Battery stabilizing device and battery stabilizing system

Abstract

The present invention relates to a battery stabilizing device and a battery stabilizing processing system, including an input section that inputs a sagger into which a waste battery crushed material is put, a conveying section that conveys the sagger into which the waste battery crushed material is put, a first stabilizing section that performs stabilization on the waste battery crushed material at a temperature of 30°C or lower, a second stabilizing section that performs stabilization on the waste battery crushed material that has passed through the first stabilizing section at a temperature of 30 to 150°C, and a discharge section that discharges the waste battery crushed material that has been stabilized, the sagger including a hot air input port that supplies hot air to the waste battery crushed material.

Description

Technical Field

[0001] This invention relates to waste batteries, and specifically to a battery stabilization device and system. Background Technology

[0002] With the increasing global demand for electric vehicles, the disposal of waste batteries generated by these vehicles is becoming a prominent social issue. Lithium-ion batteries, the main raw material for these waste batteries, contain organic solvents, explosive substances, and heavy metals such as Ni, Co, Mn, and Fe. However, Ni, Co, Mn, and Li are valuable metals and therefore have significant scarcity value. Consequently, the recycling and reuse processes for discarded lithium-ion batteries are emerging as an important research area.

[0003] Specifically, a lithium secondary battery is mainly composed of copper and aluminum as current collectors, oxides containing Li, Ni, Co, and Mn constituting the positive electrode material, and graphite as the negative electrode material. It also includes a separator separating the positive and negative electrode materials and an electrolyte injected into the separator. The solvents and salts used as the electrolyte are mainly mixed carbonate organic compounds such as ethylene carbonate and propylene carbonate, with LiPF6 being a representative salt.

[0004] In order to utilize the waste batteries, the development of waste battery recycling processes that recover valuable metals through post-processing is actively underway, after the waste batteries are crushed to generate intermediate materials such as waste battery fragments or black powder.

[0005] However, in the aforementioned waste battery recycling process, although the waste batteries vary depending on the number of times they have been used or their condition, they typically have a voltage in the range of 3.0 to 3.2V when the cell is fully discharged and a voltage close to 4V when fully charged. Therefore, modules or battery packs with dozens to hundreds of cells have considerable energy due to this residual voltage. As a result, safety issues related to battery explosion or electric shock arise when external impacts are applied to the waste batteries for physical decomposition.

[0006] To prevent this, after the decomposition, holes are created in the battery and it is discharged in salt water. The discharged battery then undergoes a crushing step, followed by high-temperature heat treatment to remove water and electrolyte.

[0007] At this time, the salt used for the brine discharge contains a large amount of substances such as Na, K, Cl, Mg, and Ca. In the case of Cl, in particular, a predetermined portion is removed during the high-temperature heat treatment. However, the black powder, which is in powder form, contains impurities such as Na, K, and Mg. The black powder is a mixture of Ni-Co-Mn-Li-O oxides and C, which are formed from the crushed waste batteries or from the crushed waste batteries after further processing to remove Al, Cu, and a portion of the separator. Therefore, there is a problem that the actual yield decreases during the acid leaching extraction process in the later stages of the battery recycling process.

[0008] In addition, in order to stably transfer the waste batteries to subsequent processing steps after crushing, it is necessary to study a stabilization system for stably removing the electrolyte contained in the crushed material. Summary of the Invention

[0009] (a) Technical problems to be solved According to one embodiment of the present invention, a battery stabilization device is provided that steadily removes electrolyte from waste battery fragments, thereby reducing impurity content and preventing fire.

[0010] According to one embodiment of the present invention, a battery stabilization system is provided that steadily removes electrolyte from waste battery fragments, thereby reducing impurity content and preventing fires.

[0011] (II) Technical Solution According to one embodiment of the present invention, a battery stabilization device may include an input section for inputting a sagger containing waste battery fragments, a conveying section for conveying the sagger containing the waste battery fragments, a first stabilization section for stabilizing the waste battery fragments at a temperature below 30°C, a second stabilization section for stabilizing the waste battery fragments after passing through the first stabilization section at a temperature between 30°C and 150°C, and a discharge section for discharging the stabilized waste battery fragments. The sagger may include a hot air inlet for supplying heat to the waste battery fragments.

[0012] In one embodiment, the first stabilizing unit may include a compressor. In another embodiment, it may include one or more weight and temperature measuring units for measuring the weight of the shredded waste battery.

[0013] In one embodiment, the weight and temperature measuring unit may include a first weight and temperature measuring unit disposed between the 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 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, wherein the intermediate stabilizing unit heats the waste battery fragments to a temperature range of 30 to 120°C, and the high-temperature stabilizing unit heats the waste battery fragments to a temperature range of 120 to 150°C.

[0014] In one embodiment, the hot air inlet is configured as a cylindrical, triangular, square, or polygonal prism shape, allowing heat to be dissipated through the outer periphery of the shape. In another embodiment, multiple hot air inlets are included, with the spacing between the multiple hot air inlets being 35 to 45% based on the horizontal length of the sagger.

[0015] In one embodiment, the height of the hot air inlet can be 25% to 50% of the height of the sagger.

[0016] In one embodiment, the sagger may have an open upper surface. In another embodiment, the sagger includes a shell surrounding the sides of the sagger and may include a mesh portion and a sealed portion disposed below the mesh portion.

[0017] According to another embodiment of the present invention, the battery stabilization treatment system may include a first step of controlling the tap density of waste battery fragments, a second step of measuring a first weight as the initial weight of the waste battery fragments and a first temperature as the initial temperature, a third step of stabilizing the waste battery fragments at a temperature below 30°C, a fourth step of measuring a second weight and a second temperature of the waste battery fragments after the third step, a fifth step of stabilizing the waste battery fragments after the fourth step at a temperature between 30°C and 150°C, a sixth step of measuring a third weight and a third temperature of the waste battery fragments after the fifth step, and a seventh step of discharging the waste battery fragments after the sixth step.

[0018] In one embodiment, the first step can control the tap density of the shredded waste battery material to be between 200 and 1400 kg / m³. 3 In one embodiment, the fifth step may be performed when the first weight and first temperature of the waste battery fragments measured in the second step and the second weight and second temperature of the waste battery fragments measured in the fourth step satisfy the following equations 1 and 2.

[0019] <Formula 1> Second weight - first weight ≤ 25% <Formula 2> Second temperature - First temperature ≤ 25℃ In one embodiment, the seventh step can be performed when the second weight and second temperature of the waste battery fragments measured in the fourth step and the third weight and third temperature of the waste battery fragments measured in the sixth step satisfy the following formulas 3 and 4.

[0020] <Formula 3> The third weight minus the second weight is ≤10%. <Formula 4> Third temperature - Second temperature ≤ 25℃ In one embodiment, the fifth step is performed by a multi-stage heat treatment, which may 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 fragments, a step may be included to control the unit waste battery fragments constituting the waste battery fragments to satisfy conditions 1 and 2 below.

[0021] <Condition 1> The layered structure is a stacked structure with more than 1 layer and less than 7 layers.

[0022] <Condition 2> Based on the longest axis in the horizontal, vertical and height directions, the size of the unit waste battery fragments is less than 100mm.

[0023] In one embodiment, prior to the first step, a step of freezing the waste battery fragments may be further included, which can be carried out by cooling to -150°C to -20°C.

[0024] (III) Beneficial Effects According to one embodiment of the present invention, the battery stabilization device includes low temperature and high temperature stabilization sections, and includes one or more weight and temperature measuring sections to confirm the weight and temperature of the waste battery fragments, thereby providing a battery stabilization device with low impurity content and preventing fire.

[0025] According to another embodiment of the present invention, the battery stabilization system includes low temperature and high temperature stabilization steps, and controls the weight and temperature of the waste battery fragments in each step, thereby providing a battery stabilization system with low impurity content and preventing fire. Attached Figure Description

[0026] Figure 1a This is a perspective view of a battery stabilization device according to an embodiment of the present invention. Figure 1bThis is a schematic diagram of a battery stabilization device according to an embodiment of the present invention.

[0027] Figure 2 A sagger according to an embodiment of the present invention is shown.

[0028] Figure 3 This is a flowchart of a battery stabilization system according to an embodiment of the present invention.

[0029] Figure 4 The diagram illustrates the change in battery voltage as a function of cooling temperature, according to an embodiment of the present invention.

[0030] Figure 5 This is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to an embodiment of the present invention.

[0031] Figure 6a and Figure 6b This is a photograph of an embodiment of the minimum cooling time according to the present invention. Figure 6c and Figure 6d This is a comparative photograph of the minimum cooling time according to the present invention.

[0032] Figure 7 This is a temperature chart of crushed material changing over time according to an embodiment of the present invention.

[0033] Figures 8a to 8c A unit battery fragment is shown as an embodiment of the invention and a comparative example.

