or more modules, measuring a charge and discharge rate of the pack unit including the plurality of modules or the spent battery having two or more modules to measure an average charge and discharge time, measuring the charge and discharge rate of the module-unit spent battery to measure the charge and discharge time of the module-unit spent battery and comparing the measured charge and discharge rate with the average charge and discharge time, determining a normal module or a defective module of the module-unit spent battery, crushing the normal module or the defective module, and drying the crushed resultant at a temperature of 200°C or lower, wherein the dried resultant can satisfy the following Equation 2.

[0018] <Formula 2>

[0019]

[0020] (In the above formula 2, w1 and w2 represent the initial weight (kg) of the crushed result and the weight (kg) of the dried result, respectively)

[0021] In one embodiment, the step of measuring the charge and discharge rate for each module and comparing it with the average charge and discharge rate to determine whether the module is normal or defective may include a step of determining whether the following equation 1 is satisfied.

[0022] <Formula 1>

[0023]

[0024] In one embodiment, after the step of measuring the charge and discharge rates for each module and comparing them with the average charge and discharge rates, the step of electrically discharging normal modules that satisfy Equation 1 to 0.1 V or less may be included. In one embodiment, after the step of measuring the charge and discharge rates for each module and comparing them with the average charge and discharge rates, the step of freezing defective modules that do not satisfy Equation 1 may be performed in a temperature range of -20° C. or less.

[0025] According to one embodiment of the present invention, a battery processing method is provided that safely discharges a battery even if it contains a short-circuited cell by checking for short-circuit in each cell through electrical discharge and safely performing a shredding process, thereby reducing the risk of fire when shredding the discharged battery.

[0026] Figure 1 is a drawing showing the temperature of the battery module itself of the present invention measured using a thermal imaging camera.

[0027] Figures 2a and 2b are graphs of temperature rise before and during battery crushing.

[0028] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "singular" and "comprising" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising" as used herein specifies a particular feature, region, integer, step, operation, element, and / or component, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0030] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0031] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0032] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, which is defined solely by the scope of the claims set forth below.

[0033] According to one embodiment of the present invention, a battery processing method may include a step of preparing a spent battery in the form of a module comprising a plurality of cells or a pack comprising a plurality of modules, and a step of determining whether the module is normal or defective. Specifically, the battery processing method of the present invention may be a battery processing method that measures the charge / discharge rate of a battery in a module or pack unit, thereby determining whether the module is normal or defective, thereby safely discharging the battery and reducing the risk of fire when the battery is crushed.

[0034] The step of preparing a module including a plurality of cells, a pack including a plurality of modules including a plurality of modules, or a spent battery having two or more modules may be a lithium secondary battery separated from an automobile, a secondary battery separated from an electronic device such as a mobile phone, a camera, or a laptop, specifically a lithium secondary battery. The lithium secondary battery may be a battery in a module unit including a plurality of cells, or a spent battery in a pack unit including a plurality of modules. The spent battery may include a normal module having a voltage of about 2.0 to 4.5 V on a cell basis and a defective module that is short-circuited and thus difficult to measure the voltage.

[0035] In the step of preparing the waste battery, if the waste battery is a pack unit including the plurality of modules or has two or more modules, a step of measuring the charging and discharging speed of the waste battery to determine an average charging and discharging speed may be included. Specifically, the step of measuring the charging and discharging speed of the waste battery to determine an average charging and discharging speed may be performed using constant-voltage discharge / recharge or constant-current discharge / recharge to uniformly charge and discharge. For a plurality of modules arranged in the pack, the average charging and discharging time of the modules can be calculated by dividing the time taken to charge and discharge the entire pack by the number of modules.

[0036] After the step of measuring the charging and discharging rates of a waste battery having a pack unit including multiple modules or two or more modules to determine an average charging and discharging rate, the waste battery in the pack unit can be disassembled into modules. Specifically, it may be a preprocessing step for calculating the charging and discharging rate of each module by disassembling the waste battery in the pack unit arranged into multiple module units.

[0037] A step of disassembling the waste batteries in the pack unit into modules, and then measuring the charging and discharging speeds of the modules, measuring the charging and discharging times of the waste batteries in the module unit, and comparing the measured charging and discharging times with the average charging and discharging times is included. Specifically, it may be a step of comparing the charging and discharging times of a plurality of the waste batteries in the module unit with the average charging and discharging times of the waste batteries in the pack unit.

