Lithium precipitation detection device and method

Abstract

A lithium precipitation detection device according to an embodiment of the disclosure includes a measurement unit configured to calculate a charge amount of a battery during a charging process and to calculate a discharge amount of the battery during a discharging process, and a control unit configured to estimate an SOC of the battery during the charging process and the discharging process, and to determine whether lithium precipitation occurs in the battery based on the estimated SOC, the charge amount, and the discharge amount.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2021-0055289, filed in Korea on April 28, 2021, the disclosure of which is incorporated herein by reference.

[0002] This disclosure relates to a lithium precipitation detection device and method, and more specifically, to a lithium precipitation detection device and method for detecting whether lithium metal has been deposited on a battery cell. Background Technology

[0003] Recently, demand for portable electronic products such as laptops, video cameras, and mobile phones has increased dramatically, and serious development has been undertaken in areas such as electric vehicles, energy storage batteries, robots, and satellites. Therefore, high-performance batteries that allow for repeated charging and discharging are being actively researched.

[0004] Currently available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries have attracted much attention because they have almost no memory effect compared to nickel-based batteries and also have a very low self-discharge rate and high energy density.

[0005] While much research is being conducted on these batteries in terms of high capacity and high density, improvements in lifespan and safety are also important. Therefore, it is necessary to suppress decomposition reactions with the electrolyte on the electrode surface and to prevent overcharging and over-discharging.

[0006] In particular, it is necessary to prevent lithium from being deposited (deposition, Li- deposition) on the surface of the negative electrode. When lithium is deposited on the surface of the negative electrode, it causes side reactions with the electrolyte and alters the kinetic energy balance of the battery, leading to battery degradation. Furthermore, because lithium metal deposits on the negative electrode surface can cause internal short circuits in the battery, there is a risk of fire and explosion due to these internal short circuits. Therefore, it is necessary to develop a technology capable of detecting whether lithium metal has been deposited on the surface of the negative electrode. Summary of the Invention

[0007] Technical issues

[0008] This disclosure is designed to address problems in the related field, and therefore relates to providing a precipitation detection apparatus and method capable of nondestructively detecting whether lithium metal has been deposited based on the charge and discharge levels of a single battery cell.

[0009] These and other objectives and advantages of this disclosure will become apparent from the following detailed description and will become even more fully apparent from exemplary embodiments of this disclosure. Furthermore, it will be readily understood that the objectives and advantages of this disclosure can be achieved by the means shown in the appended claims and combinations thereof.

[0010] Technical solution

[0011] A lithium deposition detection device according to one aspect of this disclosure may include: a measurement unit configured to calculate the charge amount of a battery cell during charging and the discharge amount of a battery cell during discharging; and a control unit configured to estimate the state of charge (SOC) of the battery cell during charging and discharging, and to determine whether lithium deposition has occurred in the battery cell based on the estimated SOC, charge amount, and discharge amount.

[0012] The control unit can be configured to compare the magnitude of the charge and discharge, and determine whether lithium deposition has occurred in the battery cell based on the comparison result.

[0013] The control unit can be configured to determine that lithium deposition has occurred when the discharge exceeds the charge.

[0014] The control unit can be configured to determine whether lithium deposition has occurred by comparing the discharge amount and the charge amount when the SOC at the start of charging is the same as the SOC at the end of discharging and the SOC at the end of charging is the same as the SOC at the start of discharging.

[0015] The control unit can be configured to: correct the discharge amount and charge amount when the SOC at the start of charging is different from the SOC at the end of discharging or when the SOC at the end of charging is different from the SOC at the start of discharging, and determine whether lithium deposition has occurred based on the comparison result of the corrected discharge amount and the corrected charge amount.

[0016] The control unit can be configured to calculate the SOC deviation between the SOC at the start of charging and the SOC at the end of charging, and to correct the charging amount based on the calculated SOC deviation.

[0017] The control unit can be configured to calculate the discharge SOC deviation between the SOC at the start time of discharge and the SOC at the end time of discharge, and to correct the discharge amount based on the calculated discharge SOC deviation.

[0018] The control unit can be configured to send the charging C-rate and discharging C-rate of the battery cells to a charging and discharging device capable of charging and discharging the battery cells.

[0019] The control unit can be configured to reduce the charging C-rate and discharging C-rate when the discharge amount is equal to or less than the charging amount and the difference between the discharge amount and the charging amount is equal to or less than a preset standard value, and to send the reduced charging C-rate and reduced discharging C-rate to the charging and discharging equipment.

[0020] The control unit can be configured to determine again whether lithium deposition has occurred based on the amount of charge of a battery cell during charging at a reduced charging C-rate and the amount of discharge of a battery cell during discharging at a reduced discharging C-rate.

[0021] The control unit can be configured to set the charging C-rate and discharging C-rate to be the same.

[0022] The measurement unit can be configured to calculate the amount of charge by integrating the charging current from the start time of charging to the end time of charging.

[0023] The measurement unit can be configured to calculate the discharge quantity by integrating the discharge current from the start time of discharge to the end time of discharge.

[0024] A battery pack according to another aspect of this disclosure may include a lithium deposition detection device according to one aspect of this disclosure.

[0025] A lithium deposition detection method according to another aspect of this disclosure may include: a charge / discharge calculation step, calculating the charge amount of a battery cell during charging and the discharge amount of a battery cell during discharging; a SOC estimation step, estimating the SOC of a battery cell during charging and discharging; and a lithium deposition judgment step, determining whether lithium deposition has occurred in a battery cell based on the estimated SOC, charge amount, and discharge amount.

[0026] Beneficial effects

[0027] According to one aspect of this disclosure, the lithium precipitation detection device has the advantage of quickly determining whether lithium has been precipitated by comparing the charge and discharge amounts of individual battery cells during operation.

[0028] The effects of this disclosure are not limited to those described above, and other unmentioned effects will be clearly understood by those skilled in the art from the description of the claims. Attached Figure Description

[0029] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are intended to provide a further understanding of the technical features of the present disclosure; therefore, the present disclosure should not be construed as limited to the drawings.

[0030] Figure 1 This is a schematic diagram illustrating a lithium precipitation detection apparatus according to an embodiment of the present disclosure.

[0031] Figure 2 This is