[0034] Figures 9a to 9c These are photographs depicting the temperature measurement process of waste batteries and the temperature trend of the crushed material under different SOC conditions.

[0035] Figure 10a The temperature trend of the fragments over time is shown. Figure 10b This is a graph showing the trend of increasing temperature of the broken material as the battery SOC% condition increases.

[0036] Figure 11 This is a graph showing the temperature of the waste battery fragments over time during the low-temperature stabilization, intermediate step, and high-temperature stabilization step according to an embodiment of the present invention.

[0037] Figure 12 A graph showing the self-heating of the broken battery fragments inside the delivery box is displayed.

[0038] Figure 13 The temperature changes of the crushed material are shown when the heating temperatures of each zone of the heat treatment used for the high-temperature stabilization step are controlled.

[0039] Figure 14The percentage (%) of electrolyte weight reduction in the shredded waste battery material after high-temperature stabilization treatment at a heat treatment temperature of 150°C is shown.

[0040] Figure 15 The temperature and weight reduction are shown based on the tap density of the battery fragments.

[0041] Figure 16 A graph showing the heating rate based on the spacing of the hot air inlets is presented.

[0042] Figure 17 A graph showing the temperature change over time based on the spacing between the hot air inlets and the spacing between the sealed parts is presented. Detailed Implementation

[0043] The terms "first," "second," and "third," etc., are used to describe various parts, components, regions, layers, and / or segments, but are not limited thereto. These terms are only used to distinguish a particular part, component, region, layer, or segment from other parts, components, regions, layers, or segments. Therefore, without departing from the scope of this invention, the first part, component, region, layer, or segment described below may be referred to as the second part, component, region, layer, or segment.

[0044] The technical terms used herein are for reference only to specific embodiments and are not intended to limit the invention. The singular forms used herein include the plural forms unless the phrase expressly indicates otherwise. The word "comprising" as used in the specification means to embody a particular feature, region, integer, step, operation, element, and / or component, and does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0045] When referring to a part as "above" or "on top of" another part, it can be directly above or on top of the other part, or it can be accompanied by other parts. Conversely, when referring to a part as "directly above" another part, no other parts are involved.

[0046] Unless otherwise defined, all terms, including technical and scientific terms as used herein, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries are further interpreted as having meanings consistent with relevant technical literature and current disclosure, and should not be construed as having ideal or highly formal meanings unless otherwise defined.

[0047] The embodiments of the present invention will now be described in detail. However, these are merely examples and the present invention is not limited thereto; the invention is defined only by the scope of the claims described below.

[0048] Figure 1aThis is a perspective view of a battery stabilization device according to an embodiment of the present invention. Figure 1b This is a schematic diagram of a battery stabilization device according to an embodiment of the present invention.

[0049] Reference Figure 1a and Figure 1b According to one embodiment, the battery stabilization device is used to stabilize waste battery fragments, including an input section, a conveying section, a first stabilizing section, a second stabilizing section, a weight and temperature measuring section, and a discharge section.

[0050] The feeding section can be a component for feeding waste battery shreds. Waste battery shreds can be the product of crushing waste batteries. By feeding the sagger containing the waste battery shreds into the feeding section, the shredded waste batteries can be fed into the battery stabilization device.

[0051] The conveying section can be a component for transporting the sagger containing the waste battery fragments into the battery stabilization device. The conveying section can also be a component that guides the sagger containing the waste battery fragments through a first stabilization section and a second stabilization section before discharging it into a discharge section. The conveying section can, for example, be a structure provided in the form of a conveyor belt.

[0052] The first stabilization unit can perform the stabilization of the waste battery fragments at low temperatures. Specifically, the first stabilization unit can transport the waste battery fragments while they are contained in the crucible, and perform stabilization of the waste battery fragments by applying hot air to the crucible.

[0053] In one embodiment, the first stabilizing section may include a first heater section at its lower part. The first heater section may supply heat to the lower part of the sagger. Specifically, the first heater section may supply hot air to the sagger to apply heat to the waste battery fragments disposed within the sagger.

[0054] Specifically, the first stabilizing unit can stabilize the waste battery fragments at a temperature below 30°C. More specifically, the first stabilizing unit can be a component that heats up and stabilizes the waste battery fragments themselves. The first stabilizing unit can prevent sudden heating and potential fire when the state of charge (SoC), which represents the residual capacity of the waste battery fragments, is above 30%.

[0055] In one embodiment, the first stabilizing unit may include a high-temperature air dryer that supplies air to minimize moisture. Specifically, the first stabilizing unit may be a component that supplies dry air to remove moisture while maintaining a temperature of 5 to 20°C, specifically 5 to 15°C. Specifically, the heater unit may be a device for generating dry air.

[0056] In one embodiment, the first stabilizing unit may include a compressor. The compressor may be a screw compressor for generating dry air. In one embodiment, the compressor may generate a pressure of less than 10 bar.

[0057] In one embodiment, the first stabilizing part may further include a first vibrating part. Specifically, the first vibrating part can, when the first stabilizing part applies hot air to the battery fragments, vibrate the battery fragments to disperse them, thereby controlling the application of heat to the battery fragments uniformly.

[0058] The second stabilization section can perform the stabilization of the waste battery fragments at high temperatures. Specifically, the second stabilization section can transport the waste battery fragments while they are contained in the crucible, and perform the stabilization of the waste battery fragments by applying hot air to the crucible to evaporate the high-temperature volatile electrolyte that has not been volatilized in the first stabilization section.

[0059] In one embodiment, the second stabilizing section may include a second heater section at its lower part. The second heater section may supply heat to the lower part of the sagger. Specifically, the second heater section may supply hot air to the sagger to apply heat to the shredded waste battery disposed within the sagger.

[0060] More specifically, the second stabilizing unit may be a component that performs the stabilization of the waste battery fragments at a temperature of 30 to 150°C. The second stabilizing unit reduces the weight of the waste battery fragments by evaporating the electrolyte within the waste battery fragments through heating them within the aforementioned temperature range, and may also reduce the tap density.

[0061] In one embodiment, the second stabilizing section may include an intermediate stabilizing section and a high-temperature stabilizing section. The intermediate stabilizing section may be a step of heating the waste battery fragments at a temperature lower than that of the high-temperature stabilizing section. In one embodiment, the intermediate stabilizing section may be a component that performs stabilization of the waste battery fragments at a temperature of 30 to 120°C. Because the second stabilizing section includes the intermediate stabilizing section, the temperature of the waste battery fragments can be raised slowly, allowing the electrolyte within the waste battery fragments to evaporate stably.

[0062] In one embodiment, the high-temperature stabilization unit may be a component that performs the stabilization of the waste battery fragments at a temperature of 120 to 150°C. As the high-temperature stabilization unit is performed within the aforementioned range, high-temperature heat is applied to the waste battery fragments stabilized by the low-temperature stabilization step to volatilize the residual electrolyte.

[0063] In one embodiment, the second stabilizing unit may further include a second vibration unit. Specifically, the first vibration unit may, when the second stabilizing unit applies hot air to the battery fragments, vibrate the battery fragments to disperse them, thereby controlling the application of heat to the battery fragments uniformly.

[0064] In one embodiment, the first stabilizing part and the second stabilizing part can be configured as a horizontal or stacked structure. Specifically, the second stabilizing part can be stacked on top of the first stabilizing part, or it can be arranged on the same line following the first stabilizing part.

[0065] In one embodiment, the first and second stabilizing units can apply heat to the shredded battery material disposed within the sagger while the sagger is moving. The weight and temperature measuring unit can be a component for measuring the weight of the shredded waste battery material. Specifically, the weight and temperature measuring unit can measure the weight and temperature of the shredded waste battery material using devices such as load cells, thermal imaging cameras, etc.

[0066] 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 disposed between the 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 third weight and temperature measuring unit disposed between the second stabilizing unit and the outlet.

[0067] The first weight and temperature measuring unit can measure the initial weight and tap density of the waste battery fragments. Specifically, the first weight and temperature measuring unit can be a component that measures the initial weight and temperature of the waste battery fragments to determine whether the subsequent stabilization treatment is satisfactory.

[0068] The first weight and temperature measuring unit can be a component that determines whether the temperature of the shredded waste battery is between -20 and 10°C, and whether the weight of the shredded waste battery is at a similar level to the weight of the waste battery before shredding. For example, it can be a component that determines whether the weight of the shredded waste battery is between 31.75 and 32.25 kg.

[0069] When the temperature and weight of the shredded waste battery are within the aforementioned range, the shredded waste battery can move along the conveyor section to the first stabilizing section. When the temperature and weight of the shredded waste battery exceed the aforementioned range, especially when the temperature decrease is large due to the initial heat generated after shredding, its movement to the first stabilizing section can be prevented, taking into account the possibility of fire caused by the shredded waste battery.

