Real-time safety diagnosis rapid and complete discharge process for recycling battery

Abstract

The present invention relates to a process for discharging a waste battery and, more specifically, to a process for discharging a waste battery by predicting the internal temperature of the waste battery on the basis of the discharge current and the inverse value of the differential capacity of the waste battery, and controlling the magnitude of the discharge current according to the predicted temperature.

Description

Real-time safety diagnostics for battery recycling and rapid complete discharge process

[0001] The present invention relates to a discharge process of a waste battery for recycling the waste battery, and more particularly, to a process capable of quickly and safely discharging a waste battery (i.e., a used battery) to 0 V before reusing or recycling it.

[0002] The use of large-capacity lithium-ion batteries is increasing due to the recent domestic declaration of carbon neutrality and the domestic electric vehicle distribution policy.

[0003] These batteries are widely used in electric or hybrid vehicles that require large electrical capacity, and electric vehicles are receiving the most attention as a means to solve the problem of climate change through carbon neutrality.

[0004] However, due to the use of such a large number of batteries, it is expected that the amount of waste batteries generated from electric vehicles will increase rapidly in the future.

[0005] Meanwhile, if used vehicle batteries that were recovered after being used in eco-friendly vehicles are immediately disposed of (e.g., through resource recovery), enormous annual disposal costs will be incurred starting in 2024, and disposal costs are expected to increase explosively starting in 2031.

[0006] To partially address these issues, used vehicle batteries must be recycled for other applications. This process involves shredding the batteries and extracting a high-purity black powder through metallurgy. However, shredding batteries for recycling, while still containing energy, can lead to fires and explosions. Therefore, recycling vehicle batteries without any guarantees poses significant technical and social risks. Therefore, a preprocessing process is essential to reduce the remaining energy in the batteries to zero before shredding.

[0007] However, in order to recycle / reuse waste batteries, there are problems such as reducing the remaining energy in the waste battery, i.e. the pre-charged power, below a certain SOC, or rapidly increasing the internal temperature of the waste battery during the discharge process even when completely discharged to 0V, so development of a discharge process for this purpose is necessary.

[0008] [Prior Art Literature]

[0009] [Patent Document]

[0010] (Patent Document 1) Republic of Korea Publication Patent No. 10-2019-0018340 (February 22, 2019)

[0011] The first problem to be solved by the present invention is to provide a battery discharge process that safely and completely discharges the pre-charged power of a waste battery in real time before reusing or recycling the waste battery.

[0012] The second problem that the present invention seeks to solve is to provide a discharge process that can predict the temperature inside a waste battery in real time by utilizing diagnostic factors such as resistance, power, and energy that can be obtained in real time.

[0013] The third problem to be solved by the present invention is to provide a discharge process capable of predicting the temperature inside a waste battery and then producing the largest discharge current within a safe temperature range.

[0014] The purposes of the present invention are not limited to those mentioned above, and other unmentioned purposes and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0015] A process for discharging a waste battery according to one embodiment of the present invention to achieve the above-mentioned problem is as follows:

[0016] (S100) A step of discharging the waste battery with a first discharge current through a connection terminal connected to a power terminal of the waste battery;

[0017] (S200) A step of monitoring dV / dQ, which is the reciprocal of the differential capacity of the waste battery, according to time or voltage;

[0018] (S300) A step of predicting the temperature inside the waste battery based on dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current; and

[0019] (S400) Based on the predicted temperature exceeding the first threshold value, a step of controlling the discharge to be performed at a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the waste battery may be included.

[0020] In one embodiment of the present invention, the step (S300) comprises:

[0021] A step of obtaining a power (P) value through dV / dQ, which is the reciprocal of the differential capacity of the above-mentioned waste battery, and the first discharge current; and

[0022] The method may include a step of predicting the temperature inside the waste battery based on at least one of the initial temperature of the waste battery, the weight of the waste battery, the power (P) value, and the energy (E) value.

[0023] In one embodiment of the present invention, based on the reciprocal of the differential capacity of the waste battery, dV / dQ, exceeding a second threshold value, the waste battery may be controlled to discharge at a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the waste battery.

