Method of confirming Performance of Secondary Battery and Apparatus of preforming the same

Abstract

A method for verifying the performance of a secondary battery and an apparatus for implementing the same are disclosed. An electrical signal in a transient state to reach a set charge / discharge voltage is Laplace transformed to derive a defect time constant. Using a plurality of defect time constants, a defect state energy, which is an energy level possessed by a defect, is derived. In addition, the charge density filling the level possessed by the defect state energy is represented as the defect state density. The performance of the secondary battery can be verified through the defect state density filling a constant level of a plurality of defect state energies.

Description

Technology Field

[0001] The present invention relates to a method and apparatus for verifying the performance of a secondary battery, and more specifically, to a method for verifying the performance of a secondary battery by modeling the secondary battery as an aggregate of defect state energy and defect state density and using this, and to an apparatus for implementing the same. Background Technology

[0002] A secondary battery is a device capable of repeatedly charging and discharging electrical energy, and consists of a positive electrode, a negative electrode, and an electrolyte. Additionally, a separator is inserted within the electrolyte. The performance of a secondary battery largely depends on the electrode materials and the type and composition of the electrolyte.

[0003] Recently, as the performance of secondary batteries continues to improve and various processes are developed, the types and density of inherent defects within the cells are increasing. In particular, internal cell defects are a factor that directly affects the current discharge characteristics and long-term stability of secondary batteries. Consequently, technologies for accurately evaluating and analyzing secondary battery degradation are becoming increasingly important.

[0004] There are various technologies for acquiring data related to the degradation of secondary batteries and evaluating their performance. For example, Korean registered patent No. 10-2237565 discloses a technology for determining the degradation state of a battery. In the said patent, specific parameters are set, and the degree of degradation of the secondary battery is determined using time-series data of voltage and current. This method has limitations in that it determines only the degradation state by deriving an initial estimated value and comparing it with other indicator values.

[0005] Furthermore, since the causes of secondary battery degradation are diverse, detailed examinations regarding how each cause affects battery performance are not being conducted. In particular, the concept of a defect is understood merely as a factor of simple failure due to the limitation that the internal state of the secondary battery cannot be physically verified.

[0006] In other words, defects are recognized solely as factors that degrade the performance of secondary batteries, and research is being conducted only in areas aimed at rapidly and accurately identifying abnormal conditions caused by defects, regardless of the type of defect. The problem to be solved

[0007] The first technical problem that the present invention aims to solve is to provide a method for verifying the performance of a secondary battery through a Laplace transform of an electrical signal in a transient state.

[0008] In addition, the second technical objective of the present invention is to provide a device for verifying the performance of a secondary battery to achieve the first technical objective. means of solving the problem

[0009] The present invention, for achieving the first technical objective described above, provides a method for verifying the performance of a secondary battery comprising: a step of performing a charge-discharge operation on the secondary battery; a step of deriving a defect time constant of an electrical signal attributable to the charge-discharge operation of the secondary battery; and a step of deriving a defect state energy, which is an energy level of a defect in 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] The present invention, for achieving the second technical objective described above, provides a performance verification device for a secondary battery comprising: a power supply unit connected to the positive and negative electrodes of the secondary battery to supply power to the secondary battery and perform a charging or discharging operation; a temperature control unit for controlling the temperature of the secondary battery; a measurement 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 defect time constant from the electrical signal of the measurement unit according to the temperature control of the temperature control unit, and deriving a defect state energy, which is an energy level of the defect in the secondary battery, and a defect state density, which is a density of charge captured in the defect state energy, from the defect time constant. Effects of the invention

[0011] According to the present invention described above, a plurality of defect time constants measured during the transient state of a secondary battery are utilized, and defect state energy is derived through the defect time constants measured for each temperature. The defect state energy is a specific energy level at which charges can be captured or released during the transient state, and this represents the electrical properties of the secondary battery. Furthermore, the defect time constant is derived through a Laplace transform, and the magnitude of the response characteristics according to the defect time constant is determined. Through this, the defect state density of the defect state energy is determined. The defect state density represents the charge density filled or captured at the corresponding energy level.

