Method and electronic device for determining the resistance of a battery cell

Abstract

A method and electronic device for determining the resistance of a battery cell are disclosed, comprising the steps of: performing an EIS analysis of a battery cell according to a plurality of temperatures including a first temperature and a second temperature to obtain a chart regarding the impedance of the battery cell according to a frequency change; extracting a first inductance of the battery cell at a first temperature based on a first graph regarding the impedance of the battery cell at a first temperature; and determining the resistance of the battery cell at a second temperature based on the first inductance, wherein the second temperature is a higher temperature than the first temperature.

Description

Technology Field

[0001] The present disclosure relates to a method for determining the resistance of a battery cell and an electronic device for performing the same. Background Technology

[0003] Pouch-type stack cells constitute the battery type installed in most electric vehicles (EVs). In the case of pouch-type stack cells, electrical resistance components, such as the ohmic resistance of the battery cell, vary due to the electrical characteristics of the foil and electrodes determined by the design. Since various resistance components affect battery output during EV operation, accurately determining the resistance components of the battery cell and conducting separate analyses based on these components is necessary to improve battery performance.

[0004] Impedance measurement methods using EIS analysis are primarily used to analyze the resistance components of battery cells, and various studies are being conducted on methods to determine resistance suitable for various types of battery cells. The problem to be solved

[0006] The embodiments disclosed in this specification aim to provide a method for determining the resistance of a battery cell and an electronic device for performing the same.

[0007] The embodiments disclosed in this specification aim to solve the technical problem of accurately measuring various types of resistances of a battery cell by considering the electrical characteristics of the battery that vary according to the battery design, such as a pouch-type stack cell.

[0008] The technical problems that this embodiment aims to solve are not limited to those described above, and other technical problems can be inferred from the following embodiments. means of solving the problem

[0010] A method for determining the resistance of a battery cell according to one embodiment comprises: a step of obtaining a chart regarding the impedance of the battery cell according to frequency change by performing an EIS analysis of the battery cell according to a plurality of temperatures including a first temperature and a second temperature; a step of extracting a first inductance of the battery cell at the first temperature based on a first graph regarding the impedance of the battery cell at the first temperature included in the chart; and a step of determining the resistance of the battery cell at the second temperature based on the first inductance, wherein the second temperature may be a higher temperature than the first temperature.

[0011] The step of determining the resistance of the battery cell at the second temperature may include the step of determining the first inductance as the second inductance of the battery cell at the second temperature.

[0012] The step of determining the resistance of the battery cell at the second temperature may include: determining the ohmic resistance of the battery cell at the second temperature by subtracting the second inductance from the value of the real impedance axis intercept of the second graph regarding the impedance of the battery cell at the second temperature; and determining the difference between the resistance at the inflection point of the second graph and the ohmic resistance of the battery cell at the second temperature as the charge transfer resistance of the battery cell at the second temperature.

[0013] The step of determining the ohmic resistance of the battery cell at the second temperature may include: obtaining a reference ohmic resistance at the second temperature based on the relationship between the second temperature and the ohmic resistance of the battery cell at the second temperature; and, when the difference between the reference ohmic resistance and the ohmic resistance of the battery cell at the second temperature is less than a threshold value, determining the ohmic resistance of the battery cell at the second temperature by subtracting the second inductance from the value of the real impedance axis intercept of the second graph regarding the impedance of the battery cell at the second temperature.

[0014] A method according to one embodiment may further include the step of applying a pulse current to a battery cell at the second temperature for a predetermined time; and the step of obtaining a final total resistance according to the change in the total resistance of the battery cell at the second temperature due to the application of the pulse current.

[0015] The step of obtaining the final total resistance at the second temperature may include obtaining the final total resistance at the second temperature based on the sum of the ohmic resistance of the battery cell at the second temperature, the charge transfer resistance of the battery cell at the second temperature, and the material transfer resistance of the battery cell at the second temperature.

[0016] The battery cell may be a pouch-type stack cell having a structure in which a positive electrode comprising an active material, a conductive material, and a binder, and a negative electrode comprising graphite, a conductive material, and a binder are stacked.

[0017] The second temperature mentioned above may be room temperature, and the first temperature may be below zero.

[0018] An electronic device according to one embodiment includes a memory for storing instructions; and a processor connected to the memory, wherein the processor is configured to perform an EIS analysis of a battery cell according to a plurality of temperatures including a first temperature and a second temperature to obtain a chart regarding the impedance of the battery cell according to a frequency change, extract a first inductance of a first graph regarding the impedance of the battery cell at the first temperature, and determine the resistance of the battery cell at the second temperature based on the first inductance, and wherein the second temperature may be a higher temperature than the first temperature. Effects of the invention

[0020] According to the proposed embodiment, one or more of the following effects can be expected.

