Apparatus and method for estimating impedance spectrum of a battery and system including the same

Abstract

Embodiments and experimental examples of the present invention relate to a device and method for estimating impedance spectrum of a battery, and a system including the same. The device for estimating impedance spectrum of a battery estimates battery impedance spectrum values in a monomer unit by obtaining measurement values from an electrochemical impedance spectroscopy (EIS) device for measuring impedance spectrum values of a battery assembly in a group or module unit and a battery charge / discharge measurement device for measuring specific parameter values due to charging or discharging by applying a pulse current to a battery assembly in a group or module unit. Accordingly, it is possible to provide an efficient and low-cost device for estimating impedance spectrum of a battery, which enables non-destructive measurement without disassembling the battery into monomer units, thereby facilitating reassembly and reducing costs.

Description

Technical Field

[0001] This application claims priority and benefit to Korean Patent Application No. 10-2021-0149820, filed on November 3, 2021, and Korean Patent Application No. 10-2022-0145075, filed on November 3, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an apparatus and method for estimating the impedance spectrum of a battery, and a system including the thereof, and more particularly to an apparatus and method for estimating the impedance spectrum of a battery, and a system including the thereof, which estimates the impedance spectrum values ​​of a single cell-to-cell battery based on group or module-to-cell battery impedance spectrum measurements. Background Technology

[0003] For batteries intended for operation or reuse, diagnostic status is of utmost importance.

[0004] Typically, to diagnose the condition of a battery, its state of charge (SOC) and state of life (SOH) are checked.

[0005] To check the state of charge (SOC) and state of life (SOH) of a battery, the impedance spectrum of a single cell is measured by electrical impedance spectroscopy (hereinafter referred to as EIS) in related technologies.

[0006] In related technologies, when using an EIS device to measure the impedance spectrum of a single battery cell, batteries arranged in groups or modules are disassembled into individual cells, and the impedance spectrum is measured by connecting the EIS measuring device to the anode (+) and cathode (-) leads of the corresponding disassembled cell. Figure 1 As shown in the diagram.

[0007] Typically, when disassembling a battery pack into modular units, non-destructive disassembly can be achieved by removing and disconnecting the bus bars connecting the battery modules. However, when disassembling individual cells within a battery module, the battery module must be disassembled by destroying the soldered portions of the cell leads using lasers or ultrasound. Therefore, unless the cell leads are replaced, it is difficult to reassemble the cells into a battery module, and the cells must be disassembled part by part to replace the cell leads before reassembling them. Summary of the Invention

[0008] Technical issues

[0009] To address this problem, the present invention aims to provide an apparatus for estimating the impedance spectrum of a high-efficiency, low-cost battery, which estimates the impedance spectrum value of a single cell based on impedance spectrum measurements of a group or module-cell battery assembly.

[0010] To address this problem, another objective of the present invention is to provide a method for estimating the impedance spectrum of a high-efficiency, low-cost battery, which estimates the impedance spectrum value of a single cell based on impedance spectrum measurements of a group or module-cell battery assembly.

[0011] To address this problem, another objective of the present invention is to provide a system for estimating the impedance spectrum of a high-efficiency, low-cost battery, which estimates the impedance spectrum value of a single cell based on impedance spectrum measurements of a group or module-cell battery assembly.

[0012] Technical solution

[0013] To achieve this objective, an apparatus for estimating the impedance spectrum of a battery cell according to an embodiment of the present invention includes: a memory; and a processor that executes at least one command stored in the memory, wherein the at least one command includes: a command instructing to acquire an impedance spectrum (EIS) measurement of the battery assembly; a command instructing to model an equivalent circuit model (ECM) of the battery assembly based on the EIS measurement and determine initial parameter values ​​of the equivalent circuit; a command instructing to derive a first parameter value by converting at least one of the initial parameter values ​​using a predefined conversion constant and to calculate a first cell voltage value based on the first parameter value; a command instructing to acquire a second cell voltage value measured by charging or discharging the battery cell; a command instructing to compare the first cell voltage value and the second cell voltage value and to correct the conversion constant based on the comparison result; a command instructing to calculate a final parameter value based on the corrected conversion constant; and a command instructing to acquire an EIS estimate of the battery cell by applying the final parameter value to the equivalent circuit.

[0014] Here, the initial parameter values ​​of the equivalent circuit may include the parameter values ​​of at least one of resistors, capacitors, inductors, and constant phase elements (CPEs).

[0015] In addition, the conversion constant can be a constant used to convert the equivalent circuit of the battery assembly into the equivalent circuit of the battery cell.

