Disposal method for waste batteries

Abstract

The present invention relates to a method for treating waste batteries, comprising the steps of preparing waste batteries, discharging the waste batteries, and crushing the discharged waste batteries, wherein the step of discharging the waste batteries has a discharge rate of 0.5V / min or less and satisfies the following formula 1: <Expression 1> 0.1≦Discharge rate × Expansion amount × Maximum temperature≦50.0 (In the above formula 1, the discharge rate is the discharge rate [Voltage / min] in the discharge stage of the waste battery, and the expansion amount [mm] and the maximum temperature [°C] respectively mean the expansion amount and the maximum temperature of the waste battery in the discharge stage of the waste battery.)

Description

[Technical Field]

[0001] The present invention relates to a method for treating batteries, and more particularly to a method for treating waste batteries. [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, for example, LiPF6.

[0004] In order to utilize the waste batteries, there is a great deal of interest in a waste battery recycling process in which the waste batteries are crushed to generate intermediate materials such as waste battery crushed material or black powder, and valuable metals are recovered through a post-process, and research into this process is being actively conducted.

[0005] To reuse these waste batteries, they must first be physically disassembled. This physical disassembly process requires stability as it can lead to problems such as battery explosion and electric shock. After the physical disassembly, holes are formed in the battery and it is discharged using salt water. After the discharge is complete, the battery is crushed and then subjected to high-temperature heat treatment to remove water and electrolyte.

[0006] When discharging batteries in saltwater, the salt used contains large amounts of impurities such as Na, K, Cl, Mg, or Ca, which are present in waste batteries. The water used in saltwater discharge contains some of the electrolyte, making it classified as wastewater, which increases the burden on the environment. With conventional discharge technology, lithium ions move from the negative electrode to the positive electrode during discharge. When the lithium ions are used up and sustained discharge begins, the Cu current collector undergoes electrolysis, causing the cations to move and cover the surface of the positive electrode.

[0007] It then grows on the Cu surface, passing through the separator and connecting to the anode, causing a short circuit. In this process, a large amount of heat is generated, and although this heat is released to the outside, it heats the electrolyte inside, increasing the risk of explosion. Summary of the Invention [Problem to be solved by the invention]

[0008] A battery disposal method according to one embodiment of the present invention provides a method for disposing of waste batteries with reduced risk of explosion during electrical discharge. [Means for solving the problem]

[0009] A method for treating waste batteries according to an embodiment of the present invention includes preparing waste batteries, discharging the waste batteries, and crushing the discharged waste batteries, wherein the discharge rate of the waste batteries in the discharging step is 0.5 Voltage / min or less, and the following formula 1 can be satisfied: <Expression 1> 0.1≦|Discharge rate × Expansion amount × Maximum temperature|≦50.0 (In the above formula 1, the discharge rate is the discharge rate [Voltage / min] in the discharge stage of the waste battery, and the expansion amount [mm] and the maximum temperature [°C] respectively mean the expansion amount and the maximum temperature of the waste battery in the discharge stage of the waste battery.)

[0010] In one embodiment, the formula 1 may satisfy a range of 0.10 to 42.0. In one embodiment, the formula 1 may satisfy a range of 0.19 to 12.0.

[0011] In one embodiment, discharging the waste battery may include measuring an expansion amount of the waste battery and controlling a discharge rate and a cooling temperature so that the expansion amount is less than 20 mm. In one embodiment, discharging the waste battery may include measuring a temperature of the waste battery.

[0012] In one embodiment, measuring the temperature of the waste battery may include controlling the temperature of the waste battery to 80° C. or less. In one embodiment, preparing the waste battery or discharging the waste battery may include cooling the waste battery.

[0013] In one embodiment, the step of cooling the waste batteries may include cooling the waste batteries to below 0° C. In one embodiment, the step of cooling may use a cooling means including at least one of a refrigerator, air at a low temperature, carbon dioxide at a low temperature, nitrogen at a low temperature, dry ice, liquid nitrogen, and water.

