Battery processing method

Abstract

The present invention relates to a battery treatment method, which relates to a method of treating a waste battery, the method comprising: a step of preparing a battery; a step of measuring a voltage of the battery; a step of subjecting the battery to a low-temperature treatment at a temperature below a minimum temperature according to the voltage of the battery; and a step of crushing the battery, the minimum temperature satisfying the following formula 1. The battery treatment method is the minimum temperature satisfying the following formula 1, <Formula 1> Minimum temperature = 21.42857 + (-21.1255) x Voltage + (-0.69264) x Voltage 2 ± 0.5 In the above formula 1, the voltage represents a battery cell reference voltage of the battery.

Description

Technical Field

[0001] This invention relates to waste batteries, and more specifically to a method for crushing batteries for recycling waste batteries. Background Technology

[0002] Due to environmental concerns, the demand and supply of electric vehicles have increased dramatically, and battery technology is a key element of electric vehicles. The disposal of waste batteries generated by electric vehicles has become a social problem. This type of electric vehicle battery is a rechargeable secondary battery characterized by containing lithium. The core components of the battery include a positive electrode material, a negative electrode material, a current collector, an electrolyte, and a separator.

[0003] The positive electrode material uses Ni, Co, and Mn oxides as raw materials, while the negative electrode material uses carbon. Aluminum and copper foil are used as current collectors. For the battery, to fit the smallest unit (cell) into a battery pack for automotive assembly, a plastic casing and steel bolts, nuts, and frames are used. In this battery, valuable metals such as Li, Ni, Co, and Mn have high value, especially Li, whose value has recently increased dramatically. Therefore, there is growing interest in the recycling and reuse of these rare components.

[0004] Even when automotive batteries have reached the end of their lifespan, they can still be reused in other areas. These other areas could include, for example, energy storage systems (ESS). In such systems, batteries that have reached the end of their lifespan are considered waste batteries.

[0005] The waste battery recycling process typically involves dismantling, discharging, crushing, and heat treatment to produce black matter, which is then refined using a wet process to become a raw material for the cathode. However, due to the fire and explosion risks associated with the battery crushing process, various methods for safe crushing are being researched.

[0006] Water discharge using water or salt water is a typical method for safely breaking down the battery. However, this requires breaking it down to the individual battery cells and additional processing to allow the solution to permeate into the cells. Therefore, it is labor-intensive, generates wastewater, and is not environmentally friendly. Furthermore, the use of salt water introduces pollution from components such as Na, Cl, K, and Mg.

[0007] As mentioned above, as a first step in the reuse of waste batteries, there is an increasing focus on safe and environmentally friendly battery disposal methods. Summary of the Invention

[0008] Technical problems to be solved The technical problem to be solved by the present invention is to provide a battery treatment method for safely crushing waste batteries.

[0009] Technical solution A battery processing method according to an embodiment of the present invention relates to a method for processing waste batteries, comprising: a step of preparing a battery; a step of measuring the voltage of the battery; a step of subjecting the battery to cryogenic treatment at a temperature below a minimum temperature according to the voltage of the battery; and a step of crushing the battery, wherein the minimum temperature satisfies the following formula 1.

[0010] <Formula 1> Minimum temperature = (21.42857 + (-21.1255) × voltage + (-0.69264) × voltage 2 ±0.5 In Equation 1 above, voltage represents the voltage of the battery.

[0011] In one embodiment, the measured voltage of the battery in the battery voltage measurement step can be 0 to 4.2V based on a single battery cell. In one embodiment, the low-temperature treatment step can be treating the battery at a temperature below 10°C.

[0012] In one embodiment, the cryogenic treatment step involves subjecting the battery to a minimum freezing time. The minimum freezing time can satisfy the following formula 2.

[0013] <Formula 2> Minimum freezing time = (1.55461 + (-0.06551 × target temperature) + (7.47E-5 × target temperature²)) × weight 0.32 ±0.45 In Equation 2 above, the target temperature represents the target temperature (°C) used for low-temperature treatment of the battery, and the weight represents the weight of the battery (kg).

[0014] In one embodiment, when the battery is a battery module having multiple individual cells, the freezing time for the battery can be 10 hours or more in the step of cryogenically treating the battery according to its voltage for a minimum freezing time. In one embodiment, the battery module can have a weight of 28 to 32 kg.