[0038] It can be determined whether the average charge and discharge time of a pack unit including multiple modules or a waste battery having two or more modules and the charge and discharge time of the waste battery in module units satisfy the following Equation 1. Specifically, if the average charge and discharge time of a pack unit including multiple modules or a waste battery having two or more modules and the charge and discharge time of the waste battery in module units satisfy the following Equation 1, it can be determined as a normal module, and if it does not satisfy Equation 1, it can be determined as a short-circuited module in which a short circuit occurs and charging and discharging are not performed smoothly.

[0039] <Formula 1>

[0040]

[0041] (In the above equation 1, t aver means the average charge and discharge time / number of module units of waste batteries per pack unit containing multiple modules or waste batteries having two or more modules, and t module refers to the charge and discharge time / cell count of the module unit waste battery)

[0042] Satisfying the above equation 1 means that the difference between the average charge and discharge time of the waste battery in the pack unit and the charge and discharge time of the waste battery in the module unit is divided by the average charge and discharge time of the waste battery in the pack unit, and the value is less than the fraction of the number of cells in the waste battery in the module unit, which may be an indicator for determining that the module is normal. In contrast, not satisfying the above equation 1 means that the difference between the average charge and discharge time of the waste battery in the pack unit and the charge and discharge time of the waste battery in the module unit is divided by the average charge and discharge time of the waste battery in the pack unit, and the value is greater than the fraction of the number of cells in the waste battery in the module unit, which means that at least one of the cells in the module is defective due to a short circuit, etc.

[0043] In this way, the present invention measures the charging and discharging speed of a waste battery to calculate the charging and discharging time, thereby easily determining whether a module in the waste battery is normal or defective.

[0044] In one embodiment, a step of electrically discharging a normal module satisfying the above formula 1 to 0.1 V or less may be included. Specifically, the normal module satisfying the above formula 1 is a module whose voltage may be lowered by electrical discharge, and by performing electrical discharge, the voltage of the module may be lowered to 0.1 V or less, specifically, 0.8 V or less, and more specifically, 0.5 V or less, based on the cell. When the normal module is electrically discharged within the above-described range, sparks do not occur and smoke or fire does not occur in the subsequent process of crushing the cell, so that the process can be safely performed. On the other hand, when the voltage exceeds the above-described range, a safety issue may occur in performing the process.

[0045] In one embodiment, a defective module that does not satisfy Equation 1 may include a step of freezing. The defective module is a module that has a problem such as a short circuit, and has a problem in that the reference voltage of the cells within the module cannot be lowered through electrical discharge. By freezing the defective module, the module can be easily discharged without generating wastewater, as occurs with salt water discharge.

[0046] In one embodiment, the step of freezing the defective module may be performed at a temperature range of -20°C or lower. In one embodiment, the step of freezing the defective module is performed at a temperature sufficient to freeze the electrolyte contained in the battery. Specifically, the step of freezing the defective module may be performed at a temperature range of, for example, -150 to -20°C. More specifically, the temperature range may be -150 to -50°C, and even more specifically, -80 to -60°C.

[0047] When the defective module is frozen in the above temperature range, the voltage remaining slightly inside the battery, for example, about 2 V to 3 V, is lowered to close to 0 V, and even if a short circuit occurs in which the positive and negative electrodes are in direct contact, no battery reaction occurs, so the battery temperature does not increase, and gas generation and combustion of the electrolyte do not occur. In addition, since the electrolyte is in a frozen state or in a state in which vaporization is suppressed, the mobility of lithium ions is very low, so that the conduction characteristics according to the movement of lithium ions can be significantly reduced, and since vaporization of the electrolyte does not occur, flammable gases such as ethylene, propylene, and hydrogen can not be generated.

[0048] If the above freezing process is performed outside the above temperature range, the voltage remaining inside the battery may not be reduced to 0 V, which may cause a battery reaction due to a short circuit, and the electrolyte may not be completely frozen, which is not appropriate. In this way, the battery processing method includes a step of freezing defective modules before crushing batteries such as lithium secondary batteries, thereby having the advantage of easily discharging defective modules that are difficult to discharge electricity, thereby preventing the risk of fire that may occur during the battery crushing process.