[0024] A process for discharging a waste battery according to one embodiment of the present invention to achieve the above-mentioned problem is as follows:

[0025] (S500) Based on the above predicted temperature being below the first threshold value, a step of controlling discharge at a third discharge current higher than the first discharge current through a connection terminal connected to the power terminal of the waste battery may be further included.

[0026] In one embodiment of the present invention, the predicted temperature calculated based on at least one of the third discharge current, the power (P) value and the energy (E) value of the waste battery may be less than the first threshold value.

[0027] A process for discharging a waste battery according to one embodiment of the present invention to achieve the above-mentioned problem is as follows:

[0028] (S600) If the voltage of the waste battery reaches a specific voltage while discharging the waste battery, a step of applying a constant voltage may be further included.

[0029] A process for discharging a waste battery according to one embodiment of the present invention to achieve the above-mentioned problem is as follows:

[0030] (S700) The step of stopping the discharge of the waste battery when the constant voltage is applied and a specific time has elapsed or the cut-off current according to the application of the constant voltage reaches a third threshold value may be further included.

[0031] A process for discharging a waste battery according to one embodiment of the present invention to achieve the above-mentioned problem is as follows:

[0032] (S800) A step of short-circuiting the battery may be further included to prevent a voltage rebound of the waste battery.

[0033] The solutions to the above problems do not enumerate all features of the present invention. The various features of the present invention, along with their corresponding advantages and effects, can be understood in more detail by referring to the specific examples below.

[0034] According to various embodiments of the present invention, a waste battery complete discharge process capable of safely and quickly completely discharging a waste battery in real time can be provided.

[0035] According to various embodiments of the present invention, it can be utilized as basic equipment for storage, transportation, and reuse of waste batteries, and it is expected that the safety of the battery reuse and recycling industry will be improved.

[0036] According to various embodiments of the present invention, a situation in which a fire occurs due to heat generation caused by resistance in an irreversible section during the process of completely discharging a waste battery can be prevented.

[0037] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

[0038] Figure 1 is a block diagram showing the configuration of a waste battery discharge device.

[0039] Figure 2 is a flowchart for explaining the discharge process according to the temperature prediction inside a waste battery.

[0040] Figure 3 shows that when the discharge of a waste battery is performed, the actual internal temperature of the waste battery and the predicted temperature (calculated temperature) of the battery derived through mathematical expression 5 of the present invention are consistent.

[0041] Fig. 4 is a graph showing a conceptual diagram (Fig. 4c) of the internal temperature change of a waste battery considering the heat generation factor of the waste battery (Fig. 4a) and the heat dissipation factor of the waste battery (Fig. 4b).

[0042] Figure 5 is a graph showing the change in dV / dQ of a waste battery over time.

[0043] Figure 6 is a graph showing the temperature change of a waste battery over time.

[0044] Figure 7 is a graph showing the actual internal temperature change of a waste battery over time.

[0045] Figure 8 is a graph showing changes in the internal temperature, current, voltage, and capacity of a waste battery over time.

[0046] The principles of preferred embodiments of the present invention will be described in detail with reference to the attached drawings and descriptions below. However, the drawings and descriptions below are intended to illustrate preferred implementation methods among various methods for effectively explaining the features of the present invention, and the present invention is not limited to the drawings and descriptions below.

[0047] While terms such as "first" or "second" may be used to describe various components, these terms should be interpreted solely to distinguish one component from another. For example, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

[0048] Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "has" should be understood to indicate the presence of a described feature, number, step, operation, component, part, or combination thereof, but not to exclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0049] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0050] Hereinafter, with reference to the attached drawings, a method for discharging a waste battery within a safe temperature range by predicting the temperature within the waste battery according to an embodiment of the present invention will be described.

[0051] In describing the present invention, the term "waste battery" may collectively refer to a waste battery that has been used and then recovered for various reasons. For example, the term "waste battery" may include, but is not limited to, a vehicle waste battery that was used in an eco-friendly vehicle (e.g., an electric vehicle, a hydrogen vehicle, etc.) and then recovered for various reasons (e.g., inspection, repair, expiration, accident, scrapping, etc.).

