Battery pack and vehicle including the same

Abstract

A battery pack capable of accurately detecting the expansion of a battery cell according to circumstances is disclosed. According to one aspect of the present invention, the battery pack includes: a battery cell having an electrode assembly, an electrolyte, a battery case, and electrode terminals; a strain measurement unit, at least a portion of which is attached to an outer surface of the battery case of the battery cell and configured to measure whether the battery case is deformed; an impedance measurement unit connected to the electrode terminals of the battery cell and configured to measure the impedance inside the battery cell; and a control unit configured to determine whether the battery cell has expanded by using a deformation measurement result obtained by the strain measurement unit and an impedance measurement result obtained by the impedance measurement unit.

Description

Technical Field

[0001] The present disclosure relates to a battery technology, and more particularly, to a technology capable of more accurately detecting a swelling condition of a battery cell included in a battery pack. Background Art

[0002] Currently available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, etc. Among them, compared with nickel-based secondary batteries, lithium secondary batteries have almost no memory effect to ensure free charge and discharge, and lithium secondary batteries have attracted much attention due to their very low discharge rate and high energy density.

[0003] Lithium secondary batteries primarily use lithium-based oxides and carbon materials as the positive and negative active materials, respectively. A lithium secondary battery comprises an electrode assembly, in which positive and negative plates, coated with positive and negative active materials, are arranged with a separator interposed therebetween; and an exterior, or battery case, for sealingly housing the electrode assembly along with an electrolyte.

[0004] Generally, lithium secondary batteries may be classified into can-type secondary batteries having an electrode assembly contained in a metal can and pouch-type secondary batteries having an electrode assembly contained in a pouch of an aluminum laminate sheet according to the shape of the exterior.

[0005] Safety is one of the most important considerations for such secondary batteries (i.e., batteries). Specifically, a swelling phenomenon may occur in a secondary battery as the secondary battery swells due to the generation of gas, etc. during use. This swelling phenomenon may occur primarily under abnormal conditions. If the swelling phenomenon is not properly detected, it may cause the secondary battery to catch fire or explode, which may lead to serious problems.

[0006] Although several technologies for detecting such expansion have been proposed to date, it is difficult to say that a fast and accurate expansion detection technology has been fully ensured. Specifically, in the case of some expansion detection configurations, battery expansion may not be accurately detected due to a malfunction or poor contact. Summary of the Invention

[0007] Technical issues

[0008] The present disclosure aims to solve the problems of the related art, and thus the present disclosure aims to provide a battery pack and a vehicle including the battery pack, which can accurately detect the expansion of battery cells contained therein according to circumstances.

[0009] These and other objects and advantages of the present disclosure can be understood from the following detailed description and will become more fully apparent from the exemplary embodiments of the present disclosure.In addition, it will be readily understood that the objects and advantages of the present disclosure can be achieved by the means shown in the appended claims and their combinations.

[0010] Technical Solution

[0011] In one aspect of the present disclosure, a battery pack is provided, comprising: a battery cell having an electrode assembly, an electrolyte, a battery case, and electrode terminals; a strain measuring unit at least partially attached to an outer surface of the battery case of the battery cell and configured to measure whether the battery case is deformed; an impedance measuring unit connected to the electrode terminals of the battery cell and configured to measure impedance inside the battery cell; and a control unit configured to determine whether the battery cell is swollen by using a deformation measurement result of the strain measuring unit and an impedance measurement result of the impedance measuring unit.

[0012] Here, the control unit may be configured to determine that the battery cell is not swollen when the impedance measured by the impedance measurement unit is less than the reference impedance even if the deformation amount measured by the deformation measurement unit is equal to or greater than the reference deformation amount.

[0013] In addition, the control unit may be configured to determine whether the impedance increases when the impedance measured by the impedance measuring unit is less than the reference impedance.

[0014] In addition, the control unit may be configured to transmit an impedance measurement start signal to the impedance measurement unit when the deformation amount measured by the deformation measurement unit is equal to or greater than a reference deformation amount.

[0015] In addition, the battery pack may further include a temperature measuring unit located around the battery cell and configured to measure a temperature of the battery cell, and the control unit may be configured to determine whether the battery cell swells by further considering a temperature measurement result of the temperature measuring unit.

[0016] In addition, the control unit can be configured to determine that the battery cell is expanded only when the deformation amount measured by the deformation measurement unit is equal to or greater than the reference deformation amount, the impedance measured by the impedance measurement unit is equal to or greater than the reference impedance, and the temperature measured by the temperature measurement unit is equal to or greater than the reference temperature.

[0017] In addition, the battery cell may be a pouch-type battery, the battery cell including a housing portion for housing an electrode assembly and an electrolyte and a sealing portion arranged around the housing portion, the deformation measuring unit may be at least partially attached to the housing portion, and the impedance measuring unit may be constructed to be at least partially placed on the sealing portion.

[0018] In addition, the battery cell may be configured such that the sealing portion is at least partially folded toward the receiving portion, and the impedance measurement unit may be configured to be at least partially interposed between the receiving portion of the battery cell and the folded sealing portion.

[0019] In addition, the strain measuring unit may be elongated in one direction to be partially bent so that one end of the strain measuring unit is attached to the printed circuit board and the other end of the strain measuring unit is attached to the receiving portion of the battery cell.

[0020] In another aspect of the present disclosure, a vehicle is further provided, which includes the battery pack according to the present disclosure.

[0021] Technical Effects

[0022] According to the present disclosure, it is possible to accurately detect the swelling of a battery cell disposed inside a battery pack.

[0023] In particular, according to an aspect of the present disclosure, since deformation and impedance are measured together, it may be determined more accurately whether a battery cell is swollen.

[0024] Furthermore, according to one aspect of the present disclosure, even if a failure occurs in a deformation measurement configuration such as a strain gauge, it is possible to verify whether the failure occurs with the help of the impedance measurement unit.

[0025] In addition, according to the embodiments of the present disclosure, by reducing the influence of the magnetic field when measuring impedance, the impedance can be measured more accurately, thereby further improving the accuracy of the configuration for detecting battery cell swelling.

