Method for determining resistance of battery cell and electronic device for performing same

Abstract

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

Description

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

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

[0002] Pouch-type stack cells are the type of battery installed in most electric vehicles (EVs). In pouch-type stack cell batteries, the electrical resistance components, such as ohmic resistance, of the battery cell vary due to the electrical characteristics of the foil and electrodes, depending on the design. Because 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 resistance components are essential for improving battery performance.

[0003] Impedance measurement using EIS analysis is mainly used as a method for analyzing the resistance component of battery cells, and various studies are being conducted on methods for determining resistance suitable for various types of battery cells.

[0004] Embodiments disclosed herein seek to provide a method for determining the resistance of a battery cell and an electronic device for performing the same.

[0005] The embodiments disclosed herein seek to solve the technical problem of accurately measuring various types of resistances of battery cells by taking into account the electrical characteristics of the battery that vary depending on the battery design, such as a pouch-type stack cell.

[0006] The technical tasks to be achieved by this embodiment are not limited to the technical tasks described above, and other technical tasks can be inferred from the following embodiments.

[0007] A method for determining resistance of a battery cell according to one embodiment includes the steps of: performing an EIS analysis of the battery cell according to a plurality of temperatures including a first temperature and a second temperature to obtain a chart regarding impedance of the battery cell according to a change in frequency; extracting a first inductance of the battery cell at the first temperature based on a first graph regarding impedance of the battery cell at the first temperature included in the chart; and determining the resistance of the battery cell at the second temperature based on the first inductance, wherein the second temperature may be a temperature higher than the first temperature.

[0008] 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.

[0009] The step of determining the resistance of the battery cell at the second temperature may include the step of determining the ohmic resistance of the battery cell at the second temperature as a value obtained by subtracting the second inductance from the real impedance axis intercept value of a second graph regarding the impedance of the battery cell at the second temperature; and the step of 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.

[0010] The step of determining the ohmic resistance of the battery cell at the second temperature may include the step of obtaining a reference ohmic resistance at the second temperature based on a relationship between the second temperature and the ohmic resistance of the battery cell at the second temperature; and the step of determining the ohmic resistance of the battery cell at the second temperature as a value obtained by excluding the second inductance from a real impedance axis intercept value of a second graph regarding the impedance of the battery cell at the second temperature when a difference between the reference ohmic resistance and the ohmic resistance of the battery cell at the second temperature is less than a threshold value.

[0011] According to one embodiment, the method may further include the step of applying a pulse current to the battery cell at the second temperature for a predefined period of time; and the step of obtaining a final total resistance according to a change in the total resistance of the battery cell at the second temperature according to the application of the pulse current.

[0012] The step of obtaining the final overall resistance at the second temperature may include the step of obtaining the final overall 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.

[0013] The above battery cell may be a pouch type stack cell having a stacked structure in which a positive electrode including an active material, a conductive material, and a binder, and a negative electrode including graphite, a conductive material, and a binder are stacked.

[0014] The second temperature may be room temperature, and the first temperature may be sub-zero temperature.

[0015] An electronic device according to one embodiment includes a memory storing a command; 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 impedance of the battery cell according to a change in frequency, extract a first inductance of a first graph regarding impedance of the battery cell at the first temperature, and determine a resistance of the battery cell at the second temperature based on the first inductance, wherein the second temperature may be a temperature higher than the first temperature.

[0016] According to the proposed embodiment, one or more of the following effects can be expected.

[0017] According to an embodiment of the present specification, an electronic device has a technical effect of being able to determine the ohmic resistance and charge transfer resistance of a battery cell by using the properties of inductance even when it is difficult to visually confirm the ohmic resistance and charge transfer resistance of a battery cell at a specific temperature in 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.

[0018] Additionally, in accordance with embodiments of the present disclosure, the electronic device has a technical effect of being able to verify the accuracy of the ohmic resistance of the battery cell determined based on a chart of the impedance of the battery cell and the inductance of the battery cell, and to determine additional resistance components such as the material transfer resistance of the battery cell.