[0052] Meanwhile, when a spent battery is completely discharged, its resistance can increase in the irreversible region, which can lead to high heat generation and potentially lead to thermal runaway / fire. While the temperature inside a spent battery can be measured using IR sensors and / or thermocouples, accurate temperature measurements are impossible due to the plastic composite insulation. Furthermore, the high current can make it difficult to detect the risk of thermal runaway during discharge.

[0053] Hereinafter, in order to solve the above-described problem, a waste battery discharge process according to an embodiment of the present invention will be described with reference to the attached drawings.

[0054] Figure 1 is a block diagram of a discharge system according to one embodiment of the present invention.

[0055] Referring to FIG. 1, a discharge system (100) according to an embodiment of the present invention adjusts current through a terminal (140) connected to a waste battery (200). It may include a discharge unit (110), a voltage measurement unit (120), and a memory unit (130).

[0056] insect The discharge unit (110) can charge or discharge the waste battery (200) by providing a charging current or a discharging current to the waste battery (200) through the connection terminal (140). In addition, the charging The discharge unit (110) can control the size of the charging current or discharge current provided to the waste battery (200) according to the change in capacity according to the voltage of the waste battery (200).

[0057] The voltage measuring unit (120) can measure and monitor the voltage within the waste battery (200) through the current flowing through the connection terminal (140). The voltage measured by the voltage measuring unit (120) can be used to monitor the change in capacity according to the voltage of the waste battery (200).

[0058] Meanwhile, the voltage measurement unit (120) may include a profile generation unit (121). The profile generation unit (121) may be configured to obtain battery information including voltage (V) and capacity (Q) for a battery cell (B).

[0059] The profile generation unit (121) may be configured to generate a battery profile indicating a correspondence between the voltage and the capacity based on the acquired battery information.

[0060] Specifically, the profile generation unit (121) can generate a battery profile by mapping corresponding voltages and capacities among the acquired battery information. In addition, the generated battery profile can be configured to be converted into a differential capacity profile indicating a correspondence between the voltage and the differential capacity for the voltage. The differential capacity is a value obtained by differentiating the capacity with respect to the voltage with respect to the corresponding voltage and capacity, and the specific details will be described later.

[0061] The memory unit (130) is Various data obtained through the discharge unit (110) and voltage measurement unit (120) can be stored. The memory unit (130) stores the above-mentioned charge It can be electrically connected to the discharge unit (110) and the voltage measurement unit (120). However, this is only one embodiment, and the memory unit (130) is the above-mentioned discharge unit. The discharge unit (110) and the voltage measurement unit (120) can be connected wirelessly.

[0062] The connection terminal of the connection part (140) is electrically connected to the power terminal of the waste battery (200), and the connection part (140) provides an electrical circuit for measuring the voltage value or current value of the waste battery (200) or charging or discharging the waste battery (200) through the connection terminal.

[0063] FIG. 2 is a flowchart illustrating a discharge process based on temperature prediction inside a waste battery according to one embodiment of the present invention. Referring to FIG. 2, the present invention:

[0064] (S100) A step of discharging the waste battery with a first discharge current through a connection terminal connected to the power terminal of the waste battery;

[0065] (S200) A step of monitoring dV / dQ, which is the reciprocal of the differential capacity of the waste battery, according to time or voltage;

[0066] (300) A step of predicting the temperature inside the waste battery based on dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current;

[0067] (S400) A step of controlling discharge at a second discharge current lower than the first discharge current through a connection terminal connected to a power terminal of the waste battery based on the predicted temperature exceeding a first threshold value;

[0068] (S500) A step of controlling discharge at a third discharge current higher than the first discharge current through a connection terminal connected to a power terminal of the waste battery based on the predicted temperature being lower than the first threshold value;

[0069] (S600) When the voltage of the waste battery reaches a specific voltage while discharging the waste battery, a step of applying a constant voltage; and

[0070] (S700) A step of stopping discharge of the waste battery when the constant voltage is applied and a specific time has elapsed or a cut-off current according to the application of the constant voltage reaches a third threshold value;

[0071] (S800) A step of short-circuiting the battery to prevent the voltage of the waste battery from rebounding.

[0072] A waste battery discharge process including the above can be provided.

[0073] Below, the configuration of the present invention will be described in more detail.

[0074] 1. (S100) A step of discharging the waste battery with a first discharge current through a connection terminal connected to the power terminal of the waste battery.