[0049] In one embodiment, the step of freezing the defective module may be performed for 15 to 36 hours. The step of freezing the defective module may be performed for 20 to 30 hours, specifically, 22 to 27 hours. By performing the step of freezing the defective module within the aforementioned time range, battery stabilization can be facilitated, and when the battery is shredded, a fire can be prevented from occurring from the battery.

[0050] If the step of freezing the defective module takes excessively longer than the above time, there is a problem of uneconomical operation. If the step of freezing the defective module is performed for excessively shorter than the above time, there is a problem of battery stabilization not being easily performed.

[0051] In one embodiment, the battery processing method may include a step of grounding the normal module after the step of discharging the electric charge. Specifically, the discharged battery, for example, the (+) and (-) poles of the module may be grounded to continuously maintain the discharged state. By including the step of grounding, the voltage of the normal module may be prevented from recovering due to the standard reduction potential difference. In one embodiment, the step of grounding the normal module may be performed for 6 hours or more. Specifically, the step of grounding the module may be performed for 8 hours or more.

[0052] In one embodiment, the battery processing method may include a step of crushing the normal module that has undergone the electric discharge or the defective module that has undergone the freezing step. Specifically, this may refer to a process of applying an impact or pressure to the battery so that a portion of the battery, which is a normal module that has undergone the electric discharge or a defective module that has undergone the freezing step, falls off. The step of crushing the normal or defective module may refer to a step of crushing the battery, a step of cutting the battery, a step of compressing the battery, or any combination thereof. Specifically, the step of crushing may include any process that can destroy the battery, which is a normal or defective module, to obtain small-sized fragments.

[0053] In one embodiment, the step of crushing the normal or defective module may include any process of compressing the battery, which is the normal or defective module, or applying an external force, such as a shear force or a tensile force, to destroy the battery. The step of crushing the normal or defective module may be performed, for example, using a crusher.

[0054] In one embodiment, the step of crushing the normal or defective module may be performed at least once. Specifically, the step of crushing may be performed at least once, either continuously or discontinuously.

[0055] In one embodiment, the step of crushing a normal or defective module may be performed under conditions in which an inert gas, carbon dioxide, nitrogen, water, or a combination thereof is supplied, or under vacuum conditions of 100 torr or less. Since the step of crushing a normal or defective module is performed under the aforementioned gaseous atmosphere, the process can be performed safely compared to when performed in an atmosphere.

[0056] In one embodiment, the step of crushing a normal or defective module may be performed in an atmosphere having an oxygen concentration of 3% or less. Specifically, the step of crushing a normal or defective module may have an oxygen concentration of 3% or less by volume, more specifically, 0.1% or less. In one embodiment, the step of crushing a normal or defective module may be performed within 6 hours.

[0057] In the above crushing step, when the concentration of the oxygen satisfies the above-mentioned range, the safety problem in the process can be solved, and if the concentration of the oxygen is excessively high, such as 6% or more, there is a problem that a fire may occur when a spark occurs in the waste battery and it reacts with the electrolyte.

[0058] In one embodiment, after the step of crushing the normal or defective module, a step of drying the crushed result at a temperature of 200°C or lower may be included. The drying step may be a step for removing the electrolyte within the crushed result.

[0059] In one embodiment, the drying step may utilize hot air. Specifically, hot air using gas may be applied to the crushed result to remove the electrolyte within the crushed result.

[0060] In one embodiment, the gas for the hot air may be an inert gas. For example, the inert gas may be carbon dioxide, nitrogen, argon, helium, or a combination thereof. Using an inert gas as the gas for the hot air provides advantages in terms of fire prevention.

[0061] In one embodiment, the drying step may be performed in an atmosphere with an oxygen concentration of 5% or less. By ensuring that the oxygen concentration satisfies the aforementioned range during the drying step, the likelihood of smoke or fire may be reduced. Specifically, some of the cut battery shreds may recover their voltage over time, and smoke may be generated as they react with the evaporated electrolyte. By performing the drying within the aforementioned oxygen concentration range, the likelihood of smoke generation from the battery shreds can be significantly reduced.