[0019] The effects of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0020] FIG. 1 is a diagram illustrating the configuration of a system for determining the resistance of a battery cell according to one embodiment.

[0021] Figure 2 is a drawing for explaining an EIS analysis method according to one embodiment.

[0022] FIG. 3 is a diagram for explaining impedance information obtained by performing temperature-dependent EIS analysis of a target battery cell according to one embodiment.

[0023] FIG. 4 is a diagram for explaining the inductance of a battery cell according to a temperature change of the target battery cell according to one embodiment.

[0024] FIG. 5 is a flowchart illustrating a method for determining the resistance of a battery cell according to one embodiment.

[0025] FIG. 6 is a diagram illustrating a process for obtaining the ohmic resistance of a target battery cell according to one embodiment.

[0026] FIG. 7 is a diagram illustrating a process for obtaining the material transfer resistance and total resistance of a target battery cell according to one embodiment.

[0027] Figure 8 is a block diagram of an electronic device according to one embodiment.

[0028] The terms used in the embodiments have been selected from widely used and common terms, taking into account the functions of the present disclosure. However, these terms may vary depending on the intentions of those skilled in the art, precedents, the emergence of new technologies, etc. Furthermore, in certain cases, terms may be arbitrarily selected by the applicant, in which case their meanings will be described in detail in the relevant description. Therefore, the terms used in this disclosure should not be defined simply as names of terms, but rather based on the meanings of the terms and the overall content of the present disclosure.

[0029] When a part of a specification is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0030] The expression "at least one of a, b, and c" described throughout the specification may encompass 'a alone', 'b alone', 'c alone', 'a and b', 'a and c', 'b and c', or 'all of a, b, and c'.

[0031] The "device" mentioned below may be implemented as a computer or portable device that can access a server or other device via 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, such as a communication-based device such as IMT (International Mobile Telecommunication), CDMA (Code Division Multiple Access), W-CDMA (W-Code Division Multiple Access), LTE (Long Term Evolution), and all types of handheld-based wireless communication devices such as smartphones and tablet PCs.

[0032] Below, embodiments of the present disclosure are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present disclosure. However, the present disclosure may be implemented in various different forms and is not limited to the embodiments described herein.

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0034]

[0035] FIG. 1 is a diagram illustrating the configuration of a system for determining the resistance of a battery cell according to one embodiment.

[0036] 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 stacked structure in which a positive electrode including an active material, a conductive material, and a binder, and a negative electrode including graphite, a conductive material, and a binder, are stacked. Alternatively, the battery cell (200) may be a cylindrical cell or a square cell, as well as a pouch-type cell. Meanwhile, FIG. 1 only illustrates components related to the present embodiment. Therefore, it will be understood by those skilled in the art related to the present embodiment that other general-purpose components may be further included in addition to the components illustrated in FIG. 1.

[0037] The electronic device (100) may include one or more sensors for measuring parameters of the battery cell (200), including the electrical conductivity of the battery cell (200) that is the resistance determination described above, and may include a memory and a processor (not shown) for various operations. That is, the electronic device (100) may perform an operation of performing EIS analysis of the battery cell (200) according to a plurality of temperatures to obtain a chart regarding the impedance of the battery cell (200) according to a change in frequency. In this case, the chart regarding the impedance of the battery cell (200) may correspond to, for example, a Nyquist plot chart.

[0038] According to one embodiment, the battery cell (200) may correspond to a battery cell in which a positive electrode including an active material, a binder, and a conductive agent and a negative electrode including graphite, a binder, and a conductive agent 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 including an active material, a conductive agent, and a binder and a negative electrode including graphite, a conductive agent, and a binder are stacked. More specifically, in one embodiment, the battery cell (200) may correspond to a pouch-type cell in a stacked form of 19 positive / negative electrode cells having a width of about 90 mm and a length of about 258 mm.

