Cell crushing material, cell crushing material comprising same, and cell processing method

Abstract

The present invention relates to: a crushed unit cell for recovering a valuable metal from a waste battery, the crushed unit cell having a layered structure including a separator in which a positive electrode or a negative electrode is laminated on at least one surface thereof; the following condition 1 and condition 2, lt are satisfied; the condition is 1gt; the layered structure is a laminated structure of 1-7 layers (1t; the condition is 2gt; the size of the crushed unit cell is 100 mm or less based on the long axis (i.e., the longest axis among the transverse direction, the longitudinal direction, and the height direction).

Description

Technical Field

[0001] The present invention relates to waste batteries, and in particular to unit cell crushed materials extracted from the waste batteries for recycling, battery crushed materials containing the unit cell crushed materials, and a battery processing method. Background Art

[0002] As the global demand for electric vehicles grows, how to deal with the waste batteries generated by these vehicles has become a social issue. As the main raw material of the waste batteries, lithium secondary batteries contain organic solvents, explosive substances and heavy metal substances such as Ni, Co, Mn and Fe, etc. However, Ni, Co, Mn and Li are valuable metals with great scarcity value, and the recycling and reuse process of discarded lithium secondary batteries has become an important research field.

[0003] Specifically, the lithium secondary battery is mainly composed of copper and aluminum used as collectors, oxides containing Li, Ni, Co, and Mn constituting positive electrode materials, and graphite used as negative electrode materials, and includes a separator for isolating the positive electrode material and the negative electrode material and an electrolyte injected into the separator. The solvent (Solvent) constituting the electrolyte and the solvent used as the salt (Salt) are mainly mixed with carbonate organics such as ethylene carbonate (Ethylene Carbonate) and propylene carbonate (Propylene Carbonate), for example, LiPF6 is used.

[0004] In order to utilize the waste batteries, a waste battery recycling process is currently being actively developed, which is used to crush the waste batteries to produce intermediate materials such as waste battery crushed materials or black powder, and then recover valuable metals through subsequent processes.

[0005] However, in the waste battery recycling process, for the waste batteries, although it varies depending on the number of times the battery is used or the state, generally each battery has a voltage in the range of 3.0V to 3.2V in a fully discharged state, and has a voltage close to 4V in a fully charged state. Therefore, a module or battery pack connected with dozens to hundreds of batteries has a considerable amount of energy in these residual voltages, so when an external impact is applied to the waste batteries for physical decomposition, there are safety issues related to battery explosion or electric shock.

[0006] In order to prevent the above situation, after the decomposition, the battery is punched and placed in salt water for discharge. The battery after the discharge is crushed and then subjected to high temperature heat treatment to remove water and electrolyte.

[0007] At this time, the salt used for the salt water discharge contains a large amount of substances such as Na, K, Cl, Mg and Ca. Among the aforementioned substances, Cl is removed to a certain extent during the high temperature heat treatment process, but the crushed material of the waste battery or the further processed crushed material to remove Al, Cu and the oxide of Ni-Co-Mn-Li-O of part of the diaphragm and the powdery powder mixed with C, that is, the black powder, contains substances such as Na, K and Mg as impurities.

[0008] The waste battery recycling process has the problem that the impurities in the subsequent acid leaching extraction process lead to a decrease in the recovery rate, so it is necessary to study methods to solve the above problem. Summary of the invention

[0009] Technical issues

[0010] According to one embodiment of the present invention, a unit cell crushed product is provided by recycling waste batteries, which has a low impurity content and prevents fire.

[0011] According to one embodiment of the present invention, a battery crusher is provided, which has the aforementioned advantages and includes at least one unit battery crusher.

[0012] According to another embodiment of the present invention, there is provided a battery processing method for stably processing waste batteries through a simple process without causing explosion and fire.

[0013] Technical Solution

[0014] According to an embodiment of the present invention, the crushed unit cells are used to recover valuable metals from waste batteries. The crushed unit cells may have a layered structure including a separator having a positive electrode or a negative electrode stacked on at least one side thereof, and satisfy the following conditions 1 and 2.

[0015] <Condition 1> The layered structure is a stacked structure of 1 to 7 layers.

[0016] <Condition 2> The size of the unit cell crushed object is 100 mm or less based on the long axis (that is, the longest axis among the lateral, longitudinal and height directions).

[0017] In one embodiment, the surface of the unit cell crushed object includes: a burning portion, which is an area where at least a portion of the surface is burned; and a normal portion, which is a surface without any trace of burning, and the area ratio of the burning portion to the normal portion is less than 30%.

[0018] In one embodiment, the burning portion may be formed at an edge portion of the surface.

[0019] A battery crushed object according to another embodiment of the present invention may include at least one of the aforementioned unit battery crushed objects.

[0020] In one embodiment, the content of the unit cell crushed material may be more than 90% of the total volume of the unit cell crushed material.

[0021] In one embodiment, the battery crushed material may contain, in wt%, Na: 0.4% or less, Ca: 0.03% or less, Mg: 0.02% or less, and K: 0.02% or less as impurities.

[0022] A battery processing method according to another embodiment of the present invention may include:

[0023] Steps for freezing the battery;

[0024] The step of crushing the frozen battery into battery crushed products; and

[0025] The step of stabilizing the battery fragments after crushing by using a cooling fluid,

[0026] The battery crushed product includes at least one unit cell crushed product, and the unit cell crushed product may 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.

[0027] <Condition 1>

[0028] The layered structure is a stacked structure of one or more layers and seven or less layers.

[0029] <Condition 2>

[0030] The size of the broken unit cells is less than 100 mm based on the long axis (ie, the longest axis among the lateral, longitudinal and height directions).