[0021] According to the embodiments of the present specification, the electronic device has the technical effect of being able to determine the ohmic resistance and charge transfer resistance of a battery cell by utilizing the properties of inductance even when it is difficult to visually confirm the ohmic resistance and charge transfer resistance of the battery cell at a specific temperature on a chart regarding the impedance of the battery cell due to the inductance component generated during the design process of the battery cell through EIS analysis.

[0022] In addition, according to the embodiments of the present specification, the electronic device can verify the accuracy of the ohmic resistance of the battery cell determined based on a chart regarding the impedance of the battery cell and the inductance of the battery cell, and has the technical effect of determining additional resistance components such as the material transfer resistance of the battery cell.

[0023] The effects of the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description in the claims. Brief explanation of the drawing

[0025] FIG. 1 is a diagram illustrating the configuration of a system for determining the resistance of a battery cell according to one embodiment. FIG. 2 is a diagram illustrating an EIS analysis method according to one embodiment. FIG. 3 is a diagram illustrating impedance information obtained by performing EIS analysis of a target battery cell according to one embodiment. FIG. 4 is a diagram illustrating the inductance of a battery cell according to a temperature change of a target battery cell according to one embodiment. FIG. 5 is a flowchart illustrating a method for determining the resistance of a battery cell according to one embodiment. FIG. 6 is a diagram illustrating the process of obtaining the ohmic resistance of a target battery cell according to one embodiment. FIG. 7 is a diagram illustrating the process of obtaining the material transfer resistance and total resistance of a target battery cell according to one embodiment. FIG. 8 is a block diagram of an electronic device according to one embodiment. Specific details for implementing the invention

[0026] The terms used in the embodiments have been selected to be as widely used as possible, taking into account their functions in the present disclosure; however, these may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant explanatory section. Therefore, terms used in the present disclosure should be defined not merely by their names, but based on their meanings and the overall content of the present disclosure.

[0027] When a part of a specification is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0028] The expression "at least one of a, b, and c" described throughout the specification may include 'a alone', 'b alone', 'c alone', 'a and b', 'a and c', 'b and c', or 'a, b, and c all'.

[0029] The "device" mentioned below may be implemented as a computer or portable device capable of accessing a server or other device through a network. Here, the computer includes, for example, a notebook, desktop, or laptop equipped with a web browser, and the portable device may include, for example, a wireless communication device that ensures portability and mobility, and may include all types of handheld-based wireless communication devices such as communication base devices like IMT (International Mobile Telecommunication), CDMA (Code Division Multiple Access), W-CDMA (W-Code Division Multiple Access), and LTE (Long Term Evolution), smartphones, tablet PCs, etc.

[0030] Embodiments of the present disclosure are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein.

[0031] Embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0033] FIG. 1 is a diagram illustrating the configuration of a system for determining the resistance of a battery cell according to one embodiment.

[0034] Referring to FIG. 1, the system (101) may operate in conjunction with an electronic device (100) that measures the resistance of a battery cell (200). In this case, the battery cell (200) may correspond to a pouch-type stack cell having a structure in which a positive electrode comprising an active material, a conductive material, and a binder, and a negative electrode comprising graphite, a conductive material, and a binder are stacked. Alternatively, the battery cell (200) may be a cylindrical cell or a prismatic cell, in addition to a pouch-type cell. Meanwhile, FIG. 1 only illustrates components related to the present embodiment. Therefore, it can be understood by those skilled in the art related to the present embodiment that other general-purpose components may be included in addition to the components illustrated in FIG. 1.

[0035] The electronic device (100) may each include one or more sensors for measuring parameters of the battery cell (200), including the electrical conductivity of the battery cell (200) that determines the resistance described above, and may include memory and a processor (not shown) for various operations. That is, such an electronic device (100) may perform an operation of obtaining a chart regarding the impedance of the battery cell (200) according to frequency change by performing an EIS analysis of the battery cell (200) according to a plurality of temperatures. In this case, the chart regarding the impedance of the battery cell (200) may correspond to, for example, a Nyquist plot chart.

