Crushed unit batteries, crushed battery products including the same, and battery processing method

Abstract

The present invention relates to crushed unit batteries, crushed battery material including the same, and a battery processing method, wherein the crushed unit batteries are for recovering valuable metals from waste batteries, and the crushed unit batteries have a layered structure including a separator membrane having a positive electrode or a negative electrode laminated on at least one surface thereof, and can satisfy the following conditions 1 and 2: <Condition 1> The layered structure is a laminated structure of 1 to 7 layers. <Condition 2> The size of the crushed unit battery is 100 mm or less based on the longest axis among the horizontal, vertical, and height directions.

Description

[Technical Field]

[0001] The present invention relates to waste batteries, and more particularly to crushed unit batteries extracted from waste battery recycling, crushed battery materials including the same, and a battery processing method. [Background technology]

[0002] As demand for electric vehicles grows worldwide, the disposal of waste batteries from these vehicles is becoming a social issue. Lithium secondary batteries, which are the main raw materials for such waste batteries, contain organic solvents, explosive materials, and heavy metals such as Ni, Co, Mn, and Fe. Ni, Co, Mn, and Li are highly valuable as valuable metals, and therefore, the recovery and reuse process of discarded lithium secondary batteries has emerged as an important research field.

[0003] Specifically, a lithium secondary battery mainly comprises copper and aluminum used as a current collector, an oxide containing Li, Ni, Co, and Mn that constitutes the cathode material, and graphite used as the anode material, a separator that separates the cathode material from the anode material, and an electrolyte that is poured into the separator. The solvent and salt that constitute the electrolyte are typically a mixture of carbonate organic compounds such as ethylene carbonate and propylene carbonate, e.g., LiPF6.

[0004] In order to utilize the waste batteries, active development has been conducted on a waste battery recycling process in which the waste batteries are crushed to generate intermediate materials such as waste battery crushed materials or black powder, and valuable metals are recovered through post-processing.

[0005] However, in the waste battery recycling process, although the waste batteries vary depending on the number of times they have been used and their condition, they generally have a voltage in the range of 3.0 to 3.2 V when fully discharged per cell and a voltage close to 4 V when fully charged. Since such residual voltages in modules or packs in which tens to hundreds of cells are connected have a very large amount of energy, when the waste batteries are physically disassembled by applying an external impact to them, safety issues arise regarding the risk of battery explosion or electric shock.

[0006] To prevent this, after disassembly, holes are created in the battery and it is discharged with salt water. After the discharge is complete, the battery is crushed and then heat-treated at high temperature to remove the water and electrolyte.

[0007] The salt used for saltwater discharge contains large amounts of substances such as Na, K, Cl, Mg, and Ca. Of these substances, Cl in particular is partially removed during high-temperature heat treatment, but the crushed waste batteries or the black powder, which is a powder containing Ni-Co-Mn-Li-O oxide and C, obtained by further processing the crushed waste batteries to remove Al, Cu, and part of the separator, still contain impurities such as Na, K, and Mg.

[0008] These impurities have the problem of reducing the recovery rate during the extraction process using acid leaching in the later step of the waste battery recycling process, and research into methods for solving this problem is needed. Summary of the Invention [Problem to be solved by the invention]

[0009] According to one embodiment of the present invention, through the recycling of waste batteries, crushed unit batteries with low impurity content and fire prevention are provided.

[0010] According to one embodiment of the present invention, a shredded battery has the above-mentioned advantages and includes at least one or more unit shredded batteries.

[0011] A battery treatment method according to another embodiment of the present invention provides a battery treatment method that can stably treat waste batteries with a simple process without causing explosion or fire. [Means for solving the problem]

[0012] According to one embodiment of the present invention, the crushed unit batteries are used to recover valuable metals from waste batteries, and the crushed unit batteries have a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface thereof, and may satisfy the following conditions 1 and 2: <Condition 1> The layered structure is a laminated structure of 1 to 7 layers. <Condition 2> The size of the crushed unit battery is 100 mm or less based on the longest axis among the horizontal, vertical, and height directions.

[0013] In one embodiment, the surface of the crushed unit battery may include a burned portion, which is an area where at least a portion of the surface has been burned, and a normal portion, which is an area where no trace of burning is found on the surface, and the area ratio of the burned portion to the normal portion may be 30% or less. In one embodiment, the burned portion may be formed on the edge portion of the surface.

[0014] According to another embodiment of the present invention, the shredded battery material may include shredded battery material containing at least one of the above-described unit shredded battery material.

[0015] In one embodiment, the content of the unit crushed battery material may be 90% or more of the total volume of the crushed battery material. In one embodiment, the crushed battery material may contain impurities, by weight, of Na: 0.4% or less, Ca: 0.03% or less, Mg: 0.02% or less, and K: 0.02% or less.

[0016] According to another embodiment of the present invention, a method for treating a battery includes the steps of: freezing the battery;

[0017] crushing the frozen batteries into battery crushes; and Stabilizing the crushed battery fragments with a cooling fluid; The crushed battery material includes at least one crushed unit battery material, and the crushed unit battery material has a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface thereof, and may satisfy the following conditions 1 and 2. <Condition 1> The layered structure is a laminated structure of 1 to 7 layers. <Condition 2> The size of the crushed unit battery is 100 mm or less based on the long axis, which is the longest axis among the horizontal, vertical, and height directions.