[0031] In one embodiment, the crushing step may include the step of controlling the proportion of the crushed unit cells to be greater than 90% of the total volume of the crushed unit cells.

[0032] In one embodiment, the step of freezing the battery may satisfy the following formula 1.

[0033] <Formula 1>

[0034] Minimum cooling time (hours) = A × (W 0.33 )

[0035] A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

[0036] In one embodiment, the freezing step may be performed by cooling to -150°C to -20°C.

[0037] In one embodiment, the step of stabilizing the crushed battery fragments by using a cooling fluid may be performed at a temperature of 15°C to 40°C.

[0038] In one embodiment, the cooling fluid can be implemented by at least any one of air, vacuum, nitrogen, inert gas, and water.

[0039] In one embodiment, when the cooling fluid is a gas, the average stabilization time may satisfy the following formula 2.

[0040] <Formula 2>

[0041] B=0.0125A 2 +2.6979A+170.9±100

[0042] In the above formula 2, A represents the size of the crushed object [mm], and B represents the stabilization time [minutes].

[0043] In one embodiment, when the cooling fluid is liquid, the average stabilization time may satisfy the following formula 3.

[0044] <Formula 3>

[0045] B=-0.0007A 2 +0.3246A+37.07±50

[0046] In the above formula 3, A represents the size of the crushed object [mm], and B represents the stabilization time [minutes].

[0047] In one embodiment, the freezing step can be performed by cooling to -60°C to -20°C, and the crushing step can be performed under vacuum conditions below 100 Torr.

[0048] In one embodiment, the recovery time required for reducing the temperature of the battery crushed product to a range of 20° C. to 50° C. in the crushing step may be less than 200 minutes.

[0049] In one embodiment, after the crushing step, a magnetic screening or specific gravity screening step may be further included to separate products with a maximum size of less than 1 mm.

[0050] Beneficial Effects

[0051] According to one embodiment of the present invention, for the valuable metal alloy, after the waste batteries are frozen at a predetermined temperature, they are subjected to a crushing step, thereby providing crushed unit batteries having a low impurity content and preventing fire.

[0052] According to another embodiment of the present invention, a battery crusher is provided, which includes at least one unit cell crusher having the aforementioned advantages.

[0053] According to another embodiment of the present invention, for a waste battery recycling method, the waste batteries are frozen at a predetermined temperature and then subjected to a crushing step, thereby providing a battery processing method that prevents combustible substances in an electrolyte from reacting with oxygen. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 FIG. 1 shows a battery voltage change based on cooling temperature according to an embodiment of the present invention.

[0055] Figure 2 is a graph showing the relationship among battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0056] Figure 3a and Figure 3b is a photograph of an embodiment of the present invention according to the minimum cooling time, Figure 3c and Figure 3d It is a photograph of the comparative example according to the minimum cooling time of the present invention.

[0057] Figure 4 FIG. 4 is a temperature curve diagram of a crushed object based on time according to an embodiment of the present invention.

[0058] Figure 5a The broken pieces of the unit cells according to one embodiment of the present invention and a comparative example are shown. Figure 5b The mixing ratio of the battery crushed objects according to one embodiment of the present invention is shown based on the weight ratio. Figure 5c The burned part and the normal part of the surface of the cell fragment are shown.

[0059] Figure 6a A graph is used to show the stabilization time when the battery fragments are stabilized in the gas cooling fluid according to one embodiment of the present invention. Figure 6b A graph is shown showing the stabilization time when a battery fragment is stabilized in a liquid cooling fluid according to one embodiment of the present invention. DETAILED DESCRIPTION

[0060] The words first, second, third, etc. are used to describe various parts, components, regions, layers and / or segments, but these parts, components, regions, layers and / or segments should not be limited by these words. These words are only used to distinguish a certain part, component, region, layer or segment from another part, component, region, layer or segment. Therefore, without departing from the scope of the present invention, the first part, first component, first region, first layer or first segment described below can also be described as the second part, second component, second region, second layer or second segment.

[0061] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. Unless the context otherwise clearly indicates the opposite, the singular form used herein is also intended to include the plural form. "Including" used in the specification may specifically refer to a certain characteristic, field, integer, step, action, element and / or component, but does not exclude the existence or addition of other characteristics, fields, integers, steps, actions, elements and / or components.

[0062] If a part is described as being on another part, it may be directly on the other part or there may be other parts therebetween. When a part is described as being directly on another part, there may be no other parts therebetween.

[0063] Although not otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. Terms defined in dictionaries should be interpreted as having the same meaning as that disclosed in the relevant technical literature and this article, and should not be interpreted in an idealized or overly formal sense.

[0064] Hereinafter, embodiments of the present invention will be described in detail. However, the following embodiments are given only as examples, and the present invention is not limited to the following embodiments, and the present invention is subject only to the scope of the claims.

[0065] According to an embodiment of the present invention, the cell crushed material is used to recover valuable metals from waste batteries, and the cell crushed material has a layered structure including a separator with a positive electrode or a negative electrode stacked on at least one side thereof. Specifically, the layered structure may include a structure in which one surface or both surfaces of the separator include a positive electrode or a negative electrode. More specifically, the number of layers of the layered structure may correspond to the number of separators.

[0066] 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, for example, positive electrode-separator-negative electrode-separator-positive electrode-separator-negative electrode may have a three-layered structure. Specifically, the unit cell fragments may have a predetermined thickness in the thickness direction as they are stacked into at least one layer.

[0067] In one embodiment, the cell fragments may satisfy the following condition 1.

[0068] <Condition 1> The layered structure may be a stacked structure of 1 to 7 layers.