[0012] The defect state energy and defect state density modeled and derived in the present invention are obtained from transient states and are used as performance indicators of secondary batteries. Through this, the performance of the secondary battery can be evaluated, and changes in performance can also be confirmed. In addition, performance degradation can be confirmed by fluctuations in defect state energy or defect state density. Brief explanation of the drawing

[0013] FIG. 1 is a graph illustrating the defect state energy and defect state density according to a preferred embodiment of the present invention. Figure 2 is a graph showing the voltage fluctuation of a secondary battery during charging and discharging operations. 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. FIG. 4 is a flowchart illustrating a method for deriving a defect time constant according to a preferred embodiment of the present invention. 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. Figure 6 is a graph showing the discharge voltage according to a measurement example of the present invention. Figure 7 is a graph showing the magnitude of the Laplace-transformed response characteristics for each defect time constant derived according to the measurement example of the present invention. 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. FIG. 9 is a schematic diagram of a device for verifying the performance of a secondary battery according to a preferred embodiment of the present invention. Specific details for implementing the invention

[0014] The present invention is susceptible to various modifications and may take various forms; therefore, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the invention to the specific disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals have been used for similar components in the description of each drawing.

[0015] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0016] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings.

[0018] Examples

[0019] In this invention, the concept of defects is introduced in the domain of evaluating and verifying the performance of secondary batteries to model the secondary battery in a new way. Typically, the term "defect" is recognized as a factor that hinders normal operation. Furthermore, an increase in defects, regardless of type, is recognized as a factor that impairs the performance of components or devices performing specific functions.

[0020] However, in the present invention, defects are interpreted as factors that drive the secondary battery in a transient state, which is a stage prior to the secondary battery performing stable operation. That is, a transient state is formed due to defects, and to scientifically interpret this transient state, the state of the defects is interpreted and evaluated in terms of energy and density, thereby reinterpreting the performance of the secondary battery. The inventors of the present invention use the following scientific grounds in reinterpreting defects.

[0021] The key elements in the charging and discharging operation of a secondary battery are the positive and negative active materials, and the charging and discharging operation is performed as charges, such as lithium ions, flow into or leach out of the crystal or layered structure of the electrode materials.

[0022] When electric charge flows across the electrolyte into the active material of the electrode, a defect is created from the perspective of the active material itself. Furthermore, if the charge introduced into the active material is released from the crystal structure through discharge, this also constitutes the creation of a defect. In other words, from a material perspective, defects in secondary batteries are interpreted as active sites capable of storing or releasing electric charge.

[0023] If a defect is interpreted as an active site, not all charges can be captured within the defect, nor can all charges captured at the defect site be released by disturbance factors. In other words, only charges in a state with a specific energy level can be captured within the defect or released from the defect. Therefore, a specific energy level is required for charges to be captured in a defect. In the present invention, this is interpreted as defect state energy. Furthermore, the density of charges with a specific energy level captured in a defect is defined as defect state density.

[0024] In the present invention, voltage or current, which is an electrical signal during the discharge operation of a secondary battery, is measured, 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.

[0025] A Laplace transform equation derived from a polynomial of complex frequency s can be converted into an equation with multiple poles. When this is inversely transformed back into the time domain, the multiple poles are converted into multiple fault time constants. The poles of the Laplace transform equation correspond to the fault time constants.

[0026] Multiple fault state energies corresponding to the derived multiple fault time constants are derived. The said fault state energy is a factor that interprets the secondary battery as a set of states having specific energy levels.

[0027] The process of deriving multiple defect time constants is the inverse Laplace transform. In the inverse Laplace transform, the absolute value of the electrical signal in the time domain corresponding to a specific time constant is derived. Based on this, the defect state density for each defect state energy is derived. The derived defect state density is an eigenvalue for a specific defect time constant, representing the pattern of charge distribution at specific energy levels in a secondary battery.

[0028] That is, in the present invention, a secondary battery in a transient state is interpreted as a set of defect state energies, which are a plurality of energy levels. In addition, the transient state of the secondary battery is identified by the defect state density, which is the density of charges captured at a specific energy level.

[0029] The performance of a secondary battery can be evaluated through the two aforementioned factors, defect state energy and defect state density, and the state of the secondary battery can be verified by tracking changes in these factors.

[0031] FIG. 1 is a graph illustrating the defect state energy and defect state density according to a preferred embodiment of the present invention.

[0032] Referring to Fig. 1, the change in charge in the fully charged state, the discharged state, and the completely discharged state is illustrated.

[0033] Graph (a) represents the fully charged state. The secondary battery has multiple defect state energies, and charges are fully filled at the set energy levels. In other words, it becomes a state where the defect state density is maximized.

