WO2025135713A1 - Battery stabilizer and battery stabilization system - Google Patents

Abstract

The present invention relates to a battery stabilizer and a battery stabilization system, and comprises: an input unit for inputting a sagger into which waste battery crushed material has been loaded; a transport unit for transporting the sagger into which the waste battery crushed material has been loaded; a first stabilization unit for stabilizing the waste battery crushed material at a temperature of 30°C or lower; a second stabilization unit for stabilizing, at a temperature of 30°C to 150°C, the waste battery crushed material that has passed through the first stabilization unit; and a discharge unit for discharging the stabilized waste battery crushed material, wherein the sagger includes a hot air inlet for supplying heat to the waste battery crushed material.

Description

Battery stabilization device and battery stabilization system

The present invention relates to waste batteries, a battery stabilization device and a battery stabilization system.

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 stabilization system to stably remove the electrolyte contained in the shredded material and transport it stably to the post-processing stage after shredding the used batteries.

According to one embodiment of the present invention, a battery stabilization device is provided that stably removes electrolyte from waste battery shreds, thereby reducing the content of impurities and preventing fire.

According to one embodiment of the present invention, a battery stabilization system is provided that stably removes electrolyte from waste battery shreds, thereby reducing the content of impurities and preventing fire.

According to one embodiment of the present invention, a battery stabilization device includes an input unit for inputting a sagger into which waste battery shreds are input, a transport unit for transporting the sagger into which the waste battery shreds are input, a first stabilization unit for stabilizing the waste battery shreds at a temperature of 30° C. or lower, a second stabilization unit for stabilizing the waste battery shreds passing through the first stabilization unit at a temperature of 30 to 150° C., and a discharge unit for discharging the stabilized waste battery shreds, wherein the sagger may include a hot air inlet for supplying heat to the waste battery shreds.

In one embodiment, the first stabilizing unit may include a compressor. In one embodiment, the first stabilizing unit may include at least one weight and temperature measuring unit for measuring the weight of the waste battery shreds.

In one embodiment, the weight and temperature measuring unit may include a first weight and temperature measuring unit disposed between the input port and the first stabilizing unit, a second weight and temperature measuring unit disposed between the first stabilizing unit and the second stabilizing unit, and a third weight and temperature measuring unit disposed between the second stabilizing unit and the discharge unit. In one embodiment, the second stabilizing unit includes an intermediate stabilizing unit and a high-temperature stabilizing unit, and the intermediate stabilizing unit may heat the waste battery shreds in a range of 30 to 120° C., and the high-temperature stabilizing unit may heat the waste battery shreds in a range of 120 to 150° C.

In one embodiment, the hot air inlet is arranged in the shape of a cylinder, a triangular prism, a square prism, or a polygonal prism, and can emit heat through the outer surface of the shape. In one embodiment, the hot air inlet includes a plurality of hot air inlets, and the spacing between the plurality of hot air inlets can be 35 to 45% based on the horizontal length of the saga.

In one embodiment, the height of the hot air inlet can be from 25% to 50% of the height of the saga. In one embodiment, the height of the hot air inlet can be from 25% to 50% of the height of the saga.

In one embodiment, the saga may have a structure with an open upper surface. In one embodiment, the saga may include a housing surrounding a side of the saga, and may include a mesh portion and a sealing portion disposed below the mesh portion.

According to another embodiment of the present invention, a battery stabilization treatment system may include a first step of controlling a tap density of waste battery shreds, a second step of measuring a first weight as an initial weight and a first temperature as an initial temperature of the waste battery shreds, a third step of stabilizing the waste battery shreds at a temperature of 30° C. or lower, a fourth step of measuring a second weight and a second temperature of the waste battery shreds that have undergone the third step, a fifth step of stabilizing the waste battery shreds that have undergone the fourth step at a temperature of 30 to 150° C., a sixth step of measuring a third weight and a third temperature of the waste battery shreds that have undergone the fifth step, and a seventh step of discharging the waste battery shreds that have undergone the sixth step.

In one embodiment, the first step can control the tap density of the waste battery shreds to 200 to 1,400 kg/m ³ . In one embodiment, the fifth step can be performed when the first weight and the first temperature of the waste battery shreds measured in the second step and the second weight and the second temperature of the waste battery shreds measured in the fourth step satisfy the following equations 1 and 2.

<Formula 1>

2nd weight - 1st weight ≤ 25%

<Formula 2>

Second temperature - First temperature ≤ 25 ℃

In one embodiment, when the second weight and the second temperature of the waste battery shreds measured in the fourth step and the third weight and the third temperature of the waste battery shreds measured in the sixth step satisfy the following equations 3 and 4, the seventh step can be performed.

<Formula 3>

3rd weight - 2nd weight ≤ 10%

<Formula 4>

3rd temperature - 2nd temperature ≤ 25 ℃

In one embodiment, the fifth step is performed by a multi-stage heat treatment, and the multi-stage heat treatment can be performed sequentially at temperatures of 30 to 120° C. and 120 to 150° C. In one embodiment, prior to the first step of controlling the tap density of the waste battery shreds, the unit waste battery shreds constituting the waste battery shreds can include a step of controlling them to satisfy the following conditions 1 and 2.

<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 waste battery shreds based on the long axis, which is the longest axis among the horizontal, vertical, and height directions, is 100 mm or less.

In one embodiment, prior to the first step, the method further comprises a step of freezing the waste battery shreds, wherein the freezing step can be performed by cooling to -150° C. to -20° C.

According to one embodiment of the present invention, a battery stabilization device includes low-temperature and high-temperature stabilization units and at least one weight and temperature measuring unit to check the weight and temperature of waste battery shreds, thereby providing a battery stabilization device having a low impurity content and preventing fire.