[0062] In one embodiment, the drying step may be performed within 6 hours, specifically, within 4 hours. When using the inert gas in the drying step, if the oxygen concentration falls outside the aforementioned range, a problem may arise in which safety is reduced in performing the process.

[0063] In one embodiment, the dried result obtained through the drying step may satisfy the following equation 2.

[0064] <Formula 2>

[0065]

[0066] (In the above formula 2, w1 and w2 represent the initial weight (kg) of the crushed result and the weight (kg) of the dried result, respectively)

[0067] The above equation 2 refers to the weight change when the crushed result is dried, and may be an indicator of the volatilization of the electrolyte. The equation 2 may satisfy 10% or less, specifically, 2.0 to 8.0%, and more specifically, 3.8 to 7.8%. When the equation 2 satisfies the above-mentioned range, the electrolyte in the crushed result is volatilized by 40% or more, so that a stabilized crushed product can be obtained. When the equation 2 exceeds the above-mentioned range, the electrolyte is not easily removed, which may cause safety issues or lower process efficiency.

[0068] A battery processing method according to another embodiment of the present invention may provide a method for processing a battery in a module unit including a plurality of cells. The battery processing method may include the steps of preparing a spent battery in a module unit including a plurality of cells, measuring a charging and discharging rate of the spent battery, evaluating the temperature of each cell within the module, and determining whether the module is normal or defective based on whether the temperature deviation of the each cell satisfies 3°C or less.

[0069] The step of measuring the charge and discharge speed of the waste battery in the module unit including the plurality of cells can be performed in the same manner as the method of measuring the charge and discharge speed of the waste battery in the module unit in the battery processing method of the waste battery in the pack unit including the plurality of modules described above.

[0070] A normal module satisfying the above formula 3 may include a step of discharging electricity, a step of crushing, and a step of drying, similar to the method of processing a battery from a unit-of-pack waste battery described above. A defective module not satisfying the above formula 3 may include a step of freezing, a step of crushing, and a step of drying, similar to the method of processing a battery from a unit-of-pack waste battery described above. Detailed descriptions thereof may refer to the above-mentioned contents to the extent that they do not contradict each other.

[0071]

[0072] Hereinafter, preferred embodiments and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0073]

[0074] <Experimental Example 1>: Method for determining and processing normal modules in a battery pack

[0075] Battery preparation stage

[0076] In the present invention, a battery is prepared as a module including a plurality of cells, and a battery pack including a plurality of the modules is prepared.

[0077]

[0078] Determining whether there is a short circuit in the battery

[0079] The above battery pack was charged and discharged. At this time, constant-voltage discharge (CVD) or constant-current discharge (CDC) was used to uniformly charge and discharge the battery. Multiple modules are arranged in the pack, and when the time required to charge and discharge the entire pack is divided by the number of modules, the average charge and discharge time of the modules is obtained. After that, disassembly is performed for each module. After disassembly for each module, charging and discharging is performed for each module, and this is performed using the same value of constant-voltage discharge or constant-current discharge used in the pack.

[0080] At this point, dividing the number of modules in the pack by the number of modules yields the average charge / discharge time (taver). By comparing the charge / discharge speeds of the separated modules, if the charge / discharge speeds differ by more than a certain amount of time, the module with the short circuit can be determined.

[0081] The average charge / discharge time (taver) and the specific time above were calculated using the following relationship.

[0082] <Average charge / discharge time (traver)>

[0083]

[0084] <Specific time>

[0085]

[0086] Through the above equation, if the difference between the average charge / discharge time of the pack and the average discharge time of the module is less than the fraction of the number of cells in the module, the module is judged to be normal. In the above equation, if the difference between the average charge / discharge time of the pack and the average discharge time of the module is greater than the fraction of the number of cells in the module, there is a high possibility that at least one cell is defective due to a short circuit or the like, and the module is judged to be defective.

[0087]

[0088] Performing electrical discharge on a normal module

[0089] An electric discharge was performed on a normal module, satisfying the above-mentioned relationship between the average charge / discharge and the specific time. The electric discharge was performed several times according to the voltage, while crushing the cell, and the occurrence of sparks and smoke and fire were measured.