[0069] The unit cell crushed object may be a layered structure having a stacked structure of more than 1 layer and less than 7 layers. Specifically, the layered structure may be a layered structure of more than 1 layer and less than 5 layers. Since the layered structure is stacked in the range, the temperature rise of the crushed object can be minimized and the heating time can be appropriately consumed. When the layered structure is stacked to be thicker than the upper limit of the range, the temperature rise increases excessively, the heating time also increases, and there is a problem of combustion leading to fire.

[0070] In one embodiment, the cell fragments may satisfy the following condition 2.

[0071] <Condition 2> The size of the unit cell crushed object may be 100 mm or less, based on the long axis (ie, the longest axis among the lateral, longitudinal and height directions).

[0072] In one embodiment, the size of the unit cell crushed object may be less than 100 mm based on the long axis. Specifically, the size of the unit cell crushed object may be less than 50 mm. If the size of the unit cell crushed object is too large, the temperature of the battery crushed object itself rises to more than 100° C., and there is a high possibility of fire.

[0073] In one embodiment, the surface of the broken unit cell may include a burning portion and a normal portion. The burning portion refers to a region where at least a portion of the surface of the broken unit cell is burned, and the normal portion refers to a normal portion on the surface without burning marks.

[0074] In one embodiment, in the surface of the unit cell crushed object, the area ratio of the burning portion to the normal portion may be 30% or less. Since the area ratio of the burning portion to the normal portion is 30% or less, the possibility of the unit cell crushed object burning and causing a fire can be prevented. If the area ratio of the burning portion to the normal portion exceeds 30%, there is a risk of the unit cell crushed object burning and causing a fire accompanied by smoke.

[0075] In one embodiment, in the surface of the unit cell crushed object, the burnt portion may be arranged at the edge of the surface. The normal portion may be arranged near the center of the surface of the unit cell crushed object. The burnt portion refers to a region with a darker color than the normal portion.

[0076] According to another embodiment of the present invention, the battery crushed object may include at least one of the aforementioned unit cell crushed objects. In one embodiment, for the battery crushed object, the content of at least one of the unit cell crushed objects may be more than 90% of the total volume of the battery crushed object. Specifically, the content of the unit cell crushed object may be more than 95% of the total volume of the battery crushed object.

[0077] Specifically, the battery crushed objects may correspond to the following: the proportion of unit cell crushed objects having a stacked structure with more than 7 layers is less than 10% of the total volume of the battery crushed objects, specifically less than 5%; or the proportion of at least one unit cell crushed object with a dimension exceeding 100 mm based on the major axis is less than 10% of the total volume of the battery crushed objects, specifically less than 5%.

[0078] As described above, since the ratio of battery crushed objects having a layered structure with more than 7 layers per unit volume in the total volume of battery crushed objects or the ratio of unit cell crushed objects having a dimension exceeding 100 mm based on the major axis satisfies the above range, fire can be prevented.

[0079] In one embodiment, the battery crushed material is recovered from waste batteries and contains impurities, which may include Na, Ca, Mg and K in weight %. The battery crushed material may be crushed residue or black powder produced by the pre-treatment process of the waste battery recycling process (i.e., the process of recovering and crushing the waste batteries).

[0080] The battery crushed material may contain impurities such as Na, Ca, Mg and K. For the battery crushed material, by reducing the content of the impurities, it is convenient to extract the valuable metal Li of the same group in the subsequent process.

[0081] The battery crushed material according to one embodiment of the present invention contains impurities, and the impurities may include, in weight %, Na: 0.4% or less and excluding 0%, Ca: 0.03% or less and excluding 0%, Mg: 0.02% or less, and K: 0.02% or less.

[0082] The reasons for limiting the content of the impurities are described below.

[0083] Na: 0.4 wt% or less, excluding 0%

[0084] Regarding sodium (Na), in the subsequent process of recovering valuable metals from the battery crushed material, sodium as part of the same group element reacts in place of lithium in the lithium hydroxide formation process to form sodium hydroxide, thereby reducing lithium recovery or causing a side effect of increasing costs in the causticizing process. For the battery crushed material, the sodium may be contained in an amount of 0.4 wt% or less, specifically, the sodium may be contained in an amount of 0.1 wt% or less.

[0085] If the sodium content is more than the above range, when Na increases, in the crystallization process of Li dissolved in the solvent after the leaching process and the solvent extraction process, Na, as the same Group 1 element as Li, has a problem of reduced yield in the process required for generating lithium carbonate.

[0086] Ca: 0.03 wt% or less, excluding 0%

[0087] 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 battery crushed product. When forming lithium aluminate, calcium has better reactivity than aluminum, so a lithium caseinate structure is formed, thereby hindering the subsequent formation of lithium aluminate that is conducive to the reaction, which will reduce the final lithium recovery rate. For the battery crushed product, the calcium may be contained in an amount of 0.03% or less, specifically, the calcium may be contained in an amount of 0.02% by weight or less.

[0088] If the calcium content is more than the above range, when Ca increases, there is a problem of increased yield and process time in the solid-liquid separation process as an impurity purification process after the leaching process. In addition, if the calcium content is too much, when the precursor nickel, cobalt, manganese hydroxide and lithium hydroxide are synthesized to generate the positive electrode material, Li[NiCoMn] 1-x Ca x )]O2, because the calcium will form an oxide structure of the positive electrode material, hindering the migration of lithium ions, thereby causing the problem of reduced battery capacity.

[0089] Mg: 0.02 wt% or less

[0090] Magnesium (Mg) is an element that makes it difficult to separate a solid phase and a liquid phase during acid leaching in a valuable metal recovery process. In the battery crushed product, the magnesium content may be 0.02 wt % or less, specifically, 0.01 wt % or less.