According to another embodiment of the present invention, a battery stabilization system includes low-temperature and high-temperature stabilization steps, and controls the weight and temperature of waste battery shreds at each step, thereby providing a battery stabilization system having a low impurity content and preventing fire occurrence.

FIG. 1A is a perspective view of a battery stabilization device according to one embodiment of the present invention, and FIG. 1B is a schematic diagram of a battery stabilization device according to one embodiment of the present invention.

Figure 2 illustrates a Sagger according to one embodiment of the present invention.

FIG. 3 is a flow chart of a battery stabilization system according to one embodiment of the present invention.

Figure 4 shows the change in voltage of a battery according to cooling temperature according to one embodiment of the present invention.

FIG. 5 is a graph showing the relationship among battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

FIGS. 6a and 6b are photographs of examples according to the minimum cooling time of the present invention, and FIGS. 6c and 6d are photographs of comparative examples according to the minimum cooling time of the present invention.

Figure 7 is a graph of temperature over time of a shredded material according to one embodiment of the present invention.

FIGS. 8A to 8C illustrate unit battery fragments according to one embodiment and a comparative example of the present invention.

Figures 9a to 9c 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 10a shows the temperature trend of the shredded material over time, and Figure 10b is a graph showing the temperature increase trend of the shredded material according to the SOC % condition of the battery.

FIG. 11 is a graph showing the temperature of waste battery shreds over time in low-temperature stabilization, intermediate stage, and high-temperature stabilization stages according to one embodiment of the present invention.

Figure 12 is a graph showing the self-heating of battery waste inside a transport vessel.

Figure 13 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 14 shows the weight reduction ratio (%) of the electrolyte in the shredded waste according to the heat treatment temperature of 150°C after high-temperature stabilization treatment of the shredded waste battery.

Figure 15 shows the temperature and weight reduction according to the tap density of battery shreds.

Figure 16 shows a graph of the heating rate according to the spacing of hot air inlets.

Figure 17 shows a graph of temperature versus time according to the spacing of the hot air inlet and the spacing of the sealing part.

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.

FIG. 1A is a perspective view of a battery stabilization device according to one embodiment of the present invention, and FIG. 1B is a schematic diagram of a battery stabilization device according to one embodiment of the present invention.

Referring to FIGS. 1A and 1B, a battery stabilization device according to one embodiment is a device for stabilizing waste battery waste, and may include an inlet section, a transport section, a first stabilization section, a second stabilization section, a weight and temperature measurement section, and a discharge section.

The inlet may be a member into which waste battery shreds are fed. The waste battery shreds may be a result of shredding waste batteries. By feeding the sagger containing the waste battery shreds through the inlet, the sagger may be fed into a battery stabilization device.

The transport unit may be a member for transporting the saga into which the waste battery shreds have been inserted within the battery stabilization device. The transport unit may be a member for guiding the saga including the waste battery shreds to be discharged through the first stabilization unit and the second stabilization unit to the discharge unit. The transport unit may be a structure arranged in the form of a conveyor belt, for example.

The first stabilizing unit can perform stabilization of the waste battery shreds at a low temperature. Specifically, the first stabilizing unit can perform stabilization of the waste battery shreds by transporting the waste battery shreds while being accommodated in the saga and applying hot air to the saga.

In one embodiment, the first stable portion may include a first heater portion at the bottom. The first heater portion may supply heat to the bottom of the saga. Specifically, the first heater portion may supply hot air to the saga to heat the waste battery shreds disposed within the saga.

Specifically, the first stabilizing unit can stabilize the waste battery shreds at a temperature of 30° C. or lower. More specifically, the first stabilizing unit can be a member in which the waste battery shreds self-heat and are stabilized. The first stabilizing unit can prevent a problem in which sudden heat generation occurs and a fire may occur when the SoC (State of Charge), which indicates the remaining capacity of the waste battery shreds, is 30% or higher.

In one embodiment, the first stabilizer may include a high-temperature air dryer for supplying air with minimized moisture. Specifically, the first stabilizer may be a member that supplies dry air from which moisture has been removed while maintaining a temperature of 5 to 20° C., specifically 5 to 15° C. Specifically, the heater may be a device that creates dry air.

In one embodiment, the first stabilizer may include a compressor. The compressor may be a screw compressor for forming dry air. In one embodiment, the compressor may form a pressure of less than 10 bar.

In one embodiment, the first stabilizing unit may further include a first vibrating unit. Specifically, the first vibrating unit may be controlled to vibrate and disperse the battery shreds when the first stabilizing unit applies hot air to the battery shreds, thereby allowing heat to be applied evenly to the battery shreds.

The second stabilizing unit can perform stabilization of the waste battery shreds at high temperatures. Specifically, the second stabilizing unit can perform stabilization of the waste battery shreds by transporting the waste battery shreds while being accommodated in the saga, and applying hot air to the saga to volatilize the high-temperature volatile electrolyte that has not been volatilized in the first stabilizing unit.

In one embodiment, the second stable portion may include a second heater portion at the bottom. The second heater portion may supply heat to the bottom of the saga. Specifically, the second heater portion may supply hot air to the saga to heat the waste battery shreds disposed within the saga.

More specifically, the second stabilizing member may be a member that stabilizes the waste battery shreds at a temperature of 30 to 150° C. The second stabilizing member heats the waste battery shreds in the aforementioned temperature range, thereby volatilizing the electrolyte in the waste battery shreds, thereby reducing the weight of the waste battery shreds and decreasing the tap density.

