Waste battery treatment method

Abstract

The invention relates to a waste battery treatment method. The waste battery treatment method comprises the following steps: preparing a waste battery; a step of discharging the waste battery; and a step of crushing the discharged waste battery, the discharge speed of the step of discharging the waste battery may be 0.5 volt / min or less, and the following formula 1 is satisfied. Lt; the formula is 1gt; 0.1 < = discharge rate * swell amount * maximum temperature < = 50.0 (In formula 1, the discharge rate is the discharge rate [volt / min] in the discharge step of the waste battery, and the swell amount [mm] and the maximum temperature [DEG C] respectively represent the swell amount and the maximum temperature of the waste battery in the discharge step of the waste battery.

Description

Technical Field

[0001] The present invention relates to a method for treating batteries. Specifically, the present invention relates to a method for treating waste batteries. Background Art

[0002] With the increasing global demand for electric vehicles, how to treat the waste batteries generated by these vehicles has become a social problem. For lithium secondary batteries, which are the main raw material substances of the waste batteries, they contain organic solvents, explosive substances, and heavy metal substances such as Ni, Co, Mn, and Fe. However, Ni, Co, Mn, and Li have great scarcity value as valuable metals, and the recycling and reuse processes of lithium secondary batteries after being discarded have become an important research field.

[0003] Specifically, lithium secondary batteries mainly consist of copper and aluminum used as current collectors, oxides containing Li, Ni, Co, and Mn that constitute the positive electrode material, and graphite used as the negative electrode material. They also include a separator for separating the positive electrode material and the negative electrode material and an electrolyte injected into the separator. The solvents used as the solvents (Solvent) and salts (Salt) for constituting the electrolyte are mainly mixed with carbonate organic compounds such as ethylene carbonate and propylene carbonate, and LiPF6 is used, for example.

[0004] In order to utilize the waste batteries, a waste battery reuse process that generates intermediate substances such as waste battery fragments or black powder by crushing the waste batteries and then recovers valuable metals through subsequent processes has attracted wide attention, and related research is being actively carried out.

[0005] In order to reuse the waste batteries, it is first necessary to physically decompose the batteries, and this physical decomposition may directly cause problems such as battery explosion or electric shock, so it is necessary to ensure the safety of the operation. After the physical decomposition, holes are formed in the batteries, and discharging is carried out in salt water. The discharged batteries are then crushed and heat-treated at high temperature to remove moisture and electrolyte.

[0006] When discharging is carried out in salt water, the salts used contain a large amount of impurities such as Na, K, Cl, Mg, or Ca, etc., and these impurities coexist with the waste batteries. Since the water used for discharging in salt water is in a state including part of the electrolyte, it is classified as wastewater, thus increasing the corresponding environmental treatment burden. For the existing developed discharging technologies, during discharging, lithium ions in the battery move from the negative electrode to the positive electrode. When the utilization of the lithium ions ends and the discharging process continues, the Cu of the current collector will undergo electrolysis, and the cations move and attach to the surface of the positive electrode.

[0007] Subsequently, it grows on the copper surface and connects to the negative electrode through the diaphragm, resulting in a short circuit. A large amount of heat is generated during this process. Although this heat is released to the outside, it heats the internal electrolyte, thereby increasing the risk of explosion. Summary of the Invention

[0008] Technical Problem to be Solved

[0009] According to an embodiment of the present invention, a method for treating waste batteries is provided, which reduces the risk of explosion during electrical discharge.

[0010] Technical Solution

[0011] A method for treating waste batteries according to an embodiment of the present invention includes: a step of preparing waste batteries; a step of discharging the waste batteries; and a step of crushing the discharged waste batteries. The discharging speed in the step of discharging the waste batteries can be 0.5 volts per minute or less and satisfies the following formula 1.

[0012] <Formula 1>

[0013] 0.1 ≤ │discharging speed × expansion amount × maximum temperature│ ≤ 50.0

[0014] In the above formula 1, the discharging speed is the discharging speed [volts per minute] in the discharging step of the waste batteries, and the expansion amount [mm] and the maximum temperature [°C] respectively represent the expansion amount and the maximum temperature of the waste batteries in the discharging step of the waste batteries.

