Abnormal degraded cell detection device and method

Abstract

The present disclosure relates to an abnormally degraded cell detection apparatus and method for detecting abnormally degraded cells. The embodiment of the invention provides an abnormally-degraded cell detection method for detecting abnormally-degraded cells of a battery module comprising a plurality of cells, and the method comprises the steps: obtaining a first statistical value representing the capacity deviation of the plurality of cells at a first time point, obtaining a second statistical value representing the capacity deviation of the plurality of cells at a second time point, the first statistical value and the second statistical value are compared to detect an anomalous degraded cell.

Description

Technical Field

[0001] The present disclosure relates to an abnormally deteriorated cell detection device and method for detecting an abnormally deteriorated cell. Background Art

[0002] Secondary batteries are batteries that can be charged and discharged, unlike primary batteries that cannot be recharged. Low-capacity secondary batteries are used in portable small electronic devices such as smartphones, feature phones, laptops, digital cameras, and video cameras, and large-capacity secondary batteries are widely used as motor drive power or storage batteries such as hybrid vehicles and electric vehicles. Secondary batteries include an electrode assembly including a positive electrode and a negative electrode, a housing that accommodates the electrode assembly, and an electrode terminal connected to the electrode assembly.

[0003] In secondary batteries, cells where events such as internal foreign matter, internal short circuit or degradation occur may cause safety problems such as thermal runaway or combustion, and abnormal cells may cause fire in the secondary battery. Therefore, early detection of abnormal cells of secondary batteries is a very important issue.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0005] The present disclosure attempts to provide an abnormally degraded cell detection device and method for detecting an abnormally degraded cell at an early stage.

[0006] However, the technical problems to be solved by the present disclosure are not limited to the above contents, and those skilled in the art will understand other purposes not mentioned herein based on the following description.

[0007] An embodiment of the present disclosure provides an abnormally degraded cell detection method for detecting an abnormally degraded cell in a battery module including a plurality of cells, comprising: obtaining a first statistical value representing a capacity deviation of the plurality of cells at a first time point, obtaining a second statistical value representing a capacity deviation of the plurality of cells at a second time point, and comparing the first statistical value and the second statistical value to detect the abnormally degraded cell.

[0008] Obtaining the first statistical value may include obtaining the first statistical value using an initial capacity value of each of the plurality of cells, and the initial capacity value may correspond to a formation capacity of each of the cells.

[0009] Obtaining a first statistical value using an initial capacity value may include obtaining an average value and a standard deviation of initial capacity values ​​of a plurality of monomers, calculating a first sigma for each of the plurality of monomers using the initial capacity value, the average value, and the standard deviation, and obtaining the first sigma calculated for each of the plurality of monomers as a first statistical value.

[0010] Obtaining a first statistical value may include: detecting a first state of charge (SOC) change amount of each of a plurality of cells during a first time period, obtaining an average value and a standard deviation of the first SOC change amounts of the plurality of cells, calculating a second sigma for each of the plurality of cells using the first SOC change amount, the average value and the standard deviation, and determining the second sigma calculated for each of the plurality of cells as the first statistical value.

[0011] Detecting the first SOC change may include: detecting a first SOC value of each of a plurality of cells in a first idle period of the battery module, detecting a second SOC value of each of a plurality of cells in a second idle period after the first idle period of the battery module, and calculating the first SOC change according to a difference between the first SOC value and the second SOC value for each of the plurality of cells.

[0012] Detecting the first SOC value may include obtaining, for each of the plurality of cells, a first cell voltage value detected at a predetermined time elapsed from a start time point of the first idle period, and determining the first SOC value using the first cell voltage value of each of the plurality of cells.

[0013] Detecting the second SOC value may include obtaining, for each of the plurality of cells, a second cell voltage value detected at a predetermined time elapsed from a start time point of the second idle period, and determining the second SOC value using the second cell voltage value of each of the plurality of cells.

[0014] Obtaining the second statistical value may include: detecting a second SOC change amount of each of a plurality of cells during a second time period, obtaining an average value and a standard deviation of the second SOC change amounts of the plurality of cells, calculating a third sigma for each of the plurality of cells using the SOC change amount, the average value and the standard deviation, and determining the third sigma calculated for each of the plurality of cells as the second statistical value.

[0015] Detecting the second SOC change may include: detecting a third SOC value of each of the multiple cells in a third idle period of the battery module, detecting a fourth SOC value of each of the multiple cells in a fourth idle period after the third idle period of the battery module, and calculating the second SOC change according to a difference between the third SOC value and the fourth SOC value for each of the multiple cells.

[0016] Detecting the third SOC value may include obtaining, for each of the plurality of cells, a third cell voltage value detected at a predetermined time elapsed from a start time point of the third idle period, and determining the third SOC value using the third cell voltage value of each of the plurality of cells.

[0017] Detecting the fourth SOC value may include obtaining, for each of the plurality of cells, a fourth cell voltage value detected at a predetermined time elapsed from a start time point of the fourth idle period, and determining the fourth SOC value using the fourth cell voltage value of each of the plurality of cells.

[0018] Detecting the second SOC change may include: for each of the plurality of cells, in each charge / discharge cycle during the second period, detecting a fourth SOC change between an idle period after charging and an idle period after discharging, and determining the second SOC change based on an average value of the fourth SOC change detected during the second period. The second period may include at least one charge / discharge cycle.

[0019] Detecting the abnormally degraded cell may include comparing a difference between the first statistic and the second statistic with a threshold value, and determining a cell whose difference is greater than or equal to the threshold value as an abnormally degraded cell.

[0020] Detecting an abnormally degraded monomer may include calculating a difference between a first statistical value and a second statistical value of each of a plurality of monomers, detecting an outlier in the difference of each of the plurality of monomers using a Grubbs test method, and determining a monomer of the plurality of monomers whose difference is an outlier as an abnormally degraded monomer.

[0021] Other embodiments provide an abnormally degraded cell detection device for detecting an abnormally degraded cell of a battery module including a plurality of cells, including: a control device configured to obtain a first statistical value representing a capacity deviation of the plurality of cells at a first time point, obtain a second statistical value representing a capacity deviation of the plurality of cells at a second time point, and detect the abnormally degraded cell by comparing the first statistical value and the second statistical value with each other.