[0016] Meanwhile, the command instructing the calculation of the first cell voltage value may include: a command instructing the equivalent circuit to be converted into a time-dependent impedance function and obtaining the internal impedance by applying initial parameter values ​​to the impedance function, and a command instructing the calculation of the first cell voltage value by multiplying the internal impedance by the current value.

[0017] In this case, the impedance function can be a function that transforms the equivalent circuit into a time-dependent function using predefined differential equations.

[0018] Meanwhile, the second cell voltage value can be the cell voltage value measured by the discharge pulse current of the battery cell.

[0019] In addition, the command indicating the correction conversion constant may include: a command indicating the correction conversion constant such that the difference between the first cell voltage value and the second cell voltage value is minimized.

[0020] To achieve this objective, a method for estimating the impedance spectrum of a battery cell according to another exemplary embodiment of the present invention includes: acquiring an impedance spectrum (EIS) measurement of the battery assembly; modeling an equivalent circuit model (ECM) of the battery assembly based on the EIS measurement and determining initial parameter values ​​for the equivalent circuit; deriving a first parameter value by converting at least one of the initial parameter values ​​using a predefined conversion constant, and calculating a first cell voltage value based on the first parameter value; acquiring a second cell voltage value measured by charging or discharging the battery cell; comparing the first cell voltage value and the second cell voltage value, and correcting the conversion constant based on the comparison result; calculating a final parameter value based on the corrected conversion constant; and obtaining an EIS estimate of the battery cell by applying the final parameter value to the equivalent circuit.

[0021] Here, at least one initial parameter value of the equivalent circuit may include the parameter value of at least one of a resistor, capacitor, inductor, and constant phase element (CPE).

[0022] In addition, the conversion constant can be a constant used to convert the equivalent circuit of the battery assembly into the equivalent circuit of the battery cell.

[0023] Meanwhile, the calculation of the first cell voltage value may include: converting the equivalent circuit into an impedance function over time, obtaining the internal impedance by applying initial parameter values ​​to the impedance function, and calculating the first cell voltage value by multiplying the internal impedance by the current value.

[0024] In this case, the impedance function can be a function that transforms the equivalent circuit into a time-dependent function using predefined differential equations.

[0025] Meanwhile, the second cell voltage value can be the cell voltage value measured by the discharge pulse current of the battery cell.

[0026] Furthermore, the correction of the conversion constant may include correcting the conversion constant to minimize the difference between the first cell voltage value and the second cell voltage value.

[0027] To achieve this objective, a system for estimating the impedance spectrum of a battery cell according to another exemplary embodiment of the present invention includes: an impedance spectroscopy (EIS) device that measures the impedance spectrum values ​​of a battery assembly; an impedance estimation device for a battery cell that calculates a first cell voltage for the battery cell and obtains an EIS estimate of the battery cell; and a battery charge / discharge measurement device that measures a second cell voltage by charging or discharging the battery cell, wherein the impedance estimation device for the battery cell models an equivalent circuit model (ECM) of the battery assembly based on the EIS device measurements and determines at least one of the initial parameter values ​​of the equivalent circuit, derives a first parameter value by transforming at least one of the initial parameter values ​​using a predefined conversion constant, calculates a first cell voltage value based on the first parameter value, corrects the conversion constant by comparing the calculated first cell voltage value with the second cell voltage value measured by the battery charge / discharge measurement device, calculates a final parameter value based on the corrected conversion constant, and obtains an EIS estimate of the battery cell by applying the final parameter value to the equivalent circuit.

[0028] Beneficial effects

[0029] According to embodiments and experimental examples of the present invention, an apparatus and method for estimating the impedance spectrum of a battery, and a system including the thereof, can provide an apparatus and method for estimating the impedance spectrum of a high-efficiency, low-cost battery, and a system including the thereof, which estimates the impedance spectrum value of a single-cell battery by acquiring measurements from an impedance spectroscopy (EIS) device that measures the impedance spectrum values ​​of a group or module-cell battery assembly and a battery charge / discharge measurement device that measures specific parameter values ​​by applying a pulse current to the group or module-cell battery assembly, thereby facilitating reassembly and reducing costs by enabling non-destructive measurements without disassembling the battery into individual cells. Attached Figure Description

[0030] Figure 1 The illustration shows an image of an electrical impedance spectroscopy (EIS) device connected to a battery cell in the related art.

[0031] Figure 2 This is a block diagram of a system for estimating the impedance spectrum of a single battery cell according to an embodiment of the present invention.

[0032] Figure 3 An image of an electrical impedance spectroscopy (EIS) device according to an embodiment of the present invention is illustrated.

[0033] Figure 4 An image of a battery charging / discharging measuring device according to an embodiment of the present invention is illustrated.

[0034] Figure 5 This is a block diagram of an apparatus for estimating impedance spectra according to an embodiment of the present invention.