[0026] Furthermore, according to the embodiment of the present disclosure, since impedance and temperature are measured together and the measurement results are compared with each other, the performance of detecting the swelling of the battery cell may be further improved.

[0027] In addition, effects according to various embodiments of the present disclosure can be achieved, and some other effects will be described later in each embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings illustrate preferred embodiments of the present disclosure, and together with the aforementioned invention are used to provide a further understanding of the technical features of the present disclosure. Therefore, the present disclosure should not be interpreted as being limited to the accompanying drawings.

[0029] Figure 1 is a block diagram schematically illustrating a functional configuration of a battery pack according to an embodiment of the present disclosure.

[0030] Figure 2 is a diagram schematically illustrating a connection configuration of a battery pack according to an embodiment of the present disclosure.

[0031] Figure 3 is a circuit diagram schematically illustrating an impedance measurement unit according to an embodiment of the present disclosure.

[0032] Figure 4is a perspective view schematically showing the configuration of a battery pack according to an embodiment of the present disclosure.

[0033] Figure 5 is a perspective view schematically showing the configuration of a battery pack according to another embodiment of the present disclosure.

[0034] Figure 6 It is along Figure 5 A cross-sectional view taken along line A1-A1′.

[0035] Reference numerals

[0036] 100: Battery cell

[0037] 110: accommodating portion, 120: sealing portion, 130: electrode terminal

[0038] 200: Deformation measurement unit

[0039] 300: Impedance measurement unit

[0040] 310: Resistor, 320: Switch, 330: Impedance Controller

[0041] 400: Control unit

[0042] 500: Storage unit

[0043] 600: Temperature measurement unit DETAILED DESCRIPTION

[0044] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms for the purpose of obtaining the best interpretation.

[0045] Therefore, the descriptions provided herein are merely preferred examples and are for illustrative purposes only, and are not intended to limit the scope of the present disclosure. It should be understood that other equivalents and modifications may be made thereto without departing from the scope of the present disclosure.

[0046] Figure 1 is a block diagram schematically showing a functional configuration of a battery pack according to an embodiment of the present disclosure. Figure 2 is a diagram schematically illustrating a connection configuration of a battery pack according to an embodiment of the present disclosure.

[0047] Reference Figure 1 and 2, a battery pack according to the present disclosure may include a battery cell 100 , a deformation measurement unit 200 , an impedance measurement unit 300 , and a control unit 400 .

[0048] The battery cell 100 is a component that is connected to the charge and discharge path C of the battery pack and can hold and release electrical energy by repeatedly performing charge and discharge, and may refer to a single secondary battery. The battery cell 100 may include an electrode assembly, an electrolyte, a battery case, and electrode terminals. Here, the electrode assembly is an assembly of electrodes and a separator, and may be constructed so that at least one positive plate and at least one negative plate are provided with a separator placed therebetween. In addition, the electrode assembly may be housed inside the battery case together with the electrolyte. Furthermore, the electrode terminal may be exposed to the outside of the battery case, and the inner end of the electrode terminal may be electrically connected to the electrode assembly housed in the battery case. At least one battery cell 100 may be provided in the battery pack.

[0049] The deformation measurement unit 200 may be configured to measure whether the battery cell 100 is deformed. Specifically, the deformation measurement unit 200 may be configured to measure whether the appearance of the battery case of the battery cell 100 has changed. To this end, the deformation measurement unit 200 may be configured to measure the displacement of a specific point or portion of the battery cell 100.

[0050] For example, the deformation measurement unit 200 may be configured to measure whether the battery case of the battery cell 100 is at least partially deformed to bulge or recess outward, to expand or contract in length, or to change its position. To this end, the deformation measurement unit 200 may be configured to be at least partially attached to the outer surface of the battery case of the battery cell 100.

[0051] The deformation measurement unit 200 may include a strain gauge sensor or may be configured as a strain gauge sensor. A strain gauge sensor is a sensor for measuring deformation relative to an external force. If the strain gauge sensor is attached to the outer surface of the battery housing, it can measure changes in the appearance of the battery housing. The strain gauge sensor can be implemented in various forms, such as an electrical strain gauge sensor that measures the deformation rate by using the change in resistance of the strain gauge, and a mechanical strain gauge sensor that measures the deformation rate by mechanically measuring the change in the distance between two points. In the present disclosure, various types of strain gauge sensors known at the time of filing this application can be used as the deformation measurement unit 200.

[0052] The impedance measurement unit 300 can be configured to measure the impedance inside the battery cell 100. To this end, the impedance measurement unit 300 can be connected to both sides of the electrode terminals of the battery cell 100 and be configured to measure the voltage across the battery cell 100. In this case, the impedance measurement unit 300 may include a voltage sensor. In addition, the impedance measurement unit 300 may include a current sensor to directly measure the current flowing in the battery cell 100. Alternatively, without directly having a current sensor, the impedance measurement unit 300 may be configured to receive information about the current flowing in the battery cell 100 from another current sensor provided in the battery pack, etc. In addition, the internal impedance of the battery cell 100 can be measured based on the voltage and current information measured or received as described above. Here, as the impedance of the battery cell 100, the impedance measurement unit 300 may be configured to measure only the resistance as the real part, or to measure both the resistance and the reactance.

[0053] Figure 3 is a circuit diagram schematically illustrating an impedance measurement unit 300 according to an embodiment of the present disclosure.

[0054] Reference Figure 3 The impedance measurement unit 300 may include a resistor element 310 connected to both ends of the battery cell 100. In addition, a switch element 320 may be provided on the connection path between the resistor element 310 and the battery cell 100. In addition, the impedance measurement unit 300 may include an impedance controller 330 and be configured to turn the switch element 320 on and off. By turning the switch element 320 on / off, the power of the battery cell 100 can be supplied to the resistor element 310 or blocked. In addition, the impedance controller 330 may be configured to sense the voltage across the resistor element 310. In addition, the impedance controller 330 may determine the magnitude of the current flowing through the resistor element 310 by sensing the voltage across the resistor element 310. In this case, the resistance value of the resistor element 310 may be pre-stored in the impedance controller 330 or the storage unit 500. In addition, the magnitude of the current determined in this manner may be considered to be the same as the magnitude of the current flowing through the battery cell 100. Furthermore, the impedance controller 330 may be configured to measure the voltage across the battery cell 100 when the switching element 320 is turned on so that current flows to the resistance element 310. Furthermore, the internal impedance of the battery cell 100 may be measured using the voltage across the battery cell 100 measured in this manner and the determined current of the battery cell 100.