[0034] Graph (b) represents the discharge state. Charges are released starting from lower energy levels. In the modeling of secondary batteries, the fault state energy is set as the energy required for charges to be released from the secondary battery during discharge; therefore, there is a tendency for low-level charges, which require relatively low energy, to be released.

[0035] Graph (c) illustrates the complete discharge state. In the complete discharge state, no charge appears at any level of defect state energy. Therefore, the defect state density appears to be almost empty.

[0036] Figure 2 is a graph showing the voltage fluctuation of a secondary battery during charging and discharging operations.

[0037] Referring to FIG. 2, the voltage of the secondary battery tends to increase during charging operation, and the voltage of the secondary battery tends to decrease during discharging operation. That is, in the initial transient state of charging or discharging operation, a transient voltage appears, and characteristics of exponential increase and decrease are exhibited. In the present invention, the state of the secondary battery is newly set using the fluctuation of the electrical signal in the transient state.

[0038] However, the transient voltage in the transient state shown in Figure 2 above is somewhat exaggerated as it is not a measured value of the actual discharge voltage of the secondary battery. This is used as a means to easily explain the transient state, and the actual voltage in the transient state fluctuates irregularly, and multiple time constants appear. By performing a Laplace transform and an inverse transform on this, multiple fault time constants can be obtained.

[0039] 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.

[0040] Referring to FIG. 3, power is supplied to the electrodes of a secondary battery to set a dischargeable state, and a charging or discharging operation is performed (S100). At the beginning of the charging or discharging operation, fluctuations in voltage or current occur, which are modeled as being caused by a defect. Therefore, a state in which fluctuations in voltage or current occur due to a defect is defined as a transient state.

[0041] Next, a fault time constant of an electrical signal, expressed as a current or voltage attributable to charges being charged or discharged from a secondary battery, is derived (S200). The fault time constant is derived from the transient state of the charge-discharge operation as described in FIG. 2. The fault time constant is a fundamental factor in determining the physical properties of the secondary battery. That is, fluctuations in the electrical signal during the transient state are interpreted based on the fault time constant. In particular, the fault time constant appears as multiple values. This is because, as illustrated in FIG. 1, the energy level of the fault does not remain in a single state but possesses various energy levels. In the present invention, the number of derived fault time constants is set to be equal to the number of fault state energies.

[0042] When the defect time constant is derived, it is determined whether the secondary battery has reached a critical temperature (S300). The critical temperature refers to the temperature at which defect state energy can be extracted. Since the charge / discharge rate of the secondary battery increases as the temperature rises, defect state energy can be extracted through changes in the charge / discharge rate according to temperature. In other words, the critical temperature is the temperature at which defect state energy can be extracted after sufficient measurement of the charge / discharge rate according to temperature.

[0043] If the secondary battery does not reach a critical temperature, the temperature of the secondary battery is changed (S400). Additionally, a new defect time constant for the secondary battery is derived under the changed temperature conditions. The above operation continues until the temperature is set to the critical temperature.

[0044] If a critical temperature is reached, the defect state energy and defect state density are derived based on the derived multiple defect time constants (S500). As previously described, the defect state energy represents the energy level of the defects in the secondary battery under specific temperature conditions. Additionally, the defect state density represents the density of charges trapped within a specific energy level.

[0045] The derived defect state energy and defect state density represent the electrical characteristics of a secondary battery in a transient state. Changes in the performance of the secondary battery can be identified through variations in defect state energy and defect state density, changes in specific energy levels or charge density due to continuous use of the secondary battery can be measured, and trends in changes in physical properties due to long-term use can be measured.

[0046] FIG. 4 is a flowchart illustrating a method for deriving a defect time constant according to a preferred embodiment of the present invention.

[0047] Referring to FIG. 4, data of electrical signals are measured and collected in a time series during a transient state (S210).

[0048] Next, the electrical signal in the time domain is converted into the complex frequency domain through a Laplace transform, and a time constant is derived (S220). If the electrical signal in the transient state is referred to as the response characteristic, the response characteristic has different values ​​depending on the temperature.

[0049] When electrical signals at a specific temperature are Laplace transformed, multiple time constants are obtained. The Laplace transforms of the measurements exhibit the characteristic that the signal varies according to the complex frequency, and their response characteristics are expressed as a polynomial of the 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 characteristics are as shown in Equation 1 below.