[0035] Figure 6 This is a flowchart describing a method for measuring the impedance spectrum of a single battery cell according to an embodiment of the present invention.

[0036] Figure 7 This is a Nyquist plot showing the impedance measurement results of a group or module-cell battery assembly at each frequency using an impedance spectroscopy (EIS) device according to an embodiment of the present invention.

[0037] Figure 8 Based on Figure 7 The equivalent circuit diagram of the battery module is obtained from the impedance measurement results.

[0038] Figure 9 The graph is a comparison of experimental examples according to the present invention, using an impedance function to which a first cell voltage value is calculated by applying a first parameter and a second cell voltage value measured by applying a discharge pulse current to the battery assembly to describe a method for estimating the impedance of a battery cell.

[0039] Figure 10 The graph is a comparison of experimental examples according to the invention, using a third cell voltage value calculated by applying the final parameter values ​​to an equivalent circuit model and a second cell voltage value measured by applying a discharge pulse current to the battery assembly to describe the method for estimating the impedance of a battery cell.

[0040] 1000: Electrical impedance spectroscopy (EIS) device

[0041] 3000: Battery charging / discharging measurement device

[0042] 5000: Impedance Spectrum Estimation Device for Single Cell Battery

[0043] S: Impedance spectrum estimation system for individual battery cells

[0044] 100: Memory

[0045] 200: Processor

[0046] 300: Transceiver

[0047] 400: Input interface device

[0048] 500: Output interface device

[0049] 600: Storage device

[0050] 700: Bus Detailed Implementation

[0051] This invention can have various modifications and embodiments, and specific embodiments will be illustrated in the accompanying drawings and described in detail in the detailed description. However, this does not limit the invention to the specific embodiments, and it should be understood that the invention encompasses all modifications, equivalents, and substitutions included within the spirit and scope of the invention. In describing each drawing, reference numerals refer to the same elements.

[0052] Terms including first, second, A, B, etc., are used to describe various constituent elements, but the constituent elements are not limited by the terms. These terms are only used to distinguish one element from another. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component without departing from the scope of the invention. The term "and / or" includes a plurality of associated disclosures or a combination of any of a plurality of associated disclosures.

[0053] It should be understood that when a component is described as "connected" or "accessed" to another component, the component may be directly connected to or accessed by the other component, or a third component may exist between them. Conversely, when a component is described as "directly connected" or "directly accessed" to another component, it can be understood that there are no components between the component and the other component.

[0054] The terminology used in this application is for describing specific embodiments only and is not intended to limit the invention. The singular form includes the plural form unless the context clearly indicates otherwise. It should be understood that the terms "comprising" or "having" indicate the presence of features, quantities, steps, operations, components, parts, or combinations thereof described in this specification, but do not preclude the possibility of the presence or addition of one or more other features, quantities, steps, operations, components, parts, or combinations thereof.

[0055] Unless otherwise defined, all terms used herein, including technical or scientific terms, shall have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries shall be interpreted as having the same meaning as in the context of the relevant art, and shall not be construed as having an ideal or overly formal meaning unless expressly defined in this application.

[0056] Preferred embodiments of the invention will be described in detail below with reference to the accompanying drawings.

[0057] Figure 2 This is a block diagram of a system for estimating the impedance spectrum of a single battery cell according to an embodiment of the present invention.

[0058] refer to Figure 2According to an embodiment of the present invention, a system S for estimating the impedance spectrum of a battery cell measures charging or discharging data based on the impedance spectrum and pulse current applied to the battery assembly to estimate the battery cell-to-cell impedance spectrum value. Here, the battery assembly may include batteries arranged in a group or module.

[0059] According to this embodiment, more specifically, the system S for estimating the impedance spectrum of a single battery cell may include an electrical impedance spectroscopy (EIS) device 1000, a charge / discharge measurement device 3000, and an impedance spectrum estimation device 5000.

[0060] In this configuration, the electrical impedance spectroscopy (EIS) device 1000 can measure the impedance of the battery assembly, the charge / discharge measurement device 3000 can measure the individual cell voltage of the battery in the battery assembly, and the impedance spectrum estimation device 5000 can estimate the individual cell impedance spectrum value based on the measurements from the electrical impedance spectroscopy (EIS) device 1000 and the charge / discharge measurement device 3000.

[0061] In the following sections, the characteristics of each component of the system S used to estimate the impedance spectrum of a single cell will be described in more detail with reference to the accompanying drawings.

[0062] Figure 3 An image of an electrical impedance spectroscopy (EIS) device according to an embodiment of the present invention is illustrated.

[0063] refer to Figure 3 The electrical impedance spectroscopy (EIS) device 1000 is connected to the battery assembly arranged in groups or modules to measure the impedance spectrum of the battery assembly.