[0055] In this embodiment, the impedance controller 330 may be configured to measure the voltage across the resistance element 310 and the current flowing through the battery cell 100 while maintaining the switching element 320 in the on state. In this case, the impedance measurement unit 300 may be considered to be configured to measure resistance as the impedance of the battery cell 100 while a DC current flows through the battery cell 100.

[0056] In addition, in the present embodiment, the impedance controller 330 may be configured to measure the current flowing in the battery cell 100 and the voltage across both ends while repeatedly turning on and off the switching element 320. In this case, the impedance measuring unit 300 may be considered to be configured to measure resistance and reactance as the impedance of the battery cell 100 in a state where an AC current flows in the battery cell 100.

[0057] According to this embodiment, a separate power supply unit is not required to measure the impedance of the battery cell 100, and the impedance can be measured using the potential of the battery cell 100 itself. In addition, the impedance of the battery cell 100 can be measured using only a simple element configuration of the switching element 320 and the resistance element 310. In addition, in this embodiment, the impedance of the battery cell 100 can be measured for both DC and AC conditions.

[0058] In addition, the impedance measurement unit 300 may be configured to measure the impedance of the battery cell 100 when a charge or discharge current flows in the charge and discharge path C of the battery cell 100, or to measure the impedance of the battery cell 100 by supplying AC or DC power, respectively, to the battery cell 100. In addition, the impedance measurement unit 300 according to the present disclosure may adopt various impedance measurement methods known at the time of filing this application, such as a 4-terminal pair impedance measurement method.

[0059] The control unit 400 may receive a deformation measurement result from the deformation measurement unit 200. In addition, the control unit 400 may receive an impedance measurement result from the impedance measurement unit 300. To this end, the control unit 400 may be connected to the deformation measurement unit 200 and the impedance measurement unit 300 and configured to send and receive signals therewith. In addition, the control unit 400 may be configured to determine whether the battery cell 100 has expanded by using the deformation measurement result and the impedance measurement result received in this manner. That is, the control unit 400 does not determine whether the battery cell 100 has expanded based on any one of the deformation measurement result of the deformation measurement unit 200 and the impedance measurement result of the impedance measurement unit 300, but may determine whether the battery cell 100 has expanded by considering the deformation measurement result and the impedance measurement result of the battery cell 100 together.

[0060] According to the embodiment of the present disclosure, whether the battery cell 100 is swollen can be detected more accurately. For example, when the expansion of the battery cell 100 is detected by the deformation measurement unit 200 such as a strain gauge sensor, it can be verified whether the expansion is actually caused by the expansion or deformation of the battery cell 100 or by a malfunction, malfunction, poor contact or poor connection of the strain gauge sensor, etc. Specifically, when the battery pack is installed in a device such as a vehicle, vibration or shock may be frequently applied to the strain gauge sensor, and thus problems such as malfunction or poor contact of the strain gauge sensor may occur. However, according to the configuration of the present disclosure, since the expansion of the battery cell 100 is verified not only by the deformation measurement unit 200 such as a strain gauge sensor but also by the impedance measurement unit 300, the accuracy can be improved.

[0061] Meanwhile, control elements such as control unit 400 or impedance controller 330 are well known in the art for executing the various control logics executed in the present disclosure, and may optionally include a processor, an application specific integrated circuit (ASIC), a chipset, a logic circuit, a register, a communication modem, a data processing device, etc. In addition, when the control logic is implemented in software, the control unit 400 can be implemented as a set of program modules. In this case, the program modules can be stored in a memory and executed by a processor. The memory can be provided inside or outside the processor and can be connected to the processor in various well-known ways. In addition, the battery pack typically includes a control module referred to as a term such as an MCU (microcontroller unit) or a BMS (battery management system). The control unit 400 can be implemented at least in part by components such as an MCU or a BMS that are typically included in a traditional battery pack.

[0062] Specifically, the control unit 400 can be configured to compare the deformation amount measured by the deformation measuring unit 200 with a reference deformation amount. Here, the reference deformation amount can be a deformation value used as a standard for determining whether the battery cell 100 is deformed, or a deformation value that distinguishes each step indicating how much the battery cell 100 is deformed. For example, the reference deformation amount can be the minimum value of the deformation amount that can determine the expansion of the battery cell 100. In this case, the reference deformation amount can be expressed in the form of a rate of change or a deformation rate of the strain gauge. Specifically, in the case of an electric strain gauge sensor, the reference deformation amount can be expressed as the rate of change of the resistance value of the Wheatstone bridge. Alternatively, in an electric strain sensor, the reference deformation amount can be represented by the resistance value itself.

[0063] In addition, the control unit 400 may be configured to compare the impedance measured by the impedance measuring unit 300 with a reference impedance. Here, the reference impedance may be a value used as a standard for the internal impedance of the battery cell 100 to determine whether it is swollen. The reference impedance may be a specific threshold value, or may be in the form of several threshold values ​​with different values. Specifically, in the case of several threshold types, the reference impedance may be a threshold value for a plurality of steps respectively indicating how much the battery cell 100 is swollen. That is, the reference impedance may be a minimum value or a maximum value for determining whether the battery cell 100 is swollen or how much the battery cell 100 is swollen. For example, the reference impedance may be an impedance value having a predetermined difference based on the impedance of the battery cell 100 in a normal state, such as the BOL (Bottom Of Life) time point of the battery cell 100 or the manufacturing time point of the battery pack.

[0064] At the same time, a reference deformation amount and a reference impedance to be compared with the measured deformation amount and impedance measurement value may be stored in advance. Specifically, the battery pack according to the present disclosure may include the following: Figure 1 In this case, the reference deformation amount and the reference impedance may be stored in the storage unit 500 in advance.