[0091] If the magnesium content exceeds the above range, there is a problem that the recovery process of nickel, cobalt, lithium, etc. is burdened. In addition, if the magnesium content is too high, when the positive electrode material is synthesized with nickel, cobalt, manganese hydroxide and lithium hydroxide in the precursor state, Li[NiCoMn] 1-x Mg x )]O2, due to the formation of the oxide structure of the positive electrode material, the migration of lithium ions is hindered, resulting in the problem of reduced battery capacity.

[0092] K: 0.02 wt% or less

[0093] Potassium (K) is also a homologue of lithium and inhibits the formation of lithium into hydroxide. For the battery crushed material, the potassium may be contained in an amount of 0.02 wt % or less, specifically, 0.01 wt % or less. If the potassium content is more than the above range, it will cause a burden in the causticizing process, and there is a problem of reducing the recovery rate of lithium.

[0094] According to another embodiment of the present invention, a battery processing method comprises: a step of freezing the battery; a step of crushing the frozen battery; and a step of stabilizing the crushed battery using a cooling fluid. The battery processing method can be a method for processing various batteries containing lithium ions. For example, the battery can be a lithium secondary battery separated from a car, a secondary battery separated from an electronic device such as a mobile phone, a camera, or a laptop computer, specifically a lithium secondary battery.

[0095] In one embodiment, the step of freezing the battery may satisfy the following formula 1.

[0096] <Formula 1>

[0097] Minimum cooling time (hours) = A × (W 0.33 )

[0098] A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

[0099] W in the above formula 1 represents the weight of the battery, for example, the weight of a battery pack, a single battery or a combination thereof. The minimum cooling time represents the time required for cooling the electrolyte in the battery to a target temperature by a cooling temperature (ie, an external cooling temperature) applied to the battery.

[0100] The step of freezing the battery is performed for more than the minimum cooling time, so that the electrolyte inside the battery is cooled, which has the advantage of being able to stably perform subsequent processes. In the step of freezing the battery, if the freezing time of the battery is less than the minimum cooling time, the electrolyte will not be cooled, and there is a risk of fire when the battery is broken.

[0101] The step of freezing the battery is carried out at a temperature sufficient to freeze the electrolyte contained in the battery. Specifically, the freezing step can be carried out at a temperature range of -150°C to -20°C, for example. Specifically, the temperature range can be -150°C to -50°C, more specifically, a temperature range of -80°C to -60°C.

[0102] If the battery is frozen in the temperature range, the residual voltage inside the battery (e.g., about 2V to 3V) drops to nearly 0V, so even if a short circuit occurs where the positive and negative electrodes are in direct contact, a battery reaction does not occur, and the battery temperature does not increase, thereby preventing the generation of electrolyte gas and combustion. In addition, since the electrolyte is in a frozen state or a state where gasification is suppressed, the mobility of lithium ions is very low, and the power-on characteristics based on the migration of lithium ions may be significantly reduced. Since gasification of the electrolyte does not occur, the generation of combustible gases such as ethylene, propylene, and hydrogen can be avoided.

[0103] If the freezing process exceeds the temperature range, for example, it is cooled to a temperature higher than -60°C, the residual voltage inside the battery will not drop to 0V, a battery reaction caused by a short circuit may occur, and the electrolyte will not be completely frozen, so it is not suitable. In addition, when cooled to -150°C, the electrolyte will be fully frozen and the internal voltage of the battery will also drop to 0V, so there is no need to lower the temperature. As described above, the battery processing method has the following advantages: before crushing a battery such as a lithium secondary battery, a freezing step is included, thereby preventing the risk of fire that may occur in the battery crushing process.

[0104] The step of crushing the frozen battery may refer to a process of applying an impact or compressive force to the battery to cause a portion of the battery to fall off. In one embodiment, the step of crushing the battery may refer to a process of crushing the battery, a process of cutting the battery, a process of compressing the battery, and a combination thereof. Specifically, the crushing step may include all processes that can destroy the battery to obtain small-sized crushed objects.

[0105] In one embodiment, the step of crushing the battery may include all processes of compressing the frozen battery or applying external force such as shear force or tensile force to destroy the battery. For example, the step of crushing the battery may be implemented using a crusher.

[0106] In one embodiment, the step of crushing the battery can be performed at least once. Specifically, the crushing step can be performed continuously or discontinuously at least once.

[0107] In one embodiment, the step of crushing the battery can be performed under the condition of supplying inert gas, carbon dioxide, nitrogen, water or a combination thereof or under the condition of a vacuum environment of less than 100 Torr. For example, if the process of freezing the battery is performed by cooling to a temperature range of -60°C to -20°C, if it is performed under the aforementioned conditions, the electrolyte can be prevented from reacting with oxygen by suppressing the supply of oxygen, and the explosion caused can be prevented, and the gasification of the electrolyte can be suppressed, thereby avoiding the generation of flammable gases such as ethylene, propylene or hydrogen.

[0108] In one embodiment, at least one of the unit cell crushed objects included in the battery crushed objects may satisfy the following condition 1.

[0109] <Condition 1>

[0110] The layered structure may have more than 1 layer and less than 7 layers.

[0111] The condition 1 may mean that the step of crushing the layered structure of the unit cell crushed product including a separator having a positive electrode or a negative electrode laminated on at least one surface thereof into a laminated structure of 1 or more layers and 7 or less layers is controlled.