[0064] According to an embodiment, an impedance spectroscopy (EIS) device 1000 is connected to the anode (+) and cathode (-) leads of a group or module to measure the impedance spectrum of the group or module.

[0065] Subsequently, the impedance spectrum (EIS) device 1000 can transmit the impedance spectrum measurement values ​​of the battery pack or module to the impedance spectrum estimation device 5000, which will be described below.

[0066] Electrical impedance spectroscopy (EIS) devices in related technologies measure the impedance spectrum of individual battery cells by connecting battery assemblies arranged in groups or modules to individual battery cells that are disassembled into individual cells. However, this is disadvantageous because disassembling the battery into individual cells will damage the solder joints of the individual cell leads, and reassembly after measurement is difficult.

[0067] However, the system S for estimating the impedance spectrum of a single cell according to an embodiment of the present invention can provide a system S for estimating the impedance spectrum of a high-efficiency, low-cost single cell, which uses an electrical impedance spectroscopy (EIS) device 1000 to measure the impedance spectrum of a group or module-cell battery assembly, and estimates the single-cell impedance spectrum value by correcting the measured impedance spectrum, so as to facilitate reassembly and reduce costs through non-destructive measurement.

[0068] Figure 4 An image of a battery charging / discharging measuring device according to an embodiment of the present invention is illustrated.

[0069] refer to Figure 4 The battery charging / discharging measurement device 3000 can be connected to battery assemblies arranged in groups or modules.

[0070] Subsequently, the battery charging / discharging measuring device 3000 performs charging or discharging of the battery, applying a pulse current to the battery to measure the individual cell voltage.

[0071] According to an embodiment, the battery charging / discharging measuring device 3000 is connected to the anode (+) and cathode (-) leads of the battery assembly and applies a pulse current to the battery assembly in the form of a group or module, thereby measuring the individual cell voltage based on battery charging or discharging.

[0072] Subsequently, the battery charging / discharging measurement device 3000 can transmit the individual cell voltage measurements based on the battery charging or discharging to the impedance spectrum estimation device 5000, which will be described below.

[0073] Figure 5 This is a block diagram of an apparatus for estimating impedance spectra according to an embodiment of the present invention.

[0074] refer to Figure 5 According to an embodiment of the present invention, the apparatus 5000 for estimating impedance spectrum receives impedance spectrum measurements and individual cell voltage measurements of a group or module-type battery assembly measured by an impedance spectroscopy (EIS) device 1000 and a battery charge / discharge measurement device 3000, in order to estimate the individual cell-cell impedance spectrum.

[0075] When the device 5000 for estimating the impedance spectrum of a single battery cell is described in more detail for each hardware component, the impedance spectrum estimation device 5000 may include a memory 100, a processor 200, a transceiver 300, an input interface device 400, an output interface device 500, and a storage device 600.

[0076] According to an embodiment, the respective components 100, 200, 300, 400, 500 and 600 contained in the impedance spectrum estimation device 500 are connected to each other via a bus 700 to communicate with each other.

[0077] In the components 100, 200, 300, 400, 500, and 600 of the impedance spectrum estimation device 5000, the memory 100 and the storage device 600 may be constituted by at least one of volatile storage media and non-volatile storage media. For example, the memory 100 and the storage device 600 may be constituted by at least one of read-only memory (ROM) and random access memory (RAM).

[0078] Among them, memory 100 may include at least one instruction executed by processor 200.

[0079] According to an embodiment, at least one instruction may include: an instruction to acquire an electrical impedance spectrum (EIS) measurement of the battery assembly; an instruction to model an equivalent circuit model (ECM) of the battery assembly based on the EIS measurement and determine initial parameter values ​​for the equivalent circuit; an instruction to derive a first parameter value by converting at least one of the initial parameter values ​​using a predefined conversion constant and to calculate a first cell voltage value based on the first parameter value; an instruction to acquire a second cell voltage value measured by charging or discharging the battery cell; an instruction to compare the first cell voltage value and the second cell voltage value and to correct the conversion constant based on the comparison result; an instruction to calculate a final parameter value based on the corrected conversion constant; and an instruction to acquire an EIS estimate of the battery cell by applying the final parameter value to the equivalent circuit.

[0080] Processor 200 may refer to a central processing unit (CPU), graphics processing unit (GPU), or dedicated processor that performs the methods according to embodiments of the present invention.

[0081] The processor 200 can execute at least one program command stored in the memory 100 as described above.

[0082] The preceding text describes a system for estimating the impedance spectrum of a battery according to an embodiment of the present invention. Below, a method for estimating the impedance spectrum of a single battery cell based on processor operations of an impedance spectrum estimation device, which is a component of the system for estimating the impedance spectrum of a battery, will be described in more detail.