[0015] In one embodiment, the above formula 1 can satisfy 0.10 to 42.0. In one embodiment, the above formula 1 can satisfy 0.19 to 12.0.

[0016] In one embodiment, the step of discharging the waste batteries may include a step of measuring the expansion amount of the waste batteries and controlling the discharging speed and the cooling temperature to be less than 20 mm. In one embodiment, the step of discharging the waste batteries may include a step of measuring the temperature of the waste batteries.

[0017] In one embodiment, the step of measuring the temperature of the waste batteries may include a step of controlling the temperature of the waste batteries to be 80 °C or less. In one embodiment, the step of preparing the waste batteries or the step of discharging the waste batteries may include a step of cooling the waste batteries.

[0018] In one embodiment, the step of cooling the waste battery may include the step of cooling it below 0°C. In one embodiment, the cooling step may utilize a cooling means including at least any one of a refrigerator, air at low temperature, carbon dioxide at low temperature, nitrogen at low temperature, dry ice, liquid nitrogen, and water.

[0019] In one embodiment, when the battery is composed of a battery pack which is a collection of a plurality of battery cells, the discharge rate may satisfy the following formula 2.

[0020] <Formula 2>

[0021] Discharge rate = (maximum voltage of the battery pack device / number of series-connected unit cells in the battery pack) × 0.04 V / minute ± 0.05

[0022] In another embodiment, the discharge rate may be less than 0.1 V / minute. In yet another embodiment, the amount of expansion of the battery may be 10.5 mm or less.

[0023] In one embodiment, when the battery is composed of a battery pack which is a collection of a plurality of battery cells, the discharge rate may satisfy the following formula 3.

[0024] <Formula 3>

[0025] Discharge rate = (maximum voltage of the battery pack device / number of series-connected unit cells in the battery pack) × 0.5 V / minute ± 0.05

[0026] In another embodiment, the discharge rate may be 0.2 V / minute or less. In yet another embodiment, the amount of expansion of the battery may be 2 mm or less.

[0027] Advantageous Effects

[0028] According to one embodiment of the present invention, there is provided a battery processing method which controls the discharge rate during the electrical discharge of a waste battery, serves as a means for controlling the surface temperature of the waste battery for discharging, and performs the discharge together with low-temperature cooling as a scheme for increasing the discharge rate. Brief Description of the Drawings

[0029] Figure 1a and Figure 1b are photos for measuring the amount of expansion of the battery according to the discharge rate.

[0030] Figure 2a and Figure 2b respectively show the temperature evaluation results and the results regarding the amount of expansion in diagrams. Detailed Description of the Embodiments

[0031] The terms 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 terms. These terms are only used to distinguish one part, component, region, layer, and / or segment from another part, component, region, layer, and / or segment. Therefore, without departing from the scope of the present invention, the first part, component, region, layer, and / or segment described below may also be described as the second part, component, region, layer, and / or segment.

[0032] The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. Unless otherwise clearly indicated to the contrary in the context, the singular forms used herein are also intended to include the plural forms. The term "comprising" used in the specification may specifically refer to a certain feature, field, integer, step, action, element, and / or component, but does not exclude the existence or addition of other features, fields, integers, steps, actions, elements, and / or components.

[0033] If a part is described as being above another part, there may be other parts directly above or between the other part. If a part is described as being directly above another part, there will be no other parts therebetween.

[0034] Although not otherwise defined, the meanings of all terms (including technical terms and scientific terms) used herein are the same as those commonly understood by those of ordinary skill in the art to which the present invention pertains. For terms defined in a dictionary, they should be interpreted as having a meaning consistent with the relevant technical literature and the content disclosed herein, and should not be interpreted in an idealized or overly formal sense.

[0035] 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 only subject to the scope of the claims.

[0036] A method for treating waste batteries according to an embodiment of the present invention may include: a step of preparing waste batteries; a step of discharging the waste batteries; and a step of crushing the discharged waste batteries.