[0050] [Formula 1]

[0051]

[0052] Here, the time constants are a, b, and c, respectively. The above formula represents the damping function, and can be expressed differently during charging.

[0053] Next, the Laplace-transformed response characteristic is inversely transformed into a time-domain response characteristic, and the consistency between the time-domain response characteristic and the original electrical signal measured in the transient state is determined (S230).

[0054] The determination of consistency involves assessing the accuracy of the Laplace transform. In other words, it is a step of determining whether the time constant derived from the Laplace transform accurately represents the electrical signal in a transient state. For example, if the response characteristics in the time domain of the inverse transform differ by more than 1% when compared with the electrical signal, waveform, and phase, the consistency may be judged to be degraded. However, the criteria for determining consistency are indicators that can be set differently depending on the user of the secondary battery.

[0055] Ultimately, it is confirmed whether the time constants derived through checking whether the two signals match accurately represent the characteristics of the transient state.

[0056] If it is determined that there is no consistency, the process of re-measuring the electrical signal in the transient state and deriving the accurate time constant is repeated. However, if the consistency falls short of the standard value, it may be because the sampling frequency for the waveform in the electrical signal measurement operation is small; therefore, a person skilled in the art may ensure consistency by increasing the sampling frequency.

[0057] Additionally, if consistency is met, the derived time constant is determined as the defect time constant (S240). In a subsequent step, the defect state energy and defect state density are derived using the defect time constant.

[0058] 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.

[0059] Referring to FIG. 5, the defect state energy is derived through defect time constants (S510).

[0060] Since the defect time constants were determined according to temperature in the previous steps, they can be used to determine the defect state energy. The defect state energy is derived by the following Equation 2.

[0061] [Equation 2]

[0062]

[0063] In Equation 2 above, τ t is the defect time constant, α is the material proportionality constant, and σ t is the defect capture cross-section, and k b is the Boltzmann constant, and E d ε represents the defect state energy, and T is the absolute temperature of the defect, referring to the absolute temperature of the secondary battery. In particular, the above Equation 2 is called the Arrhenius equation, and τ of the left-hand term t Since ε is a constant related to the reaction rate, a mathematical model relationship is formed with the absolute temperature T on the right side.

[0064] In the above mathematical formula 1, ln(τ t / T 2 When examining the relationship between ) and 1 / T, ln(τ for 1 / T t / T 2 The slope of ) is the defect state energy E d It corresponds to.

[0065] Therefore, defect state energy E d To determine, it is necessary to measure the fault time constants under at least two temperature conditions.

[0066] At a specific temperature, the fault state energy has different values ​​depending on the fault time constant.

[0067] When the defect state energy is derived, the defect state density for the defect state energy is derived (S520).

[0068] 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.

[0069] In other words, the fault time constant is coupled with the fault state energy, and the absolute value of the response characteristic appears in the complex frequency domain. Through this, the fault state density can be derived.

[0070] For example, if charges trapped at a specific fault state energy escape during a discharge operation, the total charge inside the battery changes. Here, assuming there is only one internal fault state energy, the total charge trapped at said energy level is Q t Let α be the fault time constant, and τ be the total charge present in the battery during discharge operation as follows.

[0071]

[0072] Total charge Q t ε is the defect state density N, which is the number of trapped charges per unit volume. d The charge of a unit charge q, the volume of the charge / discharge material inside the battery, and the product of the area A and the gap d are summarized as follows.

[0073]

[0074] In addition, since V=IR and I=dQ / dt, the transient voltage, which is the voltage that changes with the emission of charge, is determined by the following Equation 3.

[0075] [Equation 3]

[0076]

[0077] 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 negative or positive electrode within the battery, and d represents the gap between the negative and positive electrodes. Additionally, τ represents the fault time constant, and N d is the fault state energy E per unit volume according to the corresponding fault time constant at the corresponding fault time constant. dIt is the number of charges having and represents the defect state density. q is the charge amount of the charge. In Equation 3 above, RAdq can be interpreted as an arbitrary proportionality constant that can be determined by the physical configuration of the battery, etc. The same applies below.

[0078] Equation 3 above is the inverse transformation of a single defect time constant τ into the time domain, and τ is substituted for t in Equation 3, where V(τ) represents the magnitude of the response characteristic at the corresponding defect time constant τ in the Laplace transform. 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 Equation 3, the defect state density Nd for a specific defect state energy Ed can be obtained.