[0022] The abnormally degraded monomer detection device may further include: a storage device storing initial capacity values ​​of multiple monomers. The control device may further be configured to: calculate the first sigma of each of the multiple monomers using the initial capacity value of each of the multiple monomers and the average and standard deviation of the initial capacity values ​​of the multiple monomers, and may further be configured to use the first sigma calculated for each of the multiple monomers as the first statistical value. The initial capacity value may correspond to the formation capacity of each monomer.

[0023] The control device may also be configured to detect a first SOC change of the plurality of cells during a first period, and calculate an average value and a standard deviation of the first SOC change of the plurality of cells. The control device may also be configured to calculate a second sigma of each of the plurality of cells using the first SOC change, the average value and the standard deviation, and use the second sigma calculated for each of the plurality of cells as a first statistical value.

[0024] The control device may also be configured to: for each of the plurality of cells, use a first cell voltage value detected at a predetermined time from the start time point of the idle period after the first charge to determine a first SOC value in the idle period after the first charge. The control device may also be configured to: for each of the plurality of cells, use a second cell voltage value detected at a predetermined time from the start time point of the idle period after the first discharge to determine a second SOC value in the idle period after the first discharge. The control device may also be configured to: determine a first SOC change amount based on a difference between the first SOC value and the second SOC value.

[0025] The control device may also be configured to: detect the second SOC change amount of the plurality of cells during the second period, and calculate the average value and standard deviation of the second SOC change amount of the plurality of cells. The control device may also be configured to: use the second SOC change amount, the average value and the standard deviation to calculate the third sigma of each of the plurality of cells, and use the third sigma calculated for each of the plurality of cells as the second statistical value.

[0026] The control device may also be configured to: for each of the plurality of cells, use a third cell voltage value detected at a predetermined time from the start time point of the idle period after the second charge to determine a third SOC value in the idle period after the second charge. The control device may also be configured to: for each of the plurality of cells, use a fourth cell voltage value detected at a predetermined time from the start time point of the idle period after the second discharge to determine a fourth SOC value in the idle period after the second discharge. The control device may also be configured to: determine the second SOC change amount according to the difference between the third SOC value and the fourth SOC value.

[0027] The control device may also be configured to: for each of the plurality of cells, in each charge / discharge cycle during the second period, detect a fourth SOC change amount between an idle period after charging and an idle period after discharging, and determine the second SOC change amount based on an average value of the fourth SOC change amounts detected during the second period. The second period may include at least one charge / discharge cycle.

[0028] The control device may also be configured to compare a difference between the first statistical value and the second statistical value with a threshold value, and determine a cell whose difference is greater than or equal to the threshold value as an abnormally degraded cell.

[0029] According to the present disclosure, it is possible to prevent a safety problem from occurring due to an abnormal cell by detecting an abnormally deteriorated cell at an early stage.

[0030] However, the effects obtainable by the present disclosure are not limited to the above, and other effects not mentioned herein will be clearly understood by those skilled in the art from the following disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are used to provide a further understanding of the technical features of the present disclosure. Therefore, the present disclosure is not interpreted as being limited to the accompanying drawings.

[0032] Figure 1 An abnormally deteriorated cell detection device of a battery pack according to an embodiment is schematically shown.

[0033] Figure 2 An example of a graph representing the distribution of initial capacity sigma and current capacity sigma is shown.

[0034] Figure 3 Another example of a graph representing the distribution of initial capacity sigma and current capacity sigma is shown.

[0035] Figure 4 The abnormally deteriorated cell detection method according to the embodiment is schematically shown.

[0036] Figure 5 An example of an energy storage system including an abnormally degraded cell detection device according to an embodiment is shown. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Before description, it should be understood that the terms and words used in the specification and the appended claims should not be interpreted as having common and dictionary meanings, but should be interpreted as having meanings and concepts corresponding to the technical concept of the present disclosure in view of the principle that the inventor can appropriately define the concepts of terms and words in order to best describe his / her own invention as much as possible. Therefore, since the embodiments described in the specification and the configurations shown in the accompanying drawings are only the most preferred embodiments and configurations of the present invention, they do not represent all technical concepts of the present invention, and it should be understood that various equivalents and modified examples of the embodiments can be replaced when submitting this application. It will be further understood that when used in this specification, the terms "include" and / or "comprise" specify the presence of stated features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. "Can / can" is used when describing an embodiment of the present disclosure to include "one or more embodiments of the present disclosure".

[0038] In addition, to help understand the present disclosure, the drawings are not drawn to scale, and the sizes of some components may be exaggerated. In addition, in different embodiments, the same reference numerals may be assigned to the same elements.

[0039] When interpreting that two objects are "the same", this means that the objects are "substantially the same". Therefore, substantially the same objects may include deviations that are considered low in the art, for example, within 5%. In addition, when interpreting that certain parameters are uniform in a predetermined area, this may mean that the parameters are uniform in terms of average in the corresponding area.

[0040] Although the terms "first", "second", etc. are used to describe various elements, these elements are not limited by these terms. These terms are used to distinguish one element from another element, and unless otherwise specified, the first element may be the second element.

[0041] Throughout the specification, unless otherwise specified, each element may be in the singular or in the plural.

[0042] When an element is “on (or below)” or “over (or under)” another element, the element may be on the upper surface (or lower surface) of the other element, and intermediate elements may exist between the element and the other element above (or under) the element.

[0043] In addition, when an element is referred to as being "connected," "coupled," or "linked" to another element, the element may be directly connected or coupled to the other element, but it should be understood that there may be intermediate elements between each element, or each element may be "connected," "coupled," or "linked" to each other through another element. When an element is referred to as being coupled (e.g., electrically coupled or connected) to another element, the element may be directly coupled to the other element or indirectly coupled to the other element via one or more intermediate elements.

[0044] Throughout the specification, unless otherwise expressly stated, "A and / or B" means A or B or both A and B. In other words, the term "and / or" includes all or various combinations of multiple items that are related and arranged. Unless otherwise expressly stated, "C to D" means C or greater and D or less.

[0045] Hereinafter, an abnormally degraded cell detection device and method according to an embodiment will be described in detail with reference to necessary drawings.

[0046] Figure 1 An abnormally deteriorated cell detection device of a battery pack according to an embodiment is schematically shown.