[0070] The second weight and temperature measuring unit can be a component that measures the temperature and weight of the waste battery fragments after passing through the first stabilizing section. Specifically, the second weight and temperature measuring unit can be a component that determines whether the temperature of the waste battery fragments after passing through the first stabilizing section is between 10 and 35°C, and whether the weight of the waste battery fragments is between 30.65 and 31.15 kg. When the temperature and weight of the waste battery fragments are within the aforementioned range, the waste battery fragments can move along the conveying section to the second stabilizing section. When the temperature and weight of the waste battery fragments exceed the aforementioned range, considering the possibility of fire caused by the waste battery fragments, its movement to the second stabilizing section can be prevented.

[0071] The third weight and temperature measuring unit can be a component that measures the temperature and weight of the waste battery fragments after passing through the second stabilization section. Specifically, the third weight and temperature measuring unit can be a component that determines whether the temperature of the waste battery fragments after passing through the second stabilization section is below 100°C and whether the weight of the waste battery fragments is below 29.85 kg. When the temperature and weight of the waste battery fragments are within the aforementioned range, the waste battery fragments can be discharged through the discharge section. When the temperature and weight of the waste battery fragments exceed the aforementioned range, considering the possibility of fire caused by the waste battery fragments, their discharge into the discharge section can be prevented.

[0072] The discharge section can be a component that discharges the waste battery fragments, after passing through the second stabilization section, to subsequent processes. Specifically, the discharge section can be a component that discharges the stabilized waste battery fragments to subsequent processes. More specifically, the discharge section can discharge the battery fragments to subsequent processes and can also return the fragment receiving section containing the discharged battery fragments to the crusher.

[0073] Figure 2 A sagger according to an embodiment of the present invention is shown.

[0074] Figure 2 A perspective view of a sagger according to an embodiment of the present invention is shown. In one embodiment, the sagger may include at least one hot air inlet for supplying heat to the waste battery fragments from a heater section disposed below a first stabilizing section and a second stabilizing section, and a housing protecting the sagger. Specifically, by including at least one hot air inlet within the sagger, heat is introduced into the sagger when heat is supplied from the heaters disposed in the first and second stabilizing sections, thereby supplying heat to the waste battery fragments. The waste battery fragments can be stabilized by the heat supplied via the hot air inlet.

[0075] In one embodiment, the hot air inlet may be located in at least a portion of the sagger. Specifically, the hot air inlet can easily supply hot air into the sagger. In one embodiment, the heater section may be located on the side of the sagger to supply heat starting from the edge region of the shredded waste battery.

[0076] In one embodiment, the hot air inlet can be configured as a cylindrical, triangular, square, or polygonal prism shape. The hot air inlet can dissipate heat through the outer peripheral surface of the aforementioned shape. The hot air inlet can have the aforementioned shape and a mesh structure. The mesh structure is of a mesh-like form, which can facilitate the dissipation of heat introduced from the hot air inlet.

[0077] By supplying heat to the waste battery fragments through the hot air inlet, the electrolyte within the fragments evaporates, thereby stabilizing the waste battery fragments. Thus, by supplying hot air to the waste battery fragments, a dry method can be used to stabilize them.

[0078] In one embodiment, the hot air inlet may include multiple inlets. Multiple hot air inlets can be provided within the crucible to uniformly supply heat to the entire area within the crucible containing the shredded waste batteries.

[0079] In one embodiment, the spacing (L2) between the hot air inlets can be 35% to 45% of the horizontal length (L1) of the sagger. Specifically, the spacing between the central regions of the hot air inlets can be 35% to 45% when the cross-section is cut with reference to the X-axis and Y-axis planes of the horizontal plane of the sagger, with 100% of the length of the major axis as the reference.

[0080] By ensuring the spacing of the multiple hot air inlets meets the aforementioned range, the sagger has the advantage of a high heating rate, thus enabling a uniform supply of heat to the broken battery material. However, if the spacing of the multiple hot air inlets exceeds the aforementioned range, the heating rate within the sagger is insufficient, resulting in an inability to uniformly supply heat to the broken battery material.

[0081] In one embodiment, the height (H2) of the hot air inlet, based on the height (H1) of the sagger, can be 25% to 50%. Specifically, it can be 30% to 40%. By satisfying the aforementioned range, the height (H2) of the hot air inlet, based on the height (H1) of the sagger, has the advantage of being able to uniformly heat the broken battery material disposed within the sagger.

[0082] When the height (H2) of the hot air inlet exceeds the upper limit of the aforementioned range, there is a problem that the amount of battery fragments placed in the sagger decreases, leading to a decrease in efficiency, and there is also a problem that hot air is over-supplied to the battery fragments. When the height (H2) of the hot air inlet exceeds the lower limit of the aforementioned range, there is a problem that heat cannot be properly supplied to the battery fragments.

[0083] 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 quadrilateral, a circle, an ellipse, and a polygon. Specifically, the cross-sectional shape of the hot air inlet refers to the shape when the cross-section is cut with reference to the X-axis and Z-axis planes that serve as the vertical plane of the sagger. By having multiple shapes for the cross-sectional shape along the vertical plane of the hot air inlet, heat can be efficiently supplied to battery fragments with various shapes.

[0084] In one embodiment, the sagger may have an open shape on its upper surface. Specifically, the sagger may have an open structure with a non-sealed upper surface. This open upper surface allows heat generated by battery debris to dissipate.

[0085] In one embodiment, the casing of the sagger may include a mesh portion in at least a portion of its area. Specifically, the mesh portion has a mesh shape, thereby allowing heat generated by the battery fragments to be easily dissipated. More specifically, at least one of the four faces surrounding the side of the sagger may include a mesh portion.

[0086] In one embodiment, the casing of the sagger may include a sealed portion covering at least a portion of the casing. Specifically, the sealed portion is located at the lower part of the mesh section, thereby maintaining the efficiency of the heat introduced from the hot air inlet.

[0087] In one embodiment, based on 100% of the height of the sagger, the proportion of the sealed portion can be 30% to 80%, specifically 35% to 70%, and more specifically 60% to 70%. By satisfying the aforementioned range for the proportion of the sealed portion, the time to reach the target temperature of the first or second stable section can be minimized. When the proportion of the sealed portion exceeds the upper limit of the aforementioned range, the heat emitted by the battery fragments is not easily dissipated to the outside, thereby generating a load inside the device. When the proportion of the sealed portion exceeds the lower limit of the aforementioned range, there is a problem of increased time to reach the target temperature, leading to a decrease in process efficiency.

[0088] Reference Figure 3According to one embodiment, a battery stabilization system includes a first step of controlling the tap density of waste battery fragments, a second step of measuring a first weight as the initial weight of the waste battery fragments and a first temperature as the initial temperature, a third step of stabilizing the waste battery fragments at a temperature below 30°C, a fourth step of measuring a second weight and a second temperature of the waste battery fragments after the third step, a fifth step of stabilizing the waste battery fragments after the fourth step at a temperature between 30 and 120°C, a sixth step of measuring a third weight and a third temperature of the waste battery fragments after the fifth step, and a seventh step of discharging the waste battery fragments after the sixth step.

[0089] The first step in controlling the tap density of the waste battery shreds can be to control the tap density of the waste battery shreds to 200 to 1400 kg / m³. 3 The steps include, specifically, controlling the compaction density of the shredded waste battery material to be 500 to 1000 kg / m³. 3 The steps.

[0090] Tap density typically refers to the apparent density obtained by mechanically tapping a measuring container holding a powder sample. Specifically, to determine the tap density characteristics of the crushed lithium-ion battery waste, a commercially available battery module consisting of approximately 30 cells (30 kg each) was crushed using a crusher. The module was then placed in a casing (volume: 0.4 m x 0.7 m x 0.44 m) designed for stabilizing the crushed material, and its apparent density was measured by mechanically tapping it. More specifically, the battery weight (M, kg) was divided by the casing volume (V, m³). 3 The density (ρ=M / V) was then calculated. The tap density of the unit waste battery shredded material calculated using the aforementioned method was 200 to 600 kg / m³. 3 Specifically, the tap density can be between 240 and 400 kg / m³. 3 .

[0091] When the tap density exceeds the upper limit, the breakage of the densely stacked fragments generates heat instantaneously, posing a fire hazard. Furthermore, the space for electrolyte to drain externally narrows, reducing the amount of material that can be processed for stabilization. When the tap density exceeds the lower limit, numerous gaps are created between the fragments, occupying a large volume, necessitating additional pressurization for transfer to subsequent processes.

[0092] In one embodiment, prior to the first step of controlling the tap density of the waste battery shreds, a step may be included to control the unit waste battery shreds constituting the waste battery shreds to satisfy conditions 1 and 2 below.

[0093] <Condition 1> The layered structure is a stacked structure with more than 1 layer and less than 7 layers.

[0094] <Condition 2> Based on the longest axis in the horizontal, vertical and height directions, the size of the unit waste battery fragments is less than 100mm.