[0018] In one embodiment, the crushing step may include controlling the ratio of the crushed unit batteries to the total volume of the crushed batteries to 90% or more. In one embodiment, the freezing step may satisfy the following formula 1: <Expression 1> Minimum cooling time (Hr)=A×(W 0.33 ) (A=4×e (-0.02×dT) ,W=battery weight (kg), dT=|external cooling temperature - target temperature|, || means absolute value)

[0019] In one embodiment, the freezing step can be performed by cooling at −150° C. to −20° C. In one embodiment, the stabilizing step of the shredded battery fragments using a cooling fluid can be performed at a temperature of 15 to 40° C.

[0020] In one embodiment, the cooling fluid may be at least one of air, vacuum, nitrogen, an inert gas, and water. In one embodiment, when the cooling fluid is a gas, the stabilization average time may satisfy the following formula 2: <Expression 2> B=0.0125A 2 +2.6979A+170.9±100 (In the above formula 2, A represents the size of the crushed material [mm], and B represents the stabilization time [min])

[0021] In one embodiment, when the cooling fluid is a liquid, the stabilization average time may satisfy the following equation 3: <Expression 3> B=-0.0007A 2 +0.3246A+37.07±50 (In the above formula 3, A means the size of the crushed material [mm], and B means the stabilization time [min])

[0022] In one embodiment, the freezing step may be performed by cooling to -60°C to -20°C, and the crushing step may be performed under a vacuum atmosphere of 100 torr or less. In one embodiment, the recovery time required for lowering the temperature of the crushed battery material to a range of 20 to 50°C in the crushing step may be 200 minutes or less. In one embodiment, after the crushing step, a magnetic separation or gravity separation step may be further performed to separate products having a maximum size of 1 mm or less. [Effects of the Invention]

[0023] According to one embodiment of the present invention, valuable metal alloys can be obtained by freezing waste batteries at a predetermined temperature and then crushing them, thereby providing crushed unit batteries with low impurity content and preventing fires.

[0024] According to another embodiment of the present invention, a crushed battery product can be provided that has at least one unit crushed battery having the above-mentioned advantages.

[0025] According to another embodiment of the present invention, a method for recycling used batteries may include freezing the used batteries at a predetermined temperature and then crushing them, thereby preventing flammable substances in the electrolyte from reacting with oxygen. [Brief explanation of the drawings]

[0026] [Figure 1] 4 illustrates the change in battery voltage with cooling temperature according to one embodiment of the present invention. [Figure 2] 1 is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to an embodiment of the present invention. [Figure 3a] 1 is a photograph of an example using the minimum cooling time of the present invention. [Figure 3b] 1 is a photograph of an example using the minimum cooling time of the present invention. [Figure 3c] 1 is a photograph of a comparative example using the minimum cooling time of the present invention. [Figure 3d] 1 is a photograph of a comparative example using the minimum cooling time of the present invention. [Figure 4] 1 is a graph of temperature over time of the fragment according to one embodiment of the present invention. [Figure 5a] 1 shows crushed unit batteries according to an embodiment of the present invention and a comparative example. [Figure 5b] 1 shows a mixing ratio by weight of crushed battery material according to an embodiment of the present invention. [Figure 5c] The burned and normal areas on the surface of the crushed unit battery are shown. [Figure 6a] 1 is a graph illustrating the stabilization time when crushed batteries are stabilized with a gaseous cooling fluid, according to one embodiment of the present invention. [Figure 6b] 1 is a graph illustrating the stabilization time when crushed batteries are stabilized with a liquid cooling fluid according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Terms such as "first," "second," and "third" are used to describe various portions, components, regions, layers, and / or sections, but are not limited thereto. These terms are used only to distinguish one portion, component, region, layer, or section from another portion, component, region, layer, or section. Therefore, a first portion, component, region, layer, or section described below can be referred to as a second portion, component, region, layer, or section without departing from the scope of the present invention.

[0028] The terminology used herein is merely for the purpose of referring to particular embodiments and is not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" include the plural forms unless the phrase clearly dictates otherwise. As used in the specification, the term "comprising" refers to the inclusion of certain features, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0029] When a part is referred to as being "on" or "on" another part, this means that it is directly on or above the other part, or there may be other parts between them. In contrast, when a part is referred to as being "directly on" another part, there are no other parts between them.

[0030] Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention pertains. Terms defined in commonly used dictionaries are to be interpreted in addition to those having meanings consistent with the relevant technical literature and the presently disclosed content, and are not to be interpreted in an ideal or very formal sense unless otherwise defined.

[0031] DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the preferred embodiments of the present invention is provided by way of example only and is not intended to limit the scope of the present invention, which is defined solely by the scope of the claims set forth below.

[0032] According to one embodiment of the present invention, a shredded battery unit is used to recover valuable metals from waste batteries and has a layered structure including a separator having a positive or negative electrode laminated on at least one surface. Specifically, the layered structure may include a configuration in which a positive or negative electrode is included on one or both surfaces of the separator. More specifically, the number of layers in the layered structure may correspond to the number of separators.

[0033] The layered structure may include, for example, any one of positive electrode-separator-negative electrode, positive electrode-separator, separator-positive electrode, separator-negative electrode, and negative electrode-separator, and may have a three-layered structure such as positive electrode-separator-negative electrode-separator-positive electrode-separator-negative electrode. Specifically, the crushed unit battery may have a predetermined thickness in the thickness direction by stacking at least one layer.

[0034] In one embodiment, the unit crushed battery material may satisfy the following condition 1. <Condition 1> The layered structure may be a laminated structure of 1 to 7 layers.

