Method for checking performance of secondary battery, and apparatus for implementing same

Abstract

Disclosed are a method for checking the performance of a secondary battery, and an apparatus for implementing same. An electrical signal in a transient state for reaching a set charge / discharge voltage is Laplace-converted and derived as a defect time constant. Defect state energy, which is an energy level of a defect, is derived using a plurality of defect time constants. In addition, the density of charges filled in the level of the defect state energy is represented by a defect state density. The performance of the secondary battery may be confirmed through the defect state density filled in a predetermined level of a plurality of defect state energies.

Description

Method for verifying the performance of a secondary battery and a device for implementing the same

[0001] The present invention relates to a method and a device for verifying the performance of a secondary battery, and more particularly, to a method for verifying the performance of a secondary battery by modeling the secondary battery as a collection of defect state energies and defect state densities and using the same, and to a device for implementing the same.

[0002] A secondary battery is a device capable of repeatedly charging and discharging electrical energy. It consists of a cathode, anode, and an electrolyte. A separator is also inserted into the electrolyte. The performance of a secondary battery largely depends on the electrode materials and the type and composition of the electrolyte.

[0003] Recently, with the continuous improvement in secondary battery performance and the development of various processes, the types and density of defects within secondary battery cells are increasing. In particular, defects within cells directly impact the current discharge characteristics and long-term stability of secondary batteries. Therefore, technologies for accurately assessing and analyzing secondary battery deterioration are becoming increasingly important.

[0004] There are various techniques for acquiring data related to secondary battery deterioration and evaluating its performance through this data. For example, Korean Patent No. 10-2237565 discloses a technique for assessing the deterioration status of a battery. This patent sets specific parameters and uses time-series data on voltage and current to determine the degree of deterioration in a secondary battery. However, this method has limitations, as it only assesses the deterioration status by deriving an initial estimate and comparing it with other indicators.

[0005] Furthermore, because the causes of secondary battery deterioration are diverse, a detailed examination of the impact of each cause on secondary battery performance has not been conducted. In particular, the concept of defects is often understood as a simple defect, due to the limitations of physically verifying the internal condition of secondary batteries.

[0006] In other words, defects are recognized only as factors that deteriorate the performance of secondary batteries, and research is being conducted only in areas that aim to quickly and accurately identify abnormal conditions caused by defects, regardless of the type of defect.

[0007] The first technical task of the present invention is to provide a method for verifying the performance of a secondary battery through Laplace transform of a transient electrical signal.

[0008] In addition, the second technical task to be achieved by the present invention is to provide a device for checking the performance of a secondary battery in order to achieve the first technical task.

[0009] In order to achieve the first technical task described above, the present invention provides a method for verifying the performance of a secondary battery, comprising: performing a charge / discharge operation on a secondary battery; deriving a defect time constant of an electrical signal resulting from the charge / discharge operation of the secondary battery; and deriving a defect state energy, which is an energy level of a defect of the secondary battery, and a defect state density, which is a density of charges captured in the defect state energy, based on the defect time constant.

[0010] In order to achieve the second technical problem described above, the present invention provides a device for checking the performance of a secondary battery, the device including: a power supply unit connected to a positive electrode and a negative electrode of a secondary battery to supply power to the secondary battery to perform a charging or discharging operation; a temperature control unit for controlling the temperature of the secondary battery; a measuring unit for measuring an electrical signal during the charging or discharging operation according to a temperature change of the secondary battery; and a processor for obtaining a fault time constant from the electrical signal of the measuring unit according to the temperature control of the temperature control unit, and deriving a fault state energy, which is an energy level of a fault of the secondary battery, and a fault state density, which is a density of charges captured in the fault state energy, from the fault time constant.

[0011] According to the present invention described above, a plurality of fault time constants measured in a transient state where an overvoltage appears before a secondary battery reaches a steady state are used, and fault state energy is derived through the fault time constants measured at different temperatures. The fault state energy is a specific energy level at which charges can be captured or released in a transient state, and this is correlated with the electrical properties of the secondary battery. In addition, the fault time constant is derived through a Laplace transform, and the size of the response characteristic according to the fault time constant is determined. Through this, the fault state density of the fault state energy is determined. The fault state density represents the charge density filled or captured in the corresponding energy level.