[0036] According to one embodiment, the battery cell (200) may correspond to a battery cell in which a positive electrode comprising an active material, a binder, and a conductive material, and a negative electrode comprising graphite, a binder, and a conductive material are impregnated in an electrolyte. For example, the battery cell (200) may correspond to a pouch-type stack cell having a structure in which a positive electrode comprising an active material, a conductive material, and a binder, and a negative electrode comprising graphite, a conductive material, and a binder are stacked. More specifically, in one embodiment, the battery cell (200) may correspond to a pouch-type cell in the form of 19 positive / negative cells stacked with a width of about 90 mm and a length of about 258 mm.

[0037] For example, the positive electrode may correspond to a positive electrode in which the active material accounts for 97.5% of the mass of the active material layer, the binder for 1.5% of the mass of the binder for 1% of the mass of the active material layer, which includes the active material, the binder, and the conductive material, and the content of the conductive material for the entire active material layer of the target electrode is 1%. For example, the negative electrode may correspond to a target negative electrode in which the graphite accounts for 95% of the mass of the graphite, the binder for 3.5% of the mass of the binder for 1.5% of the mass of the graphite, the binder, and the conductive material for 1.5% of the mass of the entire active material layer of the target electrode. For example, the battery cell (200) may be impregnated in an electrolyte in which EC (ethylene carbonate) and EMC (ethyl methyl carbonate) are mixed at a concentration of 3 to 7 and LiPF6 at a concentration of 1 molar is added. However, the type of battery cell (200) in the method for determining the resistance of the battery cell (200) according to the present disclosure is not limited to the cases mentioned, and the embodiments according to the present disclosure may include not only pouch-type stack cells but also various types of battery cells (200), such as cylindrical cells and prismatic cells, various types of positive electrodes and negative electrodes, and various types of electrolytes.

[0039] FIG. 2 is a diagram illustrating an EIS analysis method according to one embodiment.

[0040] Referring to FIG. 2, the concept of electrochemical impedance spectroscopy (EIS) used to determine the resistance of a battery cell can be observed. Impedance spectroscopy refers to a method of interpreting a Nyquist plot chart (201) obtained by dividing impedance information obtained by continuously changing the frequency (210) of an AC power source and applying it to a battery cell (200) into real impedance (220) and imaginary impedance (230). Here, the Nyquist plot chart (201) may refer to a chart used to evaluate the stability of a system through a parameter plot of frequency response used in automatic control and signal processing. The Nyquist plot chart (201) may refer to a chart that visualizes a graph representing the response of a system according to a change in frequency on a complex plane including an axis for the real component and an axis for the imaginary component. A Nyquist plot chart regarding the impedance of a battery cell (200) according to one embodiment may mean a chart visualized on a complex plane including an axis for real components and an axis for imaginary components, showing a graph representing the impedance of a battery cell (200) according to the frequency change of an alternating current by applying an alternating current to the battery cell (200) for each of a plurality of temperatures, for example.

[0041] Interpreting the electrochemical process of the Nyquist plot in relation to the impedance analysis of the battery cell (200) in impedance spectroscopy involves analyzing multiple regions on the Nyquist plot. For example, a region (240) containing the real impedance (220) axis intercept value of the impedance information can be utilized to analyze the ohmic resistance related to the characteristics of the electrolyte ion conductivity of the electrolyte resistance of the battery cell (200) and the characteristics of the external electrolyte resistance.

[0042] For example, the negative region (350) of the imaginary impedance (230) axis of the impedance information obtained according to the change in frequency (210) can be used to analyze information regarding the inductance component parasitic in the battery cell (200). As will be examined below, in the case of a pouch-type stack cell, the inductance component may correspond to a resistance component that occurs due to electrical characteristics that vary depending on the design of the battery cell (200).

[0043] For example, the semicircular region (360) of the impedance information obtained according to the change in frequency (210) is a charge transfer resistance, which is a phenomenon that occurs when charge is transferred from the electrode surface / interface of the battery cell (200). It can be used to analyze charge transfer impedance information indicating the lithium ion oxidation-reduction reaction at the electrode material interface, and accordingly, information regarding the charge transfer resistance of the battery cell (200) can be obtained. For example, the linear region (270) obtained according to the change in frequency (210) may include Warburg impedance information obtained in the low frequency region, and can be used to analyze the diffusion phenomenon of lithium ions (Li ion) related to the chemical diffusion resistance of lithium ions due to interlayer insertion into the particle crystal structure within the battery cell (200).

