WO2025135682A1 - Unit battery shredded material, battery shredded material including same, and battery processing method - Google Patents

Abstract

The present invention relates to a unit battery shredded material, a battery shredded material including same, and a battery processing method. The unit battery shredded material is for recovering valuable metal from a waste battery, wherein the unit battery shredded material has a layered structure including a separation film in which a cathode or an anode is stacked on at least one surface thereof, and satisfies conditions 1 to 3 in the present specification.

Description

Unit battery shredder, battery shredder comprising the same, and method for processing batteries

The present invention relates to waste batteries, and more particularly, to unit battery shreds extracted from waste battery recycling, battery shreds including the same, and a method for processing batteries.

As the demand for electric vehicles increases worldwide, the problem of disposal of waste batteries generated from said electric vehicles is emerging as a social issue. In the case of lithium secondary batteries, which are the main raw materials of said waste batteries, organic solvents, explosive substances, and heavy metals such as Ni, Co, Mn, and Fe are contained, but in the case of Ni, Co, Mn, and Li, they have high scarcity value as valuable metals, and the recovery and recycling process after the lithium secondary batteries are discarded is emerging as an important research field.

Specifically, a lithium secondary battery mainly consists of copper and aluminum used as a current collector, Li, Ni, Co, Mn-containing oxides constituting a cathode material, and graphite utilized as an anode material, and includes a separator separating the cathode material and the anode material, and an electrolyte injected into the separator. The solvent and salt used as the electrolyte are mainly a mixture of carbonate organic substances such as ethylene carbonate and propylene carbonate, and LiPF ₆ is used as a representative salt.

In order to utilize the above-mentioned waste batteries, development is actively underway on a waste battery recycling process that crushes the waste batteries to produce intermediate materials such as waste battery shreds or black powder, and then recovers valuable metals through a post-process.

However, in the waste battery recycling process, the waste battery generally has a voltage in the range of 3.0 to 3.2 V in a fully discharged state per cell, and a voltage close to 4 V in a fully charged state, although this may vary depending on the number of times the battery has been used or its condition. Therefore, modules or packs in which tens to hundreds of cells are connected have a considerable amount of energy in this residual voltage, and thus, when physically disassembling the waste battery by applying an external shock, safety related to explosion or electric shock of the battery becomes an issue.

To prevent this, after the above disassembly, a hole is created in the battery and the battery is discharged in salt water. The battery after the above discharge is crushed and then subjected to high-temperature heat treatment to remove water and electrolyte.

At this time, the salt used in the brine discharge contains a large amount of substances such as Na, K, Cl, Mg, and Ca. Among the substances mentioned above, Cl in particular is partially removed during the high-temperature heat treatment process, but the black powder, which is a powder in the form of a mixture of oxides of Ni-Co-Mn-Li-O and C obtained by further processing the shredded material or shredded material of the waste battery to remove Al, Cu, and a part of the separator, contains impurities such as Na, K, and Mg, which causes a problem of reducing the recovery rate during the extraction process using acid leaching in the subsequent process of the battery recycling process.

In addition, research is needed on a post-processing method to remove the electrolyte contained in the shredded material in order to stably transport it to the post-processing stage after shredding the used batteries.

According to one embodiment of the present invention, through recycling of waste batteries, a unit battery shredder having a low impurity content and preventing fire occurrence is provided.

According to one embodiment of the present invention, the battery shredder has the advantages described above and comprises at least one unit battery shredder.

In another embodiment of the present invention, a method of processing a battery provides a method of producing battery shreds having the advantages described above by removing volatile materials.

In one embodiment, the unit battery shredder is a unit battery shredder for recovering valuable metals from a spent battery, wherein the unit battery shredder has a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface, and can satisfy the following conditions 1, 2, and 3.

<Condition 1> The above layered structure is a laminated structure having 1 or more layers and 7 or fewer layers.

<Condition 2> The size of the unit battery shreds based on the longest axis among the horizontal, vertical, and height directions is 100 mm or less.

<Condition 3> When the above unit battery shreds are reheated at 150°C, the weight of the above unit battery shreds decreases by 1.0% or less.

In one embodiment, the surface of the unit battery shredder includes a burnt region, which is a region where at least a portion of the surface is burned, and a top region on the surface where no burn marks are present, and the area ratio of the burnt region to the top region may be 30% or less. In one embodiment, the burnt region may be formed at an edge portion of the surface.

According to another embodiment of the present invention, the battery shredder is a unit battery shredder for recovering valuable metals from waste batteries,

The above unit battery shredder comprises at least one unit battery shredder having a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface, and satisfying the following conditions 1, 2, and 3.

<Condition 1> The above layered structure is a laminated structure having 1 or more layers and 7 or fewer layers.

<Condition 2> The size of the unit battery shreds based on the longest axis among the horizontal, vertical, and height directions is 100 mm or less.

<Condition 3> When the above unit battery shreds are reheated at 150°C, the weight of the above unit battery shreds decreases by 1.0% or less.

In one embodiment, the content of the unit battery shreds may be greater than or equal to 90% of the total volume of the battery shreds. In one embodiment, the impurities may include, in wt%, Na: 0.4% or less, Ca: 0.03% or less, Mg: 0.02% or less, and K: 0.02% or less.

According to another embodiment of the present invention, a battery processing method comprises the steps of freezing a battery, shredding the frozen battery into battery shreds, and stabilizing the shredded battery shreds, wherein the battery shreds include at least one unit battery shred, the unit battery shreds have a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface, and satisfies the following Condition 1 and Condition 2, and the stabilizing step can satisfy the following Condition 5.

<Condition 1>

The above layered structure is a laminated structure having 1 or more layers and 7 or fewer layers.

<Condition 2>

The size of the unit battery shreds based on the longest axis among the length, width, and height directions is 100 mm or less.

<Condition 5>

Low-temperature stabilization treatment is performed at 30°C or lower, and after the low-temperature stabilization treatment, high-temperature stabilization treatment is performed at 30°C or higher to 150°C.

In one embodiment, the weight of the battery shreds in the low-temperature stabilization treatment step can be reduced by 2.8 to 4.6% relative to the weight of the battery shreds before the low-temperature stabilization treatment step. In one embodiment, the weight of the battery shreds in the high-temperature stabilization treatment step can be reduced by 8 to 10% relative to the weight of the battery shreds before the low-temperature stabilization treatment step.

In one embodiment, the battery shreds may satisfy the following condition 4.

<Condition 4>

The tap density of the above battery shreds is 200 to 600 kg/m ³

In one embodiment, the low-temperature stabilization time in the low-temperature stabilization treatment may be 6 to 12 hours. In one embodiment, the high-temperature stabilization time in the high-temperature stabilization treatment may be 5 to 12 hours.

In one embodiment, the stabilization treatment may be performed at a temperature of 0 to 150° C. applied to the shredded material. In one embodiment, a battery processing method including an intermediate stabilization treatment step prior to the high temperature stabilization treatment step, wherein the intermediate stabilization treatment step may be performed at a temperature of 30 to 120° C.