[0015] In one embodiment, in the step of cryogenically treating the battery according to its voltage for a minimum freezing time, if the battery is a single cell, the freezing completion time may be 2 hours or more. In one embodiment, the single cell may have a weight of 0.5 to 1.5 kg.

[0016] In one embodiment, the battery crushing step may involve crushing the battery into a particle size range of 5 to 80 mm. In another embodiment, the battery crushing step may be performed using a twin-shaft, two-stage crusher.

[0017] In one embodiment, the battery voltage measurement step may include a step of reducing the battery voltage. In one embodiment, the battery fragments after the battery crushing step may satisfy either condition 1 or condition 2.

[0018] <Condition 1> The layered structure can be a stacked structure with more than one layer and less than seven layers.

[0019] <Condition 2> The size of the battery fragments can be less than 100mm based on the longest axis of the longest axis in the horizontal, vertical and vertical directions.

[0020] Beneficial effects According to one embodiment of the present invention, a battery handling method provides a method for safely breaking down a battery by controlling a minimum cooling temperature based on the voltage of the individual cells within the battery. Attached Figure Description

[0021] Figure 1a and Figure 1b This is a photograph of broken battery material according to an embodiment of the present invention.

[0022] Figure 2a and Figure 2b This illustrates a battery fire during the crushing step of the present invention.

[0023] Figure 3a and Figure 3b The temperature of the crusher and the crushed material is measured during the crushing step of the present invention.

[0024] Figure 4 The time required for freezing is shown based on the battery module temperature. Detailed Implementation

[0025] The terms "first," "second," "third," etc., are used to describe parts, components, regions, layers, and / or segments, but these parts, components, regions, layers, and / or segments should not be limited by these terms. These terms are only used to distinguish one part, component, region, layer, or segment from another. Therefore, without departing from the scope of the invention, the first part, component, region, layer, or segment described below can also be described as a second part, component, region, layer, or segment.

[0026] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. Unless the context clearly indicates otherwise, the singular forms used herein are intended to include the plural forms as well. The word "comprising" as used in the specification can specifically refer to a feature, domain, integer, step, action, element, and / or component, but does not exclude the presence or addition of other features, domains, integers, steps, actions, elements, and / or components.

[0027] If one part is described as being on top of another part, then other parts may exist directly on top of or in between the other part. If one part is described as being directly on top of another part, then no other parts exist in between.

[0028] Although not otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in dictionaries should be interpreted as having the same meaning as disclosed in relevant technical literature and herein, and should not be interpreted in an idealized or overly formal sense.

[0029] Embodiments of the present invention will be described in detail below. However, the following embodiments are given by way of example only, and the present invention is not limited to the following embodiments; the present invention is defined only by the scope of the claims.

[0030] A battery processing method according to an embodiment of the present invention can be a method for processing waste batteries. Specifically, the method includes: a step of preparing a battery; a step of measuring the voltage of the battery; a step of performing a cryogenic treatment on the battery at a temperature below a minimum temperature according to the battery voltage; and a step of crushing the battery. Specifically, the battery processing method of the present invention can be a method that stably processes batteries by performing a cryogenic treatment process based on the battery voltage for a minimum freezing time, ensuring that a fire will not occur when the battery is crushed.

[0031] In the battery preparation step, the battery can be, for example, a lithium secondary battery separated from a car, or a secondary battery separated from electronic devices such as mobile phones, cameras, and laptops; specifically, it can be a lithium secondary battery. Specifically, the battery can be a spent battery that has reached the end of its lifespan. The battery can have a voltage of approximately 4.5V at 100% SOC. The battery of the present invention can have a voltage of 2.0 to 4.5V. Specifically, the voltage is 2.5 to 4.0V, more specifically, it can be 3.0 to 4.0V.

[0032] The battery voltage measurement step can be a step of measuring the voltage of the battery. For example, the battery voltage measurement step can be a step of measuring the voltage of a battery module, battery pack, or individual battery cell. Specifically, the battery voltage measurement step can be a step of measuring the voltage of an individual battery cell. Specifically, the voltage measurement step can be a step of using a conventional tester to contact the terminals of the battery with the positive and negative terminals to measure the voltage of the individual battery cell. The battery voltage measurement step can also be a step of determining the state of the battery to freeze the battery using the minimum freezing time described below.