[0095] Unit waste battery shreds are used to recover valuable metals from waste batteries. They are layered structures comprising a separator with a positive or negative electrode stacked on at least one side. Specifically, the layered structure may include a configuration with a positive or negative electrode on one or both surfaces of the separator, based on the separator. More specifically, the number of layers in the layered structure may correspond to the number of separators.

[0096] The layered structure includes, for example, any one of the following: positive electrode-separator-negative electrode, positive electrode-separator, separator-positive electrode, separator-negative electrode, and negative electrode-separator. For instance, the positive electrode-separator-negative electrode-separator-positive electrode-separator-negative electrode structure can have three layers. Specifically, as the unit waste battery fragments are stacked with at least one layer, a predetermined thickness can be achieved in the thickness direction.

[0097] Condition 1 may mean that the process of breaking the layered structure of the unit waste battery fragment, which includes a separator having a positive or negative electrode stacked on at least one side, into a layered structure of more than one layer and less than seven layers is controlled.

[0098] In one embodiment, the layered structure can be a stacked structure of 1 to 7 layers. Specifically, the layered structure can be a stacked structure of 1 to 5 layers. As the layered structure is stacked within the aforementioned range, the temperature rise of the crushed material can be minimized, and the heating time can be appropriately consumed. When the layered structure is stacked thicker than the upper limit of the aforementioned range, the temperature rise increases excessively, and the heating time also increases, thus posing a combustion problem.

[0099] In one embodiment, the size of the unit waste battery fragments can be controlled to be below 100mm, specifically below 50mm, based on the longest axis in the horizontal, vertical, and height directions. When the maximum size of the waste battery fragments exceeds 100mm, as the waste battery fragments are broken, the temperature rises due to instability to the 120°C temperature range, which is the average vaporization temperature of the electrolyte, potentially causing stability problems such as fires.

[0100] In one embodiment, to satisfy conditions 1 and 2, the step of crushing the waste battery may be included. Specifically, it may further include controlling the proportion of crushed waste battery units satisfying conditions 1 and 2 to be more than 90%, specifically more than 95%, within the total volume of the crushed waste battery units. Specifically, this may correspond to controlling the proportion of crushed waste battery units having a stacked structure of more than 7 layers to be less than 10% within the total volume of the crushed waste battery units. Specifically, the proportion of crushed waste battery units having a stacked structure of more than 7 layers may be controlled to be less than 5% within the total volume of the crushed waste battery units. By satisfying the aforementioned ranges, it has the advantage of preventing fires.

[0101] The step of crushing the waste battery can mean a process of applying impact or pressure to the battery to detach a portion of the battery from it. In one embodiment, the step of crushing the waste battery can mean a process of shredding the battery, a process of cutting the battery, a process of compressing the battery, and all combinations thereof. Specifically, the crushing step can include all processes capable of destroying the battery to obtain small fragments.

[0102] In one embodiment, the step of crushing the battery may include compressing a frozen battery, or destroying the battery entirely by applying an external force such as shearing or tensile force. The step of crushing the battery may, for example, be carried out using a crusher.

[0103] In one embodiment, the step of breaking the battery may be performed at least once. Specifically, the breaking step may be performed continuously or discontinuously at least once.

[0104] In one embodiment, the battery crushing step can be carried out under conditions of supplying an inert gas, carbon dioxide, nitrogen, water, or a combination thereof, or under vacuum conditions below 100 torr. For example, when carrying out a process for freezing a battery by cooling in a temperature range of -60 to -20°C, if carried out under the aforementioned conditions, the oxygen supply is suppressed, thereby preventing the electrolyte from reacting with oxygen and preventing any resulting explosion. The vaporization of the electrolyte can be suppressed, thus preventing the generation of flammable gases such as ethylene, propylene, or hydrogen.

[0105] In one embodiment, the recovery time required to cool the shredded waste battery material to a temperature range of 20 to 50°C during the crushing step can be less than 200 minutes. Specifically, the recovery time required to cool the shredded waste battery material to a temperature range of 35 to 45°C can be less than 200 minutes.

[0106] The second step, measuring a first weight as the initial weight of the shredded waste battery material and a first temperature as the initial temperature, can be a step of measuring the initial weight and initial temperature of the shredded waste battery material. In the second step, the initial weight of the shredded waste battery material can be controlled to be between 30.65 and 31.15 kg. In the second step, the initial temperature of the shredded waste battery material can be controlled to be between 10 and 35°C.

[0107] In one embodiment, the surface of the unit waste battery fragment may include a burned portion and a normal portion. The burned portion refers to at least a portion of the surface of the unit waste battery fragment that is burned, and the normal portion refers to a normal portion on the surface without any traces of burning.

[0108] In one embodiment, the area ratio of the burning portion to the normal portion on the surface of the unit waste battery fragment can be 30% or less. By ensuring that the area ratio of the burning portion to the normal portion is 30% or less, the possibility of a fire caused by combustion of the unit waste battery fragment can be prevented. When the area ratio of the normal portion to the burning portion exceeds 30%, the unit waste battery fragment will burn, thus posing a fire hazard accompanied by smoke.

[0109] In one embodiment, the burning section may be located at the edge of the surface of the unit of shredded waste battery. The normal section may be located near the center of the surface of the unit of shredded waste battery. The burning section refers to an area that exhibits a darker color compared to the normal section.

[0110] The waste battery fragments may include one or more of the aforementioned unit waste battery fragments. In one embodiment, the content of one or more of the aforementioned unit waste battery fragments may be more than 90% of the total volume of the waste battery fragments. Specifically, the content of the unit waste battery fragments may be more than 95% of the total volume of the waste battery fragments.

[0111] Specifically, the proportion of the waste battery fragments corresponding to a unit waste battery fragment with a stacked structure of more than 7 layers is less than 10% of the total volume of the waste battery fragments, specifically less than 5%, or the proportion of one or more unit waste battery fragments with a size of more than 100mm based on the long axis is less than 10% of the total volume of the waste battery fragments, specifically less than 5%.

[0112] In this way, fires can be prevented if the proportion of waste battery fragments with a layered structure of more than 7 layers per unit volume within the total volume of waste battery fragments, or the proportion of waste battery fragments with a size of more than 100mm based on the long axis, meets the aforementioned range.

[0113] In one embodiment, the waste battery shredded material is obtained from the recycling of waste batteries and includes impurities, which, by weight percent, may include Na, Ca, Mg, and K. The waste battery shredded material may be shredded residue or black powder produced by a pretreatment process of recycling and shredding the waste batteries.

[0114] The waste battery fragments may include impurities such as Na, Ca, Mg, and K. By reducing the content of these impurities, Li, a valuable metal in the same group, can be easily extracted from the waste battery fragments in subsequent processes.

[0115] According to one embodiment of the present invention, the waste battery shreds include impurities, which, by weight percent, may include Na: less than 0.4% (excluding 0%), Ca: less than 0.03% (excluding 0%), Mg: less than 0.02%, and K: less than 0.02%.

[0116] The reasons for limiting the content of the aforementioned impurities will be explained below.

[0117] Na: less than 0.4% by weight (except 0%) Sodium (Na), as a group element, is involved in the post-processing of recovering valuable metals from the waste battery shreds. In the process of forming lithium hydroxide, sodium partially reacts to replace lithium, thereby reducing lithium recovery or increasing costs in the causticizing process. The waste battery shreds may include less than 0.4% by weight of sodium, specifically less than 0.1% by weight.

[0118] When the sodium content exceeds the aforementioned range, there is a problem that as Na increases, the actual yield of Na, as a Group 1 element like Li, decreases during the crystallization process of Li dissolved in the solvent after the leaching and solvent extraction processes, in the process required to generate lithium carbonate.

[0119] Ca: less than 0.03% by weight (except 0%) Like sodium, calcium (Ca) is an element that reduces the recovery rate of valuable metals in the subsequent processes of recovering valuable metals from the waste battery shreds. In the formation of lithium aluminate, calcium is more reactive than aluminum, forming a calcinate structure, which hinders the formation of the favorable lithium aluminate in subsequent reactions, thereby reducing the final lithium recovery rate. The waste battery shreds may include less than 0.03% of the calcium, specifically less than 0.02% by weight.

[0120] When the calcium content exceeds the aforementioned range, there is a problem that the actual yield and process time increase during the solid-liquid separation process, which is a refining process for impurities after leaching, as the Ca content increases. Furthermore, when the calcium content is excessive, it is synthesized as Li[NiCoMn] during the synthesis of nickel, cobalt, manganese hydroxides and lithium hydroxides as precursors to form the cathode material. 1-x Ca x The potassium (note: the original text is incorrect, it should be calcium) forms the oxide structure of the positive electrode material, which hinders the movement of lithium ions, thus causing a reduction in battery capacity.