[0039] For example, the positive electrode may correspond to a positive electrode in which the active material accounts for 97.5% by mass, the binder accounts for 1.5% by mass, and the conductive material accounts for 1% by mass of the total mass of the active material layer including the active material, binder, and conductive material, so that the conductive material content is 1% of the total active material layer of the target electrode. For example, the negative electrode may correspond to a target negative electrode in which the graphite accounts for 95% by mass, the binder accounts for 3.5% by mass, and the conductive material accounts for 1.5% by mass of the total mass of the graphite, binder, and conductive material, so that the conductive material content is 1.5% of the total active material layer of the target electrode. For example, the battery cell (200) may be impregnated with an electrolyte in which EC (ethylene carbonate) and EMC (ethyl methyl carbonate) are mixed in a concentration of 3 to 7 and LiPF6 is added at a concentration of 1 molar. 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 case mentioned, and the embodiment according to the present disclosure may include not only a pouch-type stack cell but also various shapes of battery cells (200) such as a cylindrical cell and a square cell, and may also include various types of positive and negative electrodes, and may also include various types of electrolytes.

[0040]

[0041] Figure 2 is a drawing for explaining an EIS analysis method according to one embodiment.

[0042] Referring to Fig. 2, the concept of electrochemical impedance spectroscopy (EIS) used to determine the resistance of a battery cell can be confirmed. Impedance spectroscopy refers to a method of interpreting a Nyquist plot chart (201) obtained by dividing the impedance information obtained by continuously changing the frequency (210) of AC power 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 that evaluates the stability of a system through a parameter plot of a frequency response used in automatic control and signal processing. The Nyquist plot chart (201) may refer to a chart that visualizes a graph representing a response of a system according to a change in frequency on a complex plane including an axis for a real component and an axis for an imaginary component. A Nyquist plot chart for 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, which represents the impedance of a battery cell (200) according to the frequency change of an alternating current applied to the battery cell (200) for each of a plurality of temperatures, for example.

[0043] Interpreting the electrochemical process of a Nyquist plot in connection with the impedance analysis of a 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 characteristics of the electrolyte ionic conductivity of the electrolyte resistance of the battery cell (200) and the ohmic resistance related to the characteristics of the external electrolyte resistance.

[0044] 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 utilized to analyze information on the inductance component parasitic on the battery cell (200). As will be discussed below, in the case of a pouch-type stack cell, the inductance component may correspond to a resistance component generated due to electrical characteristics that vary depending on the design of the battery cell (200).

[0045] For example, the semicircular area (360) of the impedance information obtained according to the change in frequency (210) is the charge transfer resistance (Charge Transfer Resistance), which is a phenomenon that occurs when charges are transferred at the electrode surface / interface of the battery cell (200). ) can be utilized to analyze charge transfer impedance information representing lithium ion redox reaction at the electrode material interface, and thus information on charge transfer resistance of the battery cell (200) can be obtained. For example, the linear region (270) acquired according to the change in frequency (210) can include Warburg impedance information acquired in the low frequency region, and can be utilized to analyze the diffusion phenomenon of lithium ions (Li ions) related to the chemical diffusion resistance of lithium ions due to interlayer insertion into the particle crystal structure within the battery cell (200).

[0046] The electronic device (100) according to the present disclosure can perform EIS analysis of the battery cell (200) according to multiple 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, the area (240) including the intercept value of the real impedance (220) axis of the impedance information and the negative area (350) of the imaginary impedance (230) axis of the impedance information are mixed together due to the inductance component that appears due to the electrical characteristics that change according to the design of the battery, 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 the method of determining the ohmic resistance of the battery cell (200) by considering the inductance component at multiple temperatures and determining the charge transfer resistance, material transfer resistance, and total resistance by using the characteristics are specifically confirmed.

[0047]

[0048] FIG. 3 is a diagram for explaining impedance information obtained by performing temperature-dependent EIS analysis of a target battery cell according to one embodiment.