[0044] The electronic device (100) according to the present disclosure can perform EIS analysis of the battery cell (200) according to a plurality of temperatures (e.g., -30°C, -20°C, 0°C, 25°C) to obtain a chart regarding the impedance of the battery cell (200) according to the change in frequency (210). For example, in the case of a pouch-type stack cell, due to the inductance component that appears due to electrical characteristics that change according to the design of the battery, the region (240) containing the real impedance (220) axis intercept value of the impedance information and the negative region (350) of the imaginary impedance (230) axis of the impedance information are mixed with each other, making it difficult to accurately determine the resistance of the battery cell (200). Below, the characteristics of the inductance component of the battery cell (200) and a method for determining the ohmic resistance of the battery cell (200) and determining the charge transfer resistance, material transfer resistance, and total resistance by considering the inductance component at a plurality of temperatures using said characteristics are specifically examined.

[0046] FIG. 3 is a diagram illustrating impedance information obtained by performing EIS analysis of a target battery cell according to one embodiment.

[0047] Referring to FIG. 3, an electronic device (100) according to one embodiment can obtain a chart (401) regarding the impedance of a battery cell according to frequency change by performing an EIS analysis of a battery cell according to a plurality of temperatures including a first temperature and a second temperature. For example, the electronic device (100) can obtain a Nyquist plot chart as the chart (401) regarding the impedance of the battery cell, and can obtain a plurality of graphs (e.g., first graph (311), second graph (312), graph (313), graph (314)) regarding the impedance of a battery cell (200) according to a plurality of temperatures included in the chart (401). The following description is based on the case where a first graph (311) regarding the impedance of a battery cell (200) according to a frequency change at a first temperature corresponding to a relatively low temperature (e.g., -30℃) is obtained, and a second graph (312), graph (313), and graph (314) regarding the impedance of a battery cell (200) according to a frequency change at a second temperature corresponding to a temperature higher than the first temperature (e.g., -20℃, 0℃, 25℃) are obtained.

[0048] When examining the second graph (312), graph (313), and graph (314), it can be observed that the size of the semicircular area of ​​impedance information obtained according to the frequency change of the first graph (311) is smaller than the size of the semicircular area of ​​impedance information obtained according to the frequency change of the second graph (312), graph (313), and graph (314), and that the ohmic resistance of each of the second graph (312), graph (313), and graph (314) is not clearly confirmed due to the influence of inductance. In other words, when the battery cell (200) is a pouch-type stack cell, it is difficult to clearly confirm the ohmic resistance through the analysis of the area including the real impedance axis intercept value of the graph as described in FIG. 3 due to the inductance of the battery cell (200), and this can be confirmed by examining the second graph (312), graph (313), and graph (314) of the chart (402) which is an enlarged chart of the relevant area of ​​the chart (401). In particular, in the case of the region (362) containing the real impedance axis intercept value of the second graph (312) at room temperature, it can be seen that even on the enlarged chart (402), due to the influence of the second inductance component of the battery cell (200) at the second temperature, it is difficult to distinguish the region containing the real impedance axis intercept value of the impedance information on the Nyquist plot described in FIG. 2, the negative region of the imaginary impedance axis of the impedance information, and the semicircle region of the impedance information obtained according to the frequency change. More specifically, it can be seen that the second inductance component is mixed in the real impedance axis intercept value of the second graph regarding the impedance of the battery cell (200) at the second temperature, making it difficult to clearly separate and analyze the ohmic resistance of the battery cell (200) at the second temperature and the second inductance of the battery cell (200) at the second temperature.

[0050] FIG. 4 is a diagram illustrating the inductance of a battery cell according to a temperature change of a battery cell according to one embodiment.

[0051] Referring to FIG. 4, the inductance (411; 412; 413; 414) of the battery cell (200) at each of multiple temperatures can be verified through the inductance chart (401) according to the temperature change of the battery cell (200). Considering that in the case of a small cell, the inductance is not large when measuring impedance, making it easy to separate the ohmic resistance and the inductance, the battery cell (200) in this case may correspond to a small cell, and the inductance (411; 412; 413; 414) of the battery cell (200) has an area of ​​approximately 12 It may have been measured based on a small monocell corresponding to. As can be seen in FIG. 5, the inductance (411) at a temperature of about 243K, the inductance (412) at a temperature of about 253K, the inductance (413) at a temperature of about 263K, and the inductance (414) at a temperature of about 273K are all about 3.8 X (H) to 3.6 X It can be confirmed that it has a value in the range (H). That is, it can be confirmed that the inductance of the battery cell (200) remains constant with respect to temperature changes, without significant differences. This can be interpreted as follows: regarding the inductance component, which corresponds to the electrical properties generated by the structural characteristics of the battery cell (200), even if the temperature of the battery cell (200) changes, there is no significant change in the structural characteristics of the battery cell (200), so the inductance component does not change significantly. In other words, the electronic device (100) according to one embodiment can obtain the inductance component at a specific temperature of a specific battery cell (200) through this, and then determine the value of the inductance component as the inductance value at a different temperature of the same battery cell (200).