[0121] Mg: less than 0.02% by weight Magnesium (Mg) is an element that makes the separation of the solid and liquid phases difficult during acid leaching in valuable metal recycling processes. The waste battery shredded material may include less than 0.02% by weight of the magnesium, specifically, less than 0.01% by weight.

[0122] When the magnesium content exceeds the aforementioned range, there is a problem of imposing a load on the recovery processes for nickel, cobalt, and lithium. Furthermore, when the magnesium content is too high, it can lead to the synthesis of Li[NiCoMn] when combined with nickel, cobalt, manganese hydroxides, and lithium hydroxides (as precursors) to form the cathode material. 1-x Mg x O2 forms an oxide structure in the positive electrode material, which hinders the movement of lithium ions, thus reducing the battery capacity.

[0123] K: less than 0.02% by weight Potassium (K) is also an element in the same group as lithium and plays a role in hindering the formation of lithium hydroxide compounds. The waste battery shreds may include less than 0.02% by weight of potassium, specifically less than 0.01% by weight. When the potassium content exceeds the aforementioned range, it can cause a load in the causticizing process, thereby reducing the lithium recovery rate.

[0124] In one embodiment, prior to the first step, the waste battery may include a freezing step. Specifically, the freezing step of the waste battery may satisfy the following formula 1.

[0125] <Formula 1> Minimum cooldown time (Hr) = A × (W) 0.33 ) (A=4×e) (-0.02×dT) W = battery weight (Kg), dT = |external cooling temperature - target temperature|, where || represents the absolute value. In Formula 1, W represents the weight of the battery, for example, the weight for a battery pack, a single battery, or a combination thereof. The minimum cooling time is at an external cooling temperature, which is the cooling temperature applied to the battery, for example, representing a target temperature for cooling the electrolyte inside the battery.

[0126] By performing the aforementioned minimum cooling time or longer, the step of freezing the waste batteries until the electrolyte inside the batteries is cooled has the advantage of enabling stable execution of subsequent processes. However, if the freezing time of the batteries is less than the minimum cooling time, there is a risk that the electrolyte may not cool properly, potentially leading to a fire hazard upon breakage.

[0127] The step of freezing the waste battery is carried out at a temperature sufficient to freeze the electrolyte contained within the battery. Specifically, the freezing step can be performed, for example, in a temperature range of -150 to -20°C. More specifically, the temperature range can be -150 to -50°C, and even more specifically, in a temperature range of -80 to -60°C.

[0128] When the waste batteries are frozen within the aforementioned temperature range, the residual voltage inside the battery, for example, approximately 2V to 3V, drops to near 0V. Therefore, even if a short circuit occurs where the positive and negative electrodes are in direct contact, the battery temperature will not increase because no battery reaction occurs, thus preventing the generation and combustion of electrolyte gas. Furthermore, since the electrolyte is in a frozen state or its vaporization is suppressed, the mobility of lithium ions is very low. The electrical characteristics associated with lithium ion movement are significantly reduced, and electrolyte vaporization does not occur, thereby preventing the generation of flammable gases such as ethylene, propylene, and hydrogen.

[0129] When the freezing process exceeds the aforementioned temperature range, for example, when cooling to a temperature above -60°C, the voltage remaining inside the battery does not drop to 0V, potentially leading to a short circuit and battery reaction, and the electrolyte is not fully frozen, which is therefore unsuitable. Furthermore, if cooling to -150°C, the electrolyte is sufficiently frozen, and the internal battery voltage also drops to 0V, so there is no need to lower the temperature further. Thus, the battery handling method, by including a freezing step before crushing batteries such as lithium-ion batteries, has the advantage of preventing fire hazards that may occur during the battery crushing process.

[0130] When the initial temperature and initial weight of the waste battery fragments are within the aforementioned range, the waste battery fragments can move along the conveyor section to the first stabilizing section. When the temperature and weight of the waste battery fragments exceed the aforementioned range, considering the possibility of fire caused by the waste battery fragments, their movement towards the first stabilizing section can be prevented.

[0131] The low-temperature stabilization step can be a step of stabilizing the crushed waste battery fragments at a temperature below 30°C. The third step of stabilizing the waste battery fragments at a temperature below 30°C can involve slowly transferring the waste battery fragments at a low temperature, transporting them while removing the electrolyte.

[0132] Specifically, the low-temperature stabilization step can be a step where the fragmented waste battery material heats up and stabilizes itself. More specifically, the heat generated by the fragmented material varies depending on the state of charge (SoC), which represents the remaining capacity of the battery.

[0133] More specifically, when the SoC is above 30%, sudden overheating may occur, potentially leading to a fire. Therefore, the low-temperature stabilization step can be a pre-emptive step to stabilize the battery at a temperature below 10°C in order to minimize the aforementioned fire hazard.

[0134] In one embodiment, the third step, as a cryogenic stabilization step, can be performed for 6 to 24 hours. When the cryogenic stabilization step exceeds the upper limit of the aforementioned time range, the fire hazard is minimized, but the manufacturing cycle becomes longer, resulting in reduced productivity. When the cryogenic stabilization step exceeds the lower limit of the aforementioned time range, the electrolyte may not be removed sufficiently and safely, potentially leading to a fire in subsequent processes.

[0135] The fourth step, which measures the second weight and second temperature of the waste battery fragments after the third step, is to measure the weight and temperature of the waste battery fragments after the low-temperature stabilization step. The third step may be a step to determine whether the waste battery fragments after low-temperature stabilization are suitable for high-temperature stabilization.

[0136] In one embodiment, a fifth step, which is a high-temperature stabilization step, can be performed when the first weight and first temperature of the waste battery fragments measured in the second step and the second weight and second temperature of the waste battery fragments measured in the fourth step satisfy the following formulas 1 and 2.

[0137] <Formula 1> Second weight - first weight ≤ 25% <Formula 2> Second temperature - First temperature ≤ 25℃ Equations 1 and 2 represent the weight reduction (%) of the waste battery fragments after low-temperature stabilization compared to the initial waste battery fragments, and the temperature difference. Specifically, Equation 1 represents the weight reduction after low-temperature stabilization treatment, and Equation 2 represents the temperature difference between the low-temperature stabilization process and the initial process.

[0138] When Equations 1 and 2 are satisfied, the waste battery fragments will not catch fire even after undergoing a high-temperature stabilization step, and the electrolyte will evaporate smoothly. When Equations 1 and 2 are not satisfied, the waste battery fragments after the low-temperature stabilization step cannot undergo the high-temperature stabilization step as a subsequent process, and can continue as the fourth step of the low-temperature stabilization step until the conditions of Equations 1 and 2 are met.

[0139] The fifth step, which stabilizes the waste battery fragments after the fourth step at a temperature of 30 to 150°C, can be a high-temperature stabilization step of the waste battery fragments at a higher temperature than the low-temperature stabilization step. Specifically, the high-temperature stabilization step can be a step of applying high-temperature heat to the waste battery fragments stabilized in the low-temperature stabilization step to volatilize the electrolyte within the waste battery fragments.

[0140] In one embodiment, the fifth step can be performed through a multi-stage heat treatment. Specifically, the fifth step can perform an intermediate stabilization step and a high-temperature stabilization step. The multi-stage heat treatment can be performed sequentially at temperatures of 30 to 120°C and 120 to 150°C.

[0141] In one embodiment, the intermediate stabilization step can be performed at a temperature higher than that of the low-temperature stabilization step but lower than that of the high-temperature stabilization step. In one embodiment, the intermediate stabilization step can be performed at 30 to 120°C. In one embodiment, the intermediate stabilization step can be performed through multiple heat treatments. The intermediate stabilization step can be performed sequentially at 30 to 60°C, 60 to 90°C, and 90 to 120°C.

[0142] In this way, by performing an intermediate stabilization step before the high-temperature stabilization step, the temperature of the waste battery fragments is slowly increased, thereby enabling the electrolyte in the waste battery fragments to evaporate stably.

[0143] In one embodiment, the high-temperature stabilization step can be performed at 120 to 150°C. Specifically, the high-temperature stabilization step can be a step of applying high-temperature heat to the waste battery fragments stabilized by the low-temperature stabilization step to volatilize the electrolyte within the waste battery fragments.

[0144] When the high-temperature stabilization step exceeds the upper limit of the aforementioned temperature range, there is a risk of fire. When the high-temperature stabilization step exceeds the lower limit of the aforementioned temperature range, there is a risk that the electrolyte in the waste battery fragments may not evaporate sufficiently.

[0145] In one embodiment, the high-temperature stabilization step can be performed for 5 to 12 hours. When the high-temperature stabilization step exceeds the upper limit of the aforementioned time range, productivity issues arise due to increased manufacturing lead time. When the high-temperature stabilization step exceeds the lower limit of the aforementioned time range, the electrolyte cannot be sufficiently removed, potentially leading to a fire in subsequent processes.