[0090] After discharge, the positive and negative poles of the module were grounded to ensure continuous discharge and prevent voltage recovery due to the standard reduction potential difference. At this time, the grounding standard was performed for more than 6 hours.

[0091] Table 1 below shows the results of measuring whether sparks occur and whether smoke and fire occur according to voltage when performing an electric discharge.

[0092] The occurrence of sparks and the occurrence of smoke and fire were measured using the following methods.

[0093] Whether a spark occurred: Using a thermal imaging camera, check whether the temperature rises by more than 20 degrees when measuring. If the temperature is more than 20 degrees, a spark occurred and is marked with ○. If the temperature is between 10 and 20 degrees, a spark occurred and is marked with △. If the temperature does not rise below 10 degrees, a spark did not occur and is marked with ×.

[0094] Smoke and fire occurrence: When performing an electric discharge, smoke or fire was visually confirmed. If smoke or fire occurred, it was marked with ○, and if no smoke or fire occurred, it was marked with ×.

[0095] Number Discharge voltage [V] Spark generation Smoke generation Fire generation Remarks Experimental example 4○○○Comparative example Experimental example 3.5○○○Comparative example Experimental example 3○○×Comparative example Experimental example 2.5○○×Comparative example Experimental example 2○○×Comparative example Experimental example 1.5○××Comparative example Experimental example 1.0○××Comparative example Experimental example 0.8△××Example Experimental example 0.5×××Example Experimental example 0.2×××Example Experimental example 0.1×××Example

[0096] Looking at Table 1 above, it was confirmed that when electric discharge was performed at a voltage lower than 1.0 V based on the cells in a module with a series-parallel structure, no sparks occurred, and when electric discharge was performed at a voltage lower than 2.0 V, no smoke occurred. Figures 2a and 2b are graphs of the temperature rise before and after battery crushing.

[0097] Figure 2a is a graph showing the temperature rise before battery shredding, and Figure 2b is a graph showing the temperature rise during battery shredding. It was confirmed that no temperature rise occurred before battery shredding, but that a temperature peak occurred when a spark occurred during battery shredding.

[0098]

[0099] Battery shredding

[0100] The above batteries were shredded using a shredder. To prevent further fires from occurring inside the shredder, inert gases such as nitrogen, argon, and carbon dioxide were introduced to maintain the oxygen content below 1 wt%. Furthermore, since the shredded material retains the battery's structure even after being shredded, the size of the shredded material was adjusted to be within 100 mm of its long axis.

[0101]

[0102] Removal of electrolyte from shredded material

[0103] The electrolyte within the shredded material was removed by supplying hot air to the shredded material. The gas for the hot air was either the atmosphere or nitrogen (N2), an inert gas. When the gas was atmospheric, the oxygen concentration was maintained at approximately 21%, and when the gas was an inert gas, the oxygen concentration was maintained at 5% or less. Thereafter, the presence or absence of smoke was determined over time. At this time, the temperature of the hot air was set to 120°C, and drying was performed for 12 hours.

[0104] Table 2 below shows whether smoke is generated when hot air is supplied to the above-mentioned shredded material, depending on the atmospheric and inert gas conditions.

[0105] Smoke generation: Whether or not the shredded material generated smoke was determined by placing the shredded material on a rotatable table and slowly rotating it at 10 rpm for 4 hours. If smoke was generated, it was marked with ○. If no smoke was generated, but a burning smell or a haze was generated, it was marked with △. If no smell or haze was generated at all, i.e. no smoke was generated, it was marked with ×.

[0106] Processing timeWhether smoke occursInert gas (oxygen content: 5% or less)Atmosphere (oxygen content: 21%)1××2××3×○4×○6△○8○○12○○16○○20○○24○○48○○

[0107] Looking at Table 2 above, when hot air was applied to the shredded material, no smoke was generated when treated for less than 2 hours under atmospheric conditions, and no smoke was generated when treated for less than 6 hours under inert gas conditions, confirming that there was no risk of fire.

[0108]

[0109] Weight measurement test of shredded material

[0110] Table 3 below shows the change in weight of the shredded material over time when nitrogen gas was used as hot air in the step of drying the electrolyte and the temperature of the hot air was set to 120°C. The weight of the shredded material was measured using the method below.