In one embodiment, the intermediate stabilization treatment step is performed by a multi-stage heat treatment, and the multi-stage heat treatment can be performed sequentially at a first temperature of 30 to 60 °C, a second temperature of 60 to 90 °C, and a third temperature of 90 to 120 °C. In one embodiment, the shredding step can include a step of controlling a proportion of the unit battery shreds to be 90% or more within the total volume of the battery shreds.

In one embodiment, the freezing step can be performed by cooling to -150° C. to -20° C. In one embodiment, the freezing step can be performed by cooling to -60° C. to -20° C., and the crushing step can be performed under vacuum conditions of 100 torr or less.

According to one embodiment of the present invention, the unit battery shredder includes low-temperature and high-temperature stabilization treatment steps at predetermined temperatures, thereby providing unit battery shredder having a low impurity content and preventing occurrence of fire.

In another embodiment of the present invention, the battery shredder provides a battery shredder having at least one unit battery shredder having the advantages described above.

According to another embodiment of the present invention, a battery processing method provides a method for producing battery shreds having the aforementioned advantages by controlling the weight reduction amount of the battery shreds by performing low-temperature and high-temperature stabilization treatment steps on the battery shreds at predetermined temperatures.

Figure 1 shows the change in voltage of a battery according to cooling temperature according to one embodiment of the present invention.

FIG. 2 is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

FIGS. 3a and 3b are photographs of examples according to the minimum cooling time of the present invention, and FIGS. 3c and 3d are photographs of comparative examples according to the minimum cooling time of the present invention.

FIG. 4 is a graph of temperature over time of a shredded material according to one embodiment of the present invention.

FIG. 5a illustrates unit battery shreds according to one embodiment of the present invention and a comparative example, FIG. 5b illustrates a mixing ratio according to a weight ratio of battery shreds according to one embodiment of the present invention, and FIG. 5c illustrates a combustion section and a top section of a surface of unit battery shreds.

Figures 6a to 6c are photographs showing the temperature measurement process of a waste battery and the temperature trend of the shredded material according to the SOC conditions.

Figure 7 is a graph showing the temperature increase trend of the shredded material according to the SOC % condition of the battery.

FIG. 8 is a graph showing the temperature of battery shreds over time in low-temperature stabilization, intermediate stage, and high-temperature stabilization stages according to one embodiment of the present invention.

Figure 9a is a schematic diagram of a stabilization device for performing a battery stabilization step, and Figure 9b is a graph showing self-heating of battery fragments inside a transport container.

Figure 10 shows the temperature change of the crushed material when the heating temperature was controlled for each section for heat treatment in the high-temperature stabilization stage.

Figure 11 shows the weight reduction ratio (%) of the electrolyte in the shredded battery according to the heat treatment temperature of 150°C after high-temperature stabilization treatment of the shredded battery.

Figure 12 shows the temperature and weight reduction according to the tap density of battery shreds.

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 only used to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Thus, 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.

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

When a part is referred to as being "on" or "on" another part, it may be directly on or above the other part, or there may be other parts intervening. In contrast, when a part is referred to as being "directly on" another part, there are no other parts intervening.

Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having a meaning consistent with the relevant technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal sense unless defined.

Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples, and the present invention is not limited thereby, and the present invention is defined only by the scope of the claims described below.

According to one embodiment of the present invention, the unit battery shredder is for recovering valuable metals from waste batteries, and has a layered structure including a separator having a cathode or a positive electrode laminated on at least one surface. Specifically, the layered structure may include a configuration in which the cathode or the positive electrode is included on one surface or both surfaces of the separator based on the separator. More specifically, the number of layers of the layered structure may correspond to the number of separators.

The above layered structure includes, for example, one of anode-separator-cathode, anode-separator, separator-anode, separator-cathode, and cathode-separator, and for example, anode-separator-cathode-separator-anode-separator-cathode may have a three-layered layered structure. Specifically, the unit battery shredder may have a predetermined thickness in the thickness direction since at least one or more layers are laminated.

In one embodiment, the unit battery shredder may satisfy the following condition 1.

<Condition 1> The above layered structure may be a laminated structure having 1 or more layers and 7 or fewer layers.

The above unit battery shredder may have a layered structure having a laminated structure of 1 to 7 layers. Specifically, the layered structure may have a layered structure of 1 to 5 layers. As the layered structure is laminated within the above range, the temperature rise of the shredder may be minimized, and the heating time may be appropriately taken. If the layered structure is laminated thicker than the upper limit of the above range, the temperature rise may excessively increase, and the heating time may also increase, which may cause a fire as it is combusted.

In one embodiment, the unit battery shredder may satisfy the following condition 2.

<Condition 2> The size of the above unit battery shreds may be 100 mm or less based on the longest axis among the width, length, and height directions.

In one embodiment, the unit battery shreds may have a size of 100 mm or less based on the longitudinal axis. Specifically, the size of the unit battery shreds may be 50 mm or less. If the size of the unit battery shreds is excessively large, there is a problem that the temperature of the battery shreds themselves may rise to 100° C. or more, which may lead to a high possibility of a fire occurring.

In one embodiment, the unit battery shredder may satisfy the following condition 3.

<Condition 3> When the above unit battery shreds are reheated to 150°C, the weight of the above unit battery shreds is reduced to 1% or less.

The above condition 3 may be an indicator of whether the unit battery shreds have undergone low-temperature and high-temperature stabilization steps. Specifically, when the unit battery shreds are reheated at 150° C. and cooled, the weight of the battery shreds before heating and the weight of the battery shreds after heating may be compared, and the weight of the battery shreds after heating may be reduced by 1% or less compared to the weight of the battery shreds before heating.

If the weight of the above unit battery shreds satisfies the above-mentioned range, the low-temperature stabilization treatment and the high-temperature stabilization treatment of the present invention have been performed, and safe unit battery shreds can be provided that can reduce the possibility of fire occurring in a post-process. If the weight of the above unit battery shreds exceeds the above-mentioned range, there is a problem that a fire occurs in a post-process because the electrolyte in the unit battery shreds does not easily volatilize.

In one embodiment, the surface of the unit battery shredder may include a burnt portion and a top portion. The burnt portion means an area where at least a portion of the surface of the unit battery shredder is burnt, and the top portion means a top portion of the surface where there are no traces of combustion.

In one embodiment, the area ratio of the combustion portion to the top portion on the surface of the unit battery shreds may be satisfactorily 30% or less. By satisfying the area ratio of the combustion portion to the top portion to be 30% or less, the unit battery shreds may be prevented from burning and causing a fire. If the area ratio of the combustion portion to the top portion exceeds 30%, there is a risk that the unit battery shreds may burn and cause a fire accompanied by smoke.

In one embodiment, on the surface of the unit battery shredder, the combustion portion may be arranged at an edge of the surface. The top portion may be arranged near the center of the surface of the unit battery shredder. The combustion portion refers to a region that exhibits a darker color compared to the top portion.