[0049] Referring to FIG. 3, an electronic device (100) according to an embodiment may perform EIS analysis of a battery cell according to a plurality of temperatures including a first temperature and a second temperature to obtain a chart (401) regarding impedance of the battery cell according to a change in frequency. For example, the electronic device (100) may obtain a Nyquist plot chart as the chart (401) regarding impedance of the battery cell, and may obtain a plurality of graphs (e.g., a first graph (311), a second graph (312), a graph (313), a graph (314)) regarding impedance of the battery cell (200) according to a plurality of temperatures included in the chart (401). Hereinafter, a description will be given based on a case where a first graph (311) is obtained 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°C), and a second graph (312), graph (313), and graph (314) are obtained 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°C, 0°C, 25°C).

[0050] Looking at the second graph (312), graph (313), and graph (314), it can be seen that the size of the semicircle area of ​​the impedance information obtained according to the frequency change of the first graph (311) is smaller than that of the semicircle area of ​​the 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 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 enlarged chart (402) of the relevant area of ​​the chart (401). In particular, in the area (362) including the real impedance axis intercept value of the second graph (312) at room temperature, it can be confirmed that it is difficult to distinguish between the area including the real impedance axis intercept value of the impedance information on the Nyquist plot described in FIG. 2, the negative area of ​​the imaginary impedance axis of the impedance information, and the semicircular area of ​​the impedance information obtained according to the frequency change due to the influence of the second inductance component of the battery cell (200) at the second temperature even on the enlarged chart (402). More specifically, it can be confirmed 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.

[0051]

[0052] FIG. 4 is a diagram for explaining the inductance of a battery cell according to a temperature change of the battery cell according to one embodiment.

[0053] Referring to Fig. 4, the inductance (411; 412; 413; 414) of the battery cell (200) at each of a plurality of temperatures can be confirmed through the inductance chart (401) according to the temperature change of the battery cell (200). In the case of a small cell, considering that the inductance at the time of impedance measurement is not large, so that the separation of ohmic resistance and inductance is easy, the battery cell (200) in this case can correspond to a small cell, and the inductance (411; 412; 413; 414) of the battery cell (200) has an area of ​​about 12 It may be 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 (H) It can be confirmed that it has a value in the range. That is, it can be confirmed that the inductance of the battery cell (200) does not differ significantly depending on the change in temperature and is maintained constant. This can be interpreted that, in the case of the inductance component corresponding to the electrical property generated due to the structural characteristics of the battery cell (200), even if the temperature of the battery cell (200) changes, the structural characteristics of the battery cell (200) do not change significantly, so the inductance component does not change significantly. In other words, the electronic device (100) according to one embodiment can obtain the inductance component of a specific battery cell (200) at a specific temperature through this, and then determine the value of the inductance component as the inductance value of the same battery cell (200) at a different temperature.

[0054]

[0055] Figure 5 is a flowchart illustrating a method for measuring target electrode resistance according to one embodiment.

[0056] As previously examined in FIG. 3, in the case of a pouch-type stack cell, the size of the semicircular region of the impedance information obtained according to the frequency change at a specific temperature (e.g., -20°C, 0°C, 25°C) is smaller than the size of the semicircular region of the impedance information obtained at a temperature lower than the specific temperature (e.g., -30°C), and it is difficult to clearly confirm the ohmic resistance through analysis of the region including the intercept value of the real impedance axis of the graph due to the inductance component. However, as examined in FIG. 4, the fact that the inductance of the battery cell (200) does not differ significantly according to the change in temperature is utilized, and a method for determining the resistance of the battery cell (200) according to the present disclosure will be described below in FIG. 5.

[0057] Referring to FIG. 5, an electronic device (100) according to an embodiment may perform 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 a change in frequency. As described above, the chart regarding the impedance of the battery cell (200) according to a change in frequency may correspond to a Nyquist plot chart. In this case, the first temperature may correspond to a subzero temperature of about -30°C as described above, and the second temperature may correspond to a temperature higher than the first temperature, for example, a 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 a change in frequency through impedance analysis as previously examined with reference 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 with reference to FIG. 3.