[0012] The defect state energy and defect state density modeled and derived in the present invention are obtained from transient conditions and utilized as performance indicators for secondary batteries. Through these measurements, the performance of the secondary battery can be evaluated and changes in performance can be identified. Furthermore, performance degradation can be identified through changes in defect state energy or defect state density.

[0013] FIG. 1 is a graph illustrating defect state energy and defect state density according to a preferred embodiment of the present invention.

[0014] Figure 2 is a graph showing the voltage fluctuation of a secondary battery during charge and discharge operations of the secondary battery.

[0015] FIG. 3 is a flowchart illustrating a method for analyzing the state of a secondary battery according to a preferred embodiment of the present invention.

[0016] FIG. 4 is a flowchart illustrating a method for deriving a fault time constant according to a preferred embodiment of the present invention.

[0017] FIG. 5 is a flowchart illustrating a method for deriving defect state energy and defect state density according to a preferred embodiment of the present invention.

[0018] Figure 6 is a graph showing a discharge voltage according to a measurement example of the present invention.

[0019] Figure 7 is a graph showing the size of the Laplace-transformed response characteristics for each defect time constant derived according to a measurement example of the present invention.

[0020] Figure 8 is a graph showing the defect state density according to the defect state energy derived according to the measurement example of the present invention.

[0021] Figure 9 is a schematic diagram of a device for checking the performance of a secondary battery according to a preferred embodiment of the present invention.

[0022] The present invention is susceptible to various modifications and variations, and specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0023] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having 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.

[0024] Hereinafter, with reference to the attached drawings, a preferred embodiment of the present invention will be described in more detail.

[0025]

[0026] Example

[0027] The present invention introduces the concept of defects in the field of evaluating and verifying secondary battery performance, thereby remodeling secondary batteries. Typically, the term "defect" is understood as a factor that impedes normal operation. Furthermore, an increase in defects, regardless of defect type, is perceived as a factor that impairs the performance of a component or device performing a specific function.

[0028] However, in the present invention, defects are interpreted as elements that drive the secondary battery in a transient state, a stage before the secondary battery achieves stable operation. That is, a transient state is created by a defect, and to scientifically interpret this transient state, the state of the defect is interpreted and evaluated in terms of energy and density, thereby reinterpreting the performance of the secondary battery. The inventors of the present invention utilize the following scientific basis for this new interpretation of defects.

[0029] The key elements in the charge / discharge operation of a secondary battery are the positive electrode active material and the negative electrode active material, and the charge / discharge operation is performed as charges such as lithium ions flow in or out within the crystal structure or layered structure of the electrode material.

[0030] When charges flow into the active material of an electrode across the electrolyte, a defect is created within the active material itself. Furthermore, if the charges introduced into the active material are released from the crystal structure during discharge, this also constitutes a defect. In other words, defects in secondary batteries are interpreted as active sites capable of storing or releasing charges from a material perspective.

[0031] If a defect is interpreted as an active site, not all charges can be trapped within the defect, nor can all charges trapped at the defect site be extracted by external factors. In other words, only charges with specific energy levels can be trapped within or extracted from the defect. Therefore, a specific energy level is required for charges to be trapped at a defect. In the present invention, this is interpreted as defect state energy. Furthermore, the density of charges with specific energy levels trapped at a defect is defined as defect state density.

[0032] In the present invention, an electrical signal, such as voltage or current, is measured during the discharge operation of a secondary battery, and a fault time constant is derived from the measured electrical signal. The fault time constant can be obtained by performing a Laplace transform on the electrical signal measured in the time domain during the discharge operation.

[0033] The Laplace transform, derived from a polynomial of complex frequency s, can be transformed into an equation with multiple poles. When this is inverted back to the time domain, the multiple poles are transformed into multiple fault time constants. The poles of the Laplace transform correspond to the fault time constants.