[0033] In one embodiment, the battery voltage measured in the battery voltage measurement step can be 0 to 4.2V based on a single battery cell. Specifically, the waste battery may have a voltage of approximately 4.2V at 100% SOC, and a voltage lower than 4.2V may be measured.

[0034] In one embodiment, the battery voltage measurement step may include a step of reducing the battery voltage. Specifically, the battery voltage may be controlled within a range of 0 to 4.2V, based on the individual battery cells. For example, the step of reducing the battery voltage can be controlled by discharging the battery cells.

[0035] The step of cryogenically treating the battery at a temperature below a minimum based on the battery's voltage can be a step of freezing and stabilizing the electrolyte contained within the battery. By treating the battery to a minimum temperature, it is possible to prevent the electrolyte and other hazardous substances from causing a fire in the event of battery breakage.

[0036] In one embodiment, the minimum temperature may satisfy Equation 1 below.

[0037] <Formula 1> Minimum temperature = 21.42857 + (-21.1255) × voltage + (-0.69264) × voltage 2 ±0.5 In Equation 1 above, voltage represents the reference voltage (V) of a single cell in the battery.

[0038] Equation 1 above refers to the minimum cooling temperature based on the reference voltage of the battery's individual cells during the battery cryogenic treatment process. Equation 1 has the formula: 21.42857 + (-21.1255) × voltage + (-0.69264) × voltage 2 The lower limit of -0.5 and 21.42857 + (-21.1255) × voltage + (-0.69264) × voltage 2 The upper limit of +0.5 means that in the battery cryogenic treatment step, the cryogenic treatment step can be performed at a temperature below the range of the lower and upper limits of Equation 1 above.

[0039] By satisfying Equation 1 above, cryogenic treatment of batteries with specific voltages can be easily performed, thereby minimizing the risk of battery fires during the breakup process. If cryogenic treatment of batteries exceeds the aforementioned range of Equation 1, stabilization of batteries with specific voltages cannot be achieved smoothly, and problems such as fires may occur when the batteries are broken up.

[0040] In one embodiment, the cryogenic treatment step may be a step of treating the battery at a temperature below 10°C. Specifically, for the cryogenic treatment step, when the battery voltage is below 1.0V, the battery is cryogenically treated at a temperature below 0°C. More specifically, when the battery voltage is between 1.5 and 2.0V, the battery is cryogenically treated at a temperature below -15°C. More specifically, when the battery voltage is approximately 2.5V, the battery may be cryogenically treated at a temperature below -30°C. More specifically, when the battery voltage is between 3 and 3.5V, the battery may be cryogenically treated at a temperature below -50°C. As described above, since the battery is cryogenically treated within a specific temperature range based on the battery cell reference voltage, it has the advantage of enabling safe crushing during the crushing process.

[0041] Because the battery undergoes a cryogenic treatment within the specified temperature range, the trace residual voltage inside the battery, such as approximately 2V to 3V, drops to near 0V. Therefore, even if a short circuit occurs where the positive and negative electrodes are in direct contact, no battery reaction will occur, and the battery temperature will not increase, thus preventing the generation and combustion of electrolyte gases. Furthermore, the electrolyte is in a frozen or suppressed vaporization state, resulting in very low lithium-ion mobility. The electrical conductivity based on lithium-ion migration is significantly reduced, preventing electrolyte vaporization and thus preventing the production of flammable gases such as ethylene, propylene, and hydrogen.

[0042] If the cryogenic treatment step is performed at a temperature higher than the stated temperature range, the residual voltage inside the battery will not drop to 0V, potentially leading to a short circuit and battery reaction. Furthermore, the electrolyte cannot be completely frozen, making this method unsuitable. As described above, by including a cryogenic treatment step before breaking up batteries such as lithium-ion batteries, the battery processing method offers the advantage of preventing fire risks that may occur during the battery breaking process.

[0043] In one embodiment, the cryogenic treatment step may include a step of treating the battery for a minimum freezing time. The minimum freezing time may satisfy the following formula 2.