[0112] In one embodiment, the layered structure may be a stacked structure of more than 1 layer and less than 7 layers. Specifically, the layered structure may be a stacked structure of more than 1 layer and less than 5 layers. Since the layered structure is stacked in the range, the temperature rise of the crushed object can be minimized and the heating time can be appropriately consumed. When the layered structure is stacked to be thicker than the upper limit of the range, the temperature rise is excessively increased, the heating time is also increased, and there is a problem of burning.

[0113] In one embodiment, at least one of the unit cell crushed objects included in the battery crushed objects may satisfy the following condition 2.

[0114] <Condition 2>

[0115] The size of the broken unit cells may be less than 100 mm based on the long axis (ie, the longest axis among the lateral, longitudinal and height directions).

[0116] In one embodiment, specifically, the size of the unit battery crushed object is less than 100 mm based on the long axis (i.e., the longest axis in the horizontal, longitudinal and height directions), and specifically, it can be controlled to be less than 50 mm in the crushing step. If the maximum size of the battery crushed object is greater than 100 mm, as the battery crushed object is crushed, the heat generated by instability rises to the average vaporization temperature of the electrolyte, i.e., the temperature region of 120°C, and stability problems such as fire may occur.

[0117] In one embodiment, the step of crushing the battery may further include the step of controlling the proportion of the unit cell crushed objects to be more than 90%, specifically more than 95%, of the total volume of the battery crushed objects. Specifically, it may correspond to controlling the proportion of the unit cell crushed objects having a stacking structure of more than 7 layers to be less than 10% of the total volume of the battery crushed objects. Specifically, the proportion of the unit cell crushed objects having a stacking structure of more than 7 layers may be controlled to be less than 5% of the total volume of the battery crushed objects. By satisfying the above range, there is an advantage of being able to prevent fire.

[0118] In one embodiment, the recovery time required for reducing the temperature of the battery crushed product to a range of 20° C. to 50° C. in the crushing step may be less than 200 minutes. Specifically, the recovery time required for reducing the temperature of the battery crushed product to a range of 35° C. to 45° C. may be less than 200 minutes.

[0119] In one embodiment, the step of stabilizing the battery fragments after crushing by using a cooling fluid may be performed at a temperature range of -20°C to 80°C. If the step is performed at a temperature range exceeding the lower limit of the temperature, additional equipment for maintaining the temperature is required, which is uneconomical. If the step is performed at a temperature range exceeding the upper limit of the temperature, the instability of the battery fragments to fire cannot be resolved.

[0120] In one embodiment, the step of stabilizing the crushed battery fragments by using a cooling fluid can be performed within a range of 30 minutes to 10 hours depending on the type of the cooling fluid. If the lower limit of the time range is exceeded, there is a problem of fire caused by re-heating, and if the upper limit of the time range is exceeded, there is a problem of increased process time leading to a decrease in production.

[0121] In one embodiment, in the step of stabilizing the battery fragments after crushing with a cooling fluid, the cooling fluid can be implemented by at least any one of air, vacuum, inert gas, nitrogen, and water. Since the battery fragments are stabilized by the cooling fluid, there is an advantage that the battery fragments with a low Na content in the impurities in the battery fragments can be obtained. For the cooling fluid, it can be confirmed that the time required for stabilization in a gas or vacuum environment is longer than the stabilization time using a liquid.

[0122] In one embodiment, for the battery treatment method, when the cooling fluid is performed by gas, the average stabilization time may satisfy the following Formula 2.

[0123] <Formula 2>

[0124] B=0.0125A 2 +2.6979A+170.9±100

[0125] In the above formula 2, A represents the size of the crushed object [mm], and B represents the stabilization time [minutes].

[0126] In one embodiment, for the battery treatment method, when the cooling fluid is liquid, the average stabilization time may satisfy the following Formula 3.

[0127] <Formula 3>

[0128] B=-0.0007A 2 +0.3246A+37.07±50

[0129] In the above formula 3, A represents the size of the crushed object [mm], and B represents the stabilization time [minutes].

[0130] The average stabilization time is expressed in minutes as the time required for the battery fragments to cool down to normal temperature after the temperature rises, and refers to the average time relative to the maximum time and the minimum time. Specifically, for Formula 2, the lower limit value can satisfy 0.0125A 2 +2.6979A+70.9 and as the upper limit value can meet 0.0125A 2 The range of +2.6979A+270.9. For equation 3, the lower limit value can be B=-0.0007A. 2 +0.3246A-12.93 and as the upper limit value, B=-0.0007A 2 The range is +0.3246A+87.07.

[0131] For the battery processing method of the present invention, if the stabilization step is performed in gas or liquid, equations 2 and 3 are satisfied respectively, thereby appropriately maintaining the stabilization of the crushed objects according to their size, which has the advantage of reducing the possibility of fire in the crushed objects.

[0132] In one embodiment, a step of separating a product having a maximum size of less than 1 mm from the crushed product may be further implemented. The separation step may be implemented by magnetic screening or specific gravity screening, or by any screening process well known in the art. As described above, due to the further implementation of the separation step, a powder mixed with positive electrode active materials, negative electrode active materials, positive electrode collectors, and negative electrode collectors may be obtained. In addition, in one embodiment, after the crushing process is implemented, a process of removing and separating the electrolyte may also be implemented. The electrolyte removal process may be performed by heat treating the crushed product or vacuum drying it.

[0133] The preferred embodiments and comparative examples of the present invention are described below. However, the following embodiment is only a preferred embodiment of the present invention, and the present invention is not limited to the following embodiment.

[0134] <Battery internal temperature based on minimum freezing time>

[0135] In the absence of freezing, the battery pack used in the embodiment is crushed using the same crusher as in the embodiment. Figure 3a and Figure 3b As shown, a short circuit caused a flame during the crushing process.