In another embodiment of the present invention, the battery shredder may include at least one of the above-described unit battery shredders. In one embodiment, the battery shredder may have a content of at least one of the unit battery shredders of 90% or more in the total volume of the battery shredder. Specifically, the content of the unit battery shredder may be at least 95% in the total volume of the battery shredder.

Specifically, the battery shreds may correspond to the content that the proportion of unit battery shreds having a laminated structure exceeding 7 layers may be 10% or less, specifically 5% or less, of the total volume of the battery shreds, or the proportion of at least one unit battery shreds having a size exceeding 100 mm in the long axis may be 10% or less, specifically 5% or less, of the total volume of the battery shreds.

In this way, fire can be prevented by satisfying the above ranges in the proportion of battery shreds having a layered structure exceeding 7 layers per unit volume within the entire volume of battery shreds or the proportion of unit battery shreds having a size exceeding 100 mm in the long axis.

In one embodiment, the battery shredder is recovered from a waste battery and includes impurities, and the impurities may include, in weight %, Na, Ca, Mg, and K. The battery shredder may be a shredder residue or black powder manufactured through a process of recovering and crushing the waste battery, which is a pretreatment process of a waste battery recycling process.

The above battery scrap may contain impurities such as Na, Ca, Mg, and K. The above battery scrap may facilitate the extraction of Li, a cognate valuable metal, in a post-process by lowering the content of the impurities.

According to one embodiment of the present invention, the battery shredder includes impurities, and the impurities may include, in wt%, Na: 0.4 % or less (excluding 0 %), Ca: 0.03 % or less (excluding 0 %), Mg: 0.02 % or less, and K: 0.02 % or less.

Below, the reasons for limiting the content of the above impurities are explained.

Na: 0.4 wt% or less (excluding 0%)

Sodium (Na) is a homologous element in the post-process of recovering valuable metals from the battery scrap, and has the side effect of lowering the recovery of lithium or increasing the cost in the causticization process by partially reacting sodium instead of lithium in the lithium hydroxide forming process to form sodium hydroxide. The battery scrap may contain 0.4 wt% or less of the sodium, and specifically, may contain 0.1 wt% or less of the sodium.

When the above sodium is contained in an amount greater than the above range, there is a problem that the yield decreases in the process required to produce lithium carbonate when Na is a Group 1 element identical to Li in the crystallization process of Li dissolved in the solvent after the leaching process and the solvent extraction process when Na increases.

Ca: 0.03 wt% or less (excluding 0%)

Calcium (Ca), like the sodium, is an element that lowers the recovery rate of valuable metals in the post-process of recovering valuable metals from the battery shreds. Calcium is more reactive than aluminum when forming lithium aluminate, and thus forms a lithium cassinate structure, thereby hindering the formation of lithium aluminate, which is advantageous for subsequent reactions, thereby lowering the final recovery rate of lithium. The battery shreds may contain 0.03% or less of the calcium, and specifically, may contain 0.02 wt% or less of the calcium.

If the calcium is contained in an amount greater than the above range, there is a problem that the yield and process time increase in the solid-liquid separation process, which is an impurity purification process after the leaching process, when Ca increases. In addition, if the content of calcium is excessively large, when nickel, cobalt, manganese hydroxide and lithium hydroxide, which are precursors, are synthesized to produce a cathode material, they are synthesized as Li[NiCoMn] _1-x Ca _x )]O ₂ , so that the potassium forms the cathode material oxide structure, which hinders the movement of lithium ions, and there is a problem that the capacity of the battery decreases.

Mg: 0.02 wt% or less

Magnesium (Mg) is an element that makes it difficult to separate solid and liquid phases during acid leaching in a metal recovery process. The battery scrap may contain 0.02 wt% or less of magnesium, specifically, 0.01 wt% or less.

When the above magnesium is contained in an amount greater than the above range, there is a problem of placing a load on the recovery process of nickel, cobalt, lithium, etc. In addition, when the content of magnesium is excessively high, when producing a cathode material by synthesizing with nickel, cobalt, manganese hydroxide and lithium hydroxide, which are precursors, it is synthesized as Li[NiCoMn] _1-x Mg _x )O ₂ , forming a cathode material oxide structure, which hinders the movement of lithium ions and reduces the capacity of the battery.

K: 0.02 wt % or less

Potassium (K) is also an element in the same group as lithium and plays a role in preventing lithium from being formed into a hydroxide compound. The battery shreds may contain potassium in an amount of 0.02 wt% or less, specifically, 0.01 wt% or less. If the potassium is contained in an amount greater than the above range, there is a problem in that it causes a load in the causticization process and reduces the lithium recovery rate.

According to another embodiment of the present invention, a battery processing method includes the steps of freezing a battery, crushing the frozen battery, and stabilizing the crushed battery. The battery processing method may be a method of processing various types of batteries including lithium ions, and the battery may be, for example, 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, and specifically, a lithium secondary battery.

In one embodiment, the step of cooling the battery may satisfy the following equation 1.

<Formula 1>

Minimum cooling time (Hr) = A × (W ^0.33 )

(A = 4 × e ^(-0.02×dT) , W = battery weight (Kg), dT = │external cooling temperature - target temperature│, ││ represents the absolute value)

In the above equation 1, W means the weight of the battery, for example, the weight of a battery pack, a single battery, or a combination thereof. The minimum cooling time means the external cooling temperature, which is the cooling temperature applied to the battery, for example, the target temperature for cooling the electrolyte inside the battery.

The step of freezing the battery has the advantage of being able to perform subsequent processes stably by cooling the electrolyte inside the battery by performing the step for a period longer than the minimum cooling time. If the step of freezing the battery is performed for a period shorter than the minimum cooling time, there is a problem that the electrolyte is not cooled, which may cause a risk of fire when crushed.

The step of freezing the battery is performed at a temperature sufficient to freeze the electrolyte contained in the battery. Specifically, the step of freezing 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 more specifically, -80 to -60°C.

When the battery 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, so that even if a short circuit occurs in which the positive and negative electrodes are in direct contact, a battery reaction does not occur, 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 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.

If the above freezing process is outside the above temperature range, for example, if it cools to a temperature higher than -60℃, the voltage remaining inside the battery will not be lowered to 0 V, so a battery reaction due to a short circuit may occur, and the electrolyte will not be completely frozen, which is not appropriate. In addition, if it is cooled to -150℃, the electrolyte is sufficiently frozen, and the voltage inside the battery will also be lowered to 0 V, so there is no need to lower it to a lower temperature. In this way, the battery processing method has the advantage of preventing the risk of fire that may occur in the battery crushing process by including a freezing step before crushing a battery such as a lithium secondary battery.

The step of crushing the frozen battery may refer to a process of applying an impact or pressure to the battery so that a portion of the battery falls off from the battery. In one embodiment, the step of crushing the battery may refer to a process of crushing the battery, a process of cutting the battery, a process of compressing the battery, and a combination thereof. Specifically, the step of crushing may include any process that can destroy the battery to obtain small-sized fragments.