[0034] A plurality of defect state energies corresponding to the derived multiple defect time constants are derived. The defect state energies are factors that interpret the secondary battery as a set of states having specific energy levels.

[0035] The process of deriving multiple fault time constants is the inverse Laplace transform. The inverse Laplace transform derives the absolute value of the time-domain electrical signal corresponding to a specific time constant. Based on this, a fault state density for each fault state energy is derived. The derived fault state density is an eigenvalue for a specific fault time constant, which represents the charge distribution pattern at a specific energy level in a secondary battery.

[0036] That is, the present invention interprets a transient secondary battery as a set of defect state energies, which are multiple energy levels. Furthermore, the transient state of a secondary battery is identified by the defect state density, which is the density of charge trapped at a specific energy level.

[0037] The performance of a secondary battery can be evaluated through the two factors described above, namely, defect state energy and defect state density, and the state of the secondary battery can be confirmed by tracking changes in these factors.

[0038]

[0039] FIG. 1 is a graph illustrating defect state energy and defect state density according to a preferred embodiment of the present invention.

[0040] Referring to Figure 1, the change in charge in a fully charged state, a discharged state, and a fully discharged state is illustrated.

[0041] Graph (a) represents the fully charged state. A secondary battery has multiple fault state energies, and all charges are filled at a set energy level. In other words, the fault state density is maximized.

[0042] Graph (b) represents the discharge state. Charges are released starting from lower energy levels. In modeling secondary batteries, the fault state energy is set to the energy required to release charges from the secondary battery during discharge operation. Therefore, charges at lower energy levels, which require relatively low energy, tend to be released.

[0043] Graph (c) depicts a fully discharged state. In a fully discharged state, no charge appears at any of the energy levels of the defect states. Therefore, the defect state density appears to be nearly empty.

[0044] Figure 2 is a graph showing the voltage fluctuation of a secondary battery during charge and discharge operations of the secondary battery.

[0045] Referring to Fig. 2, the voltage of the secondary battery tends to increase during a charging operation, and the voltage of the secondary battery tends to decrease during a discharging operation. That is, in a transient state where fluctuations in the charging voltage or discharging voltage occur at the beginning of a charging or discharging operation, a transient voltage appears, and an exponential increase and decrease characteristic is exhibited. In the present invention, the state of the secondary battery is newly set by utilizing fluctuations in the electrical signal during the transient state.

[0046] However, the transient voltage in the transient state shown in Fig. 2 is somewhat exaggerated, as it is not a measurement of the actual discharge voltage of a secondary battery. This is merely a means to facilitate the explanation of the transient state, and the voltage in an actual transient state fluctuates irregularly and exhibits multiple time constants. Laplace transforming and inversely transforming this can yield multiple fault time constants.

[0047] FIG. 3 is a flowchart illustrating a method for analyzing the state of a secondary battery according to a preferred embodiment of the present invention.

[0048] Referring to FIG. 3, power is supplied to the electrodes of the secondary battery to set a dischargeable state, and a charging or discharging operation is performed (S100).

[0049] During the initial charge / discharge cycle, voltage or current fluctuations occur, which are modeled as being caused by defects. Therefore, the state in which voltage or current fluctuations occur due to defects is defined as a transient state.

[0050] Next, the fault time constant of the electrical signal expressed as a current or voltage due to the charge being charged and discharged from the secondary battery is derived (S200). The fault time constant is derived from the transient state of the charge and discharge operation as explained in FIG. 2. The fault time constant becomes a fundamental element that determines the physical properties of the secondary battery. That is, the variation of the electrical signal in the transient state is interpreted based on the fault time constant. In particular, the fault time constant appears in multiple numbers. This is because, as illustrated in FIG. 1, the energy level of the fault does not remain in one state but has various energy levels. In the present invention, the number of derived fault time constants is set equal to the number of fault state energies.

[0051] Once the fault time constant is derived, it is determined whether the secondary battery has reached the critical temperature (S300). The critical temperature refers to the temperature at which fault state energy can be extracted. Since the charge / discharge rate of a secondary battery increases as the temperature rises, fault state energy can be extracted through changes in the charge / discharge rate depending on the temperature. In other words, the critical temperature is the temperature at which the charge / discharge rate measurement is sufficiently performed depending on the temperature, and fault state energy can be extracted.