[0111] Weight of shredded material: The weight of the shredded material was measured using a scale. The initial weight is the weight of the shredded material measured within 1 minute after shredding in the pre-drying stage. The weight after drying is the weight of the shredded material after drying with hot air. The weight change rate is the change rate of the weight after drying based on the initial weight of the shredded material.

[0112] Drying timeWeight measurement testRotation testRemarksInitial weight [Kg]Weight after drying [Kg]Weight change rate [%]Smoke generation20 minutes1.010.992○Comparative example30 minutes1.021.001.9○Comparative example1 hour1.051.13.8×Example1 hour30 minutes1.010.973.9×Example2 hours1.030.975.8×Example3 hours1.020.965.9×Example4 hours1.010.955.9×Example6 hours1.030.966.8×Example12 hours1.020.947.8×Example

[0113] Looking at Table 2 above, it was confirmed that smoke was generated from the shredded material when the weight change rate of the shredded material was 2% or less. However, it was confirmed that smoke was not generated when the weight change rate of the shredded material was 3% or more. The fact that the weight specific gravity of the shredded material changed by approximately 6% can theoretically mean that the electrolyte was reduced by more than 40%, since the total electrolyte is contained at a weight specific gravity of approximately 12 to 13%.

[0114]

[0115] <Experimental Example 2>: Method for determining and handling defective modules in a battery pack

[0116] In Experimental Example 1, defective modules were identified based on the presence or absence of an internal short circuit within the battery, and the defective modules were frozen without a separate electrical discharge. In the case of an internal short circuit, since electrical discharge does not result in discharge, freezing was used to render the module harmless. Specifically, the defective modules were subjected to cryogenic treatment at -60°C for 24 hours.

[0117] Afterwards, the batteries that underwent cryogenic treatment were crushed using a general crusher, and the battery crushing step and subsequent drying step were performed in the same manner as in Experimental Example 1. The freezing temperature during cryo-crushing varies depending on the charge level of the waste battery. When the charge level is 3 V or less based on the cell, the freezing temperature is -50 °C or lower, and when the charge level is 3.5 V or lower, it is -70 °C or lower. When the charge level is 3.5 V or higher, it is -90 °C.

[0118] After shredding, the shredders must be stored in a stabilization system without rotation, during which time self-heating occurs. The optimal shredding conditions are 10 to 50 mm, with an average shredder size of 10 to 30 mm. Larger pieces increase the risk of fire, while smaller pieces can become trapped between the shredding blades, making shredding difficult.

[0119]

[0120] <Experimental Example 3>: Judgment and Processing Method for the Battery Module Itself

[0121] In the battery preparation step of Experimental Example 1, a battery module containing multiple cells, rather than a battery pack, was prepared. The battery module can be configured in a parallel configuration using two cells, or in a parallel configuration of three to four cells. This varies depending on the battery module design. When charging and discharging a battery, heat is generated due to the movement of charges. In the case of a case visible from the outside, a thermal imaging camera can detect short-circuited cells simply by measuring the temperature difference. During charging and discharging, the amount of heat generated increases based on the standard potential of 2.5 V for a ternary battery. Below 2.5 V, the internal structure deforms, resulting in increased heat generation.

[0122] Figure 1 is a drawing showing the temperature of the battery module itself of the present invention measured using a thermal imaging camera.

[0123] Referring to Figure 1, in the present invention, charging and discharging are distinguished separately, and when discharging, the temperature deviation between individual modules is measured using a thermal imaging camera with the external case removed. The figure below shows the temperature deviation in the module, and if there is a short circuit in the center, the temperature rise appears to be slow. It was confirmed that there was an internal short circuit when the temperature deviation was more than 3℃ compared to the surroundings. In most cases of normal cells, it was confirmed that the temperature deviation occurred at 3℃ or less.

[0124] Although the preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts defined in the following claims also fall within the scope of the present invention.