[0083] Figure 6 This is a flowchart describing a method for measuring the impedance spectrum of a single battery cell according to an embodiment of the present invention.

[0084] refer to Figure 6 The processor 200 in the device 5000 for estimating the impedance spectrum of a single cell can acquire impedance spectrum measurements of a group or module-cell battery assembly (S1000).

[0085] According to an embodiment, the processor 200 can receive impedance spectrum values ​​(EIS measurements) measured by the group or module-cell battery assembly from the electrical impedance spectroscopy (EIS) device 1000.

[0086] Figure 7 This is a Nyquist plot showing the impedance measurement results of a group or module-cell battery assembly at each frequency using an impedance spectroscopy (EIS) device according to an embodiment of the present invention.

[0087] refer to Figure 7 The impedance spectrum measurement values ​​of the battery assembly (group or module) acquired by the processor 200 can be expressed as impedance output values ​​according to the frequency. Here, Z' can be the real value of the impedance Z_re, and Z'' can be the imaginary value of the impedance Z_im.

[0088] Subsequently, the processor 200 can model the equivalent circuit of the battery assembly as a group or module unit (equivalent circuit model (ECM)) based on the acquired EIS measurement values ​​(S2000), and determine at least one initial parameter value of the modeled equivalent circuit (S3000). A method for modeling the equivalent circuit of a battery, and a method for determining the initial parameter values ​​of the modeled equivalent circuit, will refer to... Figure 8 This will be described in more detail below.

[0089] Figure 8 Based on Figure 7 The equivalent circuit diagram of the battery module was obtained from the impedance measurement results.

[0090] refer to Figure 8 The processor 200 can model the equivalent circuit of the battery as having the same impedance as the impedance spectrum measurement of the battery assembly as a group or module-unit.

[0091] According to an embodiment, the amplitude and phase components representing the output characteristics of the impedance spectrum can be represented by at least one combination of resistors, capacitors, and inductors. In other words, the equivalent circuit model of a group or module-cell battery can be represented by at least one parameter among resistors R0, R1, R2, R3, and R4, capacitors C1, C2, C3, and C4, inductor L1, and a constant phase element (CPE). Here, CPE can be an impedance parameter that produces intermediate impedance characteristic values ​​for capacitors and resistors. For example, the battery equivalent circuit model (ECM) can be represented as the sum of impedance P1 depending on the electrolyte, impedance P2 depending on the EIS device, impedance P3 depending on the SEI layer, impedance P4 depending on charge movement between the electrode and electrolyte interface, and the Warburg impedance coefficient P5. Here, the impedance P2 of the EIS device can include the resistance generated by the cables of the measuring device.

[0092] Afterward, the processor 200 can determine the initial parameter values ​​of the modeled equivalent circuit.

[0093] More specifically, the processor 200 can determine the initial parameter values ​​of at least one of the resistors, capacitors, inductors, and CPEs in the equivalent circuit model of the battery based on the impedance spectrum measurements of the battery as a group or module unit, as shown in [Table 1] below.

[0094] According to an embodiment, the processor 200 can be based on Figure 7 Impedance measurements for each frequency and Figure 8 The equivalent circuit model obtained in the process is used to infer the values ​​of the variables. Subsequently, the processor 200 acquires impedance measurement result graphs for each frequency to infer the values ​​of the variables, and compares the acquired impedance measurement result values ​​with those obtained from the process. Figure 7 The impedance measurement results for each frequency are compared to the plots shown. Figure 7 The values ​​of variables that follow a similar pattern in the curve graph are used as the initial parameter values.

[0095] [Table 1]

[0096]

[0097] R0: Electrolyte resistance

[0098] L1: Inductance of the EIS device (line inductance)

[0099] R1: Resistance of the EIS device

[0100] R2: Resistance of the solid electrolyte interphase (SEI) layer

[0101] C2: Capacitance of the solid electrolyte interphase (SEI) layer

[0102] R3: Charge transfer resistor (Rct)

[0103] C3: Capacitor in the double layer

[0104] CPE1, R4, C4: Warburg impedance coefficients

[0105] Return to reference Figure 6 The processor 200 divides the initial parameter value by the conversion constant n-Factor to obtain the first parameter value of the battery cell, as shown in [Table 2] below (S4000).

[0106] Here, the conversion constant n-factor can be a constant used to convert initial parameter values ​​obtained based on a group or module-cell battery assembly into individual battery cells. According to an embodiment, the initial value of the conversion factor n-factor can be defined based on the number of battery cells contained in the battery assembly (group or module). For example, as shown in [Table 2] below, some initial values ​​R1, R2, and R3 of the conversion constant n-factor can be defined based on the number of battery cells contained in the module (20 battery cells).