In one embodiment, the step of crushing the battery may include any process of compressing the frozen battery or destroying the battery by applying an external force, such as a shear force or a tensile force. The step of crushing the battery may be performed, for example, using a crusher.

In one embodiment, the step of crushing the battery may be performed at least once. Specifically, the step of crushing may be performed at least once, either continuously or discontinuously.

In one embodiment, the step of crushing the battery comprises supplying conditions including an inert gas, carbon dioxide, nitrogen, water, or a combination thereof. Or, it can be performed under vacuum atmosphere conditions of 100 torr or less. For example, when the process of freezing the battery is performed by cooling in a temperature range of -60 to -20℃, when performed under the above-mentioned conditions, the supply of oxygen can be suppressed, preventing the electrolyte from reacting with oxygen, preventing an explosion caused thereby, and suppressing the vaporization of the electrolyte, so as not to generate flammable gases such as ethylene, propylene, or hydrogen.

In one embodiment, at least one of the unit battery shreds included in the battery shreds may satisfy the following condition 1.

<Condition 1>

The above layered structure may have 1 or more layers and 7 or fewer layers.

The above condition 1 may mean that the layered structure of the unit battery shredder including a separator having a positive or negative electrode laminated on at least one surface is controlled in the step of shredding into a layered structure of 1 or more layers and 7 or fewer layers.

In one embodiment, the layered structure may be a laminated structure having 1 or more layers and 7 or fewer layers. Specifically, the layered structure may be a laminated structure having 1 or more layers and 5 or fewer layers. As the layered structure is laminated within the above range, the temperature rise amount of the shredded material can be minimized and the heating time can be appropriately taken. If the layered structure is laminated thicker than the upper limit of the above range, the temperature rise amount excessively increases and the heating time also increases, which causes a problem of combustion.

In one embodiment, at least one of the unit battery shreds included in the battery shreds may satisfy the following condition 2.

<Condition 2>

The size of the unit battery shreds based on the long axis, which is the longest axis among the length, width, and height directions, may be 100 mm or less.

In one embodiment, the size of the unit battery shreds, specifically, the longest axis among the horizontal, vertical, and height directions, may be controlled in the shredding step to be 100 mm or less, specifically 50 mm or less. If the maximum size of the battery shreds is greater than 100 mm, the heat generation temperature caused by instability as the battery shreds are shredded may rise to a temperature range of 120° C., which is the average vaporization temperature of the electrolyte, and thus a problem in stability, such as a fire, may occur.

In one embodiment, at least one of the unit battery shreds contained within the battery shreds may satisfy the following condition 4.

<Condition 4>

The tap density of the above-mentioned shredded battery waste is 200 to 600 kg/m ³ .

The above tap density refers to the apparent density obtained by mechanically tapping a measuring container containing a typical powder sample. Specifically, in order to determine the tap density characteristics of the lithium-ion battery shredder, a commercialized battery module consisting of about 30 cells weighing 30 kg was crushed by a crusher, placed in a case (volume: 0.44 m wide × 0.7 m long × 0.5 m high) manufactured to stabilize the shredder, and mechanically tapped to measure the apparent density. More specifically, the density (ρ = M/V) was obtained by dividing the battery weight (M, kg) by the case volume (V, m3). The tap density of the unit battery shredder calculated by the above-described method is 200 to 600 kg/ ^m3 . Specifically, the tap density can be 200 to 300 kg/ ^m3 .

If the above tap density exceeds the upper limit, there is a risk of fire due to instantaneous heat generation by the short circuit of the densely stacked pieces of shredded material, and there is a problem of reduced stabilization processing capacity due to the narrow space through which the electrolyte can escape to the outside. If the above tap density exceeds the lower limit, there is a problem of many gaps between the shredded material and the volume is large, requiring an additional pressurization process to transport it to the post-process.

In one embodiment, the step of shredding the battery may further include the step of controlling the proportion of the unit battery shreds to be 90% or more, specifically 95% or more, of the total volume of the battery shreds. Specifically, this may correspond to controlling the proportion of the unit battery shreds having a laminated structure exceeding 7 layers to be 10% or less of the total volume of the battery shreds. Specifically, the proportion of the unit battery shreds having a laminated structure exceeding 7 layers may be controlled to be 5% or less of the total volume of the battery shreds. By satisfying the above range, there is an advantage in that the occurrence of a fire can be prevented.

In one embodiment, the step of stabilizing the shredded battery fragments may satisfy the following condition 5.

<Condition 5>

Low-temperature stabilization treatment is performed at 30°C or lower, and high-temperature stabilization treatment is performed at 120 to 150°C.

Specifically, the stabilizing step may include a low-temperature stabilization treatment step and a high-temperature stabilization treatment step performed at a higher temperature than the low-temperature stabilization treatment step. The stabilizing step performs the low-temperature stabilization treatment step and the high-temperature stabilization treatment step simultaneously, thereby volatilizing the electrolyte in the crushed battery waste, thereby reducing the weight of the battery waste, and decreasing the tap density.

The above low-temperature stabilization treatment step may be a step of stabilizing the crushed battery shreds at a temperature of 30° C. or lower. Specifically, the low-temperature stabilization treatment step may be a step in which the crushed battery shreds are stabilized through self-heating. More specifically, there is a difference in self-heating of the shreds depending on the condition of the SOC (State of Charge) indicating the remaining capacity of the battery. More specifically, when the SOC is 30% or higher, sudden heat generation may occur, which may cause a fire. Therefore, the low-temperature stabilization treatment step may be a preliminary step of stabilizing the battery at a temperature of 10° C. or lower in order to minimize the aforementioned fire risk.

In one embodiment, the low-temperature stabilization treatment step can be performed for 6 to 12 hours. If the low-temperature stabilization treatment step is outside the upper limit of the aforementioned time range, the fire risk is minimized, but there is a problem that the manufacturing lead time is lengthened and productivity is reduced. If the low-temperature stabilization treatment step is outside the lower limit of the aforementioned time range, the electrolyte may not be removed sufficiently safely, which may cause a problem of a post-process fire. In one embodiment, the weight of the battery shreds may be reduced by 2.8 to 4.6% in the low-temperature stabilization treatment step. Specifically, the weight of the battery shreds may be reduced by 2.8 to 4.6% compared to the weight of the battery shreds before the low-temperature stabilization treatment step is performed. Through the low-temperature stabilization treatment, the weight of the battery shreds is reduced within the aforementioned range, so that the low-temperature volatile electrolyte can be easily removed.

The above high temperature stabilization treatment step may be performed at 120 to 150° C. Specifically, the high temperature stabilization treatment step may be a step of applying high temperature heat to the battery shreds stabilized through the low temperature stabilization treatment step to volatilize the electrolyte within the battery shreds.

If the above high temperature stabilization treatment step exceeds the upper limit of the above temperature range, there is a problem of fire occurrence. If the above high temperature stabilization treatment step exceeds the lower limit of the above temperature range, there is a problem of the electrolyte in the battery shreds not being sufficiently volatilized.