[0146] The sixth step, which measures the third weight and third temperature of the waste battery fragments after the fifth step, is to measure the weight and temperature of the waste battery fragments after the high-temperature stabilization step. Specifically, the sixth step may be a step to determine whether the waste battery fragments after the high-temperature stabilization step are suitable for subsequent processes.

[0147] In one embodiment, the seventh step can be performed when the second weight and second temperature of the waste battery fragments measured in the fourth step and the third weight and third temperature of the waste battery fragments measured in the sixth step satisfy the following equations 3 and 4.

[0148] <Formula 3> The third weight minus the second weight is ≤10%. <Formula 4> Third temperature - Second temperature ≤ 25℃ Equations 3 and 4 represent the weight reduction (%) and temperature difference between the waste battery fragments after high-temperature stabilization and the waste battery fragments before the high-temperature stabilization step. When Equations 3 and 4 are satisfied, the waste battery fragments, in a state of electrolyte evaporation, will not ignite even when subsequent processes such as high-temperature reduction are performed, and possess the advantage of stability that allows for the execution of subsequent processes. When Equations 3 and 4 are not satisfied, a fire may occur due to the electrolyte within the waste battery fragments during subsequent processes, making it difficult to execute the processes. When Equations 3 and 4 are not satisfied, the waste battery fragments can continue to undergo the sixth step, which is a high-temperature stabilization step, until Equations 3 and 4 are satisfied.

[0149] The seventh step, which discharges the waste battery fragments after the sixth step, can be performed on the waste battery fragments that meet the aforementioned conditions. The waste battery fragments, after undergoing low-temperature and high-temperature stabilization steps, can be discharged for use in subsequent processes such as reduction processes.

[0150] Implementation of the invention The following describes preferred embodiments and comparative examples of the present invention. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the following embodiments.

[0151] <Experimental Example> <Based on battery internal temperature at minimum freezing time> Figure 4 This is a graph showing the change in battery voltage according to cooling temperature according to an embodiment of the present invention.

[0152] Reference Figure 4 If the battery voltage is measured while the battery is frozen to -80°C, it can be confirmed that the battery pack exhibits almost the same voltage at high temperatures of approximately 40°C, room temperature, and up to -60°C, thus preserving its battery characteristics. Then, when the temperature drops from -60°C to -70°C, the voltage drops sharply, confirming that the voltage becomes 0V below -70°C. This confirms that no short circuit occurs when the battery is frozen to temperatures between -60°C and -150°C.

[0153] Figure 5 This is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to an embodiment of the present invention.

[0154] Reference Figure 5 It can be confirmed that, according to a battery processing method of an embodiment of the present invention, in the step of freezing the battery, a minimum cooling time for cooling the battery can be derived. 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, this shows the external cooling temperature and minimum cooling time when the target temperature is set to -70°C and the battery weights are set to 2.5 kg (A), 10 kg (B), 20 kg (C), and 50 kg (D), respectively. When cooling the battery, it can be confirmed that the electrolyte of the battery begins to cool after a predetermined time, resulting in a voltage of 0V. Thus, it can be confirmed that when cooling the battery, a minimum maintenance time is required to fully cool to the interior, specifically for the electrolyte.

[0155] Specifically, in the case of heat transfer for cooling that dissipates heat to the outside, the required battery weight and cooling time can be determined by considering the battery's specific heat. Thus, in this invention, the minimum cooling time required to cool the battery can be determined using the external cooling temperature for freezing, the target temperature, and the battery weight.

[0156] Table 1 below lists the minimum cooling time based on battery weight and external cooling temperature.

[0157] Table 1 Observing Table 1 confirms that the smaller the battery weight, the less minimum cooling time is required for the battery to be cooled. Furthermore, it can be confirmed that when cooling is performed using the value of Equation 1, derived from the relationship between battery weight, external cooling temperature, and target temperature, as the minimum cooling time, the battery, specifically the electrolyte, is cooled. Moreover, when the battery is cooled for a time exceeding the value of Equation 1, no fire occurs during the subsequent battery crushing process.

[0158] Figure 6a and Figure 6b This is a photograph of an embodiment of the minimum cooling time according to the present invention. Figure 6c and Figure 6d This is a comparative photograph of the minimum cooling time according to the present invention.

[0159] Reference Figure 6a and Figure 6b This was obtained through experiments on the fire occurrence state of fragments when the battery was frozen in a shorter time than the required minimum cooling time during cooling. In the experiment, with a battery weight of 25 kg, an external cooling temperature of -95°C, and a target freezing temperature of -70°C, the experiment was conducted for 5 hours, which was 7 hours shorter than the value of Equation 1 below.

[0160] <Formula 1> Minimum cooldown time = A × (W) 0.33 ) (A=4×e) (-0.02×dT) W = battery weight (Kg), dT = |external cooling temperature - target temperature|, where || represents the absolute value. Reference Figure 6c and Figure 6d This was obtained through experiments on the fire hazard state of broken parts when the battery was frozen to a temperature exceeding the minimum freezing time required for battery cooling. In these experiments, the same battery weight, external cooling temperature, and minimum freezing time of 7 hours or more as shown in Table 2 below were used.

[0161] Table 2 below compares according to Figures 6a to 6d The fire occurrence states of the embodiments and comparative examples are shown with the same battery weight, external cooling temperature, and minimum freezing time. Regarding the determination of the fire occurrence state, if a fire is observed after the battery breaks, it is recorded as "O"; otherwise, it is recorded as "X".

[0162] Table 2 Observing Table 2, it can be confirmed that if the battery is cooled with a value smaller than that of Equation 1, which corresponds to the minimum cooling time, the electrolyte fails to cool properly, resulting in a fire after the battery breaks. Thus, when the battery is cooled with the value of Equation 1 as the minimum cooling time, it can be confirmed that the broken pieces can be stably utilized without causing a fire after the battery breaks.

[0163] <Battery Breakage Steps - Size of Broken Items> Even if a frozen battery is broken, the likelihood of a fire during the breakage is low, but depending on the battery's state of charge, there is a potential difference within the battery and within the broken material. In this invention, a standard for stabilizing the broken material is set by measuring how much the temperature of the broken material rises.

[0164] Figure 7 This is a temperature chart of the crushed material over time according to an embodiment of the present invention.

[0165] Reference Figure 7 To determine the maximum heating temperature using a 20mm fragment as a benchmark, the temperature change over time was investigated. Specifically, after breaking a battery that had undergone a freezing step, the temperature of a 20mm fragment was placed in the atmosphere and cooled by air over time. With the 20mm fragment, the maximum heating temperature was determined to be approximately 65°C. This is lower than the average vaporization temperature of the electrolyte, which is 120°C.

[0166] Table 3 below is based on the temperature rise measured according to the size of the crushed material.

[0167] Table 3 Observing Table 3, it can be confirmed that the temperature difference that causes reheating varies depending on the size of the crushed material, and it is confirmed that the average size of the crushed material must be crushed to a length axis of less than 100 mm in the transverse, longitudinal, and height directions as the stabilization temperature for process design.

[0168] Furthermore, depending on the size of the material being crushed, the required physical stabilization time is necessary. Methods for stabilizing the material include maintaining a predetermined process time at a temperature below 120°C, or maintaining a predetermined process time under an inert gas atmosphere to reduce contact with atmospheric oxygen.

[0169] In this invention, the average size of the broken material was 20 mm, and the temperature was maintained at 30°C for about 3 hours. At this time, it can be confirmed that the temperature of the broken material that had risen has dropped to the room temperature level.

[0170] For fragments smaller than 100 mm, the stabilization time is acceptable even if the holding time is within a few minutes. However, for fragments larger than 100 mm, a stabilization time of at least 3 hours is required.

[0171] <Battery Breakdown Steps - Steps for Controlling the Breakdown Layer of Battery Debris> When crushing is carried out below the minimum freezing time of the material, the material does not undergo brittle fracture at extremely low temperatures, resulting in larger material size or increased thickness due to the presence of multiple layers of positive and negative current collectors. As the thickness of the material increases, the temperature rise is greater and the heating time is longer.

[0172] Table 4 below shows the temperature rise of a unit battery fragment as a function of a layered structure, measured using a thermal imaging camera, according to an embodiment of the present invention.

[0173] Referring to Table 4 below, in the case of a layered structure, positive electrode-separator-negative electrode means one layer. When the broken material is stacked into multiple layers, it is arranged in the order of positive electrode-separator-negative electrode-separator-positive electrode-separator-negative electrode… Specifically, this means that the separator structure is arranged as one layer between the positive electrode or the negative electrode in the waste battery, thus creating multiple layers. Specifically, it can be based on the separator, with a positive electrode or a negative electrode provided on at least one side of the separator.

[0174] In Table 4 below, the average size of the broken material is evaluated as 20 mm. The temperature evaluation after breaking is based on the number of broken material layers, and the recovery time required to rise from the freezing temperature to the maximum temperature and then drop back to 40°C is measured.

[0175] At this point, the size of the broken material is measured based on the major axis of the broken material's major axis and minor axis.