[0052] If the secondary battery does not reach the critical temperature, the temperature of the secondary battery is changed (S400). Furthermore, a new fault time constant for the secondary battery is derived under the changed temperature conditions. This process continues until the temperature reaches the critical temperature.

[0053] If the critical temperature is reached, defect state energy and defect state density are derived based on the derived multiple defect time constants (S500). As described above, defect state energy represents the energy levels of defects in the secondary battery under specific temperature conditions. Furthermore, defect state density represents the density of charge trapped within a specific energy level.

[0054] The derived defect state energy and defect state density represent the electrical characteristics of a secondary battery under transient conditions. Changes in the performance of a secondary battery can be identified through fluctuations in defect state energy and defect state density. Changes in specific energy levels or charge density resulting from continuous use of the secondary battery can also be measured, and changes in physical properties over long-term use can be measured.

[0055] FIG. 4 is a flowchart illustrating a method for deriving a fault time constant according to a preferred embodiment of the present invention.

[0056] Referring to Fig. 4, data of electrical signals in a transient state are measured and collected in time series (S210).

[0057] Next, the time-domain electrical signal is transformed into the complex frequency domain through the Laplace transform, and the time constant is derived (S220). If the transient electrical signal is referred to as a response characteristic, the response characteristic has different values ​​depending on the temperature.

[0058] When electrical signals at a specific temperature are Laplace transformed, multiple time constants are obtained. The Laplace transform of the measured values ​​exhibits the characteristic that the signal fluctuates according to complex frequency, and its response characteristic is expressed as a polynomial of complex frequency s. If this is expressed as a sum of single fractions through partial fraction expansion, multiple time constants are obtained. Let us assume that the response characteristic is as shown in Equation 1 below.

[0059] [Formula 1]

[0060]

[0061] Here, the time constants are a, b, and c, respectively. The above formula represents a decay function and can be expressed in a different formula during charging.

[0062] Next, the Laplace-transformed response characteristic is inversely transformed into a response characteristic in the time domain, and the consistency between the response characteristic in the time domain and the original electrical signal measured in the transient state is determined (S230).

[0063] The consistency assessment determines the accuracy of the Laplace transform. In other words, it determines whether the time constant derived from the Laplace transform accurately represents the transient electrical signal. For example, if the inversely transformed time-domain response characteristics differ by more than 1% from the electrical signal in waveform and phase comparison, consistency may be judged to be degraded. However, the criteria for determining consistency are indicators that can be set differently depending on the secondary battery user.

[0064] Ultimately, it is confirmed whether the time constants derived by checking whether the two signals match accurately represent the characteristics of the transient state.

[0065] If consistency is determined to be lacking, the transient electrical signal is remeasured and the process of deriving an accurate time constant is repeated. However, if consistency falls below the standard, it may be due to a low sampling frequency for the waveform during the electrical signal measurement operation. Therefore, those skilled in the art can increase the sampling frequency to ensure consistency.

[0066] Additionally, if there is consistency, the derived time constant is determined as the defect time constant (S240). In the subsequent steps, the defect state energy and defect state density are derived using the defect time constant.

[0067] FIG. 5 is a flowchart illustrating a method for deriving defect state energy and defect state density according to a preferred embodiment of the present invention.

[0068] Referring to Fig. 5, the fault state energy is derived through the fault time constants (S510).

[0069] Since the defect time constants are determined based on temperature in the previous steps, they can be used to obtain the defect state energy. The defect state energy is derived using Equation 2 below.

[0070] [Formula 2]

[0071]

[0072] In the above formula 2, τ t is the defect time constant, α is the material proportionality constant, and σ t is the capture cross-sectional area of ​​the defect, and k b is the Boltzmann constant, and E d represents the defect state energy, and T is the absolute temperature of the defect, which refers to the absolute temperature of the secondary battery. In particular, the above equation 2 is called the Arrhenius equation, and the left term τ t Since is a constant related to the reaction rate, a mathematical model relationship is formed with the absolute temperature T of the right-hand side.