[0044] <Formula 2> Minimum freezing time = (1.55461 + (-0.06551 × target temperature) + (7.47E-5 × target temperature²)) × weight 0.32 ±0.45 In Equation 2 above, the target temperature represents the target temperature (°C) used for low-temperature treatment of the battery, and the weight represents the weight of the battery (kg).

[0045] Equation 2 above refers to the minimum freezing time of the battery derived from the battery's weight and freezing time. For Equation 2 above, the minimum freezing time can satisfy (1.55461 + (-0.06551 × target temperature) + (7.47E-5 × target temperature). 2 ))×weight 0.32 The lower limit is -0.45 and (1.55461 + (-0.06551 × target temperature) + (7.47E-5 × target temperature) 2 ))×weight 0.32 The range of the upper limit value of +0.45 allows for the time to satisfy the value of Equation 2 above the range of the upper and lower limits.

[0046] Since Equation 2 satisfies the aforementioned range, the minimum freezing time is considered when stabilizing the battery by cryogenic treatment before the battery crushing step and when the battery can be safely crushed during the crushing step, thereby improving economy and safety. If Equation 2 does not satisfy the aforementioned range, there is a problem that the electrolyte inside the battery will not be properly frozen and stabilized.

[0047] In one embodiment, the cryogenic treatment step of the battery can be performed for more than 2 hours. Specifically, if the battery is a battery module containing multiple battery cells, the freezing time of the battery module can be more than 10 hours. Specifically, the freezing time of the battery module can be 10 to 26 hours. The weight of the battery module can be 28 to 32 kg.

[0048] If the battery is a single cell, the freezing time for the single cell can be more than 2 hours. Specifically, it can be more than 3 hours, and more specifically, it can be 3 to 12 hours. The weight of the single cell can be 0.5 to 1.5 kg.

[0049] Because the aforementioned time is taken for the low-temperature treatment of the battery, the battery stabilization is facilitated, and a fire caused by the battery can be prevented when the battery is broken.

[0050] If the time taken for the battery freezing step is significantly longer than the stated time, it becomes uneconomical. If the time taken for the battery freezing step is significantly shorter than the stated time, battery stabilization may be difficult to achieve.

[0051] The battery crushing step can refer to a process that applies impact or pressure to the battery, causing a portion of the battery to detach from the battery. In one embodiment, the battery crushing step can refer to all processes of pulverizing the battery, cutting the battery, compressing the battery, and combinations thereof. Specifically, the crushing step can include all processes capable of destroying the battery to obtain small-sized fragments.

[0052] In one embodiment, the battery crushing step may include all processes of compressing a frozen battery or applying external forces such as shear or tensile forces to destroy the battery. For example, the battery crushing step may be carried out using a crusher.

[0053] In one embodiment, the battery crushing step can be performed at least once. Specifically, the crushing step can be performed continuously or discontinuously at least once. In one embodiment, the battery crushing step can be performed using a twin-shaft, two-stage crusher.

[0054] In one embodiment, the battery crushing step can be carried out under conditions of supplying inert gas, carbon dioxide, nitrogen, water, or a combination thereof, or under vacuum conditions below 100 Torr. For example, when the battery freezing process is carried out by cooling in a temperature range of -60 to -20°C, if carried out under the aforementioned conditions, the reaction between the electrolyte and oxygen can be prevented by suppressing the oxygen supply, thus preventing an explosion, and the vaporization of the electrolyte is suppressed, so that flammable gases such as ethylene, propylene, or hydrogen are not produced.

[0055] In one embodiment, the battery fragments broken by the battery breaking step can satisfy the following condition 1.

[0056] <Condition 1> The layered structure can be a stacked structure with more than one layer and less than seven layers.

[0057] The battery fragments can be a layered structure with one to seven layers. Specifically, the layered structure can be a layered structure with one to five layers. As the layered structure is stacked within this range, the temperature rise of the fragments is minimized, and the heating time is appropriately reduced. If the layer thickness exceeds the upper limit of this range, the temperature rise increases excessively, the heating time also increases, and there is a risk of fire during combustion.

[0058] In one embodiment, the broken battery material may satisfy the following condition 2.