[0047] refer to Figure 1 , the battery pack 10 may include a battery module 11 and a battery management system (BMS) 12, the battery module 11 includes a plurality of cells 111, and the battery management system 12 is used to manage the battery module 111. At least one charge / discharge cycle may be performed on the battery pack 10 every day. In this article, one charge / discharge cycle may include a charging period and a discharging period. In addition, one charge / discharge cycle may additionally include an idle period after the charging period and an idle period after the discharging period. For example, one charge / discharge cycle may be configured to sequentially include a charging period, an idle period, a discharging period, and an idle period. In addition, for example, one charge / discharge cycle may be configured to sequentially include a discharging period, an idle period, a charging period, and an idle period. During each idling period, both charging and discharging of the battery pack 10 may be stopped.

[0048] The BMS 12 may detect the cell voltage of each cell 111 in each idle period of the battery pack 10. That is, the BMS 12 may detect the cell voltage of each cell 111 in the idle period following the charging period, and may detect the cell voltage of each cell 111 in the idle period following the discharging period. In order to obtain voltage data close to the open circuit voltage (OCV) of each cell 111, the BMS 12 may obtain a cell voltage value measured after a predetermined time has passed from the start time point of the idle period (i.e., after the polarization voltage has been removed from the cell voltage of each cell 111) as the cell voltage value of the corresponding idle period. For example, the BMS 12 may obtain a cell voltage value measured at a time point of 20 minutes or more from the start time point of the idle period as the cell voltage value of the corresponding idle period.

[0049] The BMS 12 may use the cell voltage value detected in each idle period to obtain the state of charge (SOC) value of each cell 111. In this case, the BMS 12 may use various known methods to calculate the SOC value of each cell. For example, the BMS 12 may use OCV-SOC data corresponding to the SOC for each OCV map to obtain the SOC value of each cell 111.

[0050] The BMS 12 may transmit status data including at least one of a cell voltage value and an SOC value of each cell 111 to the abnormally degraded cell detection device 20 during each idle period. When transmitting the status data, the BMS 12 may transmit identification information of the corresponding battery module 11 and the corresponding cell 111 together so as to be able to identify which cell 111 of which battery module 11 the corresponding status data belongs to.

[0051] The abnormally degraded cell detection device 20 can detect an abnormally degraded cell by monitoring the capacity deviation between cells 111 included in the same battery module 11. In the following description, the "capacity" of the cell 111 may refer to the "usable capacity" of the cell 111. In addition, the "abnormally degraded cell" may refer to a cell that is abnormally degraded due to an abnormality such as an internal short circuit or defective electrode plate coating.

[0052] The abnormally degraded cell detection device 20 may include a communication device 21 , a storage device 22 , and a control device 23 .

[0053] The communication device 21 can perform a wired / wireless communication function between the abnormal degradation single cell detection device 20 and an external device of the abnormal degradation single cell detection device 20. For example, the communication device 21 can perform a wired / wireless communication function between the BMS 12 of the battery pack 10 and the abnormal degradation single cell detection device 20. In addition, for example, the communication device 21 can perform a wired / wireless communication function between the upper controller 30 and the abnormal degradation single cell detection device 20. The upper controller 30 is a controller capable of managing the operation of the abnormal degradation single cell detection device 20 outside the abnormal degradation single cell detection device 20, and may include a main controller of a system in which the battery pack 10 is installed, a management terminal, and the like.

[0054] The storage device 22 can store the state data (e.g., single cell voltage value, SOC value, etc.) of each single cell 111 received from the battery pack 10. The control device 23 can monitor the state data of each single cell 111 for a long time (e.g., dozens of days) to detect an abnormally degraded single cell. Therefore, when the state data of each single cell 111 is received, the control device 23 can map the state data to the corresponding battery module 11 and the corresponding single cell 111 in chronological order (i.e., by date) and store the state data in the storage device 22.

[0055] The storage device 22 can store OCV-SOC data in which the corresponding SOC is mapped for each OCV of the single cell 111. The OCV-SOC data can be obtained in advance using a reference single cell having the same characteristics as the single cell 111. For example, various methods such as experiments on the reference single cell, charge / discharge simulation, and deep learning can be used to obtain the OCV-SOC data. The storage device 22 can store the OCV-SOC data in the form of a table.

[0056] The storage device 22 can store the initial capacity value of each single cell 111 constituting the battery pack 10. The initial capacity value of each single cell 111 can be a value obtained in the manufacturing step of each single cell 111. For example, the initial capacity value of each single cell 111 can be a formation capacity value obtained in the formation process of each single cell.

[0057] The storage device 22 can store data (e.g., sigma) representing the statistical distribution (i.e., initial capacity deviation) of the initial capacity values of the plurality of single cells 111.

[0058] The following Equation 1 represents a method for calculating a statistical value (hereinafter referred to as "initial capacity sigma") representing the initial capacity deviation from the initial capacity value of each single cell 111.

[0059] [Equation 1]

[0060] Initial capacity sigma(i) = -(initial capacity value(i) - AVG(initial capacity value(1), initial capacity value(2), ..., initial capacity value(N))) / STDEV(initial capacity value(1), initial capacity value(2), ..., initial capacity value(N))

[0061] Equation 1 is used to calculate the initial capacity sigma(i) of the i-th cell 111 among the N cells 111 constituting the battery module 11. The initial capacity sigma(i) is a value indicating the degree to which the initial capacity value of the i-th cell 111 deviates from the average of the initial capacity values ​​of the N cells 111 constituting the battery module 11, and using this value, the statistical distribution of the initial capacity values ​​of the cells 111 can be confirmed. In the above equation 1, the initial capacity value of each cell 111 obtained in the manufacturing step can be used as the initial capacity value of each cell 111 as described above. In addition, AVG (initial capacity value (1), initial capacity value (2), ..., initial capacity value (N)) and STDEV (initial capacity value (1), initial capacity value (2), ..., initial capacity value (N)) respectively represent the average value and standard deviation of the initial capacity values ​​of all cells 111 constituting the battery module 11.

[0062] Table 1 below shows examples of initial capacity values ​​of each cell 111 and initial capacity sigma of each cell 111 derived therefrom.