[0075] Step (S100) is a step of discharging the waste battery through the connection terminal of the waste battery. In the present invention, step (S100) may vary depending on the characteristics of the waste battery, for example, the type of component (electrode material) constituting the waste battery.

[0076] Since vehicle batteries used in eco-friendly vehicles are recovered for various reasons, they may not be recovered in a state where the charged energy has been completely discharged.

[0077] It is extremely dangerous to recycle charged batteries without any warranty, as they carry the risk of fire or explosion if subjected to external shock or stimulation due to the energy stored inside.

[0078] Therefore, the above step (S100) is a step of discharging the waste battery through a terminal connected to the waste battery to lower the level of energy charged in the waste battery.

[0079] Meanwhile, in the waste battery discharge process according to the present invention, a step of recovering waste batteries from various devices (e.g., eco-friendly vehicles, etc.), separating the battery manufacturer's BMS and vehicle case (optional) from the waste batteries, and then preparing a battery module including N battery cells may be performed first.

[0080] Additionally, in the discharge process of a waste battery according to one embodiment of the present invention, a step of specifying the specifications of the waste battery and a step of examining the electrical flow of the waste battery may be performed before preparing the waste battery.

[0081] Specifically, the step of selecting the specifications of the waste battery may include a step of determining the type of the waste battery by considering the components (e.g., positive electrode material, negative electrode material, and electrolyte) that make up the waste battery.

[0082] Since the capacity-voltage curve of a battery, which represents the discharge characteristics of the battery, is determined by the positive and negative electrode materials, the specifications of the used battery must always be taken into consideration in order to set specific conditions of the discharge process, such as the discharge voltage and current described later.

[0083] Additionally, electrical flow testing may include insulation resistance measurement steps, voltage measurement steps, and Electrochemical Impedance Spectroscopy (EIS) measurement steps.

[0084] In this way, by performing an electrical flow test before discharging a spent battery, the electrical safety of the spent battery before the discharge process can be assessed and its State of Charge (SOC) and State of Health (SOH) can be diagnosed. The SOC and SOH measured during the electrical flow test are then used to set conditions for the subsequent discharge process.

[0085] In describing the present invention, the (discharge) voltage refers to a potential difference between the positive and negative electrodes, and is a value measured based on a single cell. In a battery module or pack, the voltage standard may vary depending on the configuration of the battery.

[0086] For example, the discharge voltage "single cell voltage*N" in a module or pack in which N (N≥2) single cells are connected in series can be the (discharge) voltage.

[0087] In the discharge process of a waste battery according to the present invention, the discharge voltage considering the positive electrode material and negative electrode material constituting the waste battery may be -1.5 V to 3.0 V, preferably -1.0 V to 2.5 V, and more preferably 0 V to 1.0 V, based on a single cell.

[0088] Meanwhile, in the discharge process of a waste battery according to the present invention, step (S100) may be to discharge the waste battery at a first current size at a specific discharge voltage through a connection terminal.

[0089] Here, the first current magnitude may be a constant current of 0.5 C (C-rate) to 5.0 C (C-rate), preferably 0.5 C (C-rate) to 3.0 C (C-rate).

[0090] Here, C-rate is an abbreviation for current rate, which refers to a battery-related characteristic that indicates the charge / discharge rate of current according to battery capacity. The actual unit is [ / h], and generally, the unit of [C] is used.

[0091] For example, if the battery capacity (the amount of current that can be used for 1 hour) is 1000 mAh and the charge / discharge current is 1 A, the C-rate is 1 C * 1 A / 1000 mAh = 1 [ / h].

[0092] 2. (S200) A step of monitoring dV / dQ, which is the reciprocal of the differential capacity of the waste battery, according to time or voltage;

[0093] In the discharge process of a waste battery according to the present invention, step (S200) is a step of monitoring the differential capacity of the waste battery.

[0094] Specifically, the above step (S200) is a step of monitoring the differential capacity while the waste battery is discharged with a first discharge current through the connection terminal.

[0095] Here, the differential capacity is a value obtained by differentiating the capacity by the voltage with respect to the corresponding voltage and capacity of the battery, which can be expressed as "dQ / dV", and the unit of the differential capacity can be [mAh / V] or [Ah / V].