In one embodiment, the second stabilizing unit may include an intermediate stabilizing unit and a high temperature stabilizing unit. The intermediate stabilizing unit may be a step of heating the waste battery shreds at a temperature lower than that of the high temperature stabilizing unit. In one embodiment, the intermediate stabilizing unit may be a member that performs stabilization of the waste battery shreds at a temperature of 30 to 120° C. Since the second stabilizing unit includes the intermediate stabilizing unit, the temperature of the waste battery shreds can be gradually increased to stably volatilize the electrolyte within the waste battery shreds.

In one embodiment, the high-temperature stabilizing unit may be a member that performs stabilization of the waste battery shreds at a temperature of 120 to 150° C. As the high-temperature stabilizing unit is performed in the above-described range, high-temperature heat may be applied to the waste battery shreds that have been stabilized through the low-temperature stabilization treatment step to volatilize the remaining electrolyte.

In one embodiment, the second stabilizing unit may further include a second vibrating unit. Specifically, the first vibrating unit may be controlled to vibrate and disperse the battery shreds when the second stabilizing unit applies hot air to the battery shreds, thereby allowing heat to be applied evenly to the battery shreds.

In one embodiment, the first stabilizer and the second stabilizer may be arranged in a horizontal or stacked structure. Specifically, the second stabilizer may be stacked on the first stabilizer, and may be arranged subsequent to the first stabilizer on the same line.

In one embodiment, the first stabilizing member and the second stabilizing member can apply heat to the battery shreds placed within the saga as the saga moves. The weight and temperature measuring member can be a member that measures the weight of the waste battery shreds. Specifically, the weight and temperature measuring member can measure the weight and temperature of the waste battery shreds with devices such as a load cell, a TC, and a thermal imaging camera.

In one embodiment, the battery stabilization device may include a weight and temperature measuring unit. The weight and temperature measuring unit may include a first weight and temperature measuring unit positioned between the inlet and the first stabilizing unit, a second weight and temperature measuring unit positioned between the first stabilizing unit and the second stabilizing unit, and a third weight and temperature measuring unit positioned between the second stabilizing unit and the discharge unit.

The first weight and temperature measuring unit can measure the initial weight and tap density of the waste battery shreds. The first weight and temperature measuring unit can measure the initial weight and tap density of the waste battery shreds. Specifically, the first weight and temperature measuring unit can be a member that measures the initial weight and temperature of the waste battery shreds to determine whether or not to proceed with the subsequent stabilization treatment.

The first weight and temperature measuring unit may be a member that determines whether the temperature of the waste battery shreds is -20 to 10° C. and whether the weight of the waste battery shreds is similar to the weight of the waste battery before shredding. For example, the first weight and temperature measuring unit may be a member that determines whether the weight of the waste battery shreds is 31.75 to 32.25 kg.

When the temperature and weight of the waste battery shreds are within the above-mentioned ranges, the waste battery shreds can be moved to the first stable section along the transport section. When the temperature and weight of the waste battery shreds are outside the above-mentioned ranges, particularly when the temperature decrease is large due to initial heat generation after shredding, the movement of the waste battery shreds to the first stable section can be prevented in consideration of problems such as fire occurrence in the waste battery shreds.

The second weight and temperature measuring unit may be a member that measures the temperature and weight of the waste battery shreds that have passed through the first stabilizing unit. Specifically, the second weight and temperature measuring unit may be a member that determines whether the temperature of the waste battery shreds that have passed through the first stabilizing unit is 10 to 35° C. and whether the weight of the waste battery shreds is 30.65 to 31.15 kg. When the temperature and weight of the waste battery shreds are within the above-described ranges, the waste battery shreds may be moved to the second stabilizing unit along the transport unit. When the temperature and weight of the waste battery shreds are outside the above-described ranges, the movement to the second stabilizing unit may be prevented in consideration of problems such as a fire outbreak in the waste battery shreds.

The third weight and temperature measuring unit may be a member that measures the temperature and weight of the waste battery shreds that have passed through the second stabilizing unit. Specifically, the third weight and temperature measuring unit may be a member that determines whether the temperature of the waste battery shreds that have passed through the second stabilizing unit is 100° C. or less and whether the weight of the waste battery shreds is 29.85 kg or less. When the temperature and weight of the waste battery shreds are within the above-described range, the waste battery shreds can be discharged through the discharge unit. When the temperature and weight of the waste battery shreds are outside the above-described range, the waste battery shreds can be prevented from being discharged through the discharge unit in consideration of problems such as the occurrence of a fire.

The discharge unit may be a member through which the waste battery shreds that have passed through the second stabilization unit are discharged to a subsequent process. Specifically, the discharge unit may be a member through which the stabilized waste battery shreds are discharged to a subsequent process. More specifically, the discharge unit discharges the battery shreds to a subsequent process, and the receiving unit that receives the shreds discharged by the battery shreds may be returned to the shredder.

Figure 2 illustrates a Sagger according to one embodiment of the present invention.

FIG. 2 is a perspective view of a sagger according to one embodiment of the present invention. In one embodiment, the sagger may include at least one hot air inlet for supplying heat to the waste battery shreds from heaters disposed below the first stabilizing portion and the second stabilizing portion, and a housing for protecting the sagger. Specifically, when heat is supplied from the heaters disposed in the first stabilizing portion and the second stabilizing portion, including at least one hot air inlet in the sagger, the heat may be supplied to the sagger, thereby supplying heat to the battery shreds. The battery shreds may be stabilized through the heat supplied through the hot air inlet.