[0063] (Table 1)

[0064]

[0065] Referring to Table 1, the smaller the initial capacity of the monomer, the larger the value of the initial capacity sigma may be. In Table 1 above, monomer #10 has the smallest initial capacity, and therefore, the initial capacity sigma of monomer #10 has a maximum value of 1.301. On the other hand, monomer #8 has the largest initial capacity, and therefore, the initial capacity sigma of monomer #8 has a minimum value of -2.394. The initial capacity sigma stored in the storage device 22 can be calculated by the control device 23 to be described later. The initial capacity sigma can be calculated by an external device (e.g., an upper controller 30) of the abnormally degraded monomer detection device 20 to be sent to the abnormally degraded monomer detection device 20.

[0066] The control device 23 can control the overall operation of the abnormally degraded cell detection device 20 .

[0067] The control device 23 may communicate with the BMS 12 or the upper controller 30 through the communication device 21. For example, the control device 23 may receive the status data of each cell 111 from the BMS 12 through the communication device 21. In addition, for example, the control device 23 may receive at least one of OCV-SOC data, the initial capacity value of each cell 111, and a statistical value (initial capacity sigma) indicating the initial capacity deviation between cells 111 from the upper controller 30 through the communication device 21.

[0068] The control device 23 may manage the data stored in the storage device 22. For example, the control device 23 may store and manage the state data of each cell 111 received from the BMS 12 in the storage device 22. In addition, for example, the control device 23 stores and manages OCV-SOC data, the initial capacity value of each cell 111, the initial capacity sigma of each cell 111, etc. in the storage device 22.

[0069] When receiving the initial capacity value of each cell 111 from the upper controller 30 , the control device 23 may calculate the initial capacity sigma of the cell 111 included in the battery module 11 using Equation 1 above.

[0070] When receiving the cell voltage value detected from each cell 111 in the idle period from the BMS 12, the control device 23 can calculate the SOC value of each cell 111 in the idle period using the received cell voltage value and the OCV-SOC data. For example, when receiving the cell voltage value detected from each cell 111 in the idle period after the charging period (hereinafter referred to as the "cell voltage value after charging") from the BMS 12, the control device 23 can obtain the SOC value corresponding to the cell voltage value after charging (hereinafter referred to as the "SOC value after charging") by using the OCV-SOC data. In addition, for example, when receiving the cell voltage value detected from each cell 111 in the idle period after the discharging period (hereinafter referred to as the "cell voltage value after discharging") from the BMS 12, the control device 23 can obtain the SOC value corresponding to the cell voltage value after discharging (hereinafter referred to as the "SOC value after discharging") by using the OCV-SOC data. The control device 23 can use the after-charge SOC value and the after-discharge SOC value calculated in this way to obtain the SOC change amount in the corresponding charge / discharge cycle (after-charge SOC value−after-discharge SOC value).

[0071] Table 2 below shows examples of the post-charge SOC values and post-discharge SOC values of each cell 111 derived from the OCV-SOC table. Table 2 also shows examples of the SOC change amounts of each cell 111 derived from the post-charge SOC values and post-discharge SOC values of each cell 111.

[0072] (Table 2)

[0073]

[0074] The control device 23 can receive the detected SOC values (post-charge SOC values and post-discharge SOC values) of each cell 111 from the BMS 12 during an idle period, and can use the received SOC values to obtain the SOC change amount (post-charge SOC value - post-discharge SOC value) in the corresponding charge / discharge cycle. The control device 23 can continuously and statistically analyze the capacity deviation of each cell 111, and detect an abnormally deteriorated cell based on the analysis result.

[0075] The capacity of the cell 111 can decrease as the deterioration progresses. For all the cells 111 constituting the same battery module 11, charging and discharging are performed under the same conditions. Therefore, the cells 111 included in the same battery module 11 should theoretically have similar degrees of deterioration and similar capacity reduction patterns. However, the deterioration of a cell 111 in which an abnormality such as an internal short circuit occurs progresses faster than that of other cells, and as a result, the rate of capacity decrease over time may increase compared to other cells. In other words, the capacity deviation between the abnormally deteriorated cell and other cells may increase over time. Therefore, by monitoring the change in the capacity deviation of the cell 111 over time, it is possible to detect a cell with a higher degree of deterioration than other cells, and thus detect a cell in which an abnormality has occurred.

[0076] The SOC change amount of the cells 111 that are charged and discharged under the same conditions depends on the capacity of each cell 111, and the smaller the capacity of the cell 111, the larger the SOC change amount per unit time. That is, a cell 111 whose capacity has decreased significantly compared to other cells due to abnormally accelerated deterioration may have a larger SOC change amount per unit time than other cells. Therefore, the SOC change amount deviation of the cells 111 can exhibit a statistical distribution similar to the capacity deviation of the cells 111.

[0077] Therefore, even if the control device 23 does not know the current capacity value of each cell 111, it can use the SOC change amount of the cell 111 to calculate a statistical value indicating the current capacity deviation of the cell 111. The following equation 2 represents a method of calculating a statistical value indicating the current capacity deviation of the cell 111 (hereinafter referred to as "current capacity sigma") based on the SOC change amount of each cell 111.

[0078] [Equation 2]

[0079] Current capacity (i) = (△SOC (i) - AVG (△SOC (1), △SOC (2), ..., △SOC (N))) / STDEV (△SOC (1), △SOC (2), ..., △SOC (N))

[0080] The above equation 2 is used to calculate the current capacity sigma(i) of the i-th cell 111 among the N cells 111 constituting the battery module 11. Referring to the above equation 2, the control device 23 can calculate the current capacity sigma(i) of the i-th cell 111 by calculating the degree to which the SOC change (SOC(i)) of the i-th cell 111 deviates from the average SOC change of the cells 111 constituting the battery module 11. The calculated current capacity sigma(i) can also be used as a value indicating the degree to which the current capacity value of the i-th cell 111 deviates from the average capacity value of the battery module 11. However, considering that the SOC change increases as the capacity becomes smaller, unlike the above equation 1, the minus sign ("-") of the numerator can be deleted in equation 2.

[0081] In Equation 2, as described above, the SOC change amount (ΔSOC) of each cell 111 can be obtained according to the difference between the SOC value after charge and the SOC value after discharge of each cell 111. In addition, AVG (ΔSOC (1), ΔSOC (2), ..., ΔSOC (N)) and STDEV (ΔSOC (1), ΔSOC (2), ..., ΔSOC (N)) respectively represent the average value and standard deviation of the SOC change amounts (ΔSOC) of all cells 111 constituting the battery module 11.