[0065] In addition, in addition to the reference deformation amount and the reference impedance, the storage unit 500 can store programs required for at least some components of the battery pack (e.g., the control unit 400) to perform their functions. The type of the storage unit 500 is not particularly limited as long as it is a known information storage device capable of writing, erasing, updating, and reading data. For example, the storage unit 500 can be implemented as an information storage device such as RAM (random access memory), SRAM (static random access memory), flash memory, hard disk, ROM (read-only memory), EEPROM (electrically erasable programmable read-only memory), register, SSD (solid state disk), SDD (silicon disk drive), and micro multimedia card, or can be configured to include at least one of them.

[0066] Preferably, the control unit 400 may be configured to determine whether the deformation amount measured by the deformation measurement unit 200 is equal to or greater than a reference deformation amount. Here, the deformation amount measured by the deformation measurement unit 200 may represent a degree of deformation compared to any one time point (for example, an initial state (BOL) in which the battery cell 100 is not degraded or a time point at which the battery pack is manufactured). In addition, the control unit 400 may be configured to determine whether the impedance measured by the impedance measurement unit 300 is greater than or equal to a reference impedance. Furthermore, the control unit 400 may be configured to determine whether the battery cell 100 is expanded by considering both a comparison result between the deformation amount measured by the deformation measurement unit 200 and the reference deformation amount and a comparison result between the impedance measured by the impedance measurement unit 300 and the reference impedance.

[0067] Furthermore, when the deformation amount measured by the deformation measurement unit 200 is equal to or greater than the reference deformation amount and the impedance measured by the impedance measurement unit 300 is equal to or greater than the reference impedance, the control unit 400 may determine that the battery cell 100 has expanded. Meanwhile, when the impedance measured by the impedance measurement unit 300 is less than the reference impedance, the control unit 400 may determine that the battery cell 100 has not expanded, even if the deformation amount measured by the deformation measurement unit 200 is greater than or equal to the reference deformation amount.

[0068] For example, when the reference deformation amount is 1.3 and the reference impedance is 1.0 mΩ, if the deformation amount measured by the deformation measurement unit 200 is 1.4 and the impedance change measured by the impedance measurement unit 300 is 2.0 mΩ, the control unit 400 can determine that the battery cell 100 has expanded. Meanwhile, when the reference deformation amount and reference impedance are the same as those in the present embodiment, if the deformation amount measured by the deformation measurement unit 200 is 1.4 but the impedance change measured by the impedance measurement unit 300 is 0.5 mΩ, the control unit 400 can determine that the battery cell 100 has not expanded.

[0069] According to this configuration of the present disclosure, when the strain measurement unit 200 detects expansion of the battery cell 100, the impedance measurement unit 300 re-verifies the expansion of the battery cell 100, thereby further improving the accuracy of detecting the expansion of the battery cell 100. Specifically, in a strain measurement unit 200 such as a strain gauge sensor, there is a high possibility that an error may occur due to a malfunction or poor contact when detecting a change in appearance. However, according to this embodiment, it is possible to more accurately determine whether the expansion of the strain measurement unit 200 was detected due to an error or was detected normally due to the expansion of the battery cell 100.

[0070] In addition, according to this configuration, even if no error occurs in the strain measurement unit 200, a serious swelling of the battery cell 100 can be detected more clearly. In this regard, more specifically, if the battery cell 100 is severely swollen, the electrical connection structure provided inside the battery cell 100 may be broken.

[0071] For example, the battery cell 100 may include a plurality of electrode tabs provided on a plurality of electrode plates and electrode leads connected to the plurality of electrode tabs. If the battery cell 100 swells severely, the connection between one or more electrode tabs and the electrode leads may be cut off inside the battery cell 100. Alternatively, in the case of a battery cell 100 including a plurality of double cells, the double cells connecting the double cells to each other may be broken. In addition, if some connections between the electrode tabs and the electrode leads or some connections between the electrode tabs are broken, the impedance inside the battery cell may increase. This can be considered to be similar to the case where the connection of some resistors among a plurality of resistors connected in parallel is cut off. Therefore, when the impedance increases enough to exceed the reference impedance, it can be predicted that the connection of at least some electrode tabs is cut off inside the battery cell 100. Therefore, the control unit 400 can determine whether the battery cell 100 is swollen by considering both the impedance change and the physical displacement change.

[0072] Furthermore, the control unit 400 may be configured to determine whether the impedance has increased. To this end, the control unit 400 may be configured to compare the currently measured impedance with the previously measured impedance. Specifically, the control unit 400 may be configured to determine whether the currently measured impedance has increased compared to the previously measured impedance. Furthermore, the control unit 400 may be configured to determine the impedance change trend, i.e., whether the impedance is increasing, decreasing, or remaining constant.

[0073] For example, if the currently measured impedance is 0.8 mΩ and the previously measured impedance was 0.6 mΩ, the control unit 400 may determine that the impedance is increasing. Meanwhile, if the previously measured impedance was 0.8 mΩ, the control unit 400 may determine that the impedance remains constant. Furthermore, the control unit 400 may estimate the increasing / decreasing trend of the impedance based on three or more impedance measurement results measured at different time points.

[0074] Specifically, if it is determined that the impedance is increasing, the control unit 400 may determine that the expansion of the battery cell 100 is gradually progressing. This is presumably a result of the number of electrode tabs ruptured inside the battery cell 100 gradually increasing.

[0075] Furthermore, if the impedance measured by the impedance measurement unit 300 is less than the reference impedance, the control unit 400 may be configured to determine whether the impedance is increasing. In this case, even if it is not determined that the battery cell 100 is swollen or a dangerous situation has occurred due to the swelling of the battery cell 100 because the impedance is less than the reference impedance, it can be predicted that the swelling of the battery cell 100 will reach a serious situation in the future. Therefore, according to this embodiment, by predicting the swelling of the battery cell 100 in advance, the control unit 400 can take measures to prevent the swelling of the battery cell 100 from becoming more serious, or perform preliminary preparations for the swelling of the battery cell 100. For example, if it is predicted that the swelling of the battery cell 100 will occur, the control unit 400 may be configured to stop or reduce the use of the battery cell 100, or issue a warning to a user such as a vehicle driver through a display unit.