[0079] However, the above Equation 3 represents the voltage variation for a specific fault time constant τ, and the result reflecting multiple time constants follows Equation 4 below.

[0080] [Equation 4]

[0081]

[0082] In Equation 4 above, V(t) represents the inverse Laplace transform transient state voltage, and the subscript a represents each fault time constant. Therefore, V(t) is the sum of the time-domain voltages attributable to all fault time constants derived through the Laplace transform in the transient state.

[0084] Manufacturing Example: Production of Half Coin Cells

[0085] NCM 622 is used as the cathode material, and LiPF6 is used as the electrolyte. Lithium foil is used as the anode material, and Celguard 2400, a polypropylene-based separator, is used. A coin-type half-cell was fabricated.

[0087] Measurement Example: Voltage measurement during the discharge section

[0088] A discharge operation is performed on the half-cell manufactured according to the above manufacturing example. The discharge operation was performed at temperature intervals 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.

[0089] Figure 6 is a graph showing the discharge voltage according to a measurement example of the present invention.

[0090] Referring to Fig. 6, it is confirmed that the discharge operation in the transient region proceeds faster as the temperature increases. Based on the data shown in the graph of Fig. 6, a Laplace transform is performed, and seven poles are derived through the factorization of a polynomial expressed in complex frequency. The seven derived poles correspond to the fault time constants.

[0091] Again, this was inversely transformed into the time domain to examine the degree of alignment with the graph in Figure 4. Since it was confirmed to be consistent with the graph, the seven poles were determined as defect time constants, and the defect state energies corresponding to the seven defect time constants were calculated using Equation 2 at 30°C.

[0092] Figure 7 is a graph showing the magnitude of the Laplace-transformed response characteristics for each defect time constant derived according to the measurement example of the present invention.

[0093] Referring to Fig. 7, the magnitude of the response characteristic corresponding to each fault time constant is displayed. In the graph above, the magnitude of the response characteristic for one fault time constant, e.g. 0.001 seconds, is shown as 0.35V, which is the result obtained using Equation 3 above.

[0094] The magnitude of the response characteristic for each of the seven derived fault time constants is represented by a peak value.

[0095] 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.

[0096] Referring to Fig. 8, the magnitude of the fault state energy for each specific fault time constant is determined by Equation 2. Additionally, the fault state density corresponding to a specific fault time constant can be determined by Equation 3.

[0097] The above graph represents the unique characteristics of a secondary battery. 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.

[0098] Therefore, based on this, changes in the performance of the secondary battery can be confirmed, and by checking the fluctuations in the data of Figure 8 above, the lifespan of the secondary battery can be predicted or performance indicators can be set.

[0100] FIG. 9 is a schematic diagram of a device for verifying the performance of a secondary battery according to a preferred embodiment of the present invention.

[0101] 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).

[0102] The power supply unit (110) is connected to the positive and negative electrodes of the secondary battery (10) and supplies power to the secondary battery (110). Through the supply of power, the secondary battery (10) can be charged and discharged. The power supply can be supplied in the form of pulses, supplied in intervals, or discharge operations can be performed.

[0103] The above power supply unit (110) is connected to the processor (140) and performs a power supply operation according to the control of the processor (140).

[0104] 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). Additionally, the temperature of the secondary battery (10) can be raised or lowered according to the control of the processor (140).

[0105] 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.

[0106] The measuring unit (130) is connected to the secondary battery (10) and measures the electrical signal generated from the secondary battery (10). The measured electrical signal is transmitted to the processor (140).

[0107] The processor (140) receives an electrical signal from the measurement unit (130) and performs a Laplace transform to convert it into the complex frequency domain. Through this, the defect time constant of the secondary battery is obtained. In addition, the defect state energy is derived through calculation, and the defect state density corresponding to the defect state energy is derived.

[0109] In the present invention described above, a plurality of defect time constants measured during the transient state of a secondary battery are utilized, and defect state energy is derived through the defect time constants measured for each temperature. Defect state energy is a specific energy level at which charges can be captured or released during the transient state, and this represents the electrical properties of the secondary battery. Furthermore, defect time constants are derived through Laplace transforms, and the magnitude of the response characteristics according to the defect time constants is determined. Through this, the defect state density of the defect state energy is determined. Defect state density represents the charge density filled or captured at the corresponding energy level.