[0082] Table 3 below shows an example of the current capacity sigma of each cell 111 derived from the SOC change amount of each cell 111 .

[0083] (Table 3)

[0084]

[0085] Referring to Table 3, the greater the SOC change in the cell, the greater the current capacity sigma may be. In Table 3 above, the SOC change of cell #8 is the largest, and therefore, the current capacity sigma of cell #8 has a maximum value of 2.957. It may be difficult to directly compare the SOC change deviation of cell 111 with the capacity deviation of cell 111. However, when the SOC change deviation of cell 111 is converted to the current capacity sigma using Equation 2 above, a direct comparison with the initial capacity sigma becomes possible, as shown in Table 3 below.

[0086] Table 4 below shows an example of the initial capacity sigma and the current capacity sigma of each cell 111. In addition, Figure 2 A graph showing the distribution of the initial capacity sigma and the current capacity sigma of Table 4 is shown.

[0087] (Table 4)

[0088]

[0089] refer to Figure 2 and Table 4, the value of the capacity sigma difference (current capacity sigma-initial capacity sigma) can increase as the initial capacity becomes larger. Therefore, it can be seen that a monomer having an increased current capacity sigma compared to the initial capacity sigma has a higher degradation rate (deterioration rate) compared to other monomers. On the other hand, it can be seen that a monomer having a reduced current capacity sigma compared to the initial capacity sigma has a lower degradation rate compared to other monomers. Accordingly, in the above Table 4, monomer #10 has the smallest initial capacity, but the degradation rate is relatively lower than the degradation rates of other monomers. On the other hand, monomer #8 has the largest initial capacity, but the degradation rate is relatively higher than the degradation rates of other monomers. In particular, it can be seen that monomer #8 has an abnormally increased capacity sigma compared to other monomers. The following Table 5 shows another example of the initial capacity sigma and the current capacity sigma of each monomer 111. In addition, Figure 3 A graph showing the distribution of the initial capacity sigma and the current capacity sigma of Table 5 is shown.

[0090] (Table 5)

[0091]

[0092] Referring to equation 1, the smaller the initial capacity of the cell, the larger the value of the initial capacity sigma of the cell may be. Referring to equation 2, the larger the SOC change of the cell, the larger the current capacity sigma may be. In addition, the smaller the capacity of the cell, the larger the SOC change of the cell may be in the same period of time. Therefore, in Figure 3 In Table 5, cell #8 is the cell with the smallest initial capacity and current capacity. Figure 3 Among the monomers in, monomer #8 is in the most degraded state in both its initial state and current state.

[0093] All cells in Table 5 are charged and discharged under the same conditions. Therefore, a cell with a much smaller initial capacity than other cells, such as cell #8, can maintain a smaller capacity than other cells even over time. Figure 3 and Table 5, cell #2 has an initial capacity and a current capacity greater than that of cell #8, but is the cell with the highest capacity sigma difference (current capacity sigma-initial capacity sigma). In other words, cell #2 is the cell with the fastest degradation rate among the cells, that is, the most degraded cell. Referring to the above, the control device 23 can detect the cell 111 with the lowest capacity in the current battery module 11, that is, the most degraded cell 111, based on the current capacity sigma. That is, the control device 23 can determine the cell 111 with the largest current capacity sigma in the battery module 11 as the most degraded cell.

[0094] The control device 23 can detect the cell 111 with the fastest degradation rate in the battery module 11 based on the change in capacity sigma (current capacity sigma-initial capacity sigma). The control device 23 can determine the cell 111 with the largest increase in capacity sigma in the battery module 11 as the cell with the fastest degradation rate, that is, the cell with the largest degradation compared to the initial state.

[0095] The control device 23 can determine the abnormally degraded monomer based on the change in the capacity sigma of each monomer 111 (current capacity sigma-initial capacity sigma). For example, the control device 23 can determine the monomer 111 whose change in capacity sigma is greater than or equal to the threshold as an abnormally degraded monomer. Here, the threshold value can be a fixed value, or it can vary depending on the change in the capacity sigma of the monomer 111. In the latter case, for example, the control device 23 can determine the threshold value based on the average value, minimum value, median value, etc. of the change in the capacity sigma of the monomer 111 included in the battery module 11.

[0096] The control device 23 may determine an abnormally degraded cell using a Grubbs test method for detecting outliers in a data set. The control device 23 may use the Grubbs test method to determine an outlier in a change in capacity sigma (current capacity sigma-initial capacity sigma) of a cell 111 included in the battery module 11. When an outlier is determined, the control device 23 may determine the corresponding cell 111 as an abnormally degraded cell.

[0097] When the most degraded cell 111 in the battery module 11 is determined, the control device 23 may send information about it (e.g., cell identification information, current capacity sigma, etc.) to the upper controller 30. When the cell 111 with the fastest degradation rate in the battery module 11 is determined, the control device 23 may send information about it (e.g., cell identification information, capacity sigma change, etc.) to the upper controller 30. When the abnormally degraded cell 111 in the battery module 11 is determined, the control device 23 may send information about it (e.g., cell identification information, etc.) to the upper controller 30.

[0098] The SOC value determined using the OCV-SOC data and the SOC change calculated using the same may include error components due to voltage measurement errors, environmental factors, and the like. The error component may vary depending on the state of the battery pack 10 at the time of cell voltage measurement. The control device 23 may flatten the error component to improve the accuracy of the SOC change and the current capacity sigma. That is, the control device 23 may calculate the average value of the SOC change of each cell 111 over a few days or when performing multiple charge / discharge cycles, and use the average value to calculate the current capacity sigma of each cell 111. In this case, in the above equation 2, the SOC change (ΔSOC) of each cell 111 may be the average value of the SOC change of each cell 111 detected for a few days or for multiple charge / discharge cycles.

[0099] The control device 23 can perform filtering on the SOC change amount to improve the accuracy of the SOC change amount and the accuracy of the current capacity sigma. For example, for a charge / discharge cycle in which the SOC change amounts of all the cells 111 are greater than or equal to a threshold value, the control device 23 can use the SOC change amount to detect the current capacity sigma of each cell 111. On the other hand, for a charge / discharge cycle in which the SOC change amount of at least one cell 111 is less than the threshold value, the control device 23 may not calculate the current capacity sigma. In addition, for example, for a charge / discharge cycle in which the average value of the SOC change amounts of the cells 111 is greater than or equal to the threshold value, the control device 23 can use the SOC change amount to detect the current capacity sigma of each cell 111. On the other hand, for a charge / discharge cycle in which the average value of the SOC change amounts of the cells 111 is less than the threshold value, the control device 23 may not calculate the current capacity sigma.