[0073] In the above mathematical expression 1, ln(τ t / T 2 ) and 1 / T, ln(τ) for 1 / T t / T 2 ) is the slope of the defect state energy E d It applies to.

[0074] Therefore, the defect state energy E d To determine the fault time constants, at least two temperature conditions need to be measured.

[0075] At a specific temperature, the defect state energy has different values ​​depending on the defect time constant.

[0076] Once the defect state energy is derived, the defect state density for the defect state energy is derived (S520).

[0077] The defect state density of the corresponding defect state energy can be derived using the absolute value of the response characteristic of the Laplace transform corresponding to a specific defect time constant and the defect time constant.

[0078] That is, the defect time constant is linked to the defect state energy, and the absolute value of the response characteristic appears in the complex frequency domain. Through this, the defect state density can be derived.

[0079] For example, if charges trapped in a specific fault state energy escape during the discharge operation, the total charge inside the battery changes. Here, assuming that the internal fault state energy is one, the total charge trapped in the energy level is Q t and if the fault time constant is τ, the total charge present in the battery during the discharge operation is as follows.

[0080]

[0081] Total charge Q t is the defect state density N, which is the number of trapped charges per unit volume. d , the unit charge q, the area A, which is the volume of the charge / discharge material inside the battery, and the gap d are multiplied as follows.

[0082]

[0083] Also, since V=IR and I=dQ / dt, the transient voltage, which is the voltage that changes according to the discharge of charge, is determined by the following equation 3.

[0084] [Formula 3]

[0085]

[0086] In Equation 3, Vτ(t) represents the voltage in the time domain according to the fault time constant τ, R represents the resistance of the battery measuring device, A represents the area of ​​the cathode or anode in the battery, and d represents the gap between the cathode and anode. In addition, τ represents the fault time constant, and N d is the fault state energy E per unit volume at that fault time constant. dis the number of charges having , and represents the density of defect states. q is the charge quantity of the charge. In the above equation 3, RAdq can be interpreted as an arbitrary proportional constant that can be determined by the physical configuration of the battery, etc. The same applies hereinafter.

[0087] The above equation 3 is the inverse transformation of one defect time constant τ into the time domain, and in the above equation 3, τ is substituted for t, and V(τ) represents the size of the response characteristic at the corresponding defect time constant τ in the Laplace transform equation. Since the defect state energy Ed for the defect time constant τ has already been derived through the Laplace transform of the electrical signal, and the defect state density Nd for a specific defect time constant τ is obtained through the above equation 3, the defect state density Nd for a specific defect state energy Ed can be obtained.

[0088] However, the above equation 3 represents the voltage fluctuation for a specific defect time constant τ, and the result reflecting multiple time constants follows equation 4 below.

[0089] [Formula 4]

[0090]

[0091] In the above equation 4, V(t) represents the voltage of the transient state after the Laplace inverse transform, and the subscript a represents each fault time constant. Therefore, V(t) becomes the sum of the time-domain voltages due to all fault time constants derived through the Laplace transform in the transient state.

[0092]

[0093] Manufacturing Example: Fabrication of Half Coin Cells

[0094] NCM 622 was used as the cathode material, and LiPF6 was used as the electrolyte. Lithium foil was used as the anode material, and Celguard2400, a polypropylene-based separator, was used. Coin-type half-cells were manufactured.

[0095]

[0096] Measurement example: Voltage measurement in the discharge section

[0097] A discharge operation was performed on the half cell manufactured by the above manufacturing example. The discharge operation was performed at a temperature interval of 10°C from 10°C to 60°C, and the discharge voltage of the half cell was measured for 100 seconds at each temperature setting.

[0098] Figure 6 is a graph showing a discharge voltage according to a measurement example of the present invention.