[0058] According to an embodiment, the electronic device (100) can extract the first inductance of the first graph regarding the impedance of the battery cell (200) at the first temperature in step S520. As examined in FIG. 3, the first graph regarding the impedance of the battery cell (200) at the first temperature has a larger size of the semicircular area of ​​the impedance information obtained according to the frequency change than the graphs regarding the impedance of the battery cell (200) at other temperatures, and thus can correspond to a graph from which the first inductance can be extracted through analysis of the negative area of ​​the imaginary impedance axis of the impedance information.

[0059] An electronic device (100) according to an embodiment can determine the resistances of a battery cell (200) at a second temperature based on the first inductance in step S530. As previously discussed in FIG. 4, the inductance of a battery cell (200) does not change significantly depending on temperature changes and remains substantially constant, so an electronic device (100) according to an embodiment can determine the first inductance as the second inductance of the battery cell (200) at the second temperature.

[0060] According to an 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. As discussed above in FIG. 3, in the case of a region including the real impedance axis intercept value of the second graph (312) at the second temperature, the ohmic resistance and inductance components are mixed, so the electronic device (100) according to an embodiment can separate the ohmic resistance at the second temperature by excluding the influence due to inductance by determining 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. 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.

[0061] In order to verify whether the value of the ohmic resistance acquired as described above is valid, the electronic device (100) may acquire a reference ohmic resistance at the second temperature based on the relationship between the ohmic resistance of the battery cell (200) at the second temperature and the second temperature, 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, may further perform an operation of determining the ohmic resistance of the battery cell (200) at the second temperature as a value obtained 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. In other words, the electronic device (100) according to one embodiment may acquire a reference ohmic resistance including information on the tendency of ohmic resistance to change according to temperature change based on the Arrhenius relationship, and may verify whether the acquired ohmic resistance is an accurate value by comparing the reference ohmic resistance with the ohmic resistance acquired according to the present disclosure, which will be described in detail with reference to FIG. 6 below.

[0062] According to an embodiment, the electronic device (100) may obtain 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 a second temperature through the preceding steps, and then apply a pulse current to the battery cell (200) at the second temperature for a predefined time to determine an additional resistance component of the battery cell (200). For example, the electronic device (100) according to an embodiment may obtain the final total resistance according to the change in the total resistance of the battery cell (200) at the second temperature according 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 described in detail below with reference to FIG. 7.

[0063]

[0064] FIG. 6 is a diagram illustrating a process for obtaining the ohmic resistance of a target battery cell according to one embodiment.

[0065] As examined 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 the Arrhenius relationship.

[0066] Referring to FIG. 6, an electronic device (100) according to an embodiment may obtain a reference ohmic resistance at a second temperature based on the Arrhenius relationship. In this case, the reference ohmic resistance may correspond to a resistance obtained based on the relationship between the absolute temperature and the 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 an embodiment of the present invention is obtained within an appropriate range. In this case, the Arrhenius relationship may be defined, for example, as in the following mathematical equation.

[0067]

[0068] In this case, K can mean the rate constant, A can mean the frequency coefficient, R can mean the gas constant, T can mean the absolute temperature, may mean activation energy. In other words, according to the Arrhenius relationship, when the absolute temperature of the system where a chemical reaction occurs increases, the speed of the chemical reaction increases, so when this is interpreted in terms of the battery cell (200), it can be seen that there is a relationship in which the movement of electrons becomes smooth. That is, when the temperature of the battery cell (200) increases according to the Arrhenius relationship, the ohmic resistance of the battery cell (200) may decrease correspondingly. The electronic device (100) according to one embodiment can obtain the reference ohmic resistance at the second temperature based on the relationship that the ohmic resistance of the battery cell (200) at the second temperature decreases as the second temperature increases, as can be confirmed through, for example, mathematical expression 1. More specifically, when examining 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 in the graph (610).