[0035] The crushed unit battery material may have a layered structure having 1 to 7 layers. Specifically, the layered structure may have 1 to 5 layers. By stacking the layered structure within the above range, the temperature rise of the crushed material is minimized and the temperature rise time is appropriate. If the layered structure is stacked thicker than the upper limit of the above range, the temperature rise increases excessively and the temperature rise time also increases, which may lead to fire due to combustion.

[0036] In one embodiment, the unit crushed battery material may satisfy the following condition 2. <Condition 2> The size of the crushed unit battery may be 100 mm or less based on the longest axis among the horizontal, vertical, and height directions.

[0037] In one embodiment, the size of the crushed unit batteries may be 100 mm or less based on the major axis. Specifically, the size of the crushed unit batteries may be 50 mm or less. If the size of the crushed unit batteries is too large, the temperature of the crushed battery itself may rise to 100°C or more, which may cause a fire.

[0038] In one embodiment, the surface of the crushed unit battery may include a burned portion and a normal portion, wherein the burned portion refers to an area where at least a portion of the surface of the crushed unit battery is burned, and the normal portion refers to a normal portion where there is no burn mark on the surface.

[0039] In one embodiment, the area ratio of the burned portion to the normal portion on the surface of the crushed unit battery may be 30% or less. By satisfying the area ratio of the burned portion to the normal portion of 30% or less, the possibility of the crushed unit battery burning and causing a fire can be prevented. If the area ratio of the burned portion to the normal portion exceeds 30%, there is a risk that the crushed unit battery will burn and cause a fire accompanied by smoke.

[0040] In one embodiment, the burnt portion may be located on the edge of the surface of the crushed unit battery, and the normal portion may be located near the center of the surface of the crushed unit battery. The burnt portion refers to an area that is darker in color than the normal portion.

[0041] According to another embodiment of the present invention, the crushed batteries may include at least one of the above-described unit crushed batteries. In one embodiment, the content of the at least one unit crushed battery may be 90% or more of the total volume of the crushed batteries. Specifically, the content of the unit crushed battery may be 95% or more of the total volume of the crushed batteries.

[0042] Specifically, the crushed battery materials may correspond to the content that the ratio of unit crushed battery materials having a stacked structure of more than 7 layers may be 10% or less, specifically 5% or less, of the total volume of the crushed battery materials, or the ratio of at least one unit crushed battery material having a size of more than 100 mm based on the major axis may be 10% or less, specifically 5% or less, of the total volume of the crushed battery materials.

[0043] In this way, the ratio of crushed batteries having a layered structure of more than 7 layers per unit volume within the total volume of crushed batteries or the ratio of unit crushed batteries whose size is more than 100 mm based on the major axis satisfies the above range, thereby preventing the occurrence of fire.

[0044] In one embodiment, the crushed battery material is collected from waste batteries and contains impurities, which may include, by weight, Na, Ca, Mg, and K. The crushed battery material may be a crushed residue or black powder produced by collecting and crushing the waste batteries, which is a pretreatment process for a waste battery recycling process.

[0045] The crushed battery material may contain impurities such as Na, Ca, Mg, and K. By reducing the content of these impurities in the crushed battery material, it is possible to facilitate the extraction of Li, a valuable metal of the same group, in a subsequent process.

[0046] According to one embodiment of the present invention, the battery crushed material contains impurities, which may include, by weight, Na: 0.4% or less (excluding 0%), Ca: 0.03% or less (excluding 0%), Mg: 0.02% or less, and K: 0.02% or less.

[0047] The reasons for limiting the content of the impurities will be explained below.

[0048] "Na: 0.4% by weight or less (0% excluded)" Sodium (Na) is a homologous element in the downstream process of recovering valuable metals from the crushed battery material. In the lithium hydroxide formation process, sodium reacts partially with lithium to form sodium hydroxide, reducing lithium recovery and increasing costs in the causticization process. The crushed battery material may contain 0.4 wt% or less of sodium, specifically 0.1 wt% or less of sodium.

[0049] If the sodium content is greater than the above range, there is a problem that the recovery rate decreases in the necessary steps when Na is an element of Group 1, the same as Li, to produce lithium carbonate during the crystallization process of Li dissolved in the solvent after the leaching process and solvent extraction process due to the increase in Na.

[0050] "Ca: 0.03% by weight or less (0% excluded)" Like sodium, calcium (Ca) is an element that reduces the recovery rate of valuable metals in the subsequent process of recovering valuable metals from the crushed battery material. Calcium is more reactive than aluminum when forming lithium aluminate, forming a lithium calcinate structure, which interferes with the formation of lithium aluminate, which is favorable for subsequent reactions, thereby reducing the final lithium recovery rate. The crushed battery material may contain calcium at 0.03% or less, specifically, 0.02% or less by weight.

[0051] If the calcium content is greater than the above range, the increase in Ca may increase the recovery rate and processing time in the solid-liquid separation process, which is a process for purifying impurities after the leaching process. Also, if the calcium content is too high, when the precursors nickel, cobalt, manganese hydroxide, and lithium hydroxide are synthesized to produce the cathode material, Li[NiCoMn] 1-x Ca x )]O2, and the potassium constitutes the oxide structure of the cathode material, hindering the movement of lithium ions and resulting in a decrease in battery capacity.

[0052] "Mg: 0.02% by weight or less" Magnesium (Mg) is an element that prevents separation of solid and liquid phases during acid leaching in the valuable metal recovery process. The crushed battery material may contain magnesium in an amount of 0.02 wt % or less, specifically 0.01 wt % or less.