[0099] Referring to Figure 6, it is confirmed that the discharge operation in the transient region progresses rapidly as the temperature increases. Based on the data depicted in the graph of Figure 6, a Laplace transform is performed, and seven poles are derived through factor separation of the polynomial expressed in complex frequency. The seven derived poles correspond to the fault time constants.

[0100] Again, this was converted back to the time domain and the graph of Fig. 4 was examined for consistency. Since the graph was confirmed to be consistent, the seven poles were determined as fault time constants, and the fault state energies corresponding to the seven fault time constants were calculated using Equation 2 at 30°C.

[0101] Figure 7 is a graph showing the size of the Laplace-transformed response characteristics for each defect time constant derived according to a measurement example of the present invention.

[0102] Referring to Figure 7, the magnitude of the response characteristic corresponding to each fault time constant is displayed. In the graph, the magnitude of the response characteristic for one fault time constant, e.g., 0.001 seconds, is shown as 0.35 V, which is the result obtained using the above equation 3.

[0103] The magnitude of the response characteristic for each of the seven derived fault time constants is represented as a peak value.

[0104] Figure 8 is a graph showing the defect state density according to the defect state energy derived according to the measurement example of the present invention.

[0105] Referring to Fig. 8, the magnitude of the defect state energy is determined for each specific defect time constant by Equation 2. In addition, the defect state density corresponding to a specific defect time constant can be determined by Equation 3.

[0106] The above graph illustrates the unique characteristics of secondary batteries. That is, each manufactured secondary battery may have a different distribution of defect state energy, and the defect state density filled at the corresponding defect state energy level may be set differently.

[0107] Accordingly, based on this, changes in the performance of the secondary battery can be confirmed, and by confirming the changes in the data of FIG. 8, the lifespan of the secondary battery can be predicted or a performance index can be set.

[0108]

[0109] Figure 9 is a schematic diagram of a device for checking the performance of a secondary battery according to a preferred embodiment of the present invention.

[0110] Referring to FIG. 9, the secondary battery performance verification device has a power supply unit (110), a temperature control unit (120), a measurement unit (130), and a processor (140).

[0111] The power supply unit (110) is connected to the positive and negative poles of the secondary battery (10) and supplies power to the secondary battery (110). By supplying power, the secondary battery (10) can be charged and discharged. The power supply can be supplied in pulse form, and can be supplied in a set interval or a discharge operation can be performed.

[0112] The above power supply unit (110) is connected to the processor (140) and performs a power supply operation under the control of the processor (140).

[0113] The temperature control unit (120) can be connected to the outside or inside of the secondary battery (10). The temperature control unit (120) can sense the temperature of the secondary battery and transmit the temperature information to the processor (140). In addition, the temperature of the secondary battery (10) can be increased or decreased under the control of the processor (140).

[0114] In particular, the temperature control unit (120) is used to obtain fault time constants at different temperatures. The fault time constants measured at different temperatures are used to derive fault state energy.

[0115] The measuring unit (130) is connected to the secondary battery (10) and measures an electrical signal generated from the secondary battery (10). The measured electrical signal is transmitted to the processor (140).

[0116] The processor (140) receives the electrical signal from the measuring unit (130) and performs a Laplace transform to convert it into a complex frequency domain. Through this, the fault time constant of the secondary battery is obtained. In addition, the processor derives the fault state energy through calculations and derives the fault state density corresponding to the fault state energy.

[0117]

[0118] In the present invention described above, a plurality of fault time constants measured in a transient state of a secondary battery are used, and fault state energy is derived through the fault time constants measured at different temperatures. The fault state energy is a specific energy level at which charges can be captured or released in a transient state, and this represents the electrical properties of the secondary battery. In addition, the fault time constant is derived through the Laplace transform, and the size of the response characteristic according to the fault time constant is determined. Through this, the fault state density of the fault state energy is determined. The fault state density represents the charge density filled or captured in the corresponding energy level.

[0119] The defect state energy and defect state density modeled and derived in the present invention are obtained from transient conditions and utilized as performance indicators for secondary batteries. Through these measurements, the performance of the secondary battery can be evaluated and changes in performance can be identified. Furthermore, performance degradation can be identified through changes in defect state energy or defect state density.