In one embodiment, the high temperature stabilization treatment step may be performed for 6 to 12 hours. If the high temperature stabilization treatment step is outside the upper limit of the above-mentioned time range, there is a problem with productivity due to an increase in manufacturing lead time. If the high temperature stabilization treatment step is outside the lower limit of the above-mentioned time range, there is a problem that the electrolyte is not sufficiently removed, which may cause a fire in the subsequent process.

In one embodiment, the weight of the battery shreds in the high-temperature stabilization treatment step may be reduced by 8 to 10% compared to the weight of the battery shreds before performing the low-temperature stabilization treatment step. Specifically, when the weight of the battery shreds satisfies the above-mentioned range, it can be confirmed that the high-temperature volatile electrolyte is easily volatilized.

For example, based on 100% of the battery's weight, the electrolyte may account for 10 to 15%. After the high-temperature stabilization treatment step is completed, about 60 to 70% of the electrolyte's weight is volatilized, which means a reduction of 9 to 10% based on 100% of the total battery weight.

In one embodiment, an intermediate stabilization treatment step may be included prior to the high temperature stabilization treatment step, and the time of the intermediate stabilization treatment step is included in the high temperature stabilization treatment time. The intermediate stabilization treatment step may be a step for volatilizing the electrolyte in the battery shreds between the low temperature stabilization treatment step and the high temperature stabilization treatment step.

The intermediate stabilization treatment step can be performed at a temperature higher than the low temperature stabilization treatment step and lower than the high temperature stabilization treatment step. In one embodiment, the intermediate stabilization treatment step can be performed at 30 to 120° C.

In one embodiment, the intermediate stabilization treatment step can be performed as a multi-stage heat treatment. The intermediate stabilization treatment step can be performed sequentially at a first temperature of 30 to 60 °C, a second temperature of 60 to 90 °C, and a third temperature of 90 to 120 °C.

In this way, by performing an intermediate stabilization treatment step prior to a high-temperature stabilization treatment step, the temperature of the battery shreds can be gradually increased to stably volatilize the electrolyte within the battery shreds.

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

<Experimental example>

<Battery internal temperature according to minimum freezing time>

Figure 1 shows the change in voltage of a battery according to cooling temperature according to one embodiment of the present invention.

Referring to Fig. 1, when the battery is frozen to -80°C and the battery voltage is measured, the battery pack shows almost the same voltage at a high temperature of about 40°C, room temperature, and -60°C, so it can be confirmed that the battery characteristics are not lost. Next, it was confirmed that when the temperature decreases from -60°C to -70°C, the voltage decreases rapidly, and the voltage becomes 0 V below -70°C. In this way, it was confirmed that a short circuit does not occur when the battery is frozen to -60 to -150°C.

FIG. 2 is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

Referring to FIG. 2, it can be confirmed that a battery processing method according to an embodiment of the present invention can derive a minimum cooling time for cooling a battery in the step of freezing a battery. Specifically, it can be confirmed that the minimum cooling time is related to the battery weight, the external cooling temperature, and the target temperature. Specifically, when the target temperature is set to -70° C. and the battery weights are 2.5 kg (A), 10 kg (B), 20 kg (C), and 50 kg (D), respectively, the external cooling temperature and the minimum cooling time are shown. When cooling the battery, it can be confirmed that the electrolyte of the battery starts cooling after a predetermined time and the voltage becomes 0 V. Through this, it can be confirmed that a minimum maintenance time is required to sufficiently cool the inside, specifically the electrolyte, when cooling the battery.

Specifically, in a heat transfer situation for cooling where heat is taken out to the outside, when considering the specific heat of the battery itself, it can be confirmed that the battery weight and time for cooling are required. In this way, in the present invention, the minimum time required for cooling can be confirmed by using the external cooling temperature for refrigeration, the target temperature, and the battery weight to cool the battery.

Table 1 below lists the minimum cooling time based on battery weight and external cooling temperature.

Battery Weight [Kg] External cooling temperature [℃] Target temperature
[℃] Equation 1 Minimum cooling time [h] A_1 2.5 -120 -70 1.9 1.9 A_2 2.5 -100 -70 2.9 2.9 A_3 2.5 -80 -70 4.4 4.4 B_1 10 -120 -70 3.1 3.1 B_2 10 -100 -70 4.6 4.6 B_3 10 -80 -70 7.0 7.0 C_1 20 -120 -70 3.9 3.9 C_2 20 -100 -70 5.8 5.8 C_3 20 -80 -70 8.8 8.8 D_1 50 -120 -70 5.3 5.3 D_2 50 -100 -70 7.9 7.9 D_3 50 -80 -70 11.9 11.9

Looking at Table 1 above, it can be seen that the smaller the battery weight, the shorter the minimum cooling time required for the battery to be cooled. In addition, it can be seen that when the value of Equation 1 derived from the relationship according to the battery weight, external cooling temperature, and target temperature is cooled with the minimum cooling time, the battery, specifically, the electrolyte of the battery, is cooled. In addition, when the battery is cooled for a time longer than the value of Equation 1, a fire does not occur during the post-process, the battery crushing process.

FIGS. 3a and 3b are photographs of examples according to the minimum cooling time of the present invention, and FIGS. 3c and 3d are photographs of comparative examples according to the minimum cooling time of the present invention.

Referring to FIGS. 3a and 3b, the fire occurrence status of shredded material when frozen for a time shorter than the minimum cooling time required for cooling the battery was tested. In the test, when the battery weight was 25 kg, the external cooling temperature was -95°C, and the target freezing temperature was -70°C, the value of Equation 1 below was 7 hours, and the test was performed for 5 hours, which is lower than the value of Equation 1 above.

<Formula 1>

Minimum cooling time = A × (W ^0.33 )

(A = 4 × e ^(-0.02×dT) , W = battery weight (Kg), dT = │external cooling temperature - target temperature│, ││ represents the absolute value)

Referring to Figures 3c and 3d, the fire occurrence status of the shredded material was tested when the battery was frozen for a minimum freezing time required for cooling. The above experiment was performed with the same battery weight as Figures 3a and 3b, the external cooling temperature, and the minimum freezing time of 7 hours or more.

Table 2 below compares the fire occurrence status of the examples and comparative examples according to the same battery weight, external cooling temperature, and minimum freezing time according to 3a to 3d. The determination of the fire occurrence status was made as follows: if fire occurrence was observed after battery crushing, “O”; otherwise, “X”.

Battery Weight [Kg] External cooling temperature [℃] Target temperature
[℃] Equation 1 Actual cooling time [h] Fire outbreak Comparative example 25 - 95 - 70 7.0 5 O Example 25 - 95 - 70 7.0 7 X

Looking at Table 2 above, it can be seen that if the battery is cooled to a value smaller than the value of Equation 1 corresponding to the minimum cooling time, the electrolyte is not cooled, and a fire occurs after the battery is crushed. In this way, it can be seen that if the battery is cooled with the value of Equation 1 as the minimum cooling time, the crushed material can be stably utilized without a fire occurring after the battery is crushed.