[0176] Table 4 Figures 8a to 8c A unit battery fragment is shown as an embodiment of the invention and a comparative example.

[0177] Reference Figure 8a It can be confirmed that the embodiments and comparative examples are based on the size of the broken pieces and the number of layers of the layered structure of the broken battery.

[0178] Simultaneously observe the above Figure 8a As can be confirmed from Table 4, when the number of layers in the layered structure is 3 or less, the temperature of the crushed material is stably maintained below 110°C. When the number of layers is more than 7, combustion is confirmed to occur after the temperature rises to above 105°C due to reaction with the electrolyte.

[0179] Reference Figure 8b The mixing ratio can be confirmed based on the weight proportion of the battery fragments. Specifically, the layered structure should have 7 layers or less. Figure 8b The weight of the broken battery fragment (on the left side) is 905g, and its layered structure consists of more than 7 layers. Figure 8b The battery fragments (on the right side) weighing 95g were mixed.

[0180] It was confirmed that when the size of the battery fragments is in a single layer, the maximum temperature rises to above 105°C when the maximum size exceeds 100mm, thus greatly increasing the likelihood of a fire. Furthermore, it was confirmed that even when the fragments are less than 100mm, the likelihood of a fire increases when the number of layers in the layered structure is 10 or more, specifically more than 7.

[0181] Table 5 below shows the fire probability in the battery fragments of the present invention, based on the weight percentage of the fragments having a layered structure of more than 7 layers.

[0182] Table 5 Observation of Table 5 confirms the results of multiple fire occurrences measured within the fragmented material at 1 kg cell units. Even when the weight proportion of fragmented material with more than 7 layers is included, as long as it is less than 10% of the total weight, almost no fires occur. Furthermore, it is confirmed that when the weight proportion of fragmented material with more than 7 layers exceeds 10% of the total weight, fires occurred in all three experiments. This confirms that the fires originated from the thicker fragmented material (7 layers or more).

[0183] Thus, it was confirmed that when the weight proportion of the broken material with more than 7 layers is less than 10% of the total weight of the broken material, specifically less than 5%, fire of the broken material can be prevented. It was also confirmed that when more than 10% of the broken material with 7 or more layers or with a size greater than 100 mm is included in the total battery broken material, the frequency of fire increases.

[0184] Furthermore, Table 6 below confirms whether smoke is generated based on the proportion of burning marks on the surface of the broken object, according to an embodiment of the present invention.

[0185] Table 6 Figure 8c The burning portion and the normal portion of the surface of a broken unit battery according to an embodiment of the present invention are shown.

[0186] Reference Figure 8c Regarding the surface of the broken battery fragments, it can be identified that there are normal areas without burning marks caused by high temperatures and surfaces with burning marks caused by high temperatures. Burned areas are those with burning marks caused by high temperatures, specifically areas that have been rapidly heated, referring to regions that exhibit a darker color compared to the normal, unburned areas. These burned areas mostly show burning at the edges.

[0187] observe Figure 8c As confirmed in Table 6, when the surface of the broken unit battery has almost no traces of combustion caused by high temperature, or when the traces of combustion within the surface area are less than 30%, combustion does not occur when evaluating whether smoke is produced. It was confirmed that when the traces of combustion within the surface area exceed 30%, a fire accompanied by smoke occurred.

[0188] <Battery stabilization steps: Temperature trend of shredded material based on SOC conditions of spent batteries> Figures 9a to 9c These are photographs of the temperature measurement process for waste batteries and the temperature trend of the crushed material based on SOC conditions.

[0189] Figure 9a and Figure 9b It is obtained by measuring the temperature of the battery before and after it breaks. Figure 8c This is based on the temperature trend of the shredded material according to the SOC conditions of waste batteries. (Refer to...) Figure 9a To measure the temperature of the waste batteries before they were crushed, a hole of approximately 30mm was drilled in the center of the battery module, and a thermocouple (TC) was installed to measure the temperature. (See reference...) Figure 8b In order to measure the temperature of the fragments after the waste battery was crushed, a thermocouple (TC) was placed in the center of the fragments for measurement.

[0190] Reference Figure 9c The graph shows temperature patterns measured at 0% and 30% of the battery's SoC (State of Charge). SoC stands for 'State of Charge', meaning the state of charge of a lithium-ion battery. Specifically, to represent the remaining battery capacity, the currently usable battery capacity is divided by the total capacity as a percentage (%). This graph was generated after the battery was frozen and shattered, and a thermocouple (TC) was placed in the center of the shattered material to measure the internal temperature of the fragments.

[0191] Figure 10a The temperature trend of the fragments over time is shown. Figure 10b This is a graph showing the trend of temperature increase in the broken material based on the SOC% condition of the battery.

[0192] Reference Figure 10a and Figure 10b It was confirmed that the temperature increased above 10 degrees Celsius over time before decreasing. Furthermore, it was confirmed that a battery with 0% SOC was broken in a frozen state, with the initial temperature rising from approximately -60°C to a maximum of approximately 30°C, and a battery with 30% SOC reaching 60°C. This confirms the necessity of prior confirmation of the SOC state of the broken material during low-temperature stabilization treatment due to its own heat generation. Specifically, it was confirmed that a fire occurred during stabilization treatment when the maximum temperature trend based on SOC conditions exceeded 80%.

[0193] <Battery Stabilization Steps> Figure 11 This is a graph showing the temperature of the battery fragments over time during the low-temperature stabilization, intermediate step, and high-temperature stabilization step according to an embodiment of the present invention.

[0194] Figure 11 This graph shows the temperature of the battery fragments during a continuous stabilization process lasting up to 24 hours, consisting of a maximum low-temperature stabilization period of 12 hours, an intermediate step, and a maximum high-temperature stabilization period of 12 hours. It confirms that by performing the intermediate and high-temperature stabilization steps after the low-temperature stabilization process, a stable battery can be obtained by preventing a rapid increase in battery temperature.

[0195] Figure 12 The temperature change in the conveyor box containing crushed material with a SOC below 30% is shown. Specifically, Figure 12 The ambient temperature refers to the temperature of the conveyor box. It can be confirmed that during the low-temperature stabilization step, the temperature inside the conveyor box rises due to the self-heating of the battery fragments during transport. Therefore, it can be confirmed that the temperature of the battery fragments is preferably controlled below 30°C during the low-temperature stabilization step.

[0196] Figure 13 The temperature changes of the crushed material are shown when the heating temperatures of each zone of the heat treatment used for the high-temperature stabilization step are controlled.

[0197] Reference Figure 13 The crushed material that underwent a low-temperature stabilization step was then subjected to a high-temperature stabilization treatment step. In the high-temperature reduction treatment step, in order to continuously heat the material, the temperature was controlled by adjusting the power (%) of the heating devices in each zone (6 zones), thereby raising the temperature of the crushed material and removing the electrolytes from it.

[0198] <Temperature Heating Mode of Crushed Material After Stabilization Treatment> Figure 14 The percentage (%) of electrolyte weight reduction in the fragments after high-temperature stabilization treatment at a heat treatment temperature of 150°C is shown.

[0199] Reference Figure 14 This paper illustrates how, during the high-temperature stabilization treatment of batteries, changing the heat treatment temperature of the broken material reduces the weight percentage (%) of the electrolyte contained in the entire broken material according to the temperature conditions. Specifically, it was confirmed that when the battery broken material that underwent high-temperature stabilization treatment was heated to 150°C, and the total amount of electrolyte contained in the battery broken material was taken as 100% by weight, the weight decreased to approximately 65% ​​by weight after high-temperature stabilization treatment. The battery broken material that underwent the high-temperature stabilization treatment is stabilized lithium-ion broken material that can be safely processed in battery processing operations such as single screening or dry high-temperature treatment.

[0200] Therefore, the main characteristics of the broken material after freeze-crushing and stabilization were confirmed. The broken material stabilized at low temperature was further stabilized at high temperature, so that when the battery broken material stabilized at 150°C was heated, the mass change before and after heating was very low.

[0201] <Change in tap density> Figure 15 The temperature and weight reduction are shown based on the tap density of the battery fragments.

[0202] Reference Figure 15 The results show that the tap densities of the broken battery fragments before low-temperature stabilization were 250, 350, 450, and 550 kg / m³. 3 The amount of weight reduction of the battery fragments during the battery stabilization step of the present invention. The tap density of the battery fragments was confirmed to be 550 kg / m³. 3 250kg / m 3 As the weight decreases sequentially, gaps form within the broken battery components, facilitating electrolyte evaporation and increasing the weight reduction of the electrolyte (100%) inside the battery.

[0203] <Evaluation Example>: Based on data from low-temperature stabilization and high-temperature stabilization conditions Table 7 below shows the weight reduction and tap density of a 20mm unit battery fragment with a layered structure having a 7-layer stacked structure, with the longest axis in the transverse, longitudinal, and height directions as the reference, when the low-temperature stabilization treatment and high-temperature stabilization treatment steps described in Table 7 are performed.