In one embodiment, the hot air inlet may be arranged in at least a portion of the sagger. Specifically, the hot air inlet may easily supply hot air into the sagger. In one embodiment, the heater unit may be arranged in a side portion of the sagger to supply heat from an edge area of the waste battery shreds.

In one embodiment, the hot air inlet may be arranged in the shape of a cylinder, a triangular column, a square column, or a polygonal column. The hot air inlet may dissipate heat through the outer surface of the aforementioned shape. The hot air inlet may have the aforementioned shape and may have a mesh structure. The mesh structure is in the form of a net and may assist in easily dissipating heat input from the hot air inlet.

By supplying heat to the waste battery shreds from the hot air inlet, the electrolyte in the waste battery shreds can be evaporated, thereby stabilizing the waste battery shreds. In this way, by supplying hot air to the waste battery shreds, the waste battery shreds can be stabilized by a dry method.

In one embodiment, the hot air inlet may include a plurality of hot air inlets. The hot air inlets may be arranged in a plurality within the saga to uniformly supply heat to the entire area where the waste battery shreds are arranged within the saga.

In one embodiment, the spacing (L2) between the hot air inlets may be 35 to 45% based on the horizontal length (L1) of the saga. Specifically, the spacing between the center regions of the hot air inlets may be 35 to 45% based on 100% of the length of the major axis when cut in cross-section based on the X-axis and Y-axis planes, which are horizontal planes for the saga.

Since the spacing between the plurality of hot air inlets satisfies the above-mentioned range, there is an advantage in that the heating rate within the saga is high, so that heat can be supplied evenly to the battery shreds. Since the spacing between the plurality of hot air inlets exceeds the above-mentioned range, there is a problem in that the heating rate within the saga is not high, so that heat cannot be supplied evenly to the battery shreds.

In one embodiment, the height (H2) of the hot air inlet may be 25% to 50% of the height (H1) of the saga. Specifically, it may be 30% to 40%. Since the height (H2) of the hot air inlet satisfies the above-described range based on the height (H1) of the saga, there is an advantage in that the battery shreds placed in the saga can be uniformly heated.

If the height (H2) of the hot air inlet exceeds the upper limit of the above-mentioned range, the amount of battery shreds placed in the chamber decreases, resulting in a decrease in efficiency, and there is a problem in which excessive hot air is supplied to the battery shreds. If the height (H2) of the hot air inlet exceeds the lower limit of the above-mentioned range, there is a problem in which heat is not supplied appropriately to the battery shreds.

In one embodiment, the cross-sectional shape along the vertical plane of the hot air inlet can satisfy at least one of a triangle, a square, a circle, an oval, and a polygon. Specifically, the cross-sectional shape of the hot air inlet refers to a shape when the cross-section is cut based on the X-axis and Z-axis planes, which are vertical planes of the saga. The cross-sectional shape along the vertical plane of the hot air inlet has various shapes, so that heat can be efficiently supplied to battery shreds having various shapes.

In one embodiment, the saga may have an opening shape on its upper surface. Specifically, the saga may have an open structure on its upper surface without being sealed. Since the upper surface of the saga has an open structure, heat generated by the battery shreds can be discharged through the open structure.

In one embodiment, the housing of the saga may include a mesh portion in at least a portion of the area. Specifically, the mesh portion has a net shape so that heat generated from the battery shreds can be easily discharged. More specifically, at least one of the four sides surrounding the side of the saga may include a mesh portion.

In one embodiment, the housing of the saga may include a sealing portion in at least a portion of the area. Specifically, the sealing portion is positioned below the mesh portion to maintain the efficiency of heat input from the hot air inlet.

In one embodiment, the ratio of the sealed portion may be 30 to 80%, specifically, 35 to 70%, and more specifically, 60 to 70%, based on 100% of the height of the saga. By satisfying the ratio of the sealed portion in the aforementioned range, the time required to reach the target temperature of the first stable portion or the second stable portion can be minimized. If the ratio of the sealed portion is outside the upper limit of the aforementioned range, the heat discharged from the battery shreds is not easily discharged to the outside, which may generate a load inside the device. If the ratio of the sealed portion is outside the lower limit of the aforementioned range, there is a problem that the time required to reach the target temperature is increased, thereby lowering the efficiency of the process.

Referring to FIG. 3, according to one embodiment, a battery stabilization system includes a first step of controlling a tap density of waste battery shreds, a second step of measuring a first weight as an initial weight and a first temperature as an initial temperature of the waste battery shreds, a third step of stabilizing the waste battery shreds at a temperature of 30° C. or lower, a fourth step of measuring a second weight and a second temperature of the waste battery shreds that have undergone the third step, a fifth step of stabilizing the waste battery shreds that have undergone the fourth step at a temperature of 30 to 120° C., a sixth step of measuring a third weight and a third temperature of the waste battery shreds that have undergone the fifth step, and a seventh step of discharging the waste battery shreds that have undergone the sixth step.

The first step of controlling the tap density of the waste battery shredded material may be a step of controlling the tap density of the waste battery shredded material to 200 to 1,400 kg/m ³ . Specifically, the first step may be a step of controlling the tap density of the waste battery shredded material to 500 to 1,000 kg/m ³ .

Tapped density usually refers to the apparent density obtained by mechanically tapping a measuring container containing a powder sample. Specifically, in order to determine the tap density characteristics of the lithium ion waste battery shredder, a commercialized battery module consisting of about 30 cells weighing 30 kg was crushed by a crusher, placed in a case (volume: 0.4 m wide × 0.7 m long × 0.44 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 waste battery shredder calculated by the above-described method is 200 to 600 kg/ ^m3 . Specifically, the tap density can be 240 to 400 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, prior to the first step of controlling the tap density of the waste battery shreds, the method may include a step of controlling the unit waste battery shreds constituting the waste battery shreds to satisfy the following conditions 1 and 2.