[0069] 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, the electronic device (100) according to one embodiment may compare the reference ohmic resistance in the reference ohmic resistance graph (610) based on the Arrhenius relationship at the same temperature with the values ​​(611, 612, 613, 614) excluding the inductance from the real impedance axis intercept value 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) may 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 the Arrhenius relationship related to the change in resistance according to temperature, rather than determining the ohmic resistance of the battery cell (200) as the value obtained by excluding the inductance from the real impedance axis intercept value of the graph regarding the impedance of the battery cell (200). Similarly, the electronic device (100) according to one embodiment can perform the same process for the charge transfer resistance of the battery cell (200) to more precisely determine the charge transfer resistance of the battery cell (200).

[0070]

[0071] FIG. 7 is a diagram illustrating a process for obtaining the material transfer resistance and total resistance of a target battery cell according to one embodiment.

[0072] Referring to FIG. 7, a change in the total resistance of a battery cell (200) to which a pulse current is applied can be confirmed through a resistance chart (701). An electronic device (100) according to an embodiment can apply a pulse current to a battery cell (200) at a second temperature for a predefined time, and obtain a final total resistance (711) according to a change in the total resistance of the battery cell (200) at the second temperature according 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, the electronic device (100) according to one embodiment may apply a pulse current to the battery cell (200) for a predefined time (e.g., 10 seconds), and determine the change in the total resistance of the battery cell (200) up to a section (712) in which the change rate of the total resistance of the battery cell (200) over time is greater than or equal to a threshold value as the sum of the ohmic resistance of the battery cell (200) at the second temperature and the charge transfer resistance of the battery cell (200) at the second temperature. In other words, the change in the total resistance (711) up to the section (712) in which the pulse current is applied to the battery cell (200) may be defined as the sum of the ohmic resistance of the battery cell (200) at the second temperature and the charge transfer resistance of the battery cell (200) at the second temperature. According to an embodiment, the electronic device (100) may determine the difference between the total resistance value after the section (712) and the final total resistance (711) at the final point in time when the application of the pulse current is terminated as the material transfer resistance at the second temperature. In other words, the final total resistance (711) at the second temperature may 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 overall resistance of the battery cell (200) at a specific temperature by applying a pulse current to the battery cell (200) for a predefined time.

[0073]

[0074] Figure 8 is a block diagram of an electronic device according to one embodiment.

[0075] Referring to FIG. 8, an electronic device (100) according to an embodiment may include a memory (801) and a processor (802). The electronic device (100) illustrated in FIG. 6 only illustrates components related to the present embodiment. Therefore, those skilled in the art will understand that, in addition to the components illustrated in FIG. 6, other general-purpose components may be further included. In an embodiment, the processor (802) may be included in a controller.

[0076] The processor (802) can control the overall operation of the electronic device (100) and process data and signals. The processor (802) can be composed of at least one hardware unit. In addition, the processor (802) can operate by one or more software modules generated by executing program codes stored in the memory (801). The processor (802) can include a memory, and the processor (802) can control the overall operation of the electronic device (100) and process data and signals by executing the program codes stored in the memory.

[0077] The processor (802) may be configured to perform 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 a change in frequency, 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 the ohmic resistance and the charge transfer resistance of the battery cell (200) at various temperatures based on the properties of the inductance of the battery cell (200) as discussed above.

[0078] According to an embodiment, the electronic device (100) may additionally include a transceiver for performing wired / wireless communication. The electronic device (100) may communicate with an external electronic device (e.g., the electronic device (100)) using the transceiver. The external electronic device may be a terminal or a server. In addition, the 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 (Bluetooth), RFID (Radio Frequency Identification), Infrared Data Association (IrDA), ZigBee, NFC (Near Field Communication), etc.