[0059] <Condition 2> The size of the battery fragments can be less than 100mm based on the longest axis of the longest axis in the horizontal, vertical and vertical directions.

[0060] In one embodiment, the battery fragments, with their long axis as a reference, can have a size of less than 100 mm. Specifically, the size of the battery fragments can be less than 50 mm. If the size of the battery fragments is too large, the temperature of the battery fragments themselves can rise above 100°C, posing a higher risk of fire.

[0061] Preferred embodiments and comparative examples of the present invention are described below. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the following embodiments.

[0062] <Experimental Example> Battery preparation steps With a SOC of 100%, batteries with voltages of 4, 3.5, 3, 2.5, 1.5, 1, 0.5, and 0V were prepared based on individual battery cells, corresponding to an NCM622 lithium-ion battery with a voltage of approximately 4.2V. The target battery voltage was adjusted by discharging, with each cell discharged at 1-10A for no more than 5 hours, progressively discharging from 3.5V to 0V. The voltage recovered within 24 hours after discharge was used as the target voltage, and the batteries were then prepared accordingly.

[0063] Table 1 below shows the amperes based on battery voltage.

[0064] Table 1 Voltage (V) Ampere (A) 4.2~3.5 10 3.5~3.0 5 3.0~0.5 3 0.5~0 1 Ultra-low temperature treatment steps To confirm the point at which the sample temperature was the same as the freezer temperature, the sample was connected to a thermometer (ThermoCouple, TC) and the freezing process was performed. The point at which the freezing was completed was then confirmed.

[0065] Battery breakage steps The batteries that have undergone the cryogenic treatment are crushed in a dual-shaft, dual-stage crusher within a particle size range of 5 to 80 mm. The crushing process is completed within 5 minutes for battery modules and within 3 minutes for individual battery cells.

[0066] Figure 2a and Figure 2b This illustrates a battery fire during the crushing step of the present invention.

[0067] Figure 2a The image shows the battery catching fire during the battery breakage process. Figure 2b The image shows the battery fragments catching fire after the battery broke. See above, reference... Figure 2a and Figure 2b Because the battery contains flammable substances such as electrolyte, applying a predetermined external force to the battery maximizes its activation energy, posing a risk of fire. Therefore, a cryogenic treatment step is needed to stabilize the flammable substances within the battery.

[0068] Figure 3a and Figure 3b The temperature of the crusher and the crushed material is measured during the crushing step of the present invention.

[0069] Figure 3a It is used to measure the internal temperature of the pulverizer. Figure 3b It measures the temperature of the material being crushed. By measuring the internal temperature of the crusher and the temperature of the material being crushed, it is possible to determine whether a battery has caught fire.

[0070] <Evaluation Example 1>: Deriving the optimal temperature range based on voltage. The purpose of cryogenic treatment of the battery is to prevent electrolyte vaporization. It was found that the temperature rise after breakage varies depending on the residual voltage within the battery. Therefore, the voltage of the battery was measured at individual cell levels, and the cryogenic treatment temperature based on this voltage was determined.

[0071] The voltage is measured using a voltage tester by contacting the terminals with the positive and negative terminals of the battery. Whether a fire has occurred is determined by visual inspection and by using thermal imaging cameras installed inside the shredder and in the shredded material recovery bin to observe temperature changes inside the shredder and in the shredded material during the shredding process. If a fire has occurred, it is indicated as ○; if no fire has occurred, it is indicated as ×.

[0072] Table 2 below shows whether a fire occurred during cryogenic treatment based on voltage.

[0073] Table 2

[0074] As shown in Table 2 above, regarding the minimum cooling temperature index based on voltage (i.e., the value of Equation 1), it has been confirmed that no fire occurred during the battery breakage process when the battery was subjected to cryogenic treatment at temperatures below the value of Equation 1. Specifically, it has been confirmed that no fire occurred when the battery was subjected to cryogenic treatment at temperatures below the upper to lower limits of Equation 1.

[0075] <Evaluation Example 2>: Minimum freezing time based on weight and freezing treatment temperature Figure 4 The time required for freezing is shown based on the battery module temperature.