[0100] When the initial capacity values of the individual cells 111 are unknown, the control device 23 can use Equation 2 above to determine the initial capacity sigma of each cell 111 during the initial use of the battery pack 10. That is, when the initial capacity values of the individual cells 111 are unknown, the control device 23 can use the SOC change amount of each cell 111 in the same way as the method for determining the current capacity sigma to determine the initial capacity sigma.

[0101] On the other hand, although Figure 1 shows a case where the abnormal degradation cell detection device 20 exists separately outside the battery pack 10, the abnormal degradation cell detection device 20 can be integrated into the battery pack 10. In this case, the above functions of the degradation cell detection device 20 can be performed by the BMS 12.

[0102] Hereinafter, Figure 4 will be described in detail the abnormal degradation cell detection method of the abnormal degradation cell detection device 20 according to the embodiment. The Figure 4 abnormal degradation cell detection method to be described later can be performed by the control device 23 of the abnormal degradation cell detection device 20 described with reference to Figure 1 description.

[0103] Figure 4 Schematically shows the abnormal degradation cell detection method according to the embodiment.

[0104] Referring to Figure 4, the abnormally degraded cell detection device 20 according to the embodiment can determine the initial capacity sigma of each cell 111 included in the battery module 11 when the battery pack 10 is initially used (S10). In step S10, the abnormally degraded cell detection device 20 can calculate the initial capacity sigma of each cell 111 using the initial capacity value of each cell 111 and the above equation 1. The calculated initial capacity sigma can be used as a statistical value representing the initial capacity deviation between the cells 111 included in the battery module 11.

[0105] Thereafter, the abnormally degraded cell detection device 20 may obtain a cell voltage value in an idle period of each cell 111 included in the battery module 11 (S11). The battery pack 10 may measure a cell voltage value of each cell 111 included in the battery module 11 in an idle period after charging and an idle period after discharging of each charge / discharge cycle. Then, the battery pack 10 may transmit state data of each cell 111 including the cell voltage value measured in each idle period to the abnormally degraded cell detection device 20.

[0106] The abnormally degraded cell detection device 20 can determine each SOC value of each cell 111 included in the battery module 11 in the idle period by using the cell voltage value obtained through step S11 (S12). In step S12, the abnormally degraded cell detection device 20 can determine the SOC value of each cell 111 using the cell voltage value of each cell 111 detected in each idle period and preset OCV-SOC data.

[0107] The abnormally degraded cell detection device 20 can determine the SOC change amount (S13) of each cell 111 included in the battery module 11 by using the SOC value determined by step S12. In step S13, the SOC change amount represents the amount by which the SOC of each cell 111 changes by charging and discharging during the corresponding charge / discharge cycle. The abnormally degraded cell detection device 20 can compare the SOC values ​​in two idle periods (idle period after charging and idle period after discharging) belonging to the same charge and discharge cycle to determine the SOC change amount of each cell 111. For example, the abnormally degraded cell detection device 20 can determine the SOC change amount of each cell 111 by subtracting the SOC value in the idle period after discharging from the SOC value in the idle period after charging.

[0108] The abnormally degraded cell detection device 20 can determine the current capacity sigma of each cell 111 included in the battery module 11 by using the SOC change amount of each cell 111 determined by step S13 (S14). In step S14, the abnormally degraded cell detection device 20 can determine the current capacity sigma of each cell 111 using the SOC change amount of each cell 111 and the above equation 2.

[0109] When the current capacity sigma of each cell 111 is determined, the abnormally degraded cell detection device 20 may compare it with the initial capacity sigma to determine the change amount of the capacity sigma of each cell 111 included in the battery module 11 (S15). In step S15, the abnormally degraded cell detection device 20 may determine the difference between the current capacity sigma and the initial capacity sigma (current capacity sigma-initial capacity sigma) as the change amount of the capacity sigma.

[0110] The abnormally degraded cell detecting device 20 may detect an abnormally degraded cell in the battery module 11 based on the amount of change in the capacity sigma of each cell 111 determined through step S15 ( S16 ).

[0111] In step S16, the abnormally degraded cell detection device 20 may compare the change amount of the capacity sigma of each cell 111 with a threshold value. The abnormally degraded cell detection device 20 may determine the cell 111 whose change amount of the capacity sigma is greater than or equal to the threshold value as an abnormally degraded cell.

[0112] In step S16, the abnormally degraded cell detection device 20 may use the Grubbs test method to detect an outlier in the amount of change in the capacity sigma of the cell 111. When an outlier is detected, the abnormally degraded cell detection device 20 may determine the corresponding cell 111 as an abnormally degraded cell.

[0113] When it is determined through step S16 that an abnormally degraded cell exists in the battery module 11 ( S17 ), the abnormally degraded cell detection device 20 may transmit information on the abnormally degraded cell to the host controller 30 ( S18 ).

[0114] The abnormally degraded cell detection device 20 may continuously perform steps S11 to S18 to continuously monitor the degradation deviation of the cell 111 and detect an abnormally degraded cell while the battery pack 10 is in use.

[0115] In the above description, in step S10, the abnormally degraded cell detection device 20 determines the initial capacity sigma using the initial capacity value of each cell 111. However, if the abnormally degraded cell detection device 20 does not know the initial capacity value of each cell 111, the initial capacity sigma of each cell 111 may be determined by performing the same steps as steps S11 to S14 during the initial use of the battery pack 10.

[0116] The abnormally degraded cell detection device 20 can be used to detect abnormally degraded cells in an energy storage system (ESS).

[0117] Figure 5 An example of an energy storage system including an abnormally degraded cell detection device according to an embodiment is shown. Figure 5 The abnormal degradation unit detection device 20 in the ESS corresponds to the reference Figures 1 to 4 The abnormally deteriorated cell detecting device 20 is described.

[0118] refer to Figure 5 ESS may include a battery bank 1 , a system BMS 2 , an energy management system (EMS) 3 , and a power conversion system (PCS) 4 .