[0053] FIG. 5 is a flowchart illustrating a method for measuring the resistance of a target electrode according to one embodiment.

[0054] As previously observed in FIG. 3, in the case of a pouch-type stack cell, at a specific temperature (e.g., -20℃, 0℃, 25℃), the size of the semicircular region of impedance information obtained according to frequency change is smaller than the size of the semicircular region of impedance information obtained at a temperature lower than that specific temperature (e.g., -30℃), and due to the inductance component, it is difficult to clearly identify the ohmic resistance through the analysis of the region including the real impedance axis intercept value of the graph. However, utilizing the fact that the inductance of the battery cell (200) does not differ significantly with temperature change as observed in FIG. 4, FIG. 5 below describes a method for determining the resistance of the battery cell (200) according to the present disclosure.

[0055] Referring to FIG. 5, an electronic device (100) according to one embodiment may perform an EIS analysis of a battery cell (200) according to a plurality of temperatures including a first temperature and a second temperature in step S510 to obtain a chart regarding the impedance of the battery cell (200) according to frequency change. As previously explained, the chart regarding the impedance of the battery cell (200) according to frequency change may correspond to a Nyquist plot chart. In this case, the first temperature may correspond to a sub-zero temperature of about -30°C as previously examined, and the second temperature may correspond to a temperature higher than the first temperature, for example, room temperature of about 25°C. An electronic device (100) according to one embodiment can obtain a chart regarding the impedance of a battery cell (200) according to frequency change through impedance analysis as previously examined in relation to FIG. 2, and can obtain a graph regarding the impedance of a battery cell (200) at a plurality of temperatures including a first temperature and a second temperature as previously examined in FIG. 3.

[0056] An electronic device (100) according to one embodiment can extract a first inductance of a first graph regarding the impedance of a battery cell (200) at a first temperature in step S520. As observed in FIG. 3, the first graph regarding the impedance of a battery cell (200) at a first temperature is larger in size in the semicircular area of ​​impedance information obtained according to frequency change than graphs regarding the impedance of a battery cell (200) at other temperatures, so it may be a graph in which the first inductance can be extracted through the analysis of the negative area of ​​the imaginary impedance axis of the impedance information.

[0057] An electronic device (100) according to one embodiment can determine the resistances of a battery cell (200) at a second temperature based on a first inductance in step S530. As previously observed in FIG. 4, since the inductance of the battery cell (200) does not change significantly with temperature changes and remains almost constant, the electronic device (100) according to one embodiment can determine the first inductance as the second inductance of the battery cell (200) at a second temperature.

[0058] An electronic device (100) according to one embodiment can determine the ohmic resistance of a battery cell (200) at a second temperature by subtracting the second inductance from the real impedance axis intercept value of a second graph regarding the impedance of a battery cell (200) at a second temperature. As previously observed in FIG. 3, in the region containing the real impedance axis intercept value of a second graph (312) at a second temperature, the ohmic resistance and inductance components are mixed. Therefore, the electronic device (100) according to one embodiment can separate the ohmic resistance at a second temperature by excluding the influence of inductance by determining the ohmic resistance of a battery cell (200) at a second temperature by subtracting the second inductance from the real impedance axis intercept value of a second graph. An electronic device (100) according to one embodiment can determine the difference between the resistance at the inflection point of the second graph and the ohmic resistance of the battery cell (200) at the second temperature as the charge transfer resistance of the battery cell (200) at the second temperature.

[0059] An electronic device (100) according to one embodiment may further perform an operation to determine the ohmic resistance of a battery cell (200) at a second temperature by obtaining a reference ohmic resistance based on the relationship between the second temperature and the ohmic resistance of the battery cell (200) at the second temperature to verify whether the value of the ohmic resistance obtained as above is valid, and if the difference between the reference ohmic resistance and the ohmic resistance of the battery cell (200) at the second temperature is less than a threshold value, the ohmic resistance of the battery cell (200) at the second temperature is determined by subtracting the second inductance from the value of the real impedance axis intercept of the second graph regarding the impedance of the battery cell (200) at the second temperature. In other words, an electronic device (100) according to one embodiment may obtain a reference ohmic resistance containing information on the change trend of the ohmic resistance according to the temperature change based on an Arrhenius relationship, and verify whether the obtained ohmic resistance is an accurate value by comparing the reference ohmic resistance with the ohmic resistance obtained according to the present disclosure, which is examined in detail below in FIG. 6.