[0076] Meanwhile, when the impedance decreases to a certain level or more compared to a previously measured value, the control unit 400 may determine that this is a temporary error of the impedance measuring unit 300 .

[0077] In addition, when the impedance measured by the impedance measurement unit 300 increases, the control unit 400 may be configured to shorten the measurement cycle of the impedance measurement unit 300 and / or the strain measurement unit 200. Specifically, when the impedance measured by the impedance measurement unit 300 is less than the reference impedance, if the impedance measured by the impedance measurement unit 300 tends to increase, the control unit 400 may allow the impedance and / or strain to be measured more frequently.

[0078] For example, if the reference impedance is 1.0 mΩ and the measured impedance is gradually increasing, such as 0.6 mΩ, 0.7 mΩ, and 0.8 mΩ, although the current impedance is still less than the reference impedance, the control unit 400 can be configured to control the impedance measurement unit 300 and / or the deformation measurement unit 200 to shorten the impedance measurement period and / or the measurement period of the deformation measurement unit 200 from 30 minutes to 20 minutes.

[0079] According to this configuration of the present disclosure, when expansion of the battery cell 100 is about to occur or is gradually progressing, impedance or physical deformation can be measured more frequently before the final expansion state is determined, thereby ensuring more accurate expansion detection. Specifically, in this embodiment, when expansion occurs in the battery cell 100, the expansion can be detected immediately, allowing for faster action to be taken.

[0080] In addition, the control unit 400 may be configured to determine whether or how many electrode joints within the battery cell 100 are broken based on the impedance measured by the impedance measurement unit 300. To this end, the control unit 400 or the storage unit 500 may include information indicating the number of broken electrode joints corresponding to a plurality of impedance values.

[0081] For example, the control unit 400 or the like may store information of 1, 2, 3, ... as the number of broken electrode joints, corresponding to impedance changes of 1.2 mΩ, 1.4 mΩ, 1.6 mΩ, ..., respectively. Furthermore, the control unit 400 may determine how many electrode joints are currently broken in the current battery cell 100 by comparing the information stored in this manner with the impedance value measured by the impedance measurement unit 300.

[0082] In addition, the control unit 400 may be configured to determine whether the expansion of the battery cell 100 has become more serious based on the number of broken electrode joints. For example, when it is determined that the number of broken electrode joints is gradually increasing to 2, 3, and 4, the control unit 400 may estimate that the expansion of the battery cell 100 has become more serious. In addition, the control unit 400 may be configured to control the charging and discharging of the battery cell 100 differently according to the degree of expansion of the battery cell 100. For example, when it is determined that one electrode joint is broken, the control unit 400 may maintain the charging and discharging of the battery cell 100 and send a warning message to the user. At the same time, when it is determined that two electrode joints are broken, the control unit 400 may turn off the charge and discharge switch to block the charging and discharging of the battery cell 100.

[0083] Furthermore, when the deformation amount measured by the deformation measurement unit 200 is equal to or greater than the reference deformation amount, the control unit 400 may be configured to transmit an impedance measurement start signal to the impedance measurement unit 300. That is, the control unit 400 may control the impedance measurement unit 300 to measure the impedance when the deformation amount of the battery cell 100 exceeds a certain level (e.g., a reference deformation amount).

[0084] For example, when the reference deformation amount is 1.2, if the measured deformation amount is 1.1, the impedance measurement unit 300 may not measure the impedance. However, if the measured deformation amount is greater than or equal to the reference deformation amount, such as 1.3, the control unit 400 may control the impedance measurement unit 300 to measure the impedance of the battery cell 100. In addition, if the impedance measurement value measured by the impedance measurement unit 300 exceeds the reference impedance, it can be determined that the battery cell 100 is swollen.

[0085] According to this configuration of the present disclosure, resource consumption can be prevented by the measurement operation of the impedance measurement unit 300. For example, according to this configuration, by reducing unnecessary impedance measurement operations of the impedance measurement unit 300, power consumption provided for impedance measurement or processing operations performed for impedance measurement can be reduced or omitted.

[0086] In addition, the battery pack according to the present disclosure may further include a temperature measuring unit 600, such as Figure 1 and Figure 2 shown.

[0087] The temperature measurement unit 600 can be configured to measure the temperature of the battery cell 100. To this end, the temperature measurement unit 600 can be configured to be located inside the battery pack, particularly around the battery cell 100. For example, the temperature measurement unit 600 can be attached to or located around the electrode terminals or battery housing of the battery cell 100. The temperature measurement unit 600 can be configured to have a temperature sensor, such as a known temperature measurement element such as a thermistor. In addition, various temperature measurement elements known at the time of filing this application can be used as part or all of the temperature measurement unit 600 of the present disclosure.

[0088] In this embodiment, the control unit 400 may be configured to further consider the temperature measurement result of the temperature measurement unit 600 when determining whether the battery cell 100 has expanded. That is, the control unit 400 may be configured to determine whether the battery cell 100 has expanded by considering the deformation amount measured by the deformation measurement unit 200, the impedance measured by the impedance measurement unit 300, and the temperature measured by the temperature measurement unit 600 together.

[0089] Specifically, the control unit 400 may be configured to compare the deformation measurement value, the impedance measurement value, and the temperature measurement value with reference values, respectively. That is, the control unit 400 may be configured to compare the deformation measured by the deformation measurement unit 200 with the reference deformation value, compare the impedance measured by the impedance measurement unit 300 with the reference impedance, and compare the temperature measured by the temperature measurement unit 600 with the reference temperature.

[0090] Here, the reference temperature may be a value that deviates by a certain level or more from the temperature range that can be measured in a normal battery cell 100. For example, the reference temperature may be a value that deviates by a certain level or more from the temperature measurement value at the BOL time point of the battery cell 100, and may represent a temperature value at which expansion of the battery cell 100 can be determined. For example, when the temperature of the battery cell 100 is 20°C to 45°C under normal operating conditions of the battery pack, the reference temperature may be set to a value outside this range (e.g., 50°C).