[0037] The step of preparing the batteries may be to prepare the substance itself as the base material for the battery crush. Specifically, the waste batteries may be waste batteries with exhausted life. For example, the waste batteries may be lithium secondary batteries, and may include battery cells disassembled from large-capacity battery packs such as electric vehicles.

[0038] The step of discharging the waste battery is a step for preventing the explosion risk caused by the remaining power in the waste battery. Specifically, the step of discharging the waste battery is a pretreatment step for preventing problems such as fire caused by external impacts applied during subsequent processes such as disassembling and crushing the waste battery.

[0039] In one embodiment, the step of discharging the waste battery can be performed by electrical discharge. Specifically, the electrical discharge can be performed at a discharge rate within a predetermined range.

[0040] In one embodiment, the discharge rate of the step of discharging the waste battery can be 0.5 volts per minute or less. Specifically, the discharge rate can be 0.05 volts per minute or less. More specifically, the discharge rate can be 0.01 to 0.05 volts per minute or less.

[0041] When discharging the battery within the discharge rate range, by keeping the expansion amount of the battery within an appropriate range, the waste battery recycling process can be carried out while maintaining stability. If the discharge rate range is higher than the range, the chemical structure inside the battery will change rapidly, so the battery becomes unstable and expands due to the gasification of the positive electrode material and electrolyte inside the battery.

[0042] In one embodiment, the step of discharging the waste battery can include the step of controlling the expansion amount of the waste battery to be less than 20 mm. The expansion amount of the battery quantifies the degree of expansion of the battery in the thickness direction during the discharge process. Specifically, it can include the steps of measuring the expansion amount of the waste battery and controlling the discharge rate and cooling temperature to be less than 20 mm.

[0043] If the expansion amount of the waste battery is higher than the aforementioned range, the side will be torn and gasified, and there is a problem of fire. In one embodiment, the step of discharging the battery can be carried out until the expansion amount of the battery is 2 mm or less. Specifically, the expansion amount of the battery can be 1 mm or less, and more specifically can be 0.5 mm or less.

[0044] If the expansion amount of the battery is higher than the range, the gasification of the positive electrode material and electrolyte causes a rapid change in the chemical structure inside the battery. Therefore, when performing subsequent processes in the waste battery recycling process, stability problems may occur.

[0045] In one embodiment, the step of discharging the waste battery can include the step of measuring the temperature of the waste battery. Specifically, the step of measuring the temperature of the waste battery can control the temperature of the waste battery to be 80 °C or less.

[0046] The step of measuring the temperature of the waste battery is the step of measuring the temperature of the waste battery during discharging the waste battery. By measuring the temperature of the waste battery, the stability of the waste battery can be confirmed and the waste battery can be discharged.

[0047] 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. By performing the step of cooling the waste battery, the discharging and crushing processes can be carried out at low temperature.

[0048] For example, the cooling step may be carried out in the step of preparing the waste battery or in the step of discharging the waste battery, or may also be carried out in both the step of preparing the waste battery and the step of discharging the waste battery. Specifically, by performing the cooling step in the step of preparing the waste battery, the amount of expansion of the waste battery in the subsequent step of discharging the waste battery can be significantly reduced.

[0049] Specifically, in the step of discharging the waste battery, when the temperature of the waste battery is higher than 80 °C, by performing the cooling step, it can be controlled within the aforementioned range. In the step of discharging the waste battery, by including the cooling step, the risk of fire caused by the expansion or destruction of the waste battery during the discharging process of the waste battery can be reduced.

[0050] In one embodiment, the cooling step may utilize a cooling means including at least any one of a refrigerator, air at low temperature, carbon dioxide at low temperature, nitrogen at low temperature, dry ice, liquid nitrogen, and water. For the air at low temperature, the carbon dioxide at low temperature, and the nitrogen at low temperature, the low temperature means a low temperature of 10 °C or lower, specifically 5 °C or lower. As a non-limiting example, the cooling means may adopt various cooling methods such as a cooling fluid method to cool the waste battery.