[0076] Reference Figure 4For a battery module weighing approximately 30 kg, the temperature will decrease over time. Therefore, the battery is subjected to cryogenic treatment at -60°C for 24 hours. Specifically, Figure 4 This graph shows the measurement results of the time required for the battery module to reach the freezer temperature of -60°C when the battery module is placed in a freezer set to -60°C. More specifically, it can be the freezing time required to freeze the battery module to the target temperature.

[0077] Table 3 below shows the temperature-based freezing time based on the weight of the battery module and individual battery cells.

[0078] Table 3

[0079] As shown in Table 2 above, when a 30kg battery module, a 1kg battery cell, or three 3kg battery cells are placed in a freezer at a set temperature, it has been confirmed that when the battery freezing time exceeds the minimum freezing time required to reach the set freezer temperature (i.e., the range in Equation 2), hazardous substances such as the electrolyte inside the battery will become stable. Specifically, when a 30kg battery module is placed in a freezer at -40℃, it has been confirmed that it requires cooling for more than 13 hours to reach the target temperature of -40℃, the same as the freezer temperature. Furthermore, it has been confirmed that when the battery cooling time is shorter than the minimum freezing time required to reach the target temperature (i.e., the lower and upper limits of Equation 2), the battery temperature will not reach the target temperature, i.e., the freezer temperature.

[0080] In contrast, when the battery cooling time exceeds the range of the lower to upper limits of Equation 2, it has been confirmed that the temperature is set to be the same as the set target temperature, i.e., the temperature of the freezer. As described above, by deriving the minimum cooling time based on the battery weight, the battery can be effectively stabilized before the battery breakage process, preventing problems such as fires.

[0081] The preferred embodiments have been 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 battery processing method, comprising: Steps for preparing batteries; The step of measuring the voltage of the battery; The step of performing cryogenic treatment on the battery at a temperature below a minimum temperature according to the battery voltage; and The step of breaking the battery. The minimum temperature satisfies the following equation 1. <Formula 1> Minimum temperature = 21.42857 + (-21.1255) × voltage + (-0.69264) × voltage 2 ± 0.5 In Equation 1 above, voltage represents the voltage of the battery.

2. The battery processing method according to claim 1, wherein, In the battery voltage measurement step, the measured voltage of the battery is 0 to 4.2V based on a single battery cell.

3. The battery processing method according to claim 1, wherein, The low-temperature treatment step involves treating the battery at a temperature below 10°C.

4. The battery processing method according to claim 1, wherein, The cryogenic treatment step involves subjecting the battery to a minimum freezing time. The minimum freezing time satisfies the following formula 2. <Formula 2> Minimum freezing time = (1.55461 + (-0.06551 × target temperature) + (7.47E - 5 × target temperature) 2 )) × weight 0.32 ±0.45 In Equation 2 above, the target temperature represents the target temperature (°C) used for low-temperature treatment of the battery, and the weight represents the weight of the battery (kg).

5. The battery processing method according to claim 1, wherein, In the step of subjecting the battery to low-temperature treatment for a minimum freezing time based on the battery voltage, When the battery is a battery module having multiple battery cells, The battery is to be frozen for more than 10 hours.

6. The battery processing method according to claim 5, wherein, The battery module has a weight of 28 to 32 kg.

7. The battery processing method according to claim 1, wherein, In the step of subjecting the battery to low-temperature treatment for a minimum freezing time based on the battery voltage, When the battery is a single battery cell The battery is to be frozen for more than 2 hours.

8. The battery processing method according to claim 7, wherein, The battery cell has a weight of 0.5 to 1.5 kg.

9. The battery processing method according to claim 1, wherein, The battery crushing step involves crushing the battery into particles ranging from 5 to 80 mm in size.

10. The battery processing method according to claim 1, wherein, The battery crushing step is performed using a dual-shaft, dual-stage crusher.

11. The battery processing method according to claim 1, wherein, The battery voltage measurement step includes a step of reducing the battery voltage.

12. The battery processing method according to claim 1, wherein, The battery fragments obtained after the battery crushing step meet either condition 1 or condition 2. <Condition 1> The layered structure is a stacked structure with one to seven layers. <Condition 2> The size of the battery fragments is less than 100mm based on the longest axis of the longest axis in the horizontal, vertical, and height directions.

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