<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 waste battery shreds based on the long axis, which is the longest axis among the horizontal, vertical, and height directions, is 100 mm or less.

The unit waste 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 waste battery shredder may have a predetermined thickness in the thickness direction since at least one or more layers are laminated.

The above condition 1 may mean that the layered structure of the unit waste 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, the size of the unit waste battery shreds, specifically, the longest axis among the width, length, 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 waste battery shreds is greater than 100 mm, the temperature of the heat generated due to instability as the waste 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, in order to satisfy the above conditions 1 and 2, the step of crushing the waste battery may be included. Specifically, the step of controlling the proportion of the unit waste battery crushed material satisfying the above conditions 1 and 2 to be 90% or more, specifically 95% or more, of the total volume of the waste battery crushed material may be further included. Specifically, this may correspond to controlling the proportion of the unit waste battery crushed material having a laminated structure exceeding 7 layers to be 10% or less of the total volume of the waste battery crushed material. Specifically, the proportion of the unit waste battery crushed material having a laminated structure exceeding 7 layers may be controlled to be 5% or less of the total volume of the waste battery crushed material. By satisfying the above range, there is an advantage of being able to prevent the occurrence of a fire.

The step of crushing the waste battery may refer to a process of applying an impact or pressure to the battery so that a part of the battery falls off from the battery. In one embodiment, the step of crushing the waste 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 can be performed under conditions of supplying an inert gas, carbon dioxide, nitrogen, water, or a combination thereof, or under vacuum 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° C., when performed under the conditions described above, the supply of oxygen can be suppressed, preventing the electrolyte from reacting with oxygen, thereby preventing an explosion caused thereby, and vaporization of the electrolyte can be suppressed, so that flammable gases such as ethylene, propylene, or hydrogen cannot be generated.

In one embodiment, the recovery time required to lower the temperature of the waste battery shreds to a range of 20 to 50° C. in the shredding step may be 200 minutes or less. Specifically, the recovery time required to lower the temperature of the waste battery shreds to a range of 35 to 45° C. may be 200 minutes or less.

The second step of measuring the first weight, which is the initial weight of the waste battery shreds, and the first temperature, which is the initial temperature, may be a step of measuring the initial weight and the initial temperature of the shredded waste battery shreds. In the second step, the initial weight of the waste battery shreds may be controlled to 30.65 to 31.15 kg. In the second step, the initial temperature of the waste battery shreds may be controlled to 10 to 35° C.

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

In one embodiment, the area ratio of the combustion portion to the top portion on the surface of the unit waste battery shredded material may be 30% or less. By satisfying the area ratio of the combustion portion to the top portion to be 30% or less, the possibility of the unit waste battery shredded material being burned and causing a fire can be prevented. If the area ratio of the combustion portion to the top portion exceeds 30%, there is a risk that the unit waste battery shredded material will be burned and cause a fire accompanied by smoke.

In one embodiment, on the surface of the unit waste 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 waste battery shredder. The combustion portion refers to a region that exhibits a darker color compared to the top portion.

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

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

In this way, when the proportion of waste battery shreds having a layered structure exceeding 7 layers per unit volume within the total volume of waste battery shreds or the proportion of unit waste battery shreds having a size exceeding 100 mm in the long axis standard satisfies the above range, fire occurrence can be prevented.

In one embodiment, the waste battery shredder is recovered from a waste battery and includes impurities, and the impurities may include, in weight %, Na, Ca, Mg, and K. The waste battery shredder may be a shred 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-mentioned waste battery shreds may contain impurities such as Na, Ca, Mg, and K. The above-mentioned waste battery shreds can facilitate the extraction of Li, a valuable metal of the same group, in a post-process by lowering the content of the impurities.

According to one embodiment of the present invention, the waste battery shredder includes impurities, and the impurities may include, in weight %, 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 spent battery shreds, 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. The spent battery shreds may contain 0.4 wt% or less of sodium, and specifically, may contain 0.1 wt% or less of 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 waste 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 lithium recovery rate. The waste 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 waste battery shreds may contain magnesium in an amount of 0.02 wt% or less, 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 of the same group as lithium, and it is an element that plays a role in preventing lithium from being formed into a hydroxide compound. The waste 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 of causing a load in the causticization process, thereby reducing the lithium recovery rate.

In one embodiment, prior to the first step, the waste battery may include a step of freezing. Specifically, the step of freezing the waste 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 waste 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 time longer than the minimum cooling time. The step of freezing the waste battery has the problem that if the battery is frozen for a time shorter than the minimum cooling time, the electrolyte may not be cooled, which may cause a risk of fire when crushed.

The step of freezing the above-mentioned waste 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 above-mentioned waste battery is frozen in the above-mentioned 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.

When the initial temperature and initial weight of the waste battery shreds are within the above-mentioned ranges, the waste battery shreds can be moved to the first stable section along the transport section. When the temperature and weight of the waste battery shreds are outside the above-mentioned ranges, the movement to the first stable section can be prevented in consideration of problems such as the occurrence of a fire in the waste battery shreds.

The above low-temperature stabilization treatment step may be a step of stabilizing the crushed waste battery fragments at a temperature of 30° C. or lower. The third step of stabilizing the waste battery fragments at a temperature of 30° C. or lower may be a step of slowly transporting the waste battery fragments in a low-temperature state while removing the electrolyte.