[0053] If the magnesium content is greater than the above range, it may cause a problem of burdening the recovery process of nickel, cobalt, lithium, etc. Also, if the magnesium content is too high, when the magnesium is synthesized with the precursors nickel, cobalt, manganese hydroxide, and lithium hydroxide to produce a cathode material, Li[NiCoMn] 1-x Mg x )]O2, which forms an oxide structure in the cathode, hindering the movement of lithium ions and reducing battery capacity.

[0054] "K: 0.02% by weight or less" Potassium (K) is also a lithium homologous element that acts to prevent lithium from being converted into hydroxide. The crushed battery material may contain 0.02 wt % or less of potassium, specifically 0.01 wt % or less. If the potassium content exceeds this range, it may cause a load in the causticization process, resulting in a decrease in the lithium recovery rate.

[0055] According to another embodiment of the present invention, a method for treating a battery includes freezing a battery, crushing the frozen battery, and stabilizing the crushed battery with a cooling fluid. The battery treatment method may be a method for treating various types of batteries, including lithium-ion batteries, and the battery may be, for example, a lithium secondary battery separated from an automobile, or a secondary battery separated from an electronic device such as a mobile phone, a camera, or a laptop, specifically, a lithium secondary battery.

[0056] In one embodiment, the step of freezing the battery may satisfy the following formula 1: <Expression 1> Minimum cooling time (Hr)=A×(W 0.33 ) (A=4×e (-0.02×dT) ,W=battery weight (kg), dT=|external cooling temperature - target temperature|, || means absolute value)

[0057] In Equation 1, W represents the weight of the battery, e.g., the weight of a battery pack, a single battery, or a combination thereof. The minimum cooling time is the external cooling temperature applied to the battery, e.g., the target temperature for cooling the electrolyte in the battery.

[0058] The step of freezing the battery is advantageous in that the electrolyte inside the battery is cooled by performing the step of freezing the battery for a minimum cooling time or more, thereby enabling subsequent processes to be performed stably. However, if the step of freezing the battery is performed for a time shorter than the minimum cooling time, the electrolyte may not be cooled, which may cause a fire hazard when the battery is crushed.

[0059] The freezing of the battery is carried out at a temperature sufficient to freeze the electrolyte contained in the battery. Specifically, the freezing can be carried out at a temperature range of, for example, -150 to -20°C. More specifically, the temperature range can be -150 to -50°C, and even more specifically, -80 to -60°C.

[0060] When the battery is frozen within this temperature range, the minute voltage remaining inside the battery, for example, about 2V to 3V, drops to nearly 0V, so even if a short circuit occurs due to direct contact between the positive and negative electrodes, no battery reaction occurs, the battery temperature does not increase, and gas generation and combustion of the electrolyte do not occur. Furthermore, because the electrolyte is in a frozen state or a state in which vaporization is suppressed, the mobility of lithium ions is very low, significantly reducing the electrical conductivity due to the lithium ion migration, and because vaporization of the electrolyte does not occur, flammable gases such as ethylene, propylene, and hydrogen are not generated.

[0061] If the freezing process is performed outside the above temperature range, for example, if the temperature is higher than -60°C, the remaining voltage inside the battery will not drop to 0V, which may cause a battery reaction due to a short circuit, and the electrolyte will not be completely frozen, which is not appropriate. Also, if the temperature is cooled to -150°C, the electrolyte will be sufficiently frozen and the internal voltage of the battery will also drop to 0V, so there is no need to lower the temperature below this. Thus, by including a step of freezing batteries such as lithium secondary batteries before shredding them, the battery disposal method has the advantage of preventing the risk of fire that may occur during the battery shredding process.

[0062] The step of crushing the frozen battery may refer to a step of applying impact or pressure to the battery so that parts of the battery fall off. In one embodiment, the step of crushing the battery may refer to a step of crushing the battery, a step of cutting the battery, a step of compressing the battery, and combinations thereof. Specifically, the step of crushing may include all steps of breaking the battery into small pieces.

[0063] In one embodiment, the step of crushing the battery may include all of the steps of crushing the frozen battery by compressing the frozen battery or applying an external force such as a shear force or a tensile force, and the step of crushing the battery may be performed using, for example, a crusher.

[0064] In one embodiment, the step of crushing the battery may be performed at least once, and more specifically, the step of crushing the battery may be performed at least once continuously or discontinuously.

[0065] In one embodiment, the step of crushing the battery may be performed under conditions of supplying an inert gas, carbon dioxide, nitrogen, water, or a combination thereof, or under a vacuum atmosphere of 100 torr or less. For example, when the freezing process of the battery is performed by cooling at a temperature range of −60 to −20° C., when performed under the above conditions, oxygen supply is suppressed to prevent the electrolyte from reacting with oxygen, thereby preventing an explosion, and vaporization of the electrolyte solution, and thus preventing the generation of flammable gases such as ethylene, propylene, or hydrogen.

[0066] In one embodiment, at least one of the unit crushed batteries included in the crushed battery may satisfy the following condition 1.

[0067] <Condition 1> The layered structure may have 1 to 7 layers.

[0068] The above condition 1 may mean that the layered structure of the crushed unit battery material, which includes a separator having a positive electrode or a negative electrode laminated on at least one surface, is controlled at a stage where the layered structure is crushed into a stacked structure of 1 to 7 layers.