[0119] The battery body 1 may include a plurality of cells (not shown) connected in series or in parallel with each other. For example, the battery body 1 may include a plurality of battery racks (or battery systems) electrically connected in series or in parallel with each other. In addition, each battery rack may include a plurality of battery modules 11 electrically connected in series or in parallel with each other. In addition, each battery module 11 may include a plurality of cells (not shown) electrically connected in series or in parallel with each other.

[0120] The battery body 1 can be charged using electric energy supplied from an electric power system (not shown) through the PCS 4. In addition, the PCS 4 can supply the electric energy stored in the battery body 1 to the electric power system through the PCS 4.

[0121] The PCS 4 can operate as a power conversion device that converts electrical characteristics (DC, AC, voltage, frequency, etc.) to transmit electric energy between the battery body 1 and the power system. Generally, electric energy in the form of DC is used in the battery body 1, and electric energy in the form of AC is used in the power system. Therefore, the PCS 4 can transmit the electric energy stored in the battery body 1 to the power system through DC-AC conversion, or can transmit the electric energy supplied from the power system to the battery body 1 through AC-DC conversion.

[0122] In addition to the above power conversion and distribution functions, the PCS 4 can also perform functions for controlling power quality, such as the active power and reactive power of the ESS. The PCS 4 can perform monitoring / control functions for monitoring the voltage and operating status of the ESS. The PCS 4 can also perform grid-connected protection functions for protecting the power system during a power outage. The PCS 4 can perform independent operation functions for driving the ESS using the battery body 1 even in the absence of power, etc.

[0123] The battery body 1 can be managed by the system BMS2. The system BMS2 can monitor the status of the battery body 1 to control the operation of the battery body 1 in an optimal state. For this purpose, the system BMS2 can perform status (cell voltage, current, temperature, SOC, state of health (SOH)) monitoring functions, control functions (e.g., temperature control, cell balancing control), and protection functions (e.g., over-discharge, over-charge, over-current prevention) on the battery cells that make up the battery body 1.

[0124] The system BMS2 can collect status data (cell voltage values, SOC values, current values, temperature values, etc.) from the battery body 1 to monitor the status of the battery body 1. The battery racks that make up the battery body 1 can collect status data from the battery modules 11 included therein and send the status data to the system BMS2. The battery racks that make up the battery body 1 can communicate with other battery racks or the system BMS2 through Controller Area Network (CAN) communication and can send and receive data in a daisy-chain method.

[0125] The EMS 3 is an integrated control device that monitors and controls the power usage of the power system and the power supply of the ESS in real time for the efficient energy operation of the ESS. The EMS 3 can monitor the status of the entire system (battery body 1, system BMS2, and PCS 4) that makes up the ESS and control the operation of the ESS.

[0126] The ESS can be operated to perform at least one charge / discharge cycle per day. One charge / discharge cycle can include a charging period, an idle period after charging, a discharging period, and an idle period after discharging.

[0127] The system BMS2 can collect status data (cell voltage values, SOC values, etc.) of each battery module 11 that makes up the battery body 1 during each idle period. The system BMS2 can send the collected status data to the abnormal degradation cell detection device 20.

[0128] The abnormal degradation cell detection device 20 that receives the status data can classify the status data of each battery module 11 and use the classified status data to perform a process for detecting abnormal degradation cells on each battery module 11. It has been referred to Figures 1 to 4The method of detecting the abnormally degraded cell of each battery module 11 by the abnormally degraded cell detecting device 20 is described in detail, and thus a redundant description thereof will be omitted.

[0129] On the other hand, despite Figure 5 The case where the abnormally degraded cell detection device 20 exists separately from the system BMS2 is shown, but the abnormally degraded cell detection device 20 may be integrated into the system BMS2. In this case, the above-mentioned function of the abnormally degraded cell detection device 20 may be performed by the system BMS2.

[0130] As described above, the abnormally degraded cell detection device 20 according to the embodiment can detect an abnormally degraded cell at an early stage. Therefore, safety problems such as combustion due to the abnormally degraded cell can be prevented.

[0131] While the invention has been described in connection with what are presently considered to be practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0132] <Description of Symbols>

[0133] 1: Battery Pack

[0134] 2: System BMS

[0135] 3: EMS

[0136] 4: PCS

[0137] 10: Battery Pack

[0138] 11: Battery module

[0139] 111: Monomer

[0140] 12: BMS

[0141] 20: Abnormal degradation unit detection device

[0142] 21: Communication device

[0143] 22: Storage device

[0144] 23: Control device

[0145] 30: Upper controller.

Claims

1. A method for detecting an abnormally deteriorated cell of a battery module including a plurality of cells, comprising: obtaining a first statistical value representing the capacity deviation of the plurality of monomers at a first time point, obtaining a second statistical value representing the capacity deviation of the plurality of monomers at a second time point, The first statistical value and the second statistical value are compared to detect abnormally degraded cells.

2. The abnormally degraded monomer detection method according to claim 1, wherein: Obtaining the first statistical value includes obtaining the first statistical value using an initial capacity value of each of the plurality of monomers, and The initial capacity value corresponds to the formation capacity of each monomer.

3. The abnormally degraded monomer detection method according to claim 2, wherein: Using the initial capacity value to obtain the first statistical value includes: Obtaining an average value and a standard deviation of the initial capacity values ​​of the plurality of monomers, For each of the plurality of monomers, calculating a first sigma using the initial capacity value, the average value, and the standard deviation, and The first sigma calculated for each of the plurality of monomers is obtained as the first statistical value.

4. The abnormally degraded monomer detection method according to claim 1, wherein: Obtaining the first statistical value includes: detecting a first state of charge (SOC) change amount of each of the plurality of cells during a first period, obtaining an average value and a standard deviation of the first SOC changes of the plurality of cells, for each of the plurality of cells, calculating a second sigma using the first SOC change amount, the average value, and the standard deviation, and The second sigma calculated for each of the plurality of monomers is determined as the first statistical value.

5. The abnormally degraded monomer detection method according to claim 4, wherein: Detecting the first SOC change includes: detecting a first SOC value of each of the plurality of cells in a first idle period of the battery module, detecting a second SOC value of each of the plurality of cells in a second idle period of the battery module after the first idle period, and The first SOC change amount is calculated according to a difference between the first SOC value and the second SOC value for each of the plurality of cells.