[0107] At the same time, as shown in [Table 2] below, the conversion constant n-factor may not be definable because the inductor L1 and capacitors C1, C2, C3 and C4 slightly affect the change in the value of impedance R (see [Equation 1] below).

[0108] [Table 2]

[0109]

[0110] Furthermore, the conversion constant can be corrected in step S8000, which will be described below, based on a comparison of the first and second cell voltage values. Therefore, the initial value of the conversion constant may not be defined as an exact value. However, as shown in [Table 2] above, it is preferable to define the conversion constant as an approximation used to convert the component-cell parameters into battery cell values.

[0111] In this embodiment, the initial value of the conversion constant can be entered by the administrator or defined as a pre-stored value corresponding to the number of battery cells.

[0112] Subsequently, the processor 200 can calculate the battery's internal impedance function over time (S5000).

[0113] More specifically, processor 200 can use differential equations to convert the equivalent circuit (ECM) of the battery assembly (pack or module, see [link]). Figure 8 Organize into functions.

[0114] For example, when describing in more detail the method by which processor 200 organizes the RC parallel components P2, P3 and P4 in the equivalent circuit as a function of time, processor 200 can organize the RC parallel components as a current I using Ohm's law (V = IR) [Equation 1].

[0115] [Equation 1]

[0116]

[0117] I R Current applied to the resistor

[0118] [Equation 2]

[0119]

[0120] I R Current applied to the resistor

[0121] I C Current applied to the capacitor

[0122] I O Discharge current

[0123] C: Capacitor

[0124] Subsequently, the processor 200 can express V(t) as E(t) based on E(3) extracted from E(2), and organize V(t) into E(t) in E(4).

[0125] [Equation 3]

[0126]

[0127] [Equation 4]

[0128]

[0129] Subsequently, processor 200 reorganizes [Equation 4] into an equation for impedance R to obtain [Equation 5].

[0130] [Equation 5]

[0131]

[0132] Therefore, while processor 200 is still using differential equations, similar to RC parallel components, to organize according to Figure 8 When the LR parallel components are in the equivalent circuit model, the processor 200 can obtain the time-dependent impedance function from the equivalent circuit model, as shown in [Equation 6] below.

[0133] [Equation 6]

[0134]

[0135] R0: Electrolyte resistance

[0136] L1: Line inductance of the EIS device

[0137] R1: Resistance of the EIS device

[0138] R2: Resistance of the solid electrolyte interphase (SEI) layer

[0139] C2: Capacitance of the SEI layer

[0140] R3: Charge transfer resistor (Rct)

[0141] C3: Capacitance in the electrode and electrolytic double layer

[0142] CPE1, R4, C4: Warburg impedance coefficients

[0143] t: time

[0144] K: constant

[0145] W: Warburg impedance coefficient

[0146] Subsequently, the processor 200 can apply the first parameter value of the cell-to-cell battery to the impedance function. In this case, W6, as the Warburg impedance, can be related to the ion diffusion rate and can be inversely proportional to the square root of the frequency. As a result, the processor 200 can calculate the internal impedance of the cell-to-cell battery.

[0147] Subsequently, the processor 200 can calculate the first cell voltage value by multiplying the battery's internal impedance by the current value (S6000). In other words, the battery's internal impedance can be used as the battery's internal resistance value.

[0148] Furthermore, the processor 200 can acquire a second cell voltage value measured by a pulse current from the battery (S7000). Here, the second cell voltage value can be a cell voltage value measured by applying a discharge pulse current from the battery charging / discharging measuring device 3000 to the group or module-cell battery assembly.

[0149] Figure 9 The graph is a comparison of experimental examples according to the present invention, using an impedance function to which a first cell voltage value is calculated by applying a first parameter and a second cell voltage value measured by applying a discharge pulse current to the battery assembly to describe a method for estimating the impedance of a battery cell.

[0150] refer to Figure 9 Since the first cell voltage value is calculated using a conversion constant defined based on the number of cells typically housed within a battery assembly (pack or module), there is a slight difference between the first cell voltage value and the second cell voltage value actually measured by applying a discharge pulse current, as a result of comparing the first cell voltage value and the second cell voltage value.

[0151] Therefore, the processor 200 can correct the conversion constant n-factor to minimize the difference between the first cell voltage value and the second cell voltage value for each cell, so as to calculate a more accurate impedance of the battery cell (S8000).

[0152] Here, the conversion constant n-factor can be a value used, as described above, to estimate the cell-to-cell value by using at least one initial parameter of the equivalent circuit constituting the group or module-cell battery assembly. In other words, the processor 200 can obtain a more accurate final cell-to-cell parameter value by correcting the conversion constant of the initial parameter applied to the equivalent circuit model according to a certain value to minimize the difference between the first cell voltage value and the second cell voltage value (S9000).