[0069] In one embodiment, the layered structure may be a laminated structure of 1 to 7 layers. Specifically, the layered structure may be a laminated structure of 1 to 5 layers. By laminating the layered structure within this range, the temperature rise of the crushed material is minimized and the temperature rise time is appropriate. If the layered structure is laminated thicker than the upper limit of this range, the temperature rise increases excessively and the temperature rise time also increases, which can lead to combustion problems.

[0070] In one embodiment, at least one of the unit crushed batteries included in the crushed battery may satisfy the following condition 2.

[0071] <Condition 2> The size of the unit crushed battery may be 100 mm or less based on the long axis, which is the longest axis among the horizontal, vertical, and height directions.

[0072] In one embodiment, the size of the unit battery fragments, specifically, the longest axis among the horizontal, vertical, and height directions, may be controlled to be 100 mm or less, specifically, 50 mm or less, during the crushing step. If the maximum size of the battery fragments is greater than 100 mm, the temperature of heat generated due to instability caused by crushing the battery fragments may rise to a temperature range of 120°C, which is the average vaporization temperature of the electrolyte, and stability issues such as fire may occur.

[0073] In one embodiment, the step of crushing the batteries may further include controlling the ratio of the crushed unit batteries to 90% or more, specifically 95% or more, of the total volume of the crushed batteries. Specifically, this may correspond to controlling the ratio of the crushed unit batteries having a stack structure of more than seven layers to 10% or less of the total volume of the crushed batteries. Specifically, the ratio of the crushed unit batteries having a stack structure of more than seven layers may be controlled to 5% or less of the total volume of the crushed batteries. By satisfying this range, there is an advantage in that the occurrence of a fire can be prevented.

[0074] In one embodiment, the recovery time required for lowering the temperature of the crushed battery materials to a range of 20 to 50°C in the crushing step may be 200 minutes or less. Specifically, the recovery time required for lowering the temperature of the crushed battery materials to a range of 35 to 45°C may be 200 minutes or less.

[0075] In one embodiment, the step of stabilizing the shredded battery fragments using a cooling fluid can be performed at a temperature range of −20 to 80° C. If the temperature is outside the lower limit, additional equipment is required to maintain the temperature, which is uneconomical, and if the temperature is outside the upper limit, the risk of fire of the shredded battery fragments cannot be resolved.

[0076] In one embodiment, the step of stabilizing the shredded battery fragments using a cooling fluid may be performed for 30 minutes to 10 hours depending on the type of cooling fluid. If the time exceeds the lower limit of the time range, there is a risk of fire due to reheating, and if the time exceeds the upper limit of the time range, there is a risk of reduced production due to an increase in processing time.

[0077] In one embodiment, the step of stabilizing the crushed battery fragments using a cooling fluid may be performed using at least one of air, vacuum, inert gas, nitrogen, and water. Stabilizing the crushed battery fragments using the cooling fluid has the advantage of reducing the sodium content of impurities in the crushed battery fragments. It has been observed that the time required for stabilization in a gas or vacuum atmosphere is longer than the time required for stabilization using a liquid cooling fluid.

[0078] In one embodiment, in the battery treatment method, when the cooling fluid is a gas, the stabilization average time may satisfy the following Equation 2:

[0079] <Expression 2> B=0.0125A 2+2.6979A+170.9±100 (In the above formula 2, A represents the size of the crushed material [mm], and B represents the stabilization time [min])

[0080] In one embodiment, in the battery treatment method, when the cooling fluid is a liquid, the stabilization average time may satisfy the following Equation 3:

[0081] <Expression 3> B=-0.0007A 2 +0.3246A+37.07±50 (In the above formula 3, A means the size of the crushed material [mm], and B means the stabilization time [min])

[0082] The average stabilization time is the time taken for the crushed battery material to cool down to room temperature after the temperature rise, expressed in minutes, and means the average time for the maximum time and the minimum time. Specifically, Equation 2 has a lower limit of 0.0125A. 2 +2.6979A+70.9 and an upper limit of 0.0125A 2 The range of +2.6979A +270.9 can be satisfied. Formula 3 has a lower limit of B = -0.0007A. 2 +0.3246A-12.93 and upper limit B=-0.0007A 2 It can satisfy the range of +0.3246A+87.07.

[0083] The battery treatment method of the present invention has the advantage that when the stabilization step is performed in gas or liquid, Equation 2 and Equation 3 are satisfied, respectively, thereby appropriately maintaining the stabilization of the crushed material according to the size of the crushed material, thereby reducing the possibility of fire of the crushed material.

[0084] In one embodiment, a step of separating products having a maximum size of 1 mm or less from the crushed product may be further carried out. The separation step may be carried out by magnetic separation or gravity separation, and any separation method commonly known in the art may be used. By further carrying out this separation step, a powder containing a mixture of a positive electrode active material, a negative electrode active material, a positive electrode current collector, and a negative electrode current collector may be obtained. In one embodiment, after the crushing step, a step of removing and separating the electrolyte may be carried out. The electrolyte removal step may be carried out by heat-treating or vacuum-drying the crushed product.

[0085] Preferred examples and comparative examples of the present invention will be described below. However, the following examples are merely preferred examples of the present invention, and the present invention is not limited to the following examples. [Example]

[0086] <Battery internal temperature based on minimum freezing time> The battery packs used in the examples were not frozen and were crushed using the same crusher as in the previous embodiment. During the crushing process, a fire occurred due to a short circuit, as shown in Figures 3a and 3b.

[0087] As described above, through the examples and comparative examples, it can be confirmed that by including a step of freezing the battery pack including the battery before crushing the battery, no short circuit occurs, no flame occurs, and excellent stability is achieved during the battery crushing step.