[0091] Furthermore, the control unit 400 may be configured to determine that the battery cell 100 has expanded only when the deformation amount measured by the deformation measurement unit 200 is greater than or equal to a reference deformation amount, the impedance measured by the impedance measurement unit 300 is greater than or equal to a reference impedance, and the temperature measured by the temperature measurement unit 600 is equal to or greater than a reference temperature. That is, the control unit 400 may determine that the battery cell 100 has expanded only when the measured deformation amount, measured impedance, and measured temperature are all equal to or greater than a reference value, and may determine that the battery cell 100 has not expanded if any one of these values ​​is less than the reference value.

[0092] For example, when the reference deformation amount is 1.2, the reference impedance is 2.0 mΩ, and the reference temperature is 50°C, even if the measured deformation amount is, for example, 1.3, which is greater than the reference deformation amount, and the measured impedance is, for example, 3.0 mΩ, which is greater than the reference impedance, if the measured temperature is 40°C less than the reference temperature, the control unit 400 may be configured to determine that the battery cell 100 has not expanded. Meanwhile, in this embodiment, if the measured deformation amount is 1.3, the measured impedance is 3.0 mΩ, and the measured temperature is 55°C, and these values ​​all exceed the reference values, the control unit 400 may be configured to ultimately determine that the battery cell 100 has expanded.

[0093] According to this construction of the present disclosure, since the degree of temperature change of the battery cell 100 as well as the degree of deformation and the degree of impedance change are taken into consideration to determine whether the battery cell 100 is expanded, it is possible to more accurately determine whether the battery cell 100 is expanded. Specifically, as described above, when the battery cell 100 expands, some of the multiple electrode joints inside the battery cell 100 may be broken. In addition, when the electrode joint is broken as described above, not only the internal impedance of the battery cell 100 but also the temperature of the battery cell 100 may increase. According to this embodiment of the present disclosure, by measuring whether the temperature of the battery cell 100 changes with the impedance change, the degree of the expansion phenomenon of the battery cell 100 can be more accurately and easily identified.

[0094] In addition, the control unit 400 may be configured to determine the expansion condition of the battery cell 100 in stages based on the deformation amount, impedance, and temperature.

[0095] For example, if none of the deformation amount, impedance, and temperature exceeds the reference value, the control unit 400 can determine that this is a first stage situation (normal situation). Next, if any one of the deformation amount, impedance, and temperature exceeds the reference value, the control unit 400 can determine that this is a second stage situation (warning situation) different from the first stage. In addition, if two factors among the deformation amount, impedance, and temperature exceed the reference value, the control unit 400 can determine that this is a third stage situation (progress situation) higher than the second stage. In addition, if three factors among the deformation amount, impedance, and temperature exceed the reference value, the control unit 400 can determine that this is a fourth stage situation (dangerous situation) higher than the third stage.

[0096] According to this embodiment of the present disclosure, it is possible to detect and predict more detailed swelling according to the progress of swelling, so that more appropriate measures can be taken according to the degree of each swelling.

[0097] In the battery pack according to the present disclosure, the battery cell 100 may be configured as a pouch-type secondary battery. In addition, the deformation measurement unit 200 and the impedance measurement unit 300 may be configured to be attached to a portion of the pouch-type secondary battery. This will be referred to as Figure 4 Describe in more detail.

[0098] Figure 4 is a perspective view schematically showing the configuration of a battery pack according to an embodiment of the present disclosure.

[0099] Reference Figure 4 The battery cell 100 may be constructed in the form of a pouch-type secondary battery. Such pouch-type secondary batteries are batteries in the form of laminated sheets in which a metal layer, such as aluminum, is placed between polymer layers and are well known at the time of filing this application. Therefore, the specific construction of the pouch-type battery will not be described in detail here.

[0100] In the case of such a pouch-type battery, the battery cell 100 may include a receiving portion 110 and a sealing portion 120. Here, the receiving portion 110 has an empty space therein and may be configured to protrude convexly outward. In addition, in the internal space of the receiving portion 110, the electrode assembly and the electrolyte may be accommodated. In addition, the sealing portion 120 may be arranged around the receiving portion 110 to surround the receiving portion 110. Specifically, in the pouch-type battery cell 100, the receiving portion 110 may be formed in the central portion of the upper bag and / or the lower bag, and the sealing portion 120 may be formed by sealing the edge portion of the bag by heat melting or the like in a state where the electrode assembly and the electrolyte are accommodated in the receiving portion 110. In addition, the sealing portion 120 may be completely formed in the area surrounding the receiving portion 110, but may not be formed in a portion thereof. For example, the sealing portion 120 may be formed on three of the four side surfaces surrounding the receiving portion 110, and the sealing portion 120 may not be formed on the remaining one side surface. Meanwhile, in the pouch-type battery cell 100, electrode leads serving as electrode terminals 130 may be interposed between the pouch-shaped case materials and exposed on at least one side.

[0101] At the same time, although Figure 4 Only one battery cell 100 is illustrated in the figure, but the battery pack according to the present disclosure may include multiple battery cells 100. In this case, at least one of the strain measurement unit 200 and the impedance measurement unit 300 may be provided for each battery cell 100 to measure the strain amount and impedance of each battery cell 100. For example, if the battery pack includes ten battery cells 100, ten strain measurement units 200 and ten impedance measurement units 300 may be included to measure the strain amount and impedance of each of the ten battery cells 100. In this case, the strain amount and impedance of each of the multiple battery cells 100 can be accurately measured.

[0102] In addition, if Figure 4 As shown, the deformation measuring unit 200 may be at least partially attached to the receiving portion 110 to measure the physical deformation of the battery cell 100. When an expansion phenomenon occurs due to gas generation inside the battery cell 100, the receiving portion 110 may be physically deformed before or larger than the sealing portion 120. For example, the deformation measuring unit 200 may be configured in the form of a sheet, such as Figure 4 As shown, the strain measuring unit 200 may be at least partially attached to the receiving portion 110 to measure the physical deformation of the receiving portion 110. In addition, other parts of the strain measuring unit 200 may be connected to another electrical component, such as a printed circuit or wiring, to transmit deformation amount measurement information measured by the strain measuring unit 200 to the control unit 400.