[0136] As described above, it can be confirmed through the Examples and Comparative Examples that, since the step of freezing the battery pack including the battery before the battery crushing is included, short circuit and flame will not occur during the battery crushing step, and excellent stability is achieved.

[0137] Figure 1 FIG. 1 shows a battery voltage change based on cooling temperature according to an embodiment of the present invention.

[0138] Reference Figure 1 It was confirmed that when the battery was frozen to -80°C and the battery voltage was measured, the battery pack showed almost the same voltage at a high temperature of about 40°C, room temperature, and -60°C, so the battery characteristics were not lost. Then, if the temperature dropped from -60°C to -70°C, the voltage dropped rapidly, and it was confirmed that the voltage reached 0 at -70°C. As mentioned above, if the battery is frozen to -60°C to -150°C, short circuit will not occur.

[0139] Figure 2 is a graph showing the relationship among battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0140] Reference Figure 2 It can be confirmed that according to the battery processing method of one embodiment of the present invention, the minimum cooling time for cooling the battery in the step of freezing 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, the figure shows the external cooling temperature and the minimum cooling time when the target temperature is set to -70°C and the battery weights are 2.5kg (A), 10kg (B), 20kg (C) and 50kg (D), respectively. When cooling the battery, after a predetermined time, it can be confirmed that the electrolyte of the battery begins to cool and the voltage becomes 0. It can be confirmed that when cooling the battery, a minimum holding time is required to fully cool the inside (specifically the electrolyte).

[0141] Specifically, it can be confirmed that in the heat transfer condition for cooling (heat is taken to the outside), if the specific heat of the battery itself is taken into account, the battery weight and the time required for cooling are required. As described above, in the present invention, in order to cool the battery, the minimum time required for cooling can be confirmed using the external cooling temperature and target temperature for freezing and the battery weight.

[0142] The following Table 1 shows the minimum cooling time based on the battery weight and the external cooling temperature.

[0143]

Table 1

[0144]

[0145] It can be confirmed from Table 1 above that the smaller the battery weight, the shorter the minimum cooling time required for the battery to be cooled. In addition, when cooling is performed using the minimum cooling time derived from the relationship between the battery weight, the external cooling temperature and the target temperature, it can be confirmed that the battery is cooled, specifically, the electrolyte of the battery is cooled. In addition, when the battery is cooled for a time greater than the value of the above formula 1, a fire will not occur during the battery crushing process in the subsequent process. Figure 3a and Figure 3b is a photograph of an embodiment of the present invention according to the minimum cooling time, Figure 3c and Figure 3d It is a photograph of the comparative example according to the minimum cooling time of the present invention.

[0146] Reference Figure 3a and Figure 3b The experiment tested the fire state of the broken objects when the freezing time during battery cooling was less than the required minimum cooling time. In the experiment, when the battery weight was 25kg, the external cooling temperature was -95℃, and the target freezing temperature was -70℃, if the value of the following formula 1 was 7 hours, the experiment was conducted for 5 hours, which was less than the value of the above formula 1.

[0147] <Formula 1>

[0148] Minimum cooling time = A × (W 0.33 )

[0149] A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

[0150] Reference Figure 3c and Figure 3d The experiment tested the fire state of the broken objects when the battery was frozen for more than the minimum freezing time required for battery cooling. In the experiment, the battery weight, external cooling temperature and Figure 3a and Figure 3b Similarly, the minimum freezing time is more than 7 hours.

[0151] Table 2 below compares Figure 3a to Figure 3d The fire occurrence status of the embodiment and the comparative example based on the same battery weight, external cooling temperature and minimum freezing time. For the judgment of the fire occurrence status, if a fire is observed after the battery is crushed, it is represented as "O", and if a fire is not observed, it is represented as "X".

[0152]

Table 2

[0153]

[0154] From Table 2 above, it can be confirmed that if the battery cooling time is less than the value of Formula 1 (equivalent to the minimum cooling time), the electrolyte will not be cooled, and a fire will occur after the battery is broken. As mentioned above, if the battery is cooled with the minimum cooling time of Formula 1, the broken materials can be stably used after the battery is broken, and a fire will not occur.

[0155] <Battery crushing steps-size of crushed objects>

[0156] Even if a frozen battery is crushed, the possibility of fire during crushing is low, but there will be a potential difference in the crushed object depending on the charge state of the battery. In the present invention, the standard for stabilizing the crushed object is set by measuring how much the temperature of the crushed object rises.

[0157] Figure 4 FIG. 4 is a temperature curve diagram of a crushed object based on time according to an embodiment of the present invention.

[0158] Figure 4 The temperature change based on time is shown in the figure to confirm the maximum heating temperature of the broken objects with a size of 20 mm. Specifically, after the battery is broken after the freezing step, the broken objects with a size of 20 mm are placed in the atmosphere, and the temperature change based on time is measured by a cooling method using air. For the broken objects with a size of 20 mm, it can be confirmed that the maximum ignition temperature is about 65°C. It can be confirmed that the maximum ignition temperature is lower than the average vaporization temperature of the electrolyte (i.e., 120°C).

[0159] Table 3 below shows the amount of temperature rise measured according to the size of the crushed objects.

[0160]

Table 3

[0161]

[0162] It can be confirmed from Table 3 above that the reheating temperature varies depending on the size of the crushed object. At the stable temperature used for process design, the average size of the crushed object should be crushed so that the long axis (i.e., the longest axis in the horizontal, vertical and height directions) is within 100 mm.

[0163] <Battery crushing steps-crushed product size>

[0164] In addition, the crushed product needs time to be physically stabilized depending on its size. As a method for stabilizing the crushed product, it is necessary to maintain the crushed product at a temperature below 120°C for a predetermined time, or to maintain the crushed product for a predetermined time under an inert gas flow to reduce contact with oxygen in the atmosphere.