<Battery shredding stage - shred size>

Even if the frozen battery is shredded, there is a low possibility of a fire occurring during the shredding, but the shredded material also has a potential difference depending on the state of charge of the battery inside the battery. In the present invention, a standard for stabilizing the shredded material is set by measuring how much the temperature of the shredded material rises.

FIG. 4 is a graph of temperature over time of a shredded material according to one embodiment of the present invention.

Figure 4 shows the temperature change over time to confirm the maximum heating temperature based on 20 mm-sized shredded materials. Specifically, after shredding a battery that has gone through a freezing step, the temperature change over time was measured by placing 20 mm-sized shredded materials among the generated shredded materials in the air and using a cooling method using air. It can be confirmed that the maximum ignition temperature is approximately 65°C for 20 mm-sized shredded materials. It can be confirmed that this is lower than the average vaporization temperature of the electrolyte, which is 120°C.

Table 3 below shows the temperature increase amount measured according to the size of the crushed material.

Average shred size (mm) 1 10 20 50 100 150 Temperature increase [℃] 30 50 65 90 110 140

Looking at Table 3 above, it can be confirmed that there is a difference in the reheating temperature depending on the size of the shredded material, and it was confirmed that, as a stabilization temperature for process design, the average size of the shredded material should be shredded to a length of 100 mm or less along the longest axis among the horizontal, vertical, and height directions.

In addition, depending on the size of the shreds, the shreds require time to be physically stabilized. As a method for stabilizing the shreds, it is necessary to maintain them for a predetermined process time under temperature conditions lower than 120℃, or to maintain them for a predetermined process time while introducing an inert gas to reduce contact with oxygen in the atmosphere.

In the present invention, the crushed material was maintained at a room temperature of 30°C for about 3 hours based on an average crushed material size of 20 mm, and at this time, it was confirmed that the increased temperature of the crushed material had dropped to the room temperature level.

For the above stabilization time, for fragments less than 100 mm, there is no problem if the holding time is within several minutes, but for fragments greater than 100 mm, the stabilization time must be at least 3 hours.

<Battery shredding stage - Shredder layer control stage of battery shredder>

When crushing is performed below the minimum freezing time of the crushed material, a problem occurs in that the crushed material is large in size or the thickness of the crushed material increases because brittle fracture does not occur in the cryogenic state or the positive and negative collectors exist in multiple layers. As the thickness of the layers of the crushed material increases, there is a problem in that the temperature increase amount is large and the heating time takes a long time.

Table 4 below shows the temperature rise according to the layered structure in a unit battery shredder according to one embodiment of the present invention, as measured by a thermal imaging camera.

Referring to Table 4 below, in the case of a layered structure, anode-separator-cathode means 1 layer, and when the shredded materials are laminated in multiple layers, they are arranged in the order of anode-separator-cathode-separator-anode-separator-cathode... Specifically, it means that the separator structure is arranged in multiple layers with the anode or the cathode in the waste battery as a 1-layer structure. Specifically, the anode or cathode may be arranged on at least one side of the separator based on the separator.

In Table 4 below, the average size of the shredded material was evaluated as 20 mm, and the temperature of each layer of the shredded material after shredding was evaluated and the recovery time required to increase from the freezing temperature to the maximum temperature and then decrease back to 40°C was measured.

At this time, the size of the shredded material was measured based on the long axis among the long and short axes of the shredded material.

Layered structure number of floors
[Floor] shred size
[mm] Maximum temperature
[℃] Below 40℃
Recovery time
[min] note Experimental example 2 20 63 110 Example Experimental example 3 20 64 110 Example Experimental example 5 20 75 144 Example Experimental example 7 20 105 200 Example Experimental example 10 100 combustion - Comparative example

FIGS. 5A to 5C illustrate unit battery fragments according to one embodiment and a comparative example of the present invention.

Referring to FIG. 5a, examples and comparative examples can be confirmed according to the size of the fragments of the unit battery fragments and the number of layers of the layered structure.

When examining the above FIG. 5a and Table 4 simultaneously, it was confirmed that when the number of layers of the layered structure was 3 or less, the temperature of the shredded material was stably maintained below 110°C, and when the number of layers was higher than 7, the temperature rose to higher than 105°C and combustion occurred because it reacted with the electrolyte.

Referring to Fig. 5b, the mixing ratio according to the weight ratio of the battery shreds can be confirmed. Specifically, the weight of the battery shreds having a layered structure of 7 layers or less (left side of Fig. 5b) was 905 g, and the weight of the battery shreds having a layered structure of more than 7 layers (right side of Fig. 5b) was mixed at 95 g.

It was confirmed that the size of the above battery shreds exceeds 100 mm for one layer, and the maximum temperature rises to over 105℃, which increases the possibility of a fire. In addition, it was confirmed that even when the size is less than 100 mm, the possibility of a fire increases when the number of layers of the layered structure is 10 or more, specifically, over 7.

Table 5 below shows the possibility of fire occurrence according to the weight % ratio of the battery shreds of the present invention, in which the layered structure exceeds 7 layers.

Over 7 floors
Weight ratio
[%] Number of experiments
[number] Frequency of fire occurrence
[number] Whether there is a fire note Experimental example less than 2 10 0 X - Experimental example 2-5 10 0 X - Experimental example 6-10 10 1 △ Smoke generation Experimental example More than 10 3 3 O Fire outbreak

Looking at Table 5 above, as a result of measuring the frequency of fire occurrence within the shredded material in units of 1 kg cells several times, it was confirmed that even when the weight ratio of the shredded material with a layered structure exceeding 7 layers was included and was less than 10% based on the total weight ratio, fire occurrence rarely occurred. In addition, it was confirmed that when the weight ratio of the shredded material with a layered structure exceeding 7 layers was included and exceeded 10% based on the total weight ratio, fire occurred in all three experiments. At this time, it was confirmed that the ignition location of the fire started in the shredded material that was thicker than 7 layers.

In this way, it was confirmed that when the weight ratio of shredded material having a layered structure exceeding 7 layers is 10% or less, specifically 5% or less, of the total weight of the shredded material, fire of the shredded material can be prevented, and it was confirmed that when the weight ratio of shredded material having a layered structure of 7 or more layers or shredded material having a size greater than 100 mm exceeds 10% of the total weight of the battery shredded material, the frequency of fire occurrence increases.

In addition, Table 6 below shows whether smoke was generated according to the ratio of combustion traces on the surface of the shredded material according to one embodiment of the present invention.

Combustion area/
Top surface area ratio
[%] Smoke generation note Experimental example 10 X Example Experimental example 20 X Example Experimental example 30 X Example Experimental example Over 30 O Comparative example

FIG. 5c illustrates a combustion section and a top section of a surface of a unit battery shredder according to one embodiment of the present invention.

Referring to Fig. 5c, the surface of the unit battery shredded material can be identified as a normal area without high-temperature combustion traces and a surface of the shredded material with high-temperature combustion traces. The combustion area is an area with high-temperature combustion traces, and may be specifically a rapidly heated area, and refers to an area with a darker color compared to the normal area, which is an unburned area. The above-mentioned combustion area appears to have mostly edges that are burned.