[0103] In addition, the impedance measurement unit 300 may be configured to be at least partially placed on the sealing portion 120. Specifically, the impedance measurement unit 300 may be provided on a printed circuit board, as shown by P in the drawings, or may be implemented using a printed circuit board P. For example, Figure 4 As shown, the impedance measurement unit 300 may include a printed circuit board and may be configured such that a path for impedance measurement is implemented by a conductor pattern formed on the printed circuit board P. Figure 3 Components such as the switching element 320, the resistance element 310, and the impedance controller 330 described in the embodiment of the present invention can be configured to be mounted on a printed circuit board. In addition, the printed circuit board for implementing the impedance measurement unit 300 can be configured to extend to the electrode terminals 130 (electrode leads) of the battery cell 100, that is, the positive lead and the negative lead, to measure the voltage at both ends between the positive lead and the negative lead. In addition, the printed circuit board P forming the impedance measurement unit 300 can be placed on the sealing portion 120. Specifically, the printed circuit board P of the impedance measurement unit 300 can be attached to the sealing portion 120.

[0104] According to this configuration of the present disclosure, since the impedance measurement unit 300 is configured to be placed on the sealing portion 120 of the battery cell 100, the space for the impedance measurement unit 300 can be reduced. Therefore, according to the configuration of the present disclosure, even if the impedance measurement unit 300 is included, the volume of the battery pack can be prevented from being significantly increased. In addition, when a plurality of secondary batteries are included in the battery pack, the plurality of secondary batteries are generally stacked so that their accommodating portions 110 face each other. Even in this configuration, the volume of the battery pack can be prevented from being increased due to the configuration of the impedance measurement unit 300 and the like.

[0105] In addition, according to this configuration, since the impedance measurement unit 300 is located near the battery cell 100, it is possible to reduce the phenomenon that the accuracy of impedance measurement is reduced due to the magnetic field caused by the current. That is, when measuring impedance, due to the current flowing in the battery cell 100 and the magnetic field in the impedance measurement path ( Figure 3 The current flowing in the path on the side of the resistor element 310 in the battery cell 100 can form a magnetic field. According to this embodiment, the distance between the current flowing through the battery cell 100 and the impedance measurement path can be very small. Therefore, the magnetic fields formed by the current flowing in the battery cell 100 and the current flowing in the impedance measurement path can cancel each other out, thereby improving the accuracy of the impedance measurement. Specifically, in Figure 3In the embodiment, the impedance measurement path may be formed to pass through the switch element 320 and the resistor element 310, and the direction of the current flowing through the resistor element 310 may be opposite to the direction of the current flowing through the battery cell 100. In addition, when the distance between the resistor element 310 and the battery cell 100 is reduced, the magnetic field cancellation effect may be further enhanced due to the currents flowing in opposite directions.

[0106] Meanwhile, when the impedance measuring unit 300 is configured to include or use a printed circuit board P as in the above embodiment, Figure 4 As shown, the control unit 400 may also be configured to be mounted on a printed circuit board P. According to this configuration of the present disclosure, the volume of the battery pack can be prevented from being greatly increased due to the control unit 400, and the signal transmission length between the impedance measurement unit 300 and the control unit 400 can also be reduced. Therefore, the accuracy of the impedance measurement can be further improved.

[0107] In addition, in this embodiment, Figure 4 As shown, a portion of the deformation measurement unit 200 can be connected to the printed circuit board P. In addition, the measurement information of the deformation measurement unit 200 can be sent to the control unit 400 through the conductor pattern provided on the printed circuit board P. In addition, in this embodiment, the temperature measurement unit 600 can also be mounted on the printed circuit board P. Specifically, the temperature measurement unit 600 can be located on the portion of the printed circuit board P that contacts the electrode terminal 130. The temperature of the battery cell 100 can be greatly increased on the electrode terminal 130 side, and the influence of the external temperature can be minimized. In this case, the temperature measurement accuracy can be further improved. In addition, according to this embodiment, the distance between the control unit 400 and other components such as the deformation measurement unit 200 or the temperature measurement unit 600 can be reduced. Therefore, it is conducive to the miniaturization of the battery pack, and the influence of noise can be reduced during signal transmission.

[0108] Figure 5 is a perspective view schematically showing the configuration of a battery pack according to another embodiment of the present disclosure, and Figure 6 It is along Figure 5 However, in Figure 6 In the cross-sectional view, for ease of illustration, the internal structure of the battery such as the electrode assembly is not drawn.

[0109] Reference Figure 5 and Figure 6, the battery cell 100 is a pouch-type secondary battery and can be configured so that the sealing portion 120 is at least partially folded toward the accommodating portion 110. For example, as shown in the drawings, among the four sealing portions 120 located around the accommodating portion 110, the sealing portions 120 on both sides of which no electrode leads are located can be folded toward the accommodating portion 110. In this configuration, the impedance measurement unit 300 can be configured to be at least partially placed between the accommodating portion 110 of the battery cell 100 and the folded sealing portion 120. Specifically, when the impedance measurement unit 300 is configured in the form of a printed circuit board, the printed circuit board can be configured to stand upright between the accommodating portion 110 and the sealing portion 120 of the battery cell 100.

[0110] According to this configuration of the present disclosure, the volume of the battery pack can be further reduced, and the influence of the magnetic field can be further reduced when measuring impedance. That is, according to this configuration, the impedance measurement unit 300, especially the impedance measurement path, can be closer to the accommodating portion 110 of the battery cell 100. Therefore, the effect of offsetting the magnetic field is increased, so it can more effectively prevent the impedance measurement from being interfered with by the magnetic field. In addition, according to this configuration, since the impedance measurement unit 300 is located inside the folded sealing portion 120 of the battery cell 100, the influence of the magnetic field formed by the battery cell 100 on the impedance measurement unit 300 can be reduced by means of the folded sealing portion 120.