[0051] In one embodiment, the waste battery treatment method may satisfy the following formula 1.

[0052] <Formula 1>

[0053] 0.10 ≤ │discharge rate × expansion amount × maximum temperature│ ≤ 50

[0054] In the above formula 1, the discharge rate is the discharge rate [volts / minute] in the discharging step of the waste battery, and the expansion amount [mm] and the maximum temperature [°C] respectively represent the expansion amount and the maximum temperature of the waste battery in the discharging step of the waste battery. The above formula 1 represents the absolute value of the product of the discharge rate, the expansion amount, and the maximum temperature, and thus has a positive value.

[0055] In one embodiment, Formula 1 above represents the product of the amount of expansion and the discharge rate of the maximum temperature of the waste battery in the step of discharging the waste battery, and can be an index of stability. Formula 1 above can satisfy 0.10 to 50.0. Specifically, Formula 1 above can satisfy 0.10 to 42.0, more specifically satisfy 0.19 to 12.0 or less, and more specifically satisfy 0.19 to 11.2.

[0056] If the value of Formula 1 above exceeds the upper limit value, there will be problems that excessive expansion and temperature rise during discharge may lead to explosion or fire. If the value of Formula 1 above exceeds the lower limit value, although the temperature and expansion are stable, the discharge rate is slow, and there is a problem of consuming too much time.

[0057] In one embodiment, when the battery is composed of a battery pack which is a set of at least one battery cell, the discharge rate in the step of discharging the battery can satisfy the following Formula 2.

[0058] <Formula 2>

[0059] Discharge rate = (maximum voltage of the battery pack device / number of series-connected unit cells in the battery pack) × 0.04 V / minute ± 0.05

[0060] The battery can be composed of a battery pack formed by arranging at least one battery cell in series. The battery pack can also be a set of modules assembled from at least one battery cell. The above Formula 2 can be an index of the discharge rate above 0 °C when the battery is a battery pack. For the above Formula 2, the maximum voltage of the battery pack device multiplied by 0.04 V / minute + 0.05 with respect to the number of series-connected unit cells in the battery pack can be the upper limit value, and the maximum voltage of the battery pack device multiplied by 0.04 V / minute - 0.05 with respect to the number of series-connected unit cells in the battery pack can be the lower limit value.

[0061] In one embodiment, when the above Formula 2 is satisfied, the discharge rate can be less than 0.5 V / minute, specifically less than 0.1 V / minute. When the above Formula 2 is satisfied, the amount of expansion of the battery can be less than 20 mm, specifically 10.5 mm or less. By satisfying the above conditions, the battery can be safely processed without the risk of fire.

[0062] In one embodiment, when the battery is composed of a battery pack which is a set of at least one battery cell, the discharge rate in the step of discharging the battery can satisfy the following Formula 3.

[0063] <Formula 3>

[0064] Discharge rate = (maximum voltage of the battery pack device / number of series-connected unit cells in the battery pack) × 0.5 V / minute ± 0.05

[0065] The above formula 3 can be an index regarding the discharge rate at a low temperature below 0°C when the battery is a battery pack. For the above formula 3, the maximum voltage of the battery pack device multiplied by 0.5 V / minute + 0.05 relative to the number of series-connected unit cells in the battery pack can be the upper limit value, and the maximum voltage of the battery pack device multiplied by 0.5 V / minute - 0.05 relative to the number of series-connected unit cells in the battery pack can be the lower limit value.

[0066] When the battery is a battery pack composed of a plurality of battery cells, by controlling the discharge rate at normal temperature or low temperature to satisfy the foregoing formula, the expansion amount of the battery can be maintained within an appropriate range, and the waste battery recycling process can be carried out while maintaining stability.

[0067] In one embodiment, when the above formula 3 is satisfied, the discharge rate can be 0.5 V / minute, specifically, it can be 0.2 V / minute or less. When the above formula 3 is satisfied, the expansion amount of the battery can be less than 20 mm, specifically, it can be 2 mm or less. By satisfying the above conditions, the battery can be safely processed without the risk of fire.