Claims

1. A step of preparing a pack unit including a plurality of modules or a waste battery having two or more modules; A step of measuring the charging and discharging speed of the above-mentioned waste battery to measure the average charging and discharging time; A step of measuring the charging and discharging speed of the module-based waste battery in the above waste battery, measuring the average charging and discharging time of the module-based waste battery, and comparing it with the average charging and discharging time; and A battery processing method comprising a step of determining a normal module or a defective module based on whether the average charge and discharge time of a waste battery having a pack unit including the plurality of modules or two or more modules and the charge and discharge time of the waste battery in module units satisfy the following Equation 1. <Formula 1> (In the above equation 1, t aver t means the average charge and discharge time / module unit of a waste battery having two or more modules or a pack unit containing multiple modules, and the number of waste batteries module refers to the charge and discharge time / cell count of the module unit waste battery) 2. In paragraph 1, A battery processing method comprising a step of electrically discharging a normal module satisfying the above formula 1 to 0.1 V or less.

3. In paragraph 2, A battery processing method comprising a step of grounding the normal module after the above electric discharging step.

4. In paragraph 2, A battery processing method comprising the step of crushing the normal module that has performed the above electric discharge.

5. In paragraph 4, A battery processing method wherein the step of crushing the above normal modules is performed in an inert gas.

6. In paragraph 4, A battery processing method wherein the step of crushing the above normal module is performed in an atmosphere having an oxygen concentration of 3% or less.

7. In paragraph 3, After the step of crushing the above normal module, A battery processing method comprising a step of drying the crushed result at a temperature of 200° C or less.

8. In paragraph 7, A battery processing method wherein the above drying step is performed in an atmosphere having an oxygen concentration of 5% or less.

9. In paragraph 1, A method for processing a battery, comprising the step of freezing the defective module.

10. In paragraph 9, A battery processing method in which the step of freezing the above defective module is performed at a temperature range of -20℃ or less.

11. In paragraph 1, A step of measuring the average charge and discharge speed by measuring the charge and discharge speed of the above-mentioned waste battery is a battery processing method in which the above-mentioned waste battery is charged and discharged with a constant voltage or constant current.

12. A step of preparing a waste battery in the form of a module unit containing a plurality of cells; A step of measuring the charging and discharging speed of the above-mentioned waste battery; A step of evaluating the temperature of each cell within the module; and A battery processing method comprising a step of determining a normal module or a defective module based on whether the temperature deviation of the above cell unit is 3℃ or less.

13. In paragraph 12, A battery processing method comprising the step of electrically discharging the above normal module to 0.1 V or less.

14. In paragraph 13, A battery processing method comprising the step of crushing the normal module that has undergone the above electric discharge in an atmosphere having an oxygen concentration of 0.5% or less.

15. In paragraph 14, After the step of crushing the above normal module, A battery processing method comprising a step of drying the crushed result at a temperature of 200° C or less.

16. In paragraph 12, A battery processing method comprising the step of cryo-crushing the above defective module.

17. A step of preparing a pack unit including a plurality of modules or a waste battery having two or more modules; A step of measuring the charging and discharging speed of the above-mentioned waste battery to measure the average charging and discharging time; A step of measuring the charge and discharge speed of a module-based waste battery in a pack unit including the plurality of modules or a waste battery having two or more modules, thereby measuring the charge and discharge time of the module-based waste battery and comparing it with the average charge and discharge time; A step for determining whether the above module unit waste battery is a normal module or a defective module; A step of crushing the above normal module or defective module; and Comprising a step of drying the above crushed result at a temperature of 200 ℃ or less, The above dried result is a battery processing method satisfying the following equation 2. <Formula 2> (In the above formula 2, w1 and w2 represent the initial weight (kg) of the crushed result and the weight (kg) of the dried result, respectively) 18. In paragraph 17, A battery processing method comprising a step of measuring the charge and discharge rates of each module and comparing them with the average charge and discharge rates to determine whether a module is normal or defective, wherein the step of determining whether the step satisfies the following equation 1 is included. <Formula 1> 19. In paragraph 18, After the step of measuring the charge and discharge speed for each module and comparing it with the average charge and discharge speed, A battery processing method comprising a step of electrically discharging a normal module satisfying the above formula 1 to 0.1 V or less.

20. In paragraph 17, After the step of measuring the charge and discharge speed for each module and comparing it with the average charge and discharge speed, A battery processing method in which the step of freezing a defective module that does not satisfy the above formula 1 is performed in a temperature range of -20°C or less.

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