[0096] In another embodiment of the present invention, the differential capacity may be “dV / dQ”, which is the reciprocal of “dQ / dV”, and the unit of the differential capacity may be [V / mAh] or [V / Ah].

[0097] While the discharge process of a waste battery is in progress, the profile generation unit (121) of the discharge system (100) continuously calculates the dQ and dV values ​​of the battery based on the battery voltage information received from the voltage measurement unit (120) and goes through the process of calculating "dQ / dV". However, if the calculation cycle is very short depending on the discharge pattern of the waste battery, when the dV value approaches 0, the differential capacity "dQ / dV" may approach infinity, and in this case, a problem may occur in the calculation process of the differential capacity.

[0098] Therefore, depending on the discharge / discharge purpose of the spent battery, instead of "dQ / dV", its reciprocal "dV / dQ" can be used as the differential capacity. In the present invention, both "dQ / dV" and "dV / dQ" are defined as differential capacity, and in some cases, when "dQ / dV" is defined as the differential capacity, "dV / dQ" can be named the reciprocal of the differential capacity for the purpose of distinguishing the terms.

[0099] The profile generation unit (121) of the discharge system (100) according to one embodiment of the present invention can generate a differential capacity profile of the battery based on battery voltage information received from the voltage measurement unit (120) and monitor the same.

[0100] Here, the differential capacity monitoring period can be 100 ms to 5 min, but this is only one example and can be set to various values.

[0101] 3. (S300) A step of predicting the temperature inside the waste battery based on dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current.

[0102] In the discharge process of a waste battery according to the present invention, step (S300) is a step of predicting the temperature inside the waste battery using dV / dQ, which is the reciprocal of the differential capacity monitored in step (S200), and the first discharge current.

[0103] As an example of the present invention, the step (S300) includes a step (S310) of obtaining an energy (E) value (≒ calorific value) generated from the battery through dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current, and an initial temperature (T) of the waste battery. i ), weight, power (P) value, energy (E) value, first discharge current and discharge voltage, and may include a step (S320) of predicting the temperature inside the waste battery.

[0104] The power (P) and energy (E) values ​​(≒ heat generation) can be derived using mathematical equations 1 and 2, respectively. Here, V represents the discharge voltage, I represents the discharge current, R represents the resistance, and t represents the time (s).

[0105] [Mathematical Formula 1]

[0106]

[0107] [Equation 2]

[0108]

[0109] The reciprocal of the differential capacity of a waste battery, dV / dQ, can be corresponding to the resistance (R) value according to Ohm's law (i.e., dV / dQ ≒ R). Therefore, power (P) and energy (E) can be derived through the following mathematical equations 3 and 4.

[0110] [Equation 3]

[0111]

[0112] [Equation 4]

[0113]

[0114] The discharge system (100) can obtain the power (P) value through dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current.

[0115] Therefore, the discharge system (100) can derive the amount of heat generated from the battery by integrating the reciprocal of the differential capacity obtained in advance and the discharge current over time. That is, the amount of heat generated from the battery can be expressed as a function of the differential capacity.

[0116] In the present invention, the heat generation amount of the battery is calculated using differential capacity rather than using the voltage (V) applied to the battery. This is because voltage (V) is not an internal factor of the battery and thus has limitations in accurately predicting the heat generation amount inside the battery.

[0117] Meanwhile, the discharge process of a waste battery according to the present invention can consider the mass factor of the battery when obtaining the energy (E) value generated from the battery. The heat generation of the battery calculated through the above mathematical expression 4 may increase as more batteries are used (e.g., battery modules with unit batteries connected). Therefore, to compensate for this, the value obtained by dividing the energy (E) value of mathematical expression 4 by the mass factor of the battery can be used as the heat generation of the battery (Mathematical expression 5 below).

[0118] [Equation 5]

[0119]

[0120] At this time, the mass factor of the battery may be defined differently depending on the usage scenario of the battery. For example, the mass factor m of the battery may be the cell mass of the battery, the pack mass, the module mass, or the total mass of elements capable of dissipating heat within the battery, with the cell mass being most preferred.

[0121] That is, the discharge process of a waste battery according to the present invention is not limited to a specific mass factor, and an appropriate mass factor can be selected depending on the usage pattern of the waste battery.