[0165] In the present invention, the crushed product is kept at a room temperature of 30° C. for about 3 hours based on an average crushed product size of 20 mm. At this time, it can be confirmed that the elevated temperature of the crushed product drops to the room temperature level.

[0166] For crushed objects below 100 mm, the stabilization time can be maintained within a few minutes, but for crushed objects exceeding 100 mm, the stabilization time should be at least 3 hours.

[0167] <Battery crushing step - crushed battery material layer control step>

[0168] When the crushed object is crushed below the minimum freezing time, the crushed object will not be brittle fractured in the ultra-low temperature state, so the size of the crushed object is large or the positive electrode collector and the negative electrode collector have multiple layers, resulting in a problem of thickening the thickness of the crushed object. Since the thickness of the layers of the crushed object is thick, the temperature rise is large and the heating time is long.

[0169] Table 4 below shows the temperature rise amount based on the layered structure in the unit cell crushed object according to one embodiment of the present invention measured using a thermal imaging camera.

[0170] Referring to Table 4 below, for the layered structure, positive electrode-separator-negative electrode refers to one layer, and when the broken objects are stacked into multiple layers, the arrangement order is positive electrode-separator-negative electrode-separator-positive electrode-separator-negative electrode... Specifically, it means that the positive electrode or the negative electrode in the waste battery has a separator structure as one layer structure arranged into multiple layers. Specifically, based on the separator, the positive electrode or the negative electrode can be configured on at least one side of the separator.

[0171] In the following Table 4, the average size of the crushed product was evaluated by 20 mm, the temperature was evaluated by the number of layers of the crushed product after crushing, and the recovery time required for the temperature to rise from the freezing temperature to the maximum temperature and then fall to 40°C was measured.

[0172] At this time, the size of the crushed object is measured based on the longer axis of the long axis and the short axis of the crushed object.

[0173]

Table 4

[0174]

[0175] Figure 5a to Figure 5c The broken pieces of unit cells according to one embodiment of the present invention and a comparative example are shown. Figure 5a It can be confirmed that the embodiment and the comparative example have different sizes of the broken pieces of the unit cell and the number of layers in the layered structure.

[0176] Also refer to the Figure 5aAs confirmed in Table 4 above, when the number of layers of the layered structure is 3 or less, the temperature of the crushed material is stably maintained below 110°C, and when the number of layers is more than 7, after the temperature rises to more than 105°C, combustion occurs due to reaction with the electrolyte.

[0177] Reference Figure 5b , the mixing ratio can be confirmed based on the weight ratio of the battery crushed material. Specifically, the layered structure is 7 layers or less ( Figure 5b The weight of the battery fragments is 905g, and the layered structure has more than 7 layers ( Figure 5b The weight of the battery crushed object (on the right side) is 95g.

[0178] In the case of one layer, when the maximum size of the battery fragments exceeds 100 mm, the maximum temperature rises to a temperature higher than 105° C., so the possibility of fire is high. In addition, even if it is less than 100 mm, if the number of layers of the layered structure is 10 or more, specifically more than 7 layers, the possibility of fire becomes high.

[0179] Table 5 below shows the probability of fire according to the weight percentage of battery crushed products having a layered structure of more than 7 layers in the present invention.

[0180]

Table 5

[0181]

[0182] As confirmed in Table 5 above, the result of measuring the frequency of fire occurrence in the crushed objects multiple times per 1 kg of battery shows that even if the crushed objects contain more than 7 layers of layered structure, if the weight ratio is less than 10% based on the total weight ratio, almost no fire will occur. In addition, if the crushed objects contain more than 7 layers of layered structure with a weight ratio of more than 10% based on the total weight ratio, fire will occur in all three experiments. In this case, the ignition position of the fire starts from the crushed objects with a thickness of more than 7 layers. As described above, if the weight ratio of the crushed objects with more than 7 layers of layered structure in the crushed objects is less than 10% relative to the total weight of the crushed objects, specifically less than 5%, the fire of the crushed objects can be prevented. When the crushed objects with more than 7 layers of layered structure or the crushed objects with a size greater than 100 mm in the entire battery crushed objects contain more than 10%, the frequency of fire occurrence becomes high.

[0183] In addition, the following Table 6 confirms whether smoke is generated according to the ratio of burning marks on the surface of the crushed object according to one embodiment of the present invention.

[0184]

Table 6

[0185]

[0186]

[0187] Figure 5c The burning part and the normal part of the surface of the cell crushed object according to one embodiment of the present invention are shown. Figure 5c , it can be confirmed that there are normal parts without burn marks caused by high temperature and broken parts with burn marks caused by high temperature on the surface of the unit cell broken objects. The burnt part is the part with burn marks caused by high temperature, which can be a rapid heating part, and refers to the area with a darker color than the normal part of the unburned part. The burnt part is mostly manifested as the edge burnt part.

[0188] Depend on Figure 5c As confirmed in Table 6 above, when there are almost no burn marks caused by high temperature on the surface of the unit cell crushed object or the burn marks in the surface area are less than 30%, no combustion occurs when evaluating whether smoke occurs, and when the burn marks in the surface area exceed 30%, a fire accompanied by smoke occurs.

[0189] <Battery Stabilization Steps - Stabilization Time>

[0190] Table 7 below shows the stabilization time according to the type of cooling fluid and the size of the crushed object. Specifically, the stabilization time refers to the time (minutes) required for the crushed object to cool down to the normal temperature of 30° C. after the temperature rises.