[0014] In one embodiment, when the battery is configured as a battery pack, which is a collection of a plurality of cells, the discharge rate may satisfy the following Equation 2: <Expression 2> Discharge rate = (maximum voltage per pack / number of series-connected cells in the pack) x 0.04V / min ±0.05

[0015] In another embodiment, the discharge rate may be less than 0.1 V / min. In yet another embodiment, the battery expansion amount may be 10.5 mm or less.

[0016] In one embodiment, when the battery is configured as a battery pack, which is a collection of a plurality of cells, the discharge rate may satisfy the following Equation 3: <Expression 3> Discharge rate = (maximum voltage per pack / number of series-connected cells in the pack) x 0.5V / min ±0.05

[0017] In another embodiment, the discharge rate may be 0.2 V / min or less. In yet another embodiment, the battery expansion amount may be 2 mm or less. [Effects of the Invention]

[0018] A battery treatment method according to an embodiment of the present invention provides a battery treatment method in which a discharge rate is controlled as a means for controlling a surface temperature of the waste battery for discharge during electrical discharge of the waste battery, and discharge is performed together with low-temperature cooling as a method for increasing the discharge rate. [Brief explanation of the drawings]

[0019] [Figure 1a] This is a photo showing the amount of battery expansion measured according to the discharge rate. [Figure 1b] This is a photo showing the amount of battery expansion measured according to the discharge rate. [Figure 2a] The graphs show the temperature evaluation results and the results for the amount of expansion. [Figure 2b]The graphs show the temperature evaluation results and the results for the amount of expansion. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] A method for treating waste batteries according to an embodiment of the present invention may include preparing waste batteries, discharging the waste batteries, and crushing the discharged waste batteries.

[0026] The step of preparing the battery may include preparing a material itself that will be used as a base material for the crushed battery material. Specifically, the waste battery may be a waste battery that has reached the end of its life. The waste battery may be, for example, a lithium secondary battery, and may include a battery cell disassembled from a large-capacity battery pack such as an electric vehicle battery pack.

[0027] The discharge of the waste battery is a step for preventing the risk of explosion due to residual electric energy in the waste battery. Specifically, the discharge of the waste battery is a pretreatment step for preventing stability problems such as fires caused by external impacts applied during subsequent processes such as dismantling and crushing the waste battery.

[0028] In one embodiment, discharging the waste battery may be performed by electrical discharge. Specifically, the electrical discharge may be performed at a discharge rate within a predetermined range.

[0029] In one embodiment, the discharge rate of the waste battery may be 0.5V / min or less. Specifically, the discharge rate may be 0.05V / min or less. More specifically, the discharge rate may be 0.01 to 0.05V / min or less.

[0030] When a battery is discharged within the above-mentioned discharge rate range, the expansion of the battery can be maintained within an appropriate range, and the waste battery can be recycled while maintaining stability. When the discharge rate is higher than the above-mentioned range, the chemical structure of the battery changes rapidly, which makes the battery unstable and causes expansion due to evaporation of the cathode material and electrolyte in the battery.

[0031] In one embodiment, discharging the waste battery may include controlling the expansion of the waste battery to less than 20 mm. The expansion of the battery is a quantification of the extent to which the battery expands in the thickness direction during discharging. Specifically, the method may include measuring the expansion of the waste battery and controlling a discharge speed and a cooling temperature so that the expansion is less than 20 mm.

[0032] If the expansion amount of the waste battery is greater than the above range, the side of the waste battery may be torn, vaporizing the battery and causing a fire. In one embodiment, the step of discharging the battery may be performed so that the expansion amount of the battery is 2 mm or less. Specifically, the expansion amount of the battery may be 1 mm or less, more specifically, 0.5 mm or less.

[0033] If the battery expansion amount is higher than the above range, the chemical structure in the battery may change suddenly due to evaporation of the cathode material and the electrolyte, which may cause stability problems when performing a subsequent process in the waste battery recycling process.

[0034] In one embodiment, the step of discharging the waste battery may include measuring a temperature of the waste battery. Specifically, the step of measuring a temperature of the waste battery may control the temperature of the waste battery to 80° C. or less.

[0035] The step of measuring the temperature of the waste battery may include measuring the temperature of the waste battery while discharging the waste battery. By measuring the temperature of the waste battery, the waste battery can be discharged while checking the stability of the waste battery.