[0122] Figure 3 shows the actual internal temperature of a battery when discharging a spent battery and the predicted temperature (calculated temperature) of the battery derived using Equation 5 above. As can be seen in Figure 3, the actual internal temperature of the spent battery and the predicted temperature of the spent battery derived using Equation 5 above are almost identical.

[0123] Meanwhile, the internal temperature of the battery may show a decreasing curve due to the heat dissipation generated during discharge of the battery (Fig. 7). In this case, the internal temperature of the battery can be derived using mathematical equation 6, which takes into account the heat dissipation factor (internal temperature decrease value).

[0124] [Equation 6]

[0125]

[0126] In the above mathematical expression 6, the expression including the constant c1 is the heating factor, and is a formula including the temperature change and the constant c2. means the heat dissipation factor

[0127] The above heat generation factor and heat dissipation factor are values ​​derived from the general formula Q=C△T related to heat capacity, and can be used to relatively accurately predict the temperature drop of the battery by calculating the amount of heat generated according to temperature change.

[0128] Here, can mean the predicted temperature (Tf) inside the waste battery at a specific point in time minus the initial temperature (Ti) of the waste battery. In other words, the heat dissipation factor is The value obtained by integrating over time can be derived by dividing the value by the weight (m) of the waste battery and then multiplying it by a negative constant (c2) (see Fig. 4), and the greater the temperature change, the greater the temperature drop of the battery.

[0129] As a result, the discharge system (100) can accurately monitor the actual temperature change of the battery during the discharge process of the battery through data corresponding to the weight and initial temperature of the waste battery, the heat generation amount calculated through the differential capacity, and the internal temperature of the battery (e.g., heat dissipation factor).

[0130] (S400) A step of controlling discharge at a second discharge current lower than the first discharge current through a connection terminal connected to a power terminal of the waste battery based on the predicted temperature exceeding the first threshold value.

[0131] In the discharge process of a waste battery according to the present invention, step (S400) is a step of lowering the discharge current value currently applied to discharge the waste battery if the temperature value predicted through step (S300) is identified as exceeding the first threshold value.

[0132] In one embodiment of the present invention, the first threshold value may be 40 to 50 degrees, preferably 45 to 50 degrees.

[0133] At this time, to determine whether to set the discharge current to a lower value, it may be monitored whether the predicted temperature is maintained for at least 30 seconds, preferably at least 1 minute, after being identified as exceeding the first threshold.

[0134] For example, if the predicted temperature is identified as exceeding the first threshold and is maintained for more than one minute, the discharge current value of the corresponding waste battery may be controlled from the first discharge current to the second discharge current.

[0135] As an example of the present invention, referring to FIGS. 5 and 6, the dV / dQ value, which is the reciprocal of the differential capacity of the spent battery, may rapidly increase in a time period of about 2,000 sec to 2,500 sec. In addition, referring to FIG. 6, when the discharge current value is 2.0 C or 1.0 C, the temperature inside the spent battery may rapidly increase as the dV / dQ value, which is the reciprocal of the differential capacity of the spent battery, rapidly increases in the corresponding time period.

[0136] At this time, the discharge system (100) can lower the temperature inside the spent battery by lowering the discharge current value. For example, the discharge system (100) can lower the temperature inside the spent battery by lowering the discharge current value from 2.0C or 1.0C to 0.3C or 0.5C. Through this, the discharge system (100) can perform a discharge operation by continuously applying a discharge current within a safe temperature range.

[0137] FIG. 8 is a graph showing changes in the internal temperature, current, voltage, and capacity of a battery over time when the above-described operation is applied, according to one embodiment of the present invention.

[0138] A discharge operation on a spent battery can be performed with a discharge current of approximately 100 A from 0 sec to 2,000 sec. As the dV / dQ value, which is the reciprocal of the differential capacity of the spent battery, increases rapidly during the time period from 2,000 sec to 2,500 sec, the temperature inside the spent battery can increase rapidly.