Looking at Fig. 5c and Table 6 above, when there were almost no traces of combustion due to high temperature on the surface of the unit battery shreds or when the traces of combustion within the surface area were 30% or less, it was confirmed that no combustion occurred when evaluating the presence or absence of smoke generation. When the traces of combustion within the surface area exceeded 30%, it was confirmed that a fire accompanied by smoke occurred.

<Battery stabilization stage: Temperature trend of shredded material according to SOC condition of waste battery>

Figures 6a to 6c are photographs showing the temperature measurement process of a waste battery and the temperature trend of the shredded material according to the SOC conditions.

FIG. 6a and FIG. 6b show the temperatures measured before and after battery shredding, and FIG. 6c shows the temperature trend of the shredded material according to the SOC condition of the spent battery. Referring to FIG. 6a, in order to measure the temperature before the spent battery was shredded, a hole of about 30 mm was drilled in the center of the battery module, and a TC (Thermal Couple) was installed to measure the temperature. Referring to FIG. 6b, in order to measure the temperature of the shredded material after the spent battery was shredded, a TC (Thermal Couple) was installed in the center of the shredded material to measure the temperature.

Referring to Fig. 6c, it shows the temperature pattern measured at 0% and 30% of the SoC condition of the battery. The SoC is an abbreviation for 'State of Charge' and means the state of charge of a lithium-ion battery. Specifically, in order to indicate the remaining capacity of the battery, the currently usable battery capacity is divided by the total capacity and expressed as a percentage (%). This is a graph measured by installing a TC (Thermal Couple) at the center of the shredded matter to measure the internal temperature of the shredded matter after the battery was cryopreserved.

Figure 7 is a graph showing the temperature increase trend of the shredded material according to the SOC % condition of the battery.

Referring to Fig. 7, it was confirmed that the battery with SoC 0% was shredded in a frozen state, and the initial temperature started at about -60℃ and increased to a maximum temperature of about 30℃, and the battery with SOC 30% was confirmed to increase to 60℃. Through this, it is necessary to confirm in advance the SOC status of the shredded material that is to be stabilized by self-heating during the low-temperature stabilization process. Specifically, it was confirmed that the maximum temperature trend according to the SOC condition was 80% or higher, and a fire occurred during the stabilization process.

<Battery stabilization stage>

FIG. 8 is a graph showing the temperature of battery shreds over time in low-temperature stabilization, intermediate stage, and high-temperature stabilization stages according to one embodiment of the present invention.

Figure 8 is a graph showing the temperature of battery shreds when stabilization treatments were continuously performed for up to a total of 24 hours by performing low-temperature stabilization for up to 12 hours, intermediate and high-temperature stabilization for up to 12 hours. It was confirmed that by performing the low-temperature stabilization process on the battery shreds and then performing the intermediate and high-temperature stabilization steps, a rapid increase in the temperature of the battery could be prevented, thereby obtaining a stabilized battery.

Figure 9a is a schematic diagram of a stabilization device for performing a battery stabilization step, and Figure 9b is a graph showing self-heating of battery fragments inside a transport container.

Referring to Fig. 9a, first, after the cryo-crushing of the battery is completed, the crushed material is put into a stabilization device. Thereafter, the low-temperature stabilization treatment is carried out while transporting the battery for up to 12 hours under temperature conditions of about 10 to 20°C or lower, while gradually removing the low-temperature electrolyte.

Fig. 9b illustrates the temperature change of the transport box containing the shredded material under the condition of SOC 30% or less. Specifically, the ambient temperature in Fig. 9b means the temperature of the transport box. During the low-temperature stabilization stage, it can be confirmed that the temperature inside the transport box increases due to the self-heating of the battery shredded material when transporting the battery shredded material. At this time, it can be confirmed that it is preferable that the temperature of the battery shredded material be controlled to be 30°C or lower during the low-temperature stabilization stage.

Figure 10 shows the temperature change of the crushed material when the heating temperature was controlled for each section for heat treatment in the high-temperature stabilization stage.

Referring to Fig. 10, the crushed material that has undergone the low-temperature stabilization step undergoes the high-temperature stabilization treatment step. In the high-temperature reduction treatment step, the temperature is controlled by adjusting the power (%) of the heating device for each section (6 sections) for continuous heat treatment, thereby increasing the temperature of the crushed material, and thus removing the electrolyte within the crushed material.

<Temperature heating pattern of stabilized shredded material>

Figure 11 shows the weight reduction ratio (%) of the electrolyte in the shredded battery according to the heat treatment temperature of 150°C after high-temperature stabilization treatment of the shredded battery.

Referring to FIG. 11, when the high-temperature stabilization treatment of the battery is performed, the heat treatment temperature of the shredded material is changed, and the weight reduction ratio (%) of the electrolyte contained in the entire shredded material is shown to some extent reduced depending on the temperature conditions. Specifically, when the battery shredded material on which the high-temperature stabilization treatment was performed was heated to 150°C, it was confirmed that when the total amount of electrolyte contained in the battery shredded material was 100 wt%, it was reduced to about 65 wt% after the high-temperature stabilization treatment. The battery shredded material on which the high-temperature stabilization treatment was performed is a stabilized lithium-ion shredded material that can safely be subjected to battery processing work in a post-process such as primary sorting or dry high-temperature treatment.

Therefore, as a major characteristic of the stabilized shredded product after cryo-fracturing, it was confirmed that the shredded product that was stabilized at low temperature was additionally stabilized at high temperature, and when the stabilized battery shredded product was heated at 150°C, the mass change before and after heating was very low.

<Tap density change>

Figure 12 shows the temperature and weight reduction according to the tap density of battery shreds.

Referring to FIG. 12, when the tap densities of the shredded battery shreds were 250, 350, 450, and 550 kg/m ³ before low-temperature stabilization, respectively, the weight reduction amount when the shredded battery shreds went through the battery stabilization step of the present invention is shown. When the tap density of the shredded battery was sequentially reduced from 550 kg/m ³ to 250 kg/m ³ , it was confirmed that a gap was formed in the shredded battery, making it easy for the electrolyte to volatilize, and the weight reduction amount compared to the weight (100%) of the electrolyte inside the battery increased.

<Evaluation Example>: Data according to low temperature stabilization and high temperature stabilization conditions

Table 7 below shows the weight reduction amount and tap density of the unit battery shreds having a layered structure of seven layers and having a size of 20 mm based on the long axis, which is the longest axis among the horizontal, vertical, and height directions, when the battery shreds were subjected to low-temperature stabilization treatment and high-temperature stabilization treatment step conditions described in Table 7 below.

At this time, a multi-stage intermediate stabilization treatment step was performed between the low-temperature stabilization treatment step and the high-temperature stabilization treatment step, and the intermediate stabilization treatment steps were heat treated continuously in the temperature ranges of 30 to 60, 60 to 90, and 90 to 120 ℃, respectively, and the high-temperature heat treatment time mentioned above was performed for 12 h including the intermediate stabilization treatment time.