[0204] At this point, multiple intermediate stabilization steps were performed between the low-temperature stabilization step and the high-temperature stabilization step. The intermediate stabilization steps were performed continuously in temperature ranges of 30 to 60, 60 to 90, and 90 to 120°C, respectively. The high-temperature heat treatment time mentioned above, which included all the intermediate stabilization time, was performed for 12 hours (h).

[0205] The weight reduction of the crushed material after the low-temperature stabilization treatment step and the high-temperature stabilization treatment step was measured by a weight measuring instrument.

[0206] Tap density was measured by mechanically tapping a commercially available battery module (comprising 30 cells) weighing approximately 30 kg. The module was crushed using a crusher, placed into a stabilized volumetric housing (0.44 m x 0.7 m x 0.5 m), and the apparent density was determined. Specifically, the battery weight (M, kg) was divided by the housing volume (V, m³). 3 To determine the density (ρ=M / V).

[0207] The weight reduction ratio after reheating of the fragments confirmed the weight reduction ratio before and after reheating of the fragments of a single battery that had undergone a high-temperature stabilization process to 150°C.

[0208] Stability is recorded as × if a fire occurs during battery breakage, and as ○ if no fire occurs.

[0209] Table 7 Referring to Table 7, the low-temperature stabilization treatment in the embodiment was carried out for 6 to 12 hours in the range of 10 to 25°C, and the high-temperature stabilization treatment was carried out for 6 to 12 hours in the range of 130 to 150°C. At this time, observing the weight reduction of the fragments after reheating confirmed that it was less than 1.0%, confirming that the weight reduction after reheating of the fragments met the requirement of less than 1.0%, and the large reduction in electrolyte ensured stability in subsequent processes. Conversely, it was confirmed that when the low-temperature stabilization treatment process was not performed, or when it was performed at a high temperature such as 40°C, there was a fire hazard to the battery, and the obtained weight reduction of the battery fragments was low. Furthermore, when the low-temperature stabilization treatment was not sufficiently performed and a high-temperature stabilization treatment was performed instead, excessive low-temperature volatile electrolyte was generated during the high-temperature treatment, further increasing the fire hazard, and the electrolyte reduction compared to the standard time was not sufficiently achieved.

[0210] <Evaluation Example>: Based on the data of the distance between the hot air inlet and the distance between the sealed parts inside the sagger. Table 8 below shows the target temperature arrival time when the spacing between the hot air inlets inside the sagger is different, and when the spacing between the sealed section and the mesh section is different.

[0211] Figure 16 A graph showing the heating rate based on the spacing of the hot air inlets is presented.

[0212] Reference Figure 16 It can be confirmed that when the spacing of the hot air inlets is 35% to 45.0% of 100% of the lateral length of the sagger, the temperature rise rate reaches the target temperature rapidly at a rate of 2.0°C / minute or higher. This confirms that maintaining the aforementioned spacing of the hot air inlets results in excellent process efficiency.

[0213] Figure 16 A graph showing the temperature change over time based on the spacing between the hot air inlets and the spacing between the sealed parts is presented.

[0214] Table 8 Refer to Table 8 and Figure 16 It can be confirmed that, based on Case 01, the arrival time in Case 02 was reduced by approximately 6%, and in Case 03 by approximately 44%. This is because the height of the sealed section meets the appropriate range, thus minimizing the time required to reach the target temperature range of the sagger. Furthermore, observation of Cases 04 and 05 confirms that the time required to reach the target temperature range of the sagger increased by approximately 5% and 2% respectively compared to Case 01. Therefore, the spacing between the hot air inlets also meets the appropriate range, thus minimizing the time required to reach the target temperature range of the sagger.

[0215] The preferred embodiments have been described in detail above, but the scope of the present invention is not limited thereto. Various modifications and improvements made by those skilled in the art using the basic concepts defined in the above claims also fall within the scope of the present invention.

Claims

1. A battery stabilization device, characterized in that, include: The feeding section is where a sagger containing shredded waste batteries is fed in. A conveying unit that transports the sagger containing the crushed waste batteries; A first stabilization step is performed on the waste battery fragments at a temperature below 30°C; A second stabilization section is performed on the waste battery fragments that have passed through the first stabilization section at a temperature of 30 to 150°C. and The stabilized waste battery fragments are discharged from the discharge section. The crucible includes a hot air inlet for supplying heat to the waste battery fragments.

2. The battery stabilization device according to claim 1, characterized in that, The first stabilizing unit includes a compressor.

3. The battery stabilization device according to claim 1, characterized in that, Also includes: One or more weight and temperature measuring units are used to measure the weight of the shredded waste battery.

4. The battery stabilization device according to claim 3, characterized in that, The weight and temperature measuring unit includes: A first weight and temperature measuring unit is disposed between the inlet and the first stabilizing part; A second weight and temperature measuring unit is disposed between the first stabilizing part and the second stabilizing part; and A third weight and temperature measuring unit is provided between the second stabilizing part and the discharge part.

5. The battery stabilization device according to claim 4, characterized in that, The second stabilizing part includes an intermediate stabilizing part and a high-temperature stabilizing part. The intermediate stabilizing section heats the waste battery fragments to a temperature range of 30 to 120°C. The high-temperature stabilization section heats the waste battery fragments to a temperature range of 120 to 150°C.

6. The battery stabilization device according to claim 1, characterized in that, The hot air inlet is located in at least a portion of the area of ​​the sagger.

7. The battery stabilization device according to claim 1, characterized in that, The hot air inlet is configured as a cylindrical, triangular, square, or polygonal prism shape, and heat is dissipated through the outer circumferential surface of the shape.

8. The battery stabilization device according to claim 6, characterized in that, Also includes: Multiple hot air inlets, Based on the horizontal length of the sagger, the spacing between the plurality of hot air inlets is 35 to 45%.

9. The battery stabilization device according to claim 1, characterized in that, Based on the height of the sagger, the height of the hot air inlet is 25% to 50%.

10. The battery stabilization device according to claim 1, characterized in that, Based on the height of the sagger, the height of the hot air inlet is 25% to 50%.

11. The battery stabilization device according to claim 1, characterized in that, The sagger has an open upper surface.

12. The battery stabilization device according to claim 1, characterized in that, The saggar includes: The shell that encloses the sides of the sagger; Network Department; and A sealing section is provided below the mesh section.

13. A battery stabilization treatment system, characterized in that, include: The first step in controlling the compaction density of crushed waste batteries; A second step involves measuring a first weight as the initial weight of the waste battery fragments and a first temperature as the initial temperature. The third step is to stabilize the waste battery fragments at a temperature below 30°C; A fourth step involves measuring the second weight and second temperature of the shredded waste battery after the third step. The fifth step involves stabilizing the waste battery fragments from the fourth step at a temperature of 30 to 150°C. A sixth step involves measuring the third weight and third temperature of the shredded waste battery material after the fifth step; and The seventh step involves discharging the shredded waste batteries from the sixth step.

14. The battery stabilization treatment system according to claim 13, characterized in that, The first step controls the compaction density of the shredded waste battery material to be between 200 and 1400 kg / m³. 3 .

15. The battery stabilization treatment system according to claim 13, characterized in that, When the first weight and first temperature of the waste battery fragments measured in the second step and the second weight and second temperature of the waste battery fragments measured in the fourth step satisfy the following equations 1 and 2, the fifth step is executed. <Formula 1> Second weight - first weight ≤ 25% <Formula 2> Second temperature - First temperature ≤ 25℃.

16. The battery stabilization treatment system according to claim 13, characterized in that, When the second weight and second temperature of the waste battery fragments measured in the fourth step and the third weight and third temperature of the waste battery fragments measured in the sixth step satisfy the following equations 3 and 4, the seventh step is executed. <Formula 3> The third weight minus the second weight is ≤10%. <Formula 4> The third temperature - the second temperature ≤ 25℃.

17. The battery stabilization treatment system according to claim 13, characterized in that, The fifth step is performed through a multi-stage heat treatment process. The multi-stage heat treatment is performed sequentially at temperatures of 30 to 120°C and 120 to 150°C.

18. The battery stabilization treatment system according to claim 13, characterized in that, Prior to the first step of controlling the tap density of the waste battery shreds, the method further includes: The steps for controlling the unit waste battery shredded material that constitutes the waste battery shredded material to meet the following conditions 1 and 2. <Condition 1> The layered structure is a stacked structure with more than 1 layer and less than 7 layers; <Condition 2> Based on the longest axis in the horizontal, vertical and height directions, the size of the unit waste battery fragments is less than 100mm.

19. The battery stabilization treatment system according to claim 13, characterized in that, Before the first step, the process also includes: freezing the shredded waste battery. The freezing step is carried out by cooling to -150°C to -20°C.

Images