[0139] As described above, the discharge system (100) can predict the temperature inside the spent battery by monitoring the dV / dQ value, which is the reciprocal of the differential capacity of the spent battery. The discharge system (100) can reduce the discharge current value to approximately 25 A after identifying that the predicted temperature value inside the spent battery exceeds the first threshold value within a time period of 2,000 sec to 2,500 sec. Accordingly, the temperature inside the spent battery can gradually decrease.

[0140] As another example of the present invention, based on the reciprocal of the differential capacity of the spent battery, dV / dQ, exceeding a second threshold value, the discharge can be controlled to be performed at a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the spent battery.

[0141] That is, if the discharge system (100) identifies that dV / dQ, which is the reciprocal of the differential capacity monitored through step (S200), exceeds the second threshold value, it can control the discharge to be performed at a second discharge current lower than the first discharge current through the connection terminal connected to the power terminal of the waste battery.

[0142] Here, the second threshold value may be set to 10 to 20, and preferably 15 to 18.

[0143] (S500) Based on the predicted temperature being below the first threshold value, control is given to discharge at a third discharge current higher than the first discharge current through the connection terminal connected to the power terminal of the waste battery.

[0144] In the discharge process of a waste battery according to the present invention, step (S500) is a step of increasing the discharge speed by controlling discharge at a third discharge current higher than the first discharge current through a connection terminal connected to the power terminal of the waste battery when the predicted temperature does not exceed the first threshold value.

[0145] At this time, the discharge system (100) can adjust the third discharge current value so that the predicted temperature value calculated based on at least one of the third discharge current, power value, and energy (E) value does not exceed the first threshold value. That is, the discharge system (100) can perform the discharge procedure with the largest discharge current within a safe temperature range.

[0146] For example, the discharge system (100) can increase the discharge current by a certain unit value. That is, if the predicted temperature does not exceed the first threshold value, the discharge system (100) can increase the discharge current by a certain unit value and then predict the temperature inside the spent battery again. If the predicted temperature inside the spent battery does not exceed the first threshold value after increasing the discharge current value from the first discharge current to the third discharge current, the discharge system (100) can increase the discharge current by a certain unit value again.

[0147] (S600) A step of applying a constant voltage when the voltage of the waste battery reaches a specific voltage while discharging the waste battery.

[0148] In the discharge process of a waste battery according to the present invention, the step (S600) is a step of applying a constant voltage (CV) to the waste battery when the voltage of the waste battery reaches a specific voltage (e.g., 0 V).

[0149] Specifically, by applying a constant voltage in the above step (S600) (i.e., by entering CV mode and performing a discharge operation on the spent battery), over-discharge of the spent battery can be induced.

[0150] Meanwhile, in the discharge process of the waste battery according to the present invention, the constant voltage applied in the step (S600) may be a voltage at which the energy level difference between the positive and negative electrodes is close to 0, i.e., a voltage close to 0 V.

[0151] In this way, by removing the remaining lithium ions from the cathode, the used battery can be completely discharged and the energy level remaining in the used battery can be minimized.

[0152] In the discharge process of a waste battery according to the present invention, the constant voltage may be 0 V to 0.5 V, preferably 0 V to 0.1 V, based on a single cell.

[0153] In the discharge process of a waste battery according to the present invention, in the step (S600), the constant voltage may be applied until a cut-off current size of 0.005 to 0.5 C, preferably 0.01 C to 0.1 C, is measured.

[0154] Here, the cut-off current refers to the current generated when a constant voltage is applied, and as the constant voltage continues to be applied, the current size gradually decreases because it approaches over-discharge. At this time, when the cut-off current size reaches 0.005 C to 0.5 C, preferably 0.01 C to 0.1 C, the applied constant voltage is stopped and the discharge is stopped.

[0155] (S700) A step of stopping the discharge of the waste battery when the constant voltage is applied and a specific time has elapsed or the cut-off current according to the constant voltage application reaches a third threshold value.

[0156] In the discharge process of a waste battery according to the present invention, the step (S700) is a step of stopping the discharge of the waste battery when a constant voltage is applied and a specific time has elapsed or a cut-off current according to the application of the constant voltage has reached a third threshold value.

[0157] Here, the cut-off current refers to the current generated by the application of a constant voltage, and as the constant voltage continues to be applied, the current size may gradually decrease because the device approaches complete discharge. At this time, when the cut-off current size reaches 0.005 C to 0.5 C, preferably 0.01 C to 0.1 C, the applied constant voltage may be stopped and the discharge may be stopped.