[0111] Meanwhile, the deformation measuring unit 200 may be constructed in the form of a sheet elongated in one direction. In this case, the deformation measuring unit 200 may be constructed so that any portion of its central portion is bent. That is, referring to Figure 6 , the deformation measurement unit 200 may include a horizontal portion extending in the left-right direction (x-axis direction) and a vertical portion extending in the vertical direction (z-axis direction). In addition, the vertical portion may be at least partially attached to the printed circuit board P to connect to the conductor pattern on the printed circuit board P. In addition, the horizontal portion may be at least partially attached to the accommodating portion 110 of the battery cell 100 to detect the deformation of the battery cell 100, especially the expansion of the battery cell 100. Specifically, when the deformation measurement unit 200 is configured in the form of an electric strain gauge sensor, most of the resistance wire may be located on the horizontal portion.

[0112] According to this embodiment of the present disclosure, it is possible to minimize volume increase while stably ensuring the performance of detecting expansion of the battery cell 100 by the strain measurement unit 200. In addition, in this case, it is possible to minimize the signal transmission path of the strain measurement unit 200.

[0113] In addition, when the impedance measurement unit 300 is configured in the form of a printed circuit board P as in the present embodiment, the printed circuit board may be a flexible printed circuit board (FPCB). According to this configuration, since the printed circuit board P can be easily bent according to the shape of the battery cell 100, components such as the impedance measurement unit 300 can be more easily mounted on the battery cell 100. Specifically, Figure 5 As shown, the impedance measurement unit 300 is mostly configured to stand upright between the accommodating portion 110 and the sealing portion 120, and the remaining portion is preferably configured to lie flat in the horizontal direction so as to contact the electrode leads of the battery cell 100. Therefore, it is preferable to use an easily bendable FPCB to make the printed circuit board forming the impedance measurement unit 300, so that a portion of the impedance measurement unit 300 is in an upright position and the other portion is in a lying position.

[0114] In addition to the above components, the battery pack according to the present disclosure may also include various components generally included in a battery pack. For example, the battery pack according to the present disclosure may include not only a battery pack housing, but also various electronic components on the charge and discharge paths of the battery pack (such as bus bars, current sensors, relays, and fuses). In addition, the battery pack according to the present disclosure may include a separate BMS for controlling the charge and discharge operations of the battery pack as a whole.

[0115] The battery pack according to the present disclosure can be applied to vehicles such as electric vehicles or hybrid vehicles. That is, the vehicle according to the present disclosure can include the battery pack according to the present disclosure. In addition to the battery pack according to the present disclosure described above, the vehicle according to the present disclosure can include well-known components installed in the vehicle, for example, a drive device such as an electric motor, electronic components such as a radio or a navigation system, a vehicle body, and a control device other than an ECU (electronic control unit).

[0116] The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are given by way of illustration only, as various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art from this detailed description.

[0117] This application claims priority from Korean Patent Application No. 10-2020-0087035 filed in Korea on Jul. 14, 2020, the disclosure of which is incorporated herein by reference.

Claims

1. A battery pack, comprising: a battery cell having an electrode assembly, an electrolyte, a battery case, and electrode terminals; a strain measuring unit at least partially attached to an outer surface of the battery case of the battery cell and configured to measure whether the battery case is deformed; an impedance measuring unit connected to the electrode terminals of the battery cell and configured to measure impedance inside the battery cell; as well as A control unit is configured to determine whether the battery cell is swollen by using the deformation measurement result of the deformation measurement unit and the impedance measurement result of the impedance measurement unit together.

2. The battery pack according to claim 1, in, The control unit is configured to determine that the battery cell is not swollen when the impedance measured by the impedance measurement unit is less than a reference impedance even if the deformation amount measured by the strain measurement unit is equal to or greater than a reference deformation amount.

3. The battery pack according to claim 1, in, The control unit is configured to determine whether the impedance increases when the impedance measured by the impedance measurement unit is less than a reference impedance.

4. The battery pack according to claim 1, in, The control unit is configured to transmit an impedance measurement start signal to the impedance measurement unit when the deformation amount measured by the deformation measurement unit is equal to or greater than a reference deformation amount.

5. The battery pack according to claim 1, further comprising: a temperature measuring unit located around the battery cell and configured to measure the temperature of the battery cell, The control unit is configured to determine whether the battery cell is expanded by further considering a temperature measurement result of the temperature measurement unit.

6. The battery pack according to claim 5, in, The control unit is configured to determine that the battery cell is expanded only when the deformation amount measured by the deformation measurement unit is equal to or greater than a reference deformation amount, the impedance measured by the impedance measurement unit is equal to or greater than a reference impedance, and the temperature measured by the temperature measurement unit is equal to or greater than a reference temperature.

7. The battery pack according to claim 1, in, The battery cell is a pouch-type battery, and includes a receiving portion in which the electrode assembly and the electrolyte are received, and a sealing portion disposed around the receiving portion. The deformation measuring unit is at least partially attached to the receiving portion, and The impedance measuring unit is configured to be at least partially placed on the sealing portion.

8. The battery pack according to claim 7, in, The battery cell is configured such that the sealing portion is at least partially folded toward the accommodating portion, and The impedance measurement unit is configured to be at least partially interposed between the receiving portion and the folded sealing portion of the battery cell.

9. The battery pack according to claim 8, in, The strain measuring unit is elongated in one direction to be partially bent so that one end of the strain measuring unit is attached to a printed circuit board and the other end of the strain measuring unit is attached to the receiving portion of the battery cell.

10. The battery pack according to claim 8, in, The strain measuring unit includes a horizontal portion extending in a left-right direction and a vertical portion extending in a vertical direction, the vertical portion being at least partially attached to a printed circuit board, and the horizontal portion being at least partially attached to the receiving portion of the battery cell.

11. The battery pack according to claim 1, in, The impedance measurement unit is connected to both sides of the electrode terminals of the battery cell and is configured to measure a voltage across the battery cell.

12. A vehicle comprising the battery pack according to any one of claims 1 to 11.

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