Specifically, the low-temperature stabilization treatment step may be a step in which the shredded waste battery shreds self-heat and are stabilized. 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 overheating may occur, which may result in a fire. Therefore, the low-temperature stabilization treatment step may be a preliminary step for stabilizing the battery at a temperature of 10° C or lower to minimize the aforementioned fire risk.

In one embodiment, the third step, which is a low-temperature stabilization step, can be performed for 6 to 24 hours. If the low-temperature stabilization treatment step is outside the upper limit of the above-mentioned 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 above-mentioned time range, the electrolyte may not be removed sufficiently safely, which may lead to a problem of a post-process fire.

The fourth step of measuring the second weight and the second temperature of the waste battery shreds that have gone through the third step is a step of measuring the weight and temperature of the waste battery shreds that have gone through the low-temperature stabilization step. The third step may be a step of determining whether the waste battery shreds that have gone through the low-temperature stabilization are suitable for high-temperature stabilization.

In one embodiment, when the first weight and the first temperature of the waste battery shreds measured in the second step and the second weight and the second temperature of the waste battery shreds measured in the fourth step satisfy the following equations 1 and 2, the fifth step, which is a high-temperature stabilization step, can be performed.

<Formula 1>

2nd weight - 1st weight ≤ 25%

<Formula 2>

Second temperature - First temperature ≤ 25 ℃

The above equations 1 and 2 represent the weight reduction (%) and temperature difference between the low-temperature stabilized waste battery shreds and the initial waste battery shreds. Specifically, the equation 1 represents the weight reduction after the low-temperature stabilization treatment, and the equation 2 represents the temperature difference before and after the low-temperature stabilization.

When the above equations 1 and 2 are satisfied, the waste battery shreds have the advantage of not causing a fire and smoothly evaporating the electrolyte even if a high-temperature stabilization step is performed. When the above equations 1 and 2 are not satisfied, the waste battery shreds that have undergone a low-temperature stabilization step cannot perform the subsequent high-temperature stabilization step, and the fourth step, which is a low-temperature stabilization step, can be continued until the conditions of the equations 1 and 2 are satisfied.

The fifth step of stabilizing the spent battery shreds that have gone through the fourth step at a temperature of 30 to 150° C. may be a high-temperature stabilization step of the spent battery shreds at a temperature higher than that of the low-temperature stabilization step. Specifically, the high-temperature stabilization step may be a step of applying high-temperature heat to the spent battery shreds that have been stabilized through the low-temperature stabilization step to volatilize the electrolyte within the spent battery shreds.

In one embodiment, the fifth step may be performed as a multi-stage heat treatment. Specifically, the fifth step may perform an intermediate stabilization step and a high-temperature stabilization step. The multi-stage heat treatment may be performed sequentially at temperatures of 30 to 120° C. and 120 to 150° C.

In one embodiment, the intermediate stabilization 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 by a multi-stage heat treatment. The intermediate stabilization treatment steps can be sequentially performed at 30 to 60 °C, 60 to 90 °C, and 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 spent battery shreds can be gradually increased to stably volatilize the electrolyte within the spent battery shreds.

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

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

In one embodiment, the high temperature stabilization step can be performed for 5 to 12 hours. If the high temperature stabilization 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 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.

The sixth step of measuring the third weight and the third temperature of the waste battery shreds that have gone through the fifth step is a step of measuring the weight and temperature of the waste battery shreds that have gone through the high-temperature stabilization step. Specifically, the sixth step may be a step of determining whether the waste battery shreds that have gone through the high-temperature stabilization step are suitable for performing a subsequent process.

In one embodiment, when the second weight and the second temperature of the waste battery shreds measured in the fourth step and the third weight and the third temperature of the waste battery shreds measured in the sixth step satisfy the following equations 3 and 4, the seventh step can be performed.

<Formula 3>

3rd weight - 2nd weight ≤ 10%

<Formula 4>

3rd temperature - 2nd temperature ≤ 25 ℃

The above equations 3 and 4 represent the weight reduction (%) and the temperature difference between the spent battery shreds that have undergone high-temperature stabilization and the spent battery shreds before performing the high-temperature stabilization step. When the above equations 3 and 4 are satisfied, there is an advantage in that even if a subsequent process, such as a high-temperature reduction process, is performed while the electrolyte in the spent battery shreds is volatilized, a fire does not occur and the subsequent process can be performed with stability. When the above equations 3 and 4 are not satisfied, there is a problem in that a fire occurs due to the electrolyte in the spent battery shreds when performing the subsequent process, making it difficult to perform the process. When the above equations 3 and 4 are not satisfied, the spent battery shreds can continuously perform the 6th step, which is the high-temperature stabilization step, until the above equations 3 and 4 are satisfied.

The seventh step of discharging the waste battery shreds that have gone through the sixth step can be performed on the waste battery shreds that satisfy the conditions described above. The waste battery shreds that have gone through the low-temperature and high-temperature stabilization steps can be discharged for use in a subsequent process such as a reduction process.

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

Referring to Fig. 4, 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 below -70°C, the voltage becomes 0 V. In this way, it was confirmed that a short circuit does not occur when the battery is frozen to -60 to -150°C.

FIG. 5 is a graph showing the relationship among battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

Referring to FIG. 5, 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 the above Table 1, it can be confirmed that the smaller the battery weight, the shorter the minimum cooling time of the battery to be cooled. In addition, it can be confirmed that when the value of Equation 1 derived from the relationship according to the battery weight, the external cooling temperature, and the 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 in the post-process, the battery crushing process. FIGS. 6a and 6b are photographs of examples according to the minimum cooling time of the present invention, and FIGS. 6c and 6d are photographs of comparative examples according to the minimum cooling time of the present invention.