[0036] In one embodiment, the step of preparing the waste battery or the step of discharging the waste battery may include a step of cooling the waste battery. The waste battery may be subjected to a discharge and crushing process at a low temperature after the cooling step.

[0037] For example, the cooling step may be performed during the waste battery preparation step, the waste battery discharge step, or the waste battery preparation step and the waste battery discharge step. Specifically, by performing the cooling step during the waste battery preparation step, the amount of expansion of the waste battery in the subsequent waste battery discharge step can be significantly reduced.

[0038] Specifically, if the temperature of the waste battery exceeds 80° C. during the discharge of the waste battery, the cooling step can be performed to control the temperature within the above range. By including the cooling step in the discharge of the waste battery, the risk of fire caused by expansion or destruction of the waste battery during the discharge of the waste battery can be reduced.

[0039] In one embodiment, the cooling step may use a cooling means including at least one of a refrigerator, low-temperature air, low-temperature carbon dioxide, low-temperature nitrogen, dry ice, liquid nitrogen, and water. In the low-temperature air, low-temperature carbon dioxide, and low-temperature nitrogen, the low temperature means a temperature of 10° C. or less, specifically 5° C. or less. As a non-limiting example, the cooling means may cool the waste battery using various cooling methods, for example, a cooling fluid method.

[0040] In one embodiment, the waste battery treatment method can satisfy the following formula 1: <Expression 1> 0.10≦|Discharge rate × Expansion amount × Maximum temperature|≦50

[0041] In the above formula 1, the discharge rate is the discharge rate [Voltage / min] in the discharge stage of the waste battery, and the expansion amount [mm] and the maximum temperature [°C] respectively mean the expansion amount and the maximum temperature of the waste battery in the discharge stage of the waste battery. The formula 1 has a positive value because it means the absolute value of the product of the discharge rate, the expansion amount, and the maximum temperature.

[0042] In one embodiment, the formula (1) represents the product of the amount of expansion of the waste battery and the discharge rate relative to the maximum temperature of the waste battery during discharging the waste battery, and may be an index of stability. The formula (1) may satisfy a range of 0.10 to 50.0. Specifically, the formula (1) may satisfy a range of 0.10 to 42.0, more specifically, a range of 0.19 to 12.0, and even more specifically, a range of 0.19 to 11.2.

[0043] If the value of formula 1 exceeds the upper limit, there is a problem that an explosion or fire may occur due to excessive expansion and temperature rise during discharge.If the value of formula 1 exceeds the lower limit, there is a problem that the temperature and expansion are stable, but the discharge speed is slow and takes an excessive time.

[0044] In one embodiment, when the battery is configured as a battery pack which is a set of at least one cell, a discharge rate in discharging the battery may satisfy the following Equation 2:

[0045] <Expression 2> Discharge rate = (maximum voltage per pack / number of series-connected cells in the pack) x 0.04V / min ±0.05

[0046] The battery may be configured as a pack in which at least one cell is arranged in series. The pack may be a collection of modules in which at least one cell is assembled. When the battery is a battery pack, Equation 2 may be an index for the discharge rate above 0°C. In Equation 2, the upper limit of the maximum voltage per pack relative to the number of series-connected cell unit batteries in the pack may be 0.04V / min + 0.05, and the lower limit of the maximum voltage per pack relative to the number of series-connected cell unit batteries in the pack may be 0.04V / min - 0.05.

[0047] In one embodiment, when formula 2 is satisfied, the discharge rate may be less than 0.5 V / min, specifically less than 0.1 V / min. When formula 2 is satisfied, the battery expansion amount may be less than 20 mm, specifically less than 10.5 mm. By satisfying these conditions, the battery can be disposed of safely and without fire hazard.

[0048] In one embodiment, when the battery is configured as a battery pack which is a set of at least one cell, a discharge rate in discharging the battery may satisfy the following Equation 3:

[0049] <Expression 3> Discharge rate = (maximum voltage per pack / number of series-connected cells in the pack) x 0.5V / min ±0.05

[0050] When the battery is a battery pack, the above formula 3 may be an index for the discharge rate at a low temperature lower than 0° C. In the formula 3, the upper limit of the maximum voltage per pack for the number of series-connected cell unit batteries in the pack may be 0.5V / min+0.05, and the lower limit of the maximum voltage per pack for the number of series-connected cell unit batteries in the pack may be 0.5V / min-0.05.