[0088] FIG. 1 shows the change in voltage of a battery with cooling temperature according to one embodiment of the present invention.

[0089] Referring to Figure 1, when the battery voltage was measured while the battery was frozen at -80°C, the battery pack showed almost the same voltage at high temperatures of about 40°C, room temperature, and temperatures up to -60°C, confirming that the battery characteristics were not lost. Next, when the temperature dropped from -60°C to -70°C, the voltage dropped sharply, and at -70°C the voltage became 0. As such, it was confirmed that no short circuit occurred when the battery was frozen at temperatures between -60 and -150°C.

[0090] FIG. 2 is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0091] Referring to FIG. 2, it can be seen that a battery treatment method according to an embodiment of the present invention can derive a minimum cooling time for cooling a battery during the freezing step. Specifically, it can be seen that the minimum cooling time is related to the battery weight, external cooling temperature, and target temperature. Specifically, the external cooling temperature and minimum cooling time are shown when the target temperature is set to -70°C and the battery weights are 2.5 kg (A), 10 kg (B), 20 kg (C), and 50 kg (D), respectively. When cooling the battery, it can be seen that the battery electrolyte begins to cool after a predetermined time and the voltage becomes zero. This indicates that a minimum maintenance time is required to sufficiently cool the battery interior, specifically the electrolyte.

[0092] Specifically, when the specific heat of the battery itself is taken into account in the heat transfer situation for cooling in which heat is taken to the outside, it is possible to confirm the battery weight and the time required for cooling. Thus, in order to cool the battery, the present invention can confirm the minimum time required for cooling using the external cooling temperature for refrigeration, the target temperature, and the battery weight.

[0093] Table 1 below lists the minimum cooling time depending on the battery weight and external cooling temperature.

[0094] [Table 1]

[0095] From Table 1 above, it can be seen that the smaller the battery weight, the shorter the minimum cooling time required for the battery to be cooled. It can also be seen that when the value of Equation 1, derived from the relationship between the battery weight, external cooling temperature, and target temperature, is reached for the minimum cooling time, the battery, specifically the battery electrolyte, is cooled. Furthermore, when the battery is cooled for a time longer than the value of Equation 1, no fire occurs during the subsequent battery crushing process. Figures 3a and 3b are photographs of an example using the minimum cooling time of the present invention, and Figures 3c and 3d are photographs of a comparative example using the minimum cooling time of the present invention.

[0096] 3a and 3b show an experiment on the fire occurrence state of crushed materials when a battery is cooled for a time shorter than the required minimum cooling time. In the experiment, the battery weight was 25 kg, the external cooling temperature was -95°C, and the target freezing temperature was -70°C. When the value of Equation 1 below is 7 hours, the experiment was conducted for 5 hours, which is shorter than the value of Equation 1.

[0097] <Expression 1> Minimum cooling time=A×(W 0.33 ) (A=4×e (-0.02×dT) ,W=battery weight (kg), dT=|external cooling temperature - target temperature|, || means absolute value)

[0098] Figures 3c and 3d show an experiment on the fire occurrence status of crushed batteries when the batteries were frozen for more than the minimum freezing time required for cooling. The experiment was conducted under the same battery weight, external cooling temperature, and minimum freezing time as Figures 3a and 3b, and was conducted for more than 7 hours.

[0099] Table 2 below compares the fire occurrence status of Examples and Comparative Examples with the same battery weight, external cooling temperature, and minimum freezing time (3a to 3d). The fire occurrence status was judged as "O" if a fire was observed after the battery was crushed, and "X" if not.

[0100] [Table 2]

[0101] Looking at Table 2 above, it can be seen that if the battery is cooled at a value less than the value of Equation 1, which corresponds to the minimum cooling time, the electrolyte is not cooled down and a fire occurs after the battery is crushed. Thus, if the battery is cooled using the value of Equation 1 as the minimum cooling time, it can be seen that the crushed battery can be stably used without a fire occurring after being crushed.

[0102] <Battery crushing stage - size of crushed pieces> Although there is a low possibility of a fire occurring during the crushing of a frozen battery, a potential difference will exist within the crushed material depending on the state of charge of the battery. In the present invention, a standard for stabilizing the crushed material is set by measuring the temperature rise of the crushed material.

[0103] FIG. 4 is a graph of temperature over time of the crushed material according to one embodiment of the present invention.

[0104] Figure 4 shows the temperature change over time to confirm the maximum heat generation temperature using 20mm-sized crushed pieces. Specifically, after crushing a battery that had gone through the freezing stage, 20mm-sized pieces were placed in the atmosphere and cooled using air to measure the temperature change over time. For 20mm-sized crushed pieces, the maximum ignition temperature was confirmed to be approximately 65°C, which is lower than the average vaporization temperature of the electrolyte, which is 120°C.

[0105] Table 3 below shows the temperature rise measured according to the size of the crushed material.

[0106] [Table 3]

[0107] From Table 3 above, it can be seen that the temperature at which the crushed material is reheated varies depending on the size of the crushed material. For process design, it was confirmed that the average size of the crushed material must be crushed to within 100 mm of the longest axis (horizontal, vertical, or height direction) at the stabilization temperature.

[0108] <Battery crushing stage - crushed material size> Depending on the size of the crushed material, time is required for the crushed material to be physically stabilized. Methods for stabilizing the crushed material include maintaining the material at a temperature lower than 120°C for a predetermined period of time, or maintaining the material in an inert gas atmosphere for a predetermined period of time to reduce contact with atmospheric oxygen.