[0060] An electronic device (100) according to one embodiment may determine additional resistance components of a battery cell (200) by applying a pulse current to the battery cell (200) at the second temperature for a predetermined time after obtaining the inductance of the battery cell (200), the ohmic resistance of the battery cell (200), and the charge transfer resistance of the battery cell (200) at the second temperature through the preceding steps. For example, an electronic device (100) according to one embodiment may obtain a final total resistance based on the change in the total resistance of the battery cell (200) at the second temperature due to the application of the pulse current. In this case, the final total resistance at the second temperature may be obtained based on the sum of the ohmic resistance of the battery cell (200) at the second temperature, the charge transfer resistance of the battery cell (200) at the second temperature, and the material transfer resistance of the battery cell (200) at the second temperature, which will be examined in detail below in FIG. 7.

[0062] FIG. 6 is a diagram illustrating the process of obtaining the ohmic resistance of a target battery cell according to one embodiment.

[0063] As seen in FIG. 5, an electronic device (100) according to one embodiment can determine the ohmic resistance of a battery cell (200) according to the present disclosure and then compare it with a reference ohmic resistance determined based on an Arrhenius relationship.

[0064] Referring to FIG. 6, an electronic device (100) according to one embodiment can obtain a reference ohmic resistance at a second temperature based on an Arrhenius relationship. In this case, the reference ohmic resistance may correspond to a resistance obtained based on the relationship between absolute temperature and resistance according to the Arrhenius relationship, and may correspond to a resistance that serves as a reference for verifying whether the ohmic resistance of a battery cell obtained according to the method for determining the resistance of a battery cell according to one embodiment has been obtained within an appropriate range. In this case, the Arrhenius relationship may be defined, for example, as shown in the following mathematical formula.

[0065]

[0066] In this case, K can represent the rate constant, A the frequency coefficient, R the gas constant, and T the absolute temperature. represents activation energy. In other words, according to the Arrhenius relationship, if the absolute temperature of the system in which the chemical reaction occurs rises, the speed of the chemical reaction increases; therefore, when interpreted from the perspective of the battery cell (200), it can be seen that there is a relationship in which the movement of electrons becomes smooth. That is, according to the Arrhenius relationship, if the temperature of the battery cell (200) rises, the ohmic resistance of the battery cell (200) can be lowered accordingly. An electronic device (100) according to one embodiment can obtain a reference ohmic resistance at a second temperature based on the relationship that as the second temperature rises, the ohmic resistance of the battery cell (200) at the second temperature decreases, for example, as can be confirmed through Equation 1. More specifically, if one examines the reference ohmic resistance chart (601) based on the Arrhenius relationship according to temperature change, the reference ohmic resistance based on the Arrhenius relationship can be obtained as shown in the graph (610).

[0067] According to one embodiment, the electronic device (100) can determine the ohmic resistance of the battery cell (200) at the second temperature by subtracting the second inductance from the real impedance axis intercept value of the second graph regarding the impedance of the battery cell (200) at the second temperature when the difference between the reference ohmic resistance and the ohmic resistance of the battery cell (200) at the second temperature is less than a threshold value. More specifically, for example, an electronic device (100) according to one embodiment can compare the reference ohmic resistance in a reference ohmic resistance graph (610) based on an Arrhenius relationship with the values ​​(611, 612, 613, 614) obtained by subtracting the inductance from the real impedance axis intercept values ​​of the graph regarding the impedance of the battery cell (200) at a specific temperature in FIG. 5, and if the difference is less than a threshold value, the values ​​(611, 612, 613, 614) can be determined as the ohmic resistance of the battery cell (200). In conclusion, the electronic device (100) according to one embodiment can determine the ohmic resistance of the battery cell (200) more precisely by comparing it with a reference ohmic resistance based on an Arrhenius relationship related to the change in resistance according to temperature, going beyond determining the ohmic resistance of the battery cell (200) by subtracting the inductance from the value of the real impedance axis intercept of the graph regarding the impedance of the battery cell (200). Similarly, the electronic device (100) according to one embodiment can determine the charge transfer resistance of the battery cell (200) more precisely by performing the same process for the charge transfer resistance of the battery cell (200).

[0069] FIG. 7 is a diagram illustrating the process of obtaining the material transfer resistance and total resistance of a target battery cell according to one embodiment.