Referring to FIGS. 6a and 6b, 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 6c and 6d, 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, external cooling temperature, and minimum freezing time of 7 hours or more as shown in Table 2 below.

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 6a to 6d. 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.

Figure 7 is a graph of temperature over time of a shredded material according to one embodiment of the present invention.

Referring to Fig. 7, in order to confirm the maximum heating temperature based on 20 mm-sized shredded materials, the temperature change over time was confirmed. Specifically, after shredding a battery that had gone through a freezing step, the 20 mm-sized shredded materials among the generated shredded materials were placed in the air and the temperature change over time was measured using a cooling method using air. In the case of 20 mm-sized shredded materials, it can be confirmed that the maximum ignition temperature is approximately 65°C. 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 re-heating temperature depending on the size of the shredded material, and it was confirmed that the average size of the shredded material should be shredded to within 100 mm in the long axis, which is the longest axis among the horizontal, vertical, and height directions, as the stabilization temperature for process design. In addition, depending on the size of the shredded material, the shredded material requires time to be physically stabilized. As a method for stabilizing the shredded material, it is necessary to continuously maintain it for a predetermined process time under temperature conditions lower than 120 ℃, or to maintain it for a predetermined process time in a state in which an inert gas is introduced 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. 8A to 8C illustrate unit battery shreds according to one embodiment and a comparative example of the present invention. Referring to FIG. 8A, examples and comparative examples can be confirmed according to the shred size and the number of layers of the layered structure of the unit battery shreds.

When examining the above FIG. 8a 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. 8b, 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. 8b) was 905 g, and the weight of the battery shreds having a layered structure of more than 7 layers (right side of Fig. 8b) 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, the results of measuring the frequency of fire occurrence within the shredded material in units of 1 kg cells several times 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, 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 occurrence was confirmed in all three experiments. At this time, it was confirmed that the ignition location of the fire started from a thick shredded material of 7 layers or more. In this way, it was confirmed that the fire of the shredded material can be prevented when the weight ratio of the shredded material having a layered structure of more than 7 layers is 10% or less, specifically 5% or less, with respect to the total weight of the shredded material. In addition, it was confirmed that the frequency of fire occurrence increases when the shredded material having a layered structure of 7 layers or more or shredded material having a size larger than 100 mm is included in more than 10% of the total battery shredded material.

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. 8C illustrates a combustion area and a top area of a surface of a unit battery shredded material according to an embodiment of the present invention. Referring to FIG. 8C, the surface of the unit battery shredded material can be identified as a top area without a combustion trace due to high temperature and a surface of the shredded material with a combustion trace due to high temperature. The combustion area is an area with a combustion trace due to high temperature, and may be specifically a rapidly heated area, and means an area that has a darker color compared to the top area, which is an unburned area. The combustion area appears to have mostly burned edges.

Looking at Fig. 8c 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 used battery>

Figures 9a to 9c 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. 9a and FIG. 9b show the temperature measured before and after battery shredding, and FIG. 8c shows the temperature trend of the shredded material according to the SOC condition of the spent battery. Referring to FIG. 9a, 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. 8b, 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. 9c, 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 10a shows the temperature trend of the shredded material over time, and Figure 10b is a graph showing the temperature increase trend of the shredded material according to the SOC % condition of the battery.

Referring to FIGS. 10A and 10B, it can be confirmed that the temperature rises to more than 10 degrees over time and then decreases. In addition, it was confirmed that the battery with SoC 0% was crushed in a frozen state, and the initial temperature started at about -60°C and increased to a maximum temperature of about 30°C, and the battery with SOC 30% was confirmed to rise to 60°C. Through this, it is necessary to confirm in advance the SOC status of the crushed material that is to be stabilized at low temperature by self-heating during stabilization. Specifically, it was confirmed that the maximum temperature trend according to the SOC condition caused a fire during stabilization when it was 80% or higher.

<Battery stabilization stage>

FIG. 11 is a graph showing the temperature of battery shreds over time in the low-temperature stabilization, intermediate stage, and high-temperature stabilization stages according to one embodiment of the present invention.

Figure 11 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.

Fig. 12 illustrates the temperature change of a transport box containing shredded materials with an SOC of 30% or less. Specifically, the ambient temperature in Fig. 12 refers to 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 self-heating of the battery shredded materials when transporting the battery shredded materials. At this time, it can be confirmed that it is preferable that the temperature of the battery shredded materials be controlled to be 30° C. or lower during the low-temperature stabilization stage.

Figure 13 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. 13, 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 14 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. 14, 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 15 shows the temperature and weight reduction according to the tap density of battery shreds.

Referring to FIG. 15, 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
since
Weight of shredded material
Amount of reduction
[%] High temperature stabilization
Processing steps
condition High temperature
stabilization
treatment
step
since
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.

<Evaluation Example>: Data according to the spacing between hot air inlets and sealing parts in Sagger

Table 8 below shows the time it takes to reach the target temperature when the spacing between the hot air inlets in the saga is different and when the spacing between the sealed part and the mesh part is different.

Figure 16 shows a graph of the heating rate according to the spacing of hot air inlets.

Referring to Fig. 16, when the spacing of the hot air inlets satisfies 35 to 45.0% of the horizontal length of the saga, it can be confirmed that the target temperature is quickly reached at a heating rate of 2.0°C/min or higher. Through this, it can be confirmed that the process efficiency is excellent when the spacing of the hot air inlets described above is maintained.

Figure 16 shows a graph of temperature versus time according to control of the gap between the hot air inlet and the gap between the sealing parts.