[0158] (S800) A step of short-circuiting the battery to prevent the voltage of the waste battery from rebounding.

[0159] In the discharge process of a spent battery according to the present invention, step (S800) is a step in which the positive and negative poles of the spent battery are artificially connected to form a short circuit, thereby eliminating residual energy within the spent battery. In typical batteries, the voltage may rise again even after discharge is completed due to the battery's inherent voltage recovery voltage characteristics. To prevent this, the positive and negative poles of the spent battery are connected to form a short circuit, thereby reducing the possibility of voltage re-rising and sparks or fire.

[0160] Meanwhile, the embodiments of the present invention described above can be written as a program that can be executed on a computer, and the written program can be stored in a medium.

[0161] A medium may permanently store a computer-executable program, or may temporarily store it for execution or download. Furthermore, a medium may be a variety of recording or storage devices, including a single or multiple hardware devices. It is not limited to media directly connected to a computer system, but may also be distributed across a network.

[0162] Examples of media may include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floptical disks; and ROM, RAM, flash memory, and other media configured to store program instructions. Furthermore, examples of other media may include recording or storage media managed by app stores that distribute applications, other sites that supply or distribute various software, servers, etc.

[0163] The embodiments described in the present invention and the accompanying drawings merely exemplify some of the technical concepts encompassed by the present invention. Therefore, the embodiments disclosed in this specification are intended to illustrate, rather than limit, the technical concepts of the present invention. Therefore, it is clear that the scope of the technical concepts of the present invention is not limited by these embodiments.

[0164] All modifications and specific embodiments that can be easily inferred by a person skilled in the art within the scope of the technical idea included in the specification and drawings of the present invention should be interpreted as being included in the scope of the present invention.

[0165] [Explanation of symbols]

[0166] 100: Battery discharge system

[0167] 110: Chung Discharge section

[0168] 111: Charge / discharge current control unit

[0169] 120: Voltage measurement unit

[0170] 130: Memory section

[0171] 140: Connection terminal

[0172] 200: Waste batteries

Claims

1. In the process of discharging a waste battery, (S100) A step of discharging the waste battery with a first discharge current through a connection terminal connected to a power terminal of the waste battery; (S200) A step of monitoring dV / dQ, which is the reciprocal of the differential capacity of the waste battery according to time or voltage; (S300) A step of predicting the temperature inside the waste battery based on dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current; and (S400) A waste battery discharging process, comprising a step of controlling discharging at a second discharge current lower than the first discharge current through a connection terminal connected to a power terminal of the waste battery based on the predicted temperature exceeding a first threshold value.

2. In paragraph 1, The above step (S300) is, A step of obtaining a power (P) value through dV / dQ, which is the reciprocal of the differential capacity of the above-mentioned waste battery, and the first discharge current; and A spent battery discharging process, comprising a step of predicting a temperature inside the spent battery based on at least one of an initial temperature of the spent battery, a weight of the spent battery, a power (P) value, and an energy (E) value of the spent battery.

3. In paragraph 2, A discharge process of a waste battery, wherein discharge is controlled to be performed at a second discharge current lower than the first discharge current through a connection terminal connected to a power terminal of the waste battery based on the reciprocal of the differential capacity of the waste battery, dV / dQ, exceeding a second threshold value.

4. In paragraph 1, (S500) A waste battery discharging process further comprising a step of controlling discharging at a third discharge current higher than the first discharge current through a connection terminal connected to a power terminal of the waste battery based on the predicted temperature being lower than the first threshold value.

5. In paragraph 4, A discharge process for a spent battery, wherein a predicted temperature calculated based on at least one of the third discharge current, the power (P) value and the energy (E) value of the spent battery is less than the first threshold value.

6. In paragraph 4, (S600) A waste battery discharging process further comprising a step of applying a constant voltage when the voltage of the waste battery reaches a specific voltage while discharging the waste battery.

7. In paragraph 6, (S700) A waste battery discharging process further comprising a step of stopping discharging of the waste battery when the constant voltage is applied and a specific time has elapsed or a cut off current according to the application of the constant voltage reaches a third threshold value.

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