[0070] Referring to FIG. 7, the change in the total resistance of the battery cell can be observed through the resistance chart (701) of the battery cell (200) to which a pulse current is applied. An electronic device (100) according to one embodiment applies a pulse current to the battery cell (200) at a second temperature for a predetermined time, and can obtain a final total resistance (711) based on the change in the total resistance of the battery cell (200) at the second temperature due to the application of the pulse current. In this case, the final total resistance (711) can be obtained based on the sum of the ohmic resistance of the battery cell (200) at the second temperature, the charge transfer resistance of the battery cell (200) at the second temperature, and the material transfer resistance of the battery cell (200) at the second temperature. More specifically, an electronic device (100) according to one embodiment applies a pulse current to a battery cell (200) for a predetermined time (e.g., 10 seconds), and the amount of change in the total resistance of the battery cell (200) up to a section (712) where the rate of change of the total resistance of the battery cell (200) over time is greater than or equal to a threshold value can be determined as the sum of the ohmic resistance of the battery cell (200) at a second temperature and the charge transfer resistance of the battery cell (200) at a second temperature. In other words, the amount of change in the total resistance (711) up to the section (712) where a pulse current is applied to the battery cell (200) can be defined as the sum of the ohmic resistance of the battery cell (200) at a second temperature and the charge transfer resistance of the battery cell (200) at a second temperature. An electronic device (100) according to one embodiment can determine the difference between the total resistance value from the interval (712) onwards and the final total resistance (711) at the final point in time when the application of pulse current ends as the material transfer resistance at the second temperature. In other words, the final total resistance (711) at the second temperature can be defined as the sum of the ohmic resistance of the battery cell (200) at the second temperature, the charge transfer resistance of the battery cell (200) at the second temperature, and the material transfer resistance (713) of the battery cell (200) at the second temperature.In conclusion, the electronic device (100) according to one embodiment can obtain the ohmic resistance and charge transfer resistance of the battery cell (200) at a specific temperature, and then obtain the material transfer resistance and final total resistance of the battery cell (200) at a specific temperature by applying a pulse current to the battery cell (200) for a predetermined time.

[0072] FIG. 8 is a block diagram of an electronic device according to one embodiment.

[0073] Referring to FIG. 8, an electronic device (100) according to one embodiment may include a memory (801) and a processor (802). The electronic device (100) illustrated in FIG. 6 is illustrated only with components related to this embodiment. Therefore, it can be understood by those skilled in the art related to this embodiment that other general-purpose components may be included in addition to those illustrated in FIG. 6. In one embodiment, the processor (802) may be included in a controller.

[0074] The processor (802) can control the overall operation of the electronic device (100) and process data and signals. The processor (802) may be composed of at least one hardware unit. Additionally, the processor (802) may be operated by one or more software modules generated by executing program code stored in memory (801). The processor (802) may include memory, and the processor (802) can control the overall operation of the electronic device (100) and process data and signals by executing program code stored in memory.

[0075] The processor (802) may be configured to perform an EIS analysis of the battery cell (200) according to a plurality of temperatures including a first temperature and a second temperature to obtain a chart regarding the impedance of the battery cell (200) according to frequency change, extract a first inductance of a first graph regarding the impedance of the battery cell (200) at the first temperature included in the chart, and determine the resistance of the battery cell (200) at the second temperature based on the first inductance. In this case, the second temperature may correspond to a temperature higher than the first temperature, and the processor (802) may determine resistances including ohmic resistance and charge transfer resistance of the battery cell (200) at various temperatures based on the properties of the inductance of the battery cell (200) as previously examined.

[0076] According to an embodiment, the electronic device (100) may additionally include a transceiver for performing wired / wireless communication. The electronic device (100) can communicate with an external electronic device (e.g., electronic device (100)) using the transceiver. The external electronic device may be a terminal or a server. Additionally, communication technologies used by the transceiver may include GSM (Global System for Mobile communication), CDMA (Code Division Multi Access), LTE (Long Term Evolution), 5G, WLAN (Wireless LAN), Wi-Fi (Wireless-Fidelity), Bluetooth, RFID (Radio Frequency Identification), Infrared Data Association (IrDA), ZigBee, NFC (Near Field Communication), etc.

[0077] A server according to the embodiments described above may include a processor, memory for storing and executing program data, permanent storage such as a disk drive, a communication port for communicating with an external device, and user interface devices such as a touch panel, a key, a button, etc. Methods implemented as software modules or algorithms may be stored on a computer-readable recording medium as computer-readable code or program instructions executable on the processor. Here, computer-readable recording media include magnetic storage media (e.g., ROM (read-only memory), RAM (random-access memory), floppy disks, hard disks, etc.) and optical reading media (e.g., CD-ROM, DVD (Digital Versatile Disc)). Computer-readable recording media may be distributed across networked computer systems, allowing computer-readable code to be stored and executed in a distributed manner. The medium may be readable by a computer, stored in memory, and executed by a processor.