The weight loss of the crushed material after the low-temperature stabilization treatment step and the high-temperature stabilization treatment step was measured using a weight measuring device.

The tapping density was measured by mechanically tapping the apparent density obtained by crushing a commercial battery module (consisting of 30 cells) of about 30 kg in a crusher and placing it in a stabilizing volume case (0.44 m long × 0.7 m wide × 0.5 m high). Specifically, the density (ρ = M/V) is obtained by dividing the battery weight (M, kg) by the volume of the case (V, m3).

The weight loss ratio after reheating the shredded material was confirmed by reheating the unit battery shredded material that had gone through the high-temperature stabilization treatment step to 150 ℃ and then checking the weight loss ratio before and after heating.

Stability was indicated as × if a fire occurred during the battery crushing process, and ○ if no fire occurred.

Tap Density
[kg/m ³ ] Low temperature stabilization
Processing step conditions Low temperature
Stabilization Processing
Step
After that
Weight of shredded material
Amount of reduction
[%] High temperature stabilization
Processing step conditions High temperature
stabilization
Processing
Step
After that
Shredded material
weight
Reduction [%] Percentage of weight loss after reheating of shredded material
[%] Stability temperature
[℃] hour
[h] temperature
[℃] hour
[h] Example 250 10 6 3.7 150 12 9.5 0.7 ○ Example 250 10 9 3.9 140 12 9.3 0.5 ○ Example 250 20 12 4.1 130 6 8.5 0.9 ○ Example 250 25 12 4.4 150 12 9.6 1.0 ○ Comparative example 250 0 24 2.5 100 5 6.4 3.1 × Comparative example 250 40 3 3.1 200 5 7.3 2.2 ×

Referring to Table 7 above, the low-temperature stabilization treatment of the example was performed in the range of 10 to 25°C for 6 to 12 hours, and the high-temperature stabilization treatment was performed in the range of 130 to 150°C for 6 to 12 hours. At this time, when examining the weight loss after reheating the shredded material, it can be confirmed that it is 1.0% or less, and since the weight loss after reheating the shredded material satisfies 1.0% or less, it was confirmed that the electrolyte reduction amount is large and stability in the post-process is secured. In contrast, when the low-temperature stabilization treatment process is not performed or is performed at a high temperature such as 40°C, there is a problem that there is a risk of battery fire, and it was confirmed that the weight loss of the obtained battery shredded material is low. In addition, when the low-temperature stabilization treatment is not sufficiently performed and the high-temperature stabilization treatment is performed, there is a problem that a low-temperature volatile electrolyte is excessively generated during the high-temperature treatment, which further increases the risk of fire, and there is a problem that the electrolyte reduction is not sufficiently achieved compared to the standard time.

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 (18)

As a unit battery shredder for recovering valuable metals from waste batteries, The above unit battery shredder is a unit battery shredder having a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface, and satisfying the following conditions 1, 2, and 3. <Condition 1> The above layered structure is a laminated structure having 1 or more layers and 7 or fewer layers. <Condition 2> The size of the unit battery shreds based on the longest axis among the horizontal, vertical, and height directions is 100 mm or less. <Condition 3> When the above unit battery shreds are reheated at 150°C, the weight of the above unit battery shreds decreases by 1.0% or less. In the first paragraph, The surface of the above unit battery shreds is a combustion zone, which is an area where at least a portion of the surface is burned, and Including a top portion with no traces of combustion on the surface, Unit battery shreds having an area ratio of the combustion zone to the above-mentioned normal zone of 30% or less. In the second paragraph, The above combustion unit is a unit battery shredder formed at the edge of the surface. As a unit battery shredder for recovering valuable metals from waste batteries, A battery shredder comprising at least one unit battery shredder having a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface, and satisfying the following conditions 1, 2, and 3. <Condition 1> The above layered structure is a laminated structure having 1 or more layers and 7 or fewer layers. <Condition 2> The size of the unit battery shreds based on the longest axis among the horizontal, vertical, and height directions is 100 mm or less. <Condition 3> When the above unit battery shreds are reheated at 150°C, the weight of the above unit battery shreds decreases by 1.0% or less. In the fourth paragraph, The content of the above unit battery shreds is 90% or more of the total volume of the above battery shreds. In the fourth paragraph, Battery scrap containing impurities in weight %, Na: 0.4 % or less, Ca: 0.03 % or less, Mg: 0.02 % or less, and K: 0.02 % or less. Steps to freeze the battery; A step of crushing the frozen battery into battery shredders; and Comprising a step of stabilizing the shredded battery waste, The above battery shreds comprise at least one unit battery shred, The above unit battery shredder has a layered structure including a separator with a positive or negative electrode laminated on at least one side, and satisfies the following conditions 1 and 2: The above stabilizing step is a battery processing method that satisfies the following condition 5. <Condition 1> The above layered structure is a laminated structure having 1 or more layers and 7 or fewer layers. <Condition 2> The size of the unit battery shreds based on the longest axis among the length, width, and height directions is 100 mm or less. <Condition 5> Low-temperature stabilization treatment is performed at 30°C or lower, and after the low-temperature stabilization treatment, high-temperature stabilization treatment is performed at 30°C or higher to 150°C. In Article 7, A battery processing method, wherein the weight of the battery shreds in the low-temperature stabilization treatment step is reduced by 2.8 to 4.6% compared to the weight of the battery shreds before performing the low-temperature stabilization treatment step. In Article 7, A battery processing method, wherein the weight of the battery shreds in the high-temperature stabilization treatment step is reduced by 8 to 10% compared to the weight of the battery shreds before performing the low-temperature stabilization treatment step. In Article 7, The above battery shredder is a battery processing method that satisfies the following condition 4. <Condition 4> The tap density of the above battery shreds is 200 to 600 kg/m ³ In Article 7, A battery treatment method wherein the low-temperature stabilization time in the above low-temperature stabilization treatment is 6 to 12 hours. In Article 7, A battery treatment method wherein the high temperature stabilization time in the above high temperature stabilization treatment is 5 to 12 hours. In Article 7, A battery processing method performed at a temperature of 0 to 150°C applied to the shredded material for stabilization treatment. In Article 7, A battery processing method including an intermediate stabilization processing step prior to the above high temperature stabilization processing step, A battery processing method wherein the intermediate stabilization treatment step is performed at a temperature of 30 to 120° C. In Article 14, The above intermediate stabilization treatment step is performed by multi-stage heat treatment, A battery processing method in which the above multi-stage heat treatment is sequentially performed at a first temperature of 30 to 60°C, a second temperature of 60 to 90°C, and a third temperature of 90 to 120°C. In Article 7, A battery processing method wherein the shredding step includes a step of controlling the proportion of the unit battery shreds to be 90% or more within the total volume of the battery shreds. In Article 7, A battery processing method in which the freezing step is performed by cooling to -150°C to -20°C. In Article 7, The above freezing step is performed by cooling to -60℃ to -20℃, A battery processing method in which the above crushing step is performed under vacuum conditions of 100 torr or less.

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