Case Saga's
Horizontal (long axis)
length
[mm] Hot air inlet
gap between
[mm] Saga's
Vertical (height)
length
[] Sealed part
height
[mm] Time to reach 120℃ Seconds (sec) Minutes (min) Case 01 710 300 500 40 3,552 59.2 Case 02 710 300 500 170 3,326 55.43 Case 03 710 300 500 323.5 1,997 33.17 Case 04 710 200 500 40 3,736 62.27 Case 05 710 340 500 40 3,634 60.57

Referring to Table 8 and FIG. 16 above, it can be seen that the reaching time was reduced by about 6% in Case 02 and about 44% in Case 03 compared to Case 01, so that the time taken to reach the target temperature range of the saga can be minimized by satisfying the appropriate height range of the sealing portion. In addition, looking at Case 04 and Case 05, it can be seen that the time taken to reach the target temperature range of the saga increased by about 5% and 2%, respectively, compared to Case 01. Accordingly, the spacing between the hot air inlets also satisfies the appropriate range, so that the time taken to reach the target temperature range of the saga can be minimized.

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 (19)

An inlet for feeding Sagger containing used battery shreds; A transport unit transporting the above-mentioned saga into which the above-mentioned waste battery shreds are put; A first stabilizing unit for stabilizing the waste battery shreds at a temperature of 30°C or less; A second stabilizing unit for stabilizing the waste battery fragments that have passed through the first stabilizing unit at a temperature of 30 to 150°C; and Including a discharge unit for discharging the stabilized waste battery fragments, The above-mentioned battery stabilization device includes a hot air inlet for supplying heat to the waste battery shredder. In the first paragraph, The above first stabilizing unit is a battery stabilizing device including a compressor. In the first paragraph, A battery stabilization device comprising at least one weight and temperature measuring unit for measuring the weight of the waste battery shreds. In the third paragraph, The above weight and temperature measuring unit, A first weight and temperature measuring unit disposed between the above-mentioned inlet and the first stabilizing unit; A second weight and temperature measuring unit disposed between the first stabilizing unit and the second stabilizing unit; and A battery stabilization device including a third weight and temperature measuring unit disposed between the second stabilizing unit and the discharge unit. In the fourth paragraph, The above second stable portion includes an intermediate stable portion and a high temperature stable portion, The above intermediate stabilizing unit heats the waste battery shreds to a temperature range of 30 to 120°C, The above high temperature stabilizing unit is a battery stabilizing device that heats the waste battery shreds to a range of 120 to 150°C. In the first paragraph, The above hot air inlet is a battery stabilizing device positioned in at least a part of the above Sagger. In the first paragraph, The above hot air inlet is arranged in the shape of a cylinder, a triangular column, a square column, or a polygonal column, A battery stabilizing device that dissipates heat through the outer surface of the above shape. In Article 6, Containing a plurality of said hot air inlets, A battery stabilizing device wherein the spacing between the plurality of hot air inlets is 35 to 45% of the horizontal length of the saga. In the first paragraph, A battery stabilizing device wherein the height of the hot air inlet is 25% to 50% of the height of the saga. In the first paragraph, A battery stabilizing device wherein the height of the hot air inlet is 25% to 50% of the height of the saga. In the first paragraph, The above-mentioned battery stabilizing device has a structure with an open upper surface. In the first paragraph, The above saga comprises a housing surrounding the side of the above saga, A battery stabilizing device comprising a mesh portion and a sealing portion arranged below the mesh portion. Step 1: Controlling the tap density of waste battery shredder; A second step of measuring a first weight, which is an initial weight of the above-mentioned waste battery shreds, and a first temperature, which is an initial temperature; A third step of stabilizing the above-mentioned waste battery shreds at a temperature of 30°C or lower; A fourth step of measuring the second weight and second temperature of the waste battery shreds that have gone through the third step; A fifth step of stabilizing the waste battery shreds that have gone through the fourth step at a temperature of 30 to 150°C; A sixth step of measuring the third weight and third temperature of the waste battery shreds that have gone through the fifth step; and A battery stabilization treatment system including a seventh step of discharging the waste battery shreds that have passed through the sixth step. In Article 13, The above first step is a battery stabilization treatment system that controls the tap density of the waste battery shreds to 200 to 1,400 kg/m ³ . In Article 13, A battery stabilization treatment system that performs step 5 when the first weight and the first temperature of the waste battery shreds measured in the second step and the second weight and the second temperature of the waste battery shreds measured in the fourth step satisfy the following equations 1 and 2. <Formula 1> 2nd weight - 1st weight ≤ 25% <Formula 2> Second temperature - First temperature ≤ 25 ℃ In Article 13, A battery stabilization treatment system that performs step 7 when the second weight and the second temperature of the waste battery shreds measured in step 4 and the third weight and the third temperature of the waste battery shreds measured in step 6 satisfy the following equations 3 and 4. <Formula 3> 3rd weight - 2nd weight ≤ 10% <Formula 4> 3rd temperature - 2nd temperature ≤ 25 ℃ In Article 13, The above fifth step is performed by multi-stage heat treatment, A battery stabilization treatment system in which the above multi-stage heat treatment is sequentially performed at temperatures of 30 to 120°C and 120 to 150°C. In Article 13, Before the first step of controlling the tap density of the above-mentioned waste battery shredder, A battery stabilization processing system comprising a step of controlling the unit waste battery shredder constituting the above waste battery shredder to satisfy the following conditions 1 and 2. <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 waste battery shreds based on the long axis, which is the longest axis among the horizontal, vertical, and height directions, is 100 mm or less. In Article 13, Prior to the first step, a step of freezing the waste battery shreds is further included, A battery processing system in which the above freezing step is performed by cooling to -150°C to -20°C.

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