[0109] In the present invention, the crushed material having an average size of 20 mm is maintained at room temperature of 30° C. for about 3 hours, and it can be confirmed that the temperature of the crushed material has dropped to room temperature.

[0110] In the case of crushed material of 100 mm or less, the stabilization time can be kept within a few minutes without causing any problems, but in the case of crushed material of more than 100 mm, the stabilization time must be at least 3 hours.

[0111] <Battery crushing stage - Crushed material layer control stage for battery crushers> When crushing is performed for less than the minimum freezing time of the crushed material, problems occur such as the size of the crushed material being large because brittle fracture does not occur due to the cryogenic temperature of the crushed material, or the thickness of the crushed material being large due to the existence of multiple layers of positive and negative electrode current collectors. As the thickness of the crushed material becomes thicker, there is a problem that the temperature rise is large and the heating time is long.

[0112] Table 4 below shows the temperature rise due to the layered structure of the crushed unit battery according to one embodiment of the present invention, measured using a thermal imaging camera.

[0113] Referring to Table 4 below, in the case of a layered structure, a positive electrode-separator-negative electrode means one layer, and when the crushed materials are stacked in multiple layers, they are arranged in the order of positive electrode-separator-negative electrode-separator-positive electrode-separator-negative electrode.... Specifically, it means that a separator structure is arranged in multiple layers between the positive electrode or the negative electrode in the waste battery. Specifically, the positive electrode or the negative electrode may be arranged on at least one side of the separator based on the separator.

[0114] In Table 4 below, the average size of the crushed material was evaluated to be 20 mm, and the temperature evaluation for each layer of crushed material after crushing and the recovery time required for the temperature to rise from the freezing temperature to the maximum and then drop back down to 40°C were measured.

[0115] At this time, the size of the crushed material was measured based on the major axis of the major and minor axes of the crushed material.

[0116] [Table 4]

[0117] 5a to 5c show crushed unit batteries according to an embodiment of the present invention and a comparative example, and Fig. 5a shows the crushed unit battery size and the number of layered structure layers of the embodiment and the comparative example.

[0118] Looking at FIG. 5a and Table 4 together, it was confirmed that when the number of layers in the layered structure is 3 or less, the temperature of the crushed material is stably maintained at 110°C or less, and when the number of layers is 7 or more, the temperature rises to over 105°C and then reacts with the electrolyte, causing combustion.

[0119] Figure 5b shows the mixing ratio by weight of the crushed battery material. Specifically, the weight of the crushed battery material with a layered structure of 7 layers or less (left side of Figure 5b) was 905g, and the weight of the crushed battery material with a layered structure of more than 7 layers (right side of Figure 5b) was 95g.

[0120] In the case of a single-layer battery, if the size of the crushed battery exceeds 100mm, the maximum temperature will rise to over 105°C, increasing the possibility of a fire. In addition, even if the size is less than 100mm, if the number of layers in the layered structure is 10 or more, specifically more than 7, the possibility of a fire increases.

[0121] Table 5 below shows the possibility of fire occurrence depending on the weight percentage of crushed battery material of the present invention having a layered structure exceeding 7 layers.

[0122] [Table 5]

[0123] As shown in Table 5, the fire occurrence frequency was measured several times within the crushed battery in 1kg cell units. The results showed that even if the crushed battery contained more than seven layers of layered structure material, fires rarely occurred when the weight ratio of the crushed battery was less than 10% of the total weight. Furthermore, fires occurred in all three experiments when the weight ratio of the crushed battery with more than seven layers of layered structure material exceeded 10% of the total weight. The fires were confirmed to have started in thicker crushed battery material with seven or more layers. Thus, it was confirmed that fires could be prevented when the weight ratio of the crushed battery with more than seven layers of layered structure material was less than 10% of the total weight of the crushed battery material, specifically less than 5%. The fire occurrence frequency increased when the crushed battery contained more than 10% of the total weight of the crushed battery material with more than seven layers of layered structure material or pieces larger than 100 mm.

[0124] Table 6 below shows whether smoke is generated or not depending on the ratio of burning traces on the surface of the crushed material according to one embodiment of the present invention.

[0125] [Table 6]

[0126] Figure 5c shows burned and normal portions on the surface of crushed unit batteries according to one embodiment of the present invention. Referring to Figure 5c, the surface of the crushed unit batteries shows normal portions with no traces of burning due to high temperatures, and surfaces with traces of burning due to high temperatures. The burned portions are areas with traces of burning due to high temperatures, and may specifically be rapidly heated areas, and refer to areas that are darker in color than the normal portions, which are unburned. It can be seen that the edges of the burned portions are mostly burned.

[0127] Referring to Figure 5c and Table 6, when the surface of the crushed unit battery showed almost no traces of combustion due to high temperature or the traces of combustion within the surface area were less than 30%, it was confirmed that no combustion occurred when evaluating whether smoke was generated. When the traces of combustion within the surface area exceeded 30%, it was confirmed that a fire accompanied by smoke had occurred.

[0128] <Battery stabilization stage - stabilization time> Table 7 below shows the stabilization time depending on the type of cooling fluid and the size of the crushed material. Specifically, the stabilization time refers to the time (min) required for the crushed material to cool down to room temperature (30°C) after the temperature rise.

[0129] [Table 7]

[0130] 6a is a graph showing the stabilization time when crushed battery material is stabilized with a gas cooling fluid according to an embodiment of the present invention. Referring to FIG. 6a, the graph shows the stabilization time depending on the size of the crushed battery material when a gas cooling fluid is used. Specifically, the average stabilization time of the gas is the average time of the maximum time and the minimum time, and satisfies Equation 2 above.