[0079] The server according to the above-described embodiments may include a processor, a memory for storing and executing program data, permanent storage such as a disk drive, a communication port for communicating with an external device, and a user interface device 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 codes or program instructions executable on the processor. Here, the computer-readable recording medium includes a magnetic storage medium (e.g., read-only memory (ROM), random-access memory (RAM), floppy disk, hard disk, etc.) and an optical reading medium (e.g., CD-ROM, DVD (Digital Versatile Disc)). The computer-readable recording medium may be distributed to computer systems connected to a network, so that the computer-readable code may be stored and executed in a distributed manner. The medium may be readable by a computer, stored in a memory, and executed by a processor.

[0080]

[0081] The present embodiment may be represented by functional block configurations and various processing steps. These functional blocks may be implemented by various hardware and / or software configurations that perform specific functions. For example, the embodiment may employ direct circuit configurations such as memory, processing, logic, look-up tables, etc., which may perform various functions under the control of one or more microprocessors or other control devices. Similarly, the present embodiment may be implemented in a programming or scripting language such as C, C++, Java, assembler, etc., including various algorithms implemented as a combination of data structures, processes, routines, or other programming configurations. Functional aspects may be implemented as algorithms that execute on one or more processors. Furthermore, the present embodiment may employ conventional techniques for electronic configuration, signal processing, and / or data processing. Terms such as "mechanism," "element," "means," and "composition" can be used broadly and are not limited to mechanical or physical structures. These terms can also encompass a series of software routines, such as those associated with a processor.

[0082] The above-described embodiments are merely examples, and other embodiments may be implemented within the scope of the claims set forth below.

Claims

1. In the method of determining the resistance of a battery cell, A step of performing EIS analysis of the 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 change in frequency; A step of extracting a first inductance of a 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 above chart; and A step of determining the resistance of the battery cell at the second temperature based on the first inductance, The above second temperature is a temperature higher than the above first temperature. How to determine the resistance of a battery cell.

2. In paragraph 1, The step of determining the resistance of the battery cell at the second temperature is: Including a step of determining the first inductance as the second inductance of the battery cell at the second temperature. How to determine the resistance of a battery cell.

3. In paragraph 1, The step of determining the resistance of the battery cell at the second temperature is: A step of determining the ohmic resistance of the battery cell 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 at the second temperature; and Including a step of 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. How to determine the resistance of a battery cell.

4. In paragraph 3, The step of determining the ohmic resistance of the battery cell at the second temperature is as follows: 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; Including a step of determining the ohmic resistance of the battery cell 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 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. How to determine the resistance of a battery cell.

5. In paragraph 1, A step of applying a pulse current to a battery cell at the second temperature for a predefined time; and Further comprising a step of obtaining a final total resistance according to a change in the total resistance at the second temperature of the battery cell according to the application of the pulse current. How to determine the resistance of a battery cell.

6. In paragraph 5, The step of obtaining the final total resistance at the above second temperature is: A step of obtaining a final overall 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, How to determine the resistance of a battery cell.

7. In paragraph 1, The above battery cell, A cathode including an active material, a conductive material and a binder, A pouch type stack cell having a structure in which a cathode including graphite, a conductive material and a binder is stacked. How to determine the resistance of a battery cell.

8. In paragraph 1, The above second temperature is room temperature, The above first temperature is below zero, How to determine the resistance of a battery cell.

9. A non-transitory computer-readable recording medium recording a program for executing the method of any one of clauses 1 to 8 on a server.

10. In electronic devices, memory for storing instructions; and comprising a processor connected to the above memory, The above processor, By performing EIS analysis of a battery cell at multiple temperatures including a first temperature and a second temperature, a chart of the impedance of the battery cell according to frequency change is obtained, Extract the first inductance of the first graph regarding the impedance of the battery cell at the first temperature included in the above chart, and It is set to determine the resistance of the battery cell at the second temperature based on the first inductance, The above second temperature is a temperature higher than the above first temperature. Electronic devices.

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