[0153] For example, when a battery assembly (group or module) consists of 20 individual cells, the processor 200 can correct the equivalent circuit parameter values ​​for each individual cell, as shown in [Table 3] below.

[0154] [Table 3]

[0155]

[0156] Figure 10 The graph is a comparison of experimental examples according to the invention, using a third cell voltage value calculated by applying the final parameter values ​​to an equivalent circuit model and a second cell voltage value measured by applying a discharge pulse current to the battery assembly to describe the method for estimating the impedance of a battery cell.

[0157] refer to Figure 10 According to an embodiment of the present invention, the third cell voltage can be a value calculated by multiplying the internal impedance obtained by applying the final parameter to the impedance function by the current value.

[0158] According to an embodiment, it can be confirmed by comparing the results of the third cell voltage and the second cell voltage measured by inputting the actual discharge pulse current that the third cell voltage calculated by using the final parameter value obtained by correcting the conversion constant is similar to the second cell voltage measured by applying the actual discharge pulse current.

[0159] Return to reference Figure 6 The processor 200 applies the corrected cell-to-cell final parameter values ​​individually to the equivalent circuit model to estimate the impedance spectrum of each cell (S10000).

[0160] According to an embodiment, the processor 200 can obtain an impedance spectrum estimate for each cell by substituting impedance spectrum measurements obtained from a group or module-cell battery assembly into a corrected equivalent circuit model to which corrected final parameter values ​​are applied. In this case, the corrected final parameter values ​​can also be converted into impedance spectrum values ​​(Zre and Zim) and used.

[0161] The foregoing describes apparatus and methods for estimating the impedance spectrum of a battery according to embodiments and experimental examples of the present invention, as well as systems including the foregoing.

[0162] According to embodiments and experimental examples of the present invention, an apparatus and method for estimating the impedance spectrum of a battery, and a system including the thereof, may be an apparatus and method for estimating the impedance spectrum of a high-efficiency, low-cost battery, and a system including the thereof, which estimates the impedance spectrum value of a single-cell battery by acquiring measured values ​​from an impedance spectroscopy (EIS) device that measures the impedance spectrum values ​​of a group or module-cell battery assembly and a battery charge / discharge measurement device that measures specific parameter values ​​by applying a pulse current to the group or module-cell battery assembly, thereby facilitating reassembly and reducing costs by enabling non-destructive measurements without disassembling the battery into individual cells.

[0163] The operation of the methods according to embodiments and experimental examples of the present invention can be implemented as a computer-readable program or code in a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording devices that store data that can be deciphered by a computer system. Furthermore, a computer-readable recording medium can store and execute programs or code that can be distributed across computer systems connected via a network and read by computers in a distributed manner.

[0164] Furthermore, computer-readable recording media may include hardware devices specifically configured to store and execute program commands, such as ROM, RAM, flash memory, etc. Examples of program commands include high-level language code executable by a computer using an interpreter, and machine language code created by a compiler.

[0165] Some aspects of the invention are described in the context of apparatus, but may also be represented depending on the description of the corresponding method, and here, a block or apparatus corresponds to a method step or a feature of that method step. Similarly, aspects described in the context of a method may also be represented as corresponding blocks or items or features of corresponding apparatus. Some or all of the method steps may be performed by (or using) hardware devices such as microprocessors, programmable computers, or electronic circuits. In some embodiments, at least one of the most important method steps may be performed by such a device.

[0166] The invention has been described with reference to preferred embodiments thereof; however, those skilled in the art will understand that the invention may be modified and altered in various ways without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An apparatus for estimating the impedance spectrum of a single battery cell, the apparatus comprising: Memory; as well as A processor that executes at least one command stored in the memory. Wherein, the at least one command includes: This command instructs the acquisition of electrical impedance spectral measurements of a battery assembly comprising multiple individual cells. A command instructing the modeling of the equivalent circuit model (ECM) of the battery assembly based on the impedance spectrum measurements and determining the initial parameter values ​​of the equivalent circuit. The command instructs the deriving of a first parameter value by transforming at least one of the initial parameter values ​​using a predefined conversion constant, and the calculation of a first cell voltage value based on the first parameter value, wherein the conversion constant is a constant used to convert the equivalent circuit of the battery assembly into the equivalent circuit of the battery cell. A command instructing the acquisition of a second cell voltage value measured by charging or discharging the battery cell. A command indicating that the first cell voltage value and the second cell voltage value are compared and that the conversion constant is corrected based on the comparison result. Commands instructing the calculation of final parameter values ​​based on corrected transformation constants, and A command instructing the application of the final parameter values ​​to the equivalent circuit to obtain an estimate of the resistivity spectrum of the battery cell.