[0131] FIG. 6b is a graph illustrating the stabilization time for battery shreds stabilized with a liquid cooling fluid, according to one embodiment of the present invention.

[0132] Figure 6b shows the stabilization time depending on the size of the fragments when using a liquid as the cooling fluid. Specifically, the average stabilization time of the liquid is the average of the maximum and minimum times, and satisfies Equation 3 above.

[0133] <Battery stabilization stage - comparison of components of final crushed material> Table 8 below shows the Na content in impurities after the stabilization step using cooling fluids, which are air, vacuum (1 torr), argon (Ar), nitrogen, tap water, saltwater with a concentration of 1% or less, saltwater with a concentration of 10% or less, and saltwater with a concentration of 15% or less.

[0134] [Table 8]

[0135] Table 8 above shows that in the cooling fluid test to stabilize the crushed material after freeze-fracturing, the impurity Na showed a low level of 0.054% in air, but when salt such as salt was present at about 15%, the Na level rose to 0.83%. This makes it possible to control various impurities contained in salt. Table 9 below compares the Na, K, Mg, and Ca content of crushed material that was stabilized in air after freeze-fracturing (Example 1) and crushed material that was discharged in brine containing 15% salt (Comparative Example 1).

[0136] [Table 9]

[0137] As can be seen from Table 9 above, the crushed batteries produced through the battery recycling method that involves freeze-crushing and stabilization steps have lower impurity contents, specifically the contents of Na, K, Mg, and Ca, compared to the crushed batteries produced by salt water discharge.

[0138] Although the preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts defined in the following claims also fall within the scope of the present invention.

Claims

1. A crushed battery unit for recovering valuable metals from waste batteries, The crushed unit batteries have a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface thereof, and satisfy the following conditions 1 and 2: <Condition 1> The layered structure is a laminated structure of 1 to 7 layers. <Condition 2> The size of the crushed unit battery is 100 mm or less based on the longest axis among the horizontal, vertical, and height directions.

2. The surface of the crushed unit battery is a burned portion in which at least a portion of the surface is burned; and The surface includes a normal portion with no traces of burning, The crushed unit battery according to claim 1 , wherein an area ratio of the burned portion to the normal portion is 30% or less.

3. The crushed unit battery material according to claim 2 , wherein the burned portion is formed on an edge portion of the surface.

4. A crushed battery product comprising at least one unit crushed battery product according to any one of claims 1 to 3.

5. The crushed battery material according to claim 4, wherein the content of the unit crushed battery material is 90% or more of the total volume of the crushed battery material.

6. The crushed battery material according to claim 4, containing impurities, by weight, of Na: 0.4% or less, Ca: 0.03% or less, Mg: 0.02% or less, and K: 0.02% or less.

7. freezing the battery; crushing the frozen batteries into battery fragments; and Stabilizing the crushed battery fragments with a cooling fluid; The crushed battery material includes at least one crushed unit battery material, The crushed unit batteries have a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface thereof, and satisfy the following conditions 1 and 2: <Condition 1> The layered structure is a laminated structure of 1 to 7 layers. <Condition 2> The size of the crushed unit battery is 100 mm or less based on the longest axis among the horizontal, vertical, and height directions.

8. The battery treatment method according to claim 7 , wherein the crushing step includes controlling the ratio of the unit crushed batteries to a total volume of the crushed batteries to 90% or more.

9. 8. The battery treatment method of claim 7, wherein the step of freezing the battery satisfies the following formula 1: <Formula 1> Minimum cooling time (Hr) = A × (W ０．３３ ) (A = 4 × e （－０．０２×ｄＴ） , W = battery weight (kg), dT = |external cooling temperature-target temperature|, || means absolute value)

10. 8. The method of claim 7, wherein the freezing step is performed by cooling the battery at a temperature between -150°C and -20°C.

11. 8. The battery processing method according to claim 7, wherein the stabilizing the crushed battery fragments using a cooling fluid is performed at a temperature of 15 to 40°C.

12. 8. The battery treatment method according to claim 7, wherein the cooling fluid is at least one of air, vacuum, nitrogen, an inert gas, and water.

13. 8. The battery treatment method of claim 7, wherein when the cooling fluid is gas, the stabilization average time satisfies the following formula 2: <Formula 2> <h2 style=";text-align:left;direction:ltr">B=0.0125A<h2 style=";text-align:left;direction:ltr"> ２ <h2 style=";text-align:left;direction:ltr"> 22562222222 (In the above formula 2, A means the size of the crushed material [mm], and B means the stabilization time [min])

14. 8. The battery treatment method of claim 7, wherein when the cooling fluid is a liquid, the stabilization average time satisfies the following formula 3: <Formula 3> B=-0.0007A ２ +0.3246A+37.07±50 (In the above formula 3, A means the size of the crushed material [mm], and B means the stabilization time [min])

15. The freezing step is carried out by cooling at -60°C to -20°C, 8. The battery treatment method according to claim 7, wherein the crushing step is performed under a vacuum atmosphere of 100 torr or less.

16. 8. The battery treatment method according to claim 7, wherein the recovery time required for lowering the temperature of the crushed battery material to a range of 20 to 50° C. in the crushing step is 200 minutes or less.

17. 8. The battery treatment method according to claim 7, further comprising a step of performing magnetic separation or gravity separation after the crushing step to separate products having a maximum size of 1 mm or less.

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