[0051] When the battery is a battery pack including a plurality of cells, the discharge rate is controlled to satisfy the above formula at room temperature or a low temperature, whereby the expansion amount of the battery can be maintained within an appropriate range, and the waste battery can be recycled while maintaining stability.

[0052] In one embodiment, when formula 3 is satisfied, the discharge rate may be 0.5 V / min or less, specifically 0.2 V / min or less. When formula 3 is satisfied, the battery expansion amount may be less than 20 mm, specifically 2 mm or less. By satisfying these conditions, the battery can be disposed of safely and without fire hazard.

[0053] The step of crushing the battery may refer to a step of applying impact or pressure to the battery so that a portion of the battery falls off. In one embodiment, the step of crushing the battery may refer to a step of pulverizing the battery, a step of cutting the battery, or a combination thereof. Specifically, the crushing step may refer to any step of breaking the battery to obtain small pieces.

[0054] In one embodiment, the step of crushing the battery may be a crushing method using at least one of shear, compression, and tension. Specifically, the crushing may be performed using at least one of a hammer mill, a ball mill, and an agitation ball mill. The hammer mill may perform at least one of disintegration, punching, and milling, and it is clear that the crushing may be performed using various types of crushing or grinding devices, for example, an industrial grinder, as a non-limiting example.

[0055] In one embodiment, the crushing step can be performed at least once, and more specifically, the crushing step can be performed at least once continuously or discontinuously.

[0056] Preferred examples and comparative examples of the present invention will be described below. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples. [Example]

[0057] Experimental example 1 - Battery temperature / expansion measurement In the experimental examples of the present invention, the amount of battery expansion was measured by measuring the change in thickness using a micrometer.

[0058] According to an experimental example of the present invention, a waste battery in an NCM pouch type was prepared, and the amount of battery expansion was measured at the temperature and discharge rate shown in Table 1 below.

[0059] 1a and 1b are photographs showing the measurement of the expansion amount of a battery according to an embodiment of the present invention.

[0060] Figures 2a and 2b are graphs showing the results of the temperature evaluation and the expansion amount, respectively.

[0061] 1a and 1b and 2a and 2b, specifically, the battery was electrically discharged at room temperature at 0.04V / min-cell. When the temperature and expansion amount were measured, it was confirmed that the battery had risen to a maximum of 65°C. At the time of the temperature rise of 65°C, the maximum expansion amount of the battery was confirmed to be 4.3mm.

[0062] In this way, the maximum temperature and expansion amount of the battery were measured by adjusting the expansion amount and temperature. When the discharge rate was 0.05V / min or less, the battery did not break down or catch fire, but when the maximum temperature rose to 80°C and the battery was discharged at 0.1V / min, the side of the battery broke, vaporized, and exploded.

[0063] <Experimental Example 1> The battery was subjected to electrical discharge at room temperature at 0.01 V / min.

[0064] <Experimental Example 2> The battery was subjected to electrical discharge at room temperature at 0.02 V / min.

[0065] <Experimental Example 3> The battery was subjected to electrical discharge at room temperature at 0.04 V / min.

[0066] <Experimental Example 4> The battery was subjected to electrical discharge at room temperature at 0.05 V / min.

[0067] <Experimental Example 5> The battery was subjected to electrical discharge at room temperature at 0.1 V / min.

[0068] Table 1 below shows the degree of battery swelling and the risk of fire or damage depending on the battery discharge rate. [Table 1] Referring to Table 1 above, it was confirmed that fires can be prevented when discharging a battery at room temperature at a discharge rate of 0.05V / min or less. At a discharge rate of 0.1V / min, which is higher than 0.05V / min, the maximum temperature was as high as 95°C, the expansion amount was 20mm or more, and the side broke, causing vaporization and a fire.

[0069] Experimental example 2 - Battery cooling To prevent a battery from exploding or burning due to evaporation of the internal electrolyte, a method was proposed in which the battery temperature was lowered before discharging. Specifically, when performing electrical discharge for forced discharge, the battery temperature was lowered before discharging.