[0068] The step of crushing the battery may refer to a process of applying impact or pressure to the battery so that a part of the battery falls off. In one embodiment, the step of crushing the battery may refer to a process of pulverizing the battery, a process of cutting, and a combination thereof. Specifically, the crushing process may refer to all processes capable of obtaining small fragments by destroying the battery.

[0069] In one embodiment, the step of crushing the battery may employ a crushing method using at least one of shear, compression, and tensile forces. Specifically, the crushing step may be carried out by at least one of, for example, a hammer mill, a ball mill, and a stirred ball mill. The hammer mill may perform at least one of the steps of decomposition, stamping, and milling, which are non-limiting examples, and obviously, various crushing or pulverizing devices such as an industrial pulverizer can be used for pulverization.

[0070] In one embodiment, the crushing step may be carried out more than once. Specifically, the crushing process may be carried out continuously or discontinuously more than once.

[0071] The preferred embodiments and comparative examples of the present invention will be described below. However, the following embodiments are only a preferred embodiment of the present invention, and the present invention is not limited to the following embodiments.

[0072] Experimental Example 1 - Measuring Battery Temperature / Expansion

[0073] In the experimental example of the present invention, for the expansion amount of the battery, the thickness change was measured using a micrometer.

[0074] According to the experimental example of the present invention, a soft-packaged NCM waste battery was prepared, and the amount of battery swelling was measured at the temperatures and discharge rates shown in Table 1 below.

[0075] Figure 1a and Figure 1b are photos showing the amount of swelling of the battery according to an embodiment of the present invention.

[0076] Figure 2a and Figure 2b respectively show the temperature evaluation results and the results regarding the amount of swelling in graphs.

[0077] Referring to Figure 1a and Figure 1b and also Figure 2a and Figure 2b , specifically, by electrically discharging the battery, the discharge was carried out at normal temperature and 0.04 volts / minute-cell. At this time, when the temperature and the amount of swelling as the amount of expansion were measured, it was confirmed that the temperature rose up to 65 °C at most. When it rose to 65 °C, the maximum amount of swelling of the battery was 4.3 mm.

[0078] As described above, the amount of battery swelling or temperature was adjusted to measure the maximum temperature and the amount of swelling. When the discharge rate was 0.05 V / minute or less, there was no battery damage or fire, but if the maximum temperature rose to 80 °C, when discharging at 0.1 V / minute, the side surface of the battery was torn and vaporized, causing an explosion.

[0079] <Experimental Example 1>

[0080] By electrically discharging the battery, it was carried out at 0.01 V / minute at normal temperature.

[0081] <Experimental Example 2>

[0082] By electrically discharging the battery, it was carried out at 0.02 V / minute at normal temperature.

[0083] <Experimental Example 3>

[0084] By electrically discharging the battery, it was carried out at 0.04 V / minute at normal temperature.

[0085] <Experimental Example 4>

[0086] By electrically discharging the battery, it was carried out at 0.05 V / minute at normal temperature.

[0087] <Experimental Example 5>

[0088] By electrically discharging the battery, it was carried out at 0.1 V / minute at normal temperature.

[0089] Table 1 below shows the amount of swelling of the battery according to the battery discharge rate and whether there is a fire or damage.

[0090]

Table 1

[0091]

[0092] It is confirmed from Table 1 above that in order to discharge the battery at normal temperature, discharging at a discharge rate of 0.05 V / min or less can prevent fire. When the discharge rate is 0.1 V / min which is higher than 0.05 V / min, the maximum temperature reaches as high as 95 °C, the expansion amount is 20 mm or more, and the side is torn and vaporized to cause a fire.

[0093] Experimental Example 2 - Performing Battery Cooling

[0094] When the battery explodes or catches fire due to the vaporization of the internal electrolyte, as a means to prevent explosion or fire, a method of discharging after pre-lowering the temperature of the battery has been proposed. Specifically, when performing electrical discharge for forced discharge, the battery will be discharged after its temperature is lowered.