Claims

1. A step of performing a charge / discharge operation on a secondary battery; A step of deriving a fault time constant through Laplace transform of an electrical signal resulting from the charge / discharge operation of the secondary battery; and A method for verifying the performance of a secondary battery, comprising the step of deriving a defect state energy, which is an energy level of a defect of the secondary battery, and a defect state density, which is a density of charges captured in the defect state energy, based on the defect time constant.

2. A method for verifying the performance of a secondary battery, characterized in that in the first paragraph, the defect time constant is derived from a transient state in which the electrical signal fluctuates.

3. In the second paragraph, the step of deriving the defect time constant is, A step of measuring data of the electrical signal in a time series manner in the above transient state; A step of deriving a time constant by performing a Laplace transform on the measured electrical signal; A step of inversely transforming the above Laplace transformed response characteristic into the time domain to determine the consistency between the electrical signal and the inversely transformed response characteristic; and A method for verifying the performance of a secondary battery, characterized in that it comprises a step of determining the derived time constant as the defect time constant when there is consistency.

4. A method for verifying the performance of a secondary battery, characterized in that, after the step of deriving the defect time constant in the first paragraph, the method further includes a step of determining whether a critical temperature, which is a temperature at which the defect state air can be extracted, has been reached by measuring the charge / discharge speed of the secondary battery according to a change in temperature.

5. A method for verifying the performance of a secondary battery, characterized in that a new fault time constant is derived if the secondary battery does not reach the critical temperature in the fourth paragraph.

6. In the first paragraph, the step of deriving the defect state energy and the defect state density is, A step of deriving the fault state energy through the fault time constant; and A method for verifying the performance of a secondary battery, characterized by including a step of deriving the defect state density for the defect state energy using the absolute value of the response characteristic of the Laplace transform and the defect time constant.

7. In the sixth paragraph, the defect state energy is ln(τ) for 1 / T. t / T 2 ) is the slope, and T is the absolute temperature of the secondary battery, τ t A method for verifying the performance of a secondary battery, characterized in that it represents the above defect time constant.

8. A method for verifying the performance of a secondary battery, characterized in that in paragraph 6, the defect state density is derived according to the following mathematical formula 3. [Formula 3] In Equation 3, Vτ(t) represents the voltage in the time domain according to the fault time constant τ, R represents the resistance of the battery measuring device, A represents the area of ​​the cathode or anode in the battery, and d represents the gap between the cathode and anode. In addition, τ represents the fault time constant, and N d is the fault state energy E per unit volume at the corresponding fault time constant. d is the number of charges having , and represents the density of the defect states. q is the amount of charge.

9. A method for verifying the performance of a secondary battery, characterized in that the defect time constant in paragraph 1 is plural.

10. A power supply unit connected to the positive and negative electrodes of a secondary battery to supply power to the secondary battery to perform a charging or discharging operation; A temperature control unit for controlling the temperature of the secondary battery; A measuring unit for measuring an electrical signal during the charging or discharging operation according to a temperature change of the secondary battery; A device for verifying the performance of a secondary battery, comprising a processor for obtaining a defect time constant from the electrical signal of the measuring unit according to the temperature control of the temperature control unit, and deriving a defect state energy, which is an energy level of a defect of the secondary battery, and a defect state density, which is a density of charges captured in the defect state energy, from the defect time constant.

11. A device for verifying the performance of a secondary battery, characterized in that in the 10th paragraph, the defect state energy is derived through the defect time constants derived at different temperatures.

12. A device for verifying the performance of a secondary battery, characterized in that in the 10th paragraph, the defect state density is derived according to the following mathematical formula 4. [Formula 4] In Equation 4, Vτ(t) represents the voltage in the time domain according to the fault time constant τ, R represents the resistance of the battery measuring device, A represents the area of ​​the cathode or anode in the battery, and d represents the gap between the cathode and anode. In addition, τ represents the fault time constant, and N d is the fault state energy E per unit volume at the corresponding fault time constant. d is the number of charges having , and represents the density of the defect states. q is the amount of charge.

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