[0191]

Table 7

[0192]

[0193] Figure 6a The graph shows the stabilization time when the battery fragments are stabilized in the gas cooling fluid according to one embodiment of the present invention. Figure 6a , which shows the stabilization time according to the size of the crushed object when gas is used as the cooling fluid. Specifically, the average stabilization time of the gas is the average time of the maximum time and the minimum time, which can satisfy the above-mentioned formula 2.

[0194] Figure 6b A graph is shown showing the stabilization time when a battery fragment is stabilized in a liquid cooling fluid according to one embodiment of the present invention.

[0195] Reference Figure 6b , which shows the stabilization time according to the size of the crushed objects when liquid is used as the cooling fluid. Specifically, the average stabilization time of the liquid is the average time of the maximum time and the minimum time, which can satisfy the above-mentioned formula 3.

[0196] <Battery stabilization step - Comparison of the components of the final crushed product>

[0197] Table 8 below shows the Na content in the impurities after the stabilization step using a cooling fluid. The cooling fluid refers to air, vacuum (1 Torr), argon (Ar), nitrogen, tap water, brine concentration of 1% or less, brine concentration of 10% or less, and brine concentration of 15% or less.

[0198]

Table 8

[0199]

[0200] From Table 8 above, it can be confirmed that in the cooling fluid test for stabilizing the crushed product after freeze crushing, the impurity Na content in the air is as low as 0.054%, but if about 15% of salt such as table salt is contained, the Na rises to 0.83%. Thus, various impurities contained in the salt can be controlled at once. Table 9 below compares the Na, K, Mg and Ca component values ​​of the crushed product that has been subjected to the step of stabilizing the crushed product in the air after freeze crushing (Example 1) and the crushed product that has been subjected to brine discharge with brine containing 15% salt (Comparative Example 1).

[0201]

Table 9

[0202] Na[%] K[％] Mg[%] Ca[%] Saline 10% 0.50 0.023 0.032 0.031 Brine 15% (Comparative Example 1 0.830 0.027 0.049 0.034 Air (Example 1) 0.054 <0.010 <0.010 0.02 vacuum 0.054 <0.010 <0.010 <0.010 Argon 0.056 <0.010 <0.010 <0.010 Nitrogen 0.053 <0.010 <0.010 <0.010 Tap water 0.08 <0.015 <0.023 0.031

[0203] It can be confirmed from Table 9 above that the battery crushed product produced by the battery recycling method through the frozen crushing and stabilization steps has a lower content of impurities, specifically, less content of Na, K, Mg, and Ca, compared with the battery crushed product produced by brine discharge.

[0204] The preferred embodiments are described in detail above, but the scope of the present invention is not limited to the above embodiments. Various modifications and improvements made by those skilled in the art using the basic concepts defined in the claims also fall within the scope of the present invention.

Claims

1. A unit cell crusher for recovering valuable metals from waste batteries, wherein: The unit cell crushed product has a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface thereof, and satisfies the following conditions 1 and 2, <Condition 1> The layered structure is a stacked structure of 1 or more layers and 7 or less layers, <Condition 2> The size of the unit cell crushed object is 100 mm or less based on the long axis, that is, the longest axis in the lateral, longitudinal and height directions.

2. The unit cell crushed object according to claim 1, wherein: The surface of the unit cell fragments comprises: a burning portion, the burning portion being an area where at least a portion of the surface is burned; and Normal part, the normal part is that there is no burning mark on the surface, The area ratio of the burning portion to the normal portion is 30% or less.

3. The unit cell crushed object according to claim 2, wherein: The burning portion is formed at an edge portion of the surface.

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

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

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

7. A battery processing method, comprising: Steps for freezing the battery; The step of crushing the frozen battery into battery crushed products; and The step of stabilizing the battery fragments after crushing by using a cooling fluid, The battery crushed object comprises at least one unit cell crushed object, The unit cell crushed product has a layered structure including a separator having a positive electrode or a negative electrode laminated on at least one surface thereof, and satisfies the following conditions 1 and 2, <Condition 1> The layered structure is a stacked structure of more than 1 layer and less than 7 layers, <Condition 2> The size of the unit cell crushed product is 100 mm or less based on the long axis, that is, the longest axis among the lateral, longitudinal and height directions.

8. The battery processing method according to claim 7, wherein: The crushing step includes the step of controlling the ratio of the crushed unit cells to be 90% or more of the total volume of the crushed unit cells.

9. The battery processing method according to claim 7, wherein: The step of freezing the battery satisfies the following formula 1: <Formula 1> Minimum cooling time (hours) = A × (W 0.33 ) A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

10. The battery processing method according to claim 7, wherein: The freezing step is performed by cooling to -150°C to -20°C.

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

12. The battery processing method according to claim 7, wherein: The cooling fluid is implemented by at least any one of air, vacuum, nitrogen, inert gas, and water.

13. The battery processing method according to claim 7, wherein: When the cooling fluid is a gas, the average stabilization 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"> +2.6979A+170.9±100 In the above formula 2, A represents the size of the crushed object [mm], and B represents the stabilization time [minutes].

14. The battery processing method according to claim 7, wherein: When the cooling fluid is liquid, the average stabilization time satisfies the following formula 3: <Formula 3> B=-0.0007A 2 +0.3246A+37.07±50 In the above formula 3, A represents the size of the crushed object [mm], and B represents the stabilization time [minutes].

15. The battery processing method according to claim 7, wherein: The freezing step is carried out by cooling to -60°C to -20°C, The crushing step is performed under vacuum conditions below 100 Torr.

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

17. The battery processing method according to claim 7, wherein: After the crushing step, a magnetic screening or specific gravity screening step is further included to separate products with a maximum size of less than 1 mm.

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