[0079] The present embodiment may be represented by functional block configurations and various processing steps. These functional blocks may be implemented by various numbers of hardware and / or software configurations that execute specific functions. For example, the embodiment may employ integrated circuit configurations such as memory, processing, logic, look-up tables, etc., capable of executing various functions by the control of one or more microprocessors or other control devices. Similar to how components may be implemented as software programming or software elements, the present embodiment may be implemented in programming or scripting languages ​​such as C, C++, Java, assembler, etc., including various algorithms implemented as combinations of data structures, processes, routines, or other programming configurations. Functional aspects may be implemented as algorithms executed on one or more processors. Additionally, the present embodiment may employ prior art for electronic configuration, signal processing, and / or data processing. Terms such as "mechanism," "element," "means," and "configuration" may be used broadly and are not limited to mechanical and physical configurations. The above terms may include the meaning of a series of software processes (routines) in conjunction with processors, etc.

[0080] The aforementioned embodiments are merely examples, and other embodiments may be implemented within the scope of the claims set forth below.

Claims

Claim 1 A method for determining the resistance of a battery cell comprises: a step of obtaining a Nyquist plot chart regarding the impedance of the battery cell according to frequency change by performing an EIS analysis of the battery cell according to a plurality of temperatures including a first temperature and a second temperature; a step of extracting a first inductance of the battery cell at the first temperature based on a first graph regarding the impedance of the battery cell at the first temperature; and a step of determining the resistance of the battery cell at the second temperature by determining the first inductance as the second inductance of the battery cell at the second temperature based on the first inductance, wherein the second temperature is a room temperature and is a temperature higher than the first temperature, which is a sub-zero temperature. Claim 2 delete Claim 3 A method for determining the resistance of a battery cell according to claim 1, wherein the step of determining the resistance of the battery cell at the second temperature comprises: determining the ohmic resistance of the battery cell at the second temperature by subtracting the second inductance from the value of the real impedance axis intercept of the second graph regarding the impedance of the battery cell at the second temperature; and determining the difference between the resistance at the inflection point of the second graph and the ohmic resistance of the battery cell at the second temperature as the charge transfer resistance of the battery cell at the second temperature. Claim 4 A method for determining the resistance of a battery cell according to claim 3, wherein the step of determining the ohmic resistance of the battery cell at the second temperature comprises: a step of obtaining a reference ohmic resistance at the second temperature based on the relationship between the second temperature and the ohmic resistance of the battery cell at the second temperature; and a step of determining the ohmic resistance of the battery cell at the second temperature by subtracting the second inductance from the value of the real impedance axis intercept of a second graph regarding the impedance of the battery cell at the second temperature when the difference between the reference ohmic resistance and the ohmic resistance of the battery cell at the second temperature is less than a threshold value. Claim 5 A method for determining the resistance of a battery cell according to claim 1, further comprising: a step of applying a pulse current to a battery cell at a second temperature for a predetermined time; and a step of obtaining a final total resistance according to the change in the total resistance of the battery cell at the second temperature due to the application of the pulse current. Claim 6 A method for determining the resistance of a battery cell, wherein the step of obtaining the final total resistance at the second temperature comprises obtaining the final total resistance at the second temperature based on the sum of the ohmic resistance of the battery cell at the second temperature, the charge transfer resistance of the battery cell at the second temperature, and the material transfer resistance of the battery cell at the second temperature. Claim 7 A method for determining the resistance of a battery cell according to claim 1, wherein the battery cell is a pouch-type stack cell having a structure in which a positive electrode comprising an active material, a conductive material, and a binder, and a negative electrode comprising graphite, a conductive material, and a binder are stacked. Claim 8 delete Claim 9 A computer-readable, non-transient recording medium having a program for executing the method of any one of paragraphs 1 and 3 through 7 on a server. Claim 10 An electronic device comprising: a memory for storing instructions; and a processor connected to said memory, wherein the processor performs an EIS analysis of a battery cell according to a plurality of temperatures including a first temperature and a second temperature to obtain a Nyquist plot chart regarding the impedance of the battery cell according to frequency change, extracts a first inductance of a first graph regarding the impedance of the battery cell at said first temperature, and is configured to determine the resistance of the battery cell at said second temperature by determining the first inductance as the second inductance of the battery cell at said second temperature based on said first inductance, and said second temperature is a room temperature and is a higher temperature than the first temperature, which is a sub-zero temperature.

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