[0110] The defect state energy and defect state density modeled and derived in the present invention are obtained from transient states and are used as performance indicators of secondary batteries. Through this, the performance of the secondary battery can be evaluated, and changes in performance can also be confirmed. In addition, performance degradation can be confirmed by fluctuations in defect state energy or defect state density. Explanation of the symbols

[0111] 110: Power supply unit 120: Temperature control unit 130 : Measurement unit 140 : Processor

Claims

Claim 1 A method for verifying the performance of a secondary battery using a secondary battery performance verification device having a power supply unit, a temperature control unit, a measurement unit, and a processor, comprising: a step of supplying power to the secondary battery through the power supply unit to perform a charge / discharge operation; a step of measuring an electrical signal fluctuating in the transient state of the charge / discharge operation through the measurement unit, and deriving a defect time constant through a Laplace transform of the measured electrical signal through the processor; a step of measuring the charge / discharge rate of the secondary battery according to the temperature change of the secondary battery measured through the temperature control unit after deriving the defect time constant, and determining whether a critical temperature has been reached, which is a temperature at which defect state energy, an energy level of the defect of the secondary battery, can be extracted; and a step of deriving the defect state energy and the defect state density, which is the density of charge captured in the defect state energy, through the processor when the temperature of the secondary battery reaches the critical temperature, based on the defect time constant. Claim 2 delete Claim 3 A method for verifying the performance of a secondary battery according to claim 1, wherein the step of deriving the defect time constant comprises: a step of measuring the data of the electrical signal in a time series during the transient state; a step of deriving the time constant by performing a Laplace transform on the measured electrical signal; a step of determining the consistency between the electrical signal and the inversely transformed response characteristic by inversely transforming the Laplace transformed response characteristic into the time domain; and a step of determining the derived time constant as the defect time constant if there is consistency. Claim 4 delete Claim 5 A method for verifying the performance of a secondary battery according to claim 1, characterized in that if the secondary battery does not reach a critical temperature, a new defect time constant is derived. Claim 6 A method for verifying the performance of a secondary battery according to claim 1, wherein the step of deriving the defect state energy and the defect state density comprises: a step of deriving the defect state energy through the defect time constant; and 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. Claim 7 In paragraph 6, the defect state energy is ln(τ / T) with respect to 1 / T. 2 A method for verifying the performance of a secondary battery, characterized in that ) is the slope, where T is the absolute temperature of the secondary battery and τ represents the defect time constant. Claim 8 A method for verifying the performance of a secondary battery according to claim 6, characterized in that the defect state density is derived according to the following Equation 3.[Equation 3] In Equation 3, Vτ(t) represents the voltage in the time domain according to the fault time constant, R represents the resistance of the battery measuring device, A represents the area of ​​the negative or positive electrode within the battery, and d represents the distance between the negative and positive electrodes. Additionally, 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 It is the number of charges having and represents the defect state density. q is the charge amount of the charge. Claim 9 A method for verifying the performance of a secondary battery according to claim 1, wherein the defect correction constant is a plurality. Claim 10 A performance verification device for a secondary battery comprising: a power supply unit connected to the positive and negative electrodes of the secondary battery to supply power to the secondary battery and perform a charging or discharging operation; a temperature control unit for measuring the temperature of the secondary battery and changing the temperature of the secondary battery; a measurement unit for measuring an electrical signal that fluctuates in the transient state of the charging or discharging operation according to the temperature change of the secondary battery; and a processor that receives the measured temperature from the temperature control unit, measures the charging / discharging rate according to the change in the measured temperature to determine whether a critical temperature has been reached, and when the secondary battery reaches the critical temperature, derives a defect time constant by performing a Laplace transform on the measured electrical signal, and extracts from the defect time constant a defect state energy, which is an energy level of the defect in the secondary battery, and a defect state density, which is a density of charge captured in the defect state energy. Claim 11 A performance verification device for a secondary battery according to claim 10, characterized in that the defect state energy is derived through the defect time constants derived at different temperatures. Claim 12 A performance verification device for a secondary battery according to claim 10, characterized in that the defect state density is derived according to the following Equation 4.[Equation 4] In Equation 4, Vτ(t) represents the voltage in the time domain according to the fault time constant, R represents the resistance of the battery measuring device, A represents the area of ​​the negative or positive electrode within the battery, and d represents the distance between the negative and positive electrodes. Additionally, 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 It is the number of charges having and represents the defect state density. q is the charge amount of the charge.

Images