[0095] Table 2 below shows the expansion amounts (mm) at normal temperature and low temperature (-20 °C) when the discharge rates are 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.2, and 0.5 respectively.

[0096]

Table 2

[0097]

[0098] It is confirmed from Table 2 above that for the expansion amount of the battery at normal temperature, when the discharge rate is 0.1 V / min or more, the expansion amount is as high as 20 mm or more. In contrast, when carried out at low temperature (-20 °C), it has been confirmed that the expansion amount of the battery is significantly reduced. For the discharge rates in Table 2 above, it is not limited to battery cells, and battery cells can be connected in series to form a module or a battery pack. At this time, the discharge rates of the series-connected battery cells can be multiplied. For example, for a 500 V battery pack, 125 battery cells of 4 V can be connected in series or processed by boosting. Therefore, when discharging is carried out with a battery pack device, the discharge rates that can satisfy the following Formula 3 and Formula 4 at normal temperature and low temperature respectively.

[0099] <Formula 3>

[0100] Discharge rate at normal temperature (above 0 °C) = (Maximum voltage of battery pack device / Number of series-connected unit cells in battery pack) × 0.04 V / min

[0101] <Formula 4>

[0102] Discharge rate at low temperature (less than 0 °C) = (Maximum voltage of battery pack device / Number of series-connected unit cells in battery pack) × 0.5 V / min

[0103] The preferred embodiments have been described in detail above. However, the scope of the rights of the present invention is not limited to the above embodiments, and 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 rights of the present invention.

Claims

1. A method for treating waste batteries, comprising: A step of preparing waste batteries; A step of discharging the waste batteries; And A step of crushing the discharged waste batteries, The discharging speed of the step of discharging the waste batteries is below 0.5 volts per minute and satisfies the following formula 1, <Formula 1> 0.1 ≤ │discharging speed × expansion amount × maximum temperature│ ≤ 50.0 In the above formula 1, the discharging speed is the discharging speed [volts per minute] in the discharging step of the waste batteries, and the expansion amount [mm] and the maximum temperature [°C] respectively represent the expansion amount and the maximum temperature of the waste batteries in the discharging step of the waste batteries.

2. The method for treating waste batteries according to claim 1, wherein The above formula 1 satisfies 0.10 to 42.

0.

3. The method for treating waste batteries according to claim 1, wherein The above formula 1 satisfies 0.19 to 12.

0.

4. The method for treating waste batteries according to claim 1, wherein The step of discharging the waste batteries includes a step of measuring the expansion amount of the waste batteries and controlling the discharging speed and the cooling temperature so that the expansion amount is less than 20 mm.

5. The method for treating waste batteries according to claim 1, wherein The step of discharging the waste batteries includes a step of measuring the temperature of the waste batteries.

6. The method for treating waste batteries according to claim 5, wherein The step of measuring the temperature of the waste batteries includes a step of controlling the temperature of the waste batteries to be below 80 °C.

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

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

9. The method for treating waste batteries according to claim 7, wherein The cooling step uses a cooling means including at least any one of a refrigerating machine, air at low temperature, carbon dioxide at low temperature, nitrogen at low temperature, dry ice, liquid nitrogen, and water.

10. The method for treating waste batteries according to claim 1, wherein When the battery is composed of a battery pack which is a collection of multiple battery cells, the discharging speed satisfies the following formula 2, <Formula 2> Discharging speed = (maximum voltage of the battery pack device / number of series-connected unit batteries in the battery pack) × 0.04 V / minute ± 0.

05.

11. The method for treating waste batteries according to claim 10, wherein The discharging speed is less than 0.1 V / minute.

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

13. The method for treating waste batteries according to claim 7, wherein When the battery is composed of a battery pack which is a collection of multiple battery cells, the discharging speed satisfies the following formula 3, <Formula 3> Discharging speed = (maximum voltage of the battery pack device / number of series-connected unit batteries in the battery pack) × 0.5 V / minute ± 0.

05.

14. The waste battery treatment method according to claim 13, wherein, the discharging speed is 0.2 V / minute or less.

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

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