6. The abnormally degraded monomer detection method according to claim 5, wherein: Detecting the first SOC value includes: obtaining, for each of the plurality of cells, a first cell voltage value detected at a predetermined time elapsed from a start time point of the first idle period, and determining the first SOC value using the first cell voltage value of each cell of the plurality of cells, and Detecting the second SOC value includes: obtaining, for each of the plurality of cells, a second cell voltage value detected at a predetermined time elapsed from a start time point of the second idle period, and The second SOC value is determined using the second cell voltage value of each cell of the plurality of cells.

7. The abnormally degraded monomer detection method according to claim 1, wherein: Obtaining the second statistical value includes: detecting a second SOC change amount of each of the plurality of cells during a second period, obtaining an average value and a standard deviation of the second SOC changes of the plurality of cells, for each of the plurality of cells, calculating a third sigma using the SOC change amount, the average value, and the standard deviation, and The third sigma calculated for each of the plurality of monomers is determined as the second statistical value.

8. The abnormally deteriorated monomer detection method according to claim 7, wherein: Detecting the second SOC change includes: detecting a third SOC value of each of the plurality of cells in a third idle period of the battery module, detecting a fourth SOC value of each of the plurality of cells in a fourth idle period after the third idle period of the battery module, and The second SOC change amount is calculated according to a difference between the third SOC value and the fourth SOC value for each of the plurality of cells.

9. The abnormally deteriorated monomer detection method according to claim 8, wherein: Detecting the third SOC value includes: obtaining, for each of the plurality of cells, a third cell voltage value detected at a predetermined time elapsed from a start time point of the third idle period, and determining the third SOC value using the third cell voltage value of each cell of the plurality of cells, and Detecting the fourth SOC value includes: obtaining, for each of the plurality of cells, a fourth cell voltage value detected at a predetermined time elapsed from a start time point of the fourth idle period, and The fourth SOC value is determined using the fourth cell voltage value of each cell of the plurality of cells.

10. The abnormally degraded monomer detection method according to claim 7, wherein: Detecting the second SOC change includes: detecting, for each of the plurality of cells, a fourth SOC change amount between an idle period after charging and an idle period after discharging in each charge / discharge cycle during the second period, determining the second SOC change amount according to an average value of the fourth SOC change amount detected during the second period, and The second period includes at least one charge / discharge cycle.

11. The abnormally degraded monomer detection method according to claim 1, wherein: Detecting the abnormally degraded monomer includes: comparing a difference between the first statistical value and the second statistical value with a threshold, and A cell whose difference is greater than or equal to the threshold value is determined as an abnormally deteriorated cell.

12. The abnormally degraded monomer detection method according to claim 1, wherein: Detecting the abnormally degraded monomer includes: calculating a difference between the first statistical value and the second statistical value of each monomer in the plurality of monomers, using a Grubbs test method to detect outliers in the difference for each monomer in the plurality of monomers, and A cell whose difference value is an outlier among the plurality of cells is determined as an abnormally deteriorated cell.

13. An abnormally deteriorated cell detection device for detecting an abnormally deteriorated cell of a battery module including a plurality of cells, comprising: The control device is configured to obtain a first statistic representing a capacity deviation of the plurality of cells at a first time point, obtain a second statistic representing a capacity deviation of the plurality of cells at a second time point, and detect an abnormally deteriorated cell by comparing the first statistic and the second statistic with each other.

14. The abnormally degraded cell detection device according to claim 13, further comprising a storage device for storing the initial capacity values ​​of the plurality of monomers, in, The control device is also configured to: calculating a first sigma for each of the plurality of monomers using the initial capacity value for each of the plurality of monomers and an average and a standard deviation of the initial capacity values ​​for the plurality of monomers; as well as using the first sigma calculated for each of the plurality of monomers as the first statistical value, and The initial capacity value corresponds to the formation capacity of each monomer.

15. The abnormally degraded cell detection device according to claim 13, wherein: The control device is also configured to: detecting a first SOC change amount of the plurality of cells during a first period; calculating an average value and a standard deviation of the first SOC changes of the plurality of cells; calculating a second sigma for each of the plurality of cells using the first SOC change, the average value, and the standard deviation; as well as The second sigma calculated for each of the plurality of monomers is used as the first statistical value.

16. The abnormally degraded cell detection device according to claim 15, wherein: The control device is also configured to: determining, for each of the plurality of cells, a first cell voltage value detected at a predetermined time elapsed from a start time point of the idle period after the first charge, a first SOC value in the idle period after the first charge; determining, for each of the plurality of cells, a second SOC value in the idle period after the first discharge using a second cell voltage value detected at a predetermined time elapsed from a start time point of the idle period after the first discharge; as well as The first SOC change amount is determined according to a difference between the first SOC value and the second SOC value.

17. The abnormally degraded cell detection device according to claim 13, wherein: The control device is also configured to: detecting a second SOC change amount of the plurality of cells during a second period; Calculating an average value and a standard deviation of the second SOC changes of the plurality of cells; calculating a third sigma of each of the plurality of cells using the second SOC change, the average value, and the standard deviation; as well as The third sigma calculated for each of the plurality of monomers is used as the second statistical value.

18. The abnormally degraded cell detection device according to claim 17, wherein: The control device is also configured to: determining, for each of the plurality of cells, a third cell voltage value detected at a predetermined time elapsed from a start time point of the idle period after the second charge, a third SOC value in the idle period after the second charge; determining, for each of the plurality of cells, a fourth cell voltage value detected at a predetermined time elapsed from a start time point of the idle period after the second discharge, a fourth SOC value in the idle period after the second discharge; as well as The second SOC change amount is determined according to a difference between the third SOC value and the fourth SOC value.

19. The abnormally degraded cell detection device according to claim 17, wherein: The control device is also configured to: detecting, for each of the plurality of cells, a fourth SOC change amount between an idle period after charging and an idle period after discharging in each charge / discharge cycle during the second period; as well as determining the second SOC change amount according to an average value of the fourth SOC change amount detected during the second period, and The second period includes at least one charge / discharge cycle.

20. The abnormally degraded cell detection device according to claim 13, wherein: The control device is also configured to: comparing a difference between the first statistical value and the second statistical value with a threshold; as well as A cell whose difference is greater than or equal to the threshold value is determined as an abnormally deteriorated cell.

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