[0070] Table 2 below shows the expansion amount (mm) at room temperature and low temperature (-20°C) when the discharge rate is 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.2, and 0.5. [Table 2] Referring to Table 2 above, it was confirmed that the amount of battery expansion at room temperature was high, at 20 mm or more, when the discharge rate was 0.1 V / min or higher. In contrast, it was confirmed that the amount of battery expansion significantly decreased when discharged at low temperatures (-20°C). The discharge rates in Table 2 above are not limited to cells; cells can be connected in series to form modules or packs, and the cells can be discharged at the same rate. For example, a 500 V pack can be constructed by connecting 125 4 V cells in series or by boosting the voltage. Therefore, when discharging at the pack level, the discharge rates of Equations 3 and 4 below can be satisfied at room temperature and low temperatures, respectively.

[0071] <Expression 3> Discharge rate at room temperature (above 0°C) = (maximum voltage per pack / number of cells connected in series in the pack) x 0.04V / min

[0072] <Expression 4> Discharge rate at low temperatures (below 0°C) = (maximum voltage per pack / number of cells connected in series in the pack) x 0.5V / min

[0073] 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. Preparing waste batteries; discharging the waste battery; and Crushing the discharged waste batteries; The step of discharging the waste battery is performed at a discharge rate of 0.5 Voltage / min or less, A waste battery treatment method that satisfies the following formula 1. <Formula 1> 0.1≦|Discharge rate×Expansion amount×Maximum temperature|≦50.0 (In the above formula 1, the discharge rate is the discharge rate [Voltage / min] in the discharge stage of the waste battery, and the expansion amount [mm] and the maximum temperature [°C] respectively mean the expansion amount and the maximum temperature of the waste battery in the discharge stage of the waste battery.)

2. The waste battery treatment method according to claim 1, wherein the formula 1 satisfies 0.10 to 42.

0.

3. The waste battery treatment method according to claim 1, wherein the formula 1 satisfies 0.19 to 12.

0.

4. 2. The method of claim 1, wherein the discharging the waste battery comprises measuring an expansion amount of the waste battery and controlling a discharge rate and a cooling temperature so that the expansion amount is less than 20 mm.

5. The waste battery treatment method according to claim 1 , wherein the step of discharging the waste battery includes a step of measuring a temperature of the waste battery.

6. The waste battery treatment method according to claim 5 , wherein the step of measuring the temperature of the waste battery includes a step of controlling the temperature of the waste battery to 80° C. or less.

7. The waste battery treatment method according to claim 1 , wherein the step of preparing the waste battery or the step of discharging the waste battery includes a step of cooling the waste battery.

8. The method for treating waste batteries according to claim 7 , wherein the step of cooling the waste batteries includes a step of cooling the waste batteries to 0° C. or below.

9. 8. The waste battery processing method according to claim 7, wherein the cooling step uses a cooling means including at least one of a refrigerator, air at a low temperature, carbon dioxide at a low temperature, nitrogen at a low temperature, dry ice, liquid nitrogen, and water.

10. 2. The waste battery treatment method according to claim 1, wherein when the battery is constituted by a battery pack which is a collection of a plurality of cells, the discharge rate satisfies the following formula 2: <Formula 2> Discharge rate = (maximum voltage per pack / number of series-connected unit cells in the pack) x 0.04 V / min ± 0.05

11. The waste battery treatment method according to claim 10, wherein the discharge rate is less than 0.1 V / min.

12. The waste battery processing method according to claim 10, wherein the expansion amount of the battery is 10.5 mm or less.

13. 8. The waste battery treatment method according to claim 7, wherein when the battery is constituted by a battery pack which is a collection of a plurality of cells, the discharge rate satisfies the following formula 3: <Formula 3> Discharge rate = (maximum voltage per pack / number of series-connected unit cells in the pack) x 0.5 V / min ± 0.05

14. The waste battery treatment method according to claim 13, wherein the discharge rate is 0.2 V / min or less.

15. The waste battery processing method according to claim 13, wherein the expansion amount of the battery is 2 mm or less.

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