2. The apparatus for estimating the impedance spectrum of a single battery cell according to claim 1, wherein, The initial parameter values ​​of the equivalent circuit include parameter values ​​of at least one of a resistor, a capacitor, an inductor, and a constant phase element (CPE).

3. The apparatus for estimating the impedance spectrum of a single battery cell according to claim 1, wherein, The command instructing the calculation of the voltage value of the first cell includes: A command instructing the equivalent circuit to be converted into a time-dependent impedance function and obtaining the internal impedance by applying the initial parameter values ​​to the impedance function, and This command instructs the calculation of the first cell voltage value by multiplying the internal impedance by the current value.

4. The apparatus for estimating the impedance spectrum of a single battery cell according to claim 3, wherein, The impedance function is a function that transforms the equivalent circuit into a time-dependent function using a predefined differential equation.

5. The apparatus for estimating the impedance spectrum of a single battery cell according to claim 1, wherein, The second cell voltage value is the cell voltage value measured by the discharge pulse current of the battery cell.

6. The apparatus for estimating the impedance spectrum of a single battery cell according to claim 1, wherein, Commands instructing the correction of the conversion constant include: A command that instructs the correction of the conversion constant to minimize the difference between the first cell voltage value and the second cell voltage value.

7. A method for estimating the impedance spectrum of a single battery cell, the method comprising: Obtain electrical impedance spectral measurements of a battery module comprising multiple individual cells; The equivalent circuit model (ECM) of the battery assembly is modeled based on the measured electrical impedance spectrum values, and the initial parameter values ​​of the equivalent circuit are determined. A first parameter value is derived by transforming at least one of the initial parameter values ​​using a predefined conversion constant, and a first cell voltage value is calculated based on the first parameter value, wherein the conversion constant is a constant used to convert the equivalent circuit of the battery assembly into the equivalent circuit of the battery cell; Obtain a second cell voltage value measured by charging or discharging the battery cell; The first cell voltage value and the second cell voltage value are compared, and the conversion constant is corrected based on the comparison result; The final parameter values ​​are calculated based on the corrected transformation constant; as well as The resistivity spectrum estimate of the battery cell is obtained by applying the final parameter value to the equivalent circuit.

8. The method for estimating the impedance spectrum of a single battery cell according to claim 7, wherein, At least one initial parameter value of the equivalent circuit includes the parameter value of at least one of a resistor, a capacitor, an inductor, and a constant phase element (CPE).

9. The method for estimating the impedance spectrum of a single battery cell according to claim 7, wherein, The calculation of the first single-cell voltage value includes: The equivalent circuit is converted into a time-dependent impedance function, and the internal impedance is obtained by applying the initial parameter values ​​to the impedance function. The voltage value of the first cell is calculated by multiplying the internal impedance by the current value.

10. The method for estimating the impedance spectrum of a single battery cell according to claim 9, wherein, The impedance function is a function that transforms the equivalent circuit into a time-dependent function using a predefined differential equation.

11. The method for estimating the impedance spectrum of a single battery cell according to claim 7, wherein, The second cell voltage value is the cell voltage value measured by the discharge pulse current of the battery cell.

12. The method for estimating the impedance spectrum of a single battery cell according to claim 7, wherein, The correction of the conversion constant includes: correcting the conversion constant such that the difference between the first cell voltage value and the second cell voltage value is minimized.

13. A system for estimating the impedance spectrum of a single battery cell, the system comprising: An impedance spectroscopy device is used to measure the impedance spectrum of a battery module comprising multiple individual cells. The impedance estimation device of the battery cell calculates the first cell voltage for the battery cell and obtains the estimated value of the impedance spectrum of the battery cell. as well as A battery charging / discharging measuring device that measures the voltage of a second individual battery cell by charging or discharging the individual battery cell. The impedance estimation device for the battery cell: The equivalent circuit model (ECM) of the battery assembly is modeled based on the measurements from the impedance spectroscopy device, and at least one of the initial parameter values ​​for the equivalent circuit is determined. A first parameter value is derived by transforming at least one of the initial parameter values ​​using a predefined transformation constant, and a first cell voltage value is calculated based on the first parameter value. The transformation constant is a constant used to convert the equivalent circuit of the battery assembly to the equivalent circuit of the battery cell. The conversion constant is corrected by comparing the calculated first cell voltage value with the second cell voltage value measured by the battery charge / discharge measuring device. The final parameter values ​​are calculated based on the corrected transformation constant, and The estimated resistivity spectrum of the battery cell is obtained by applying the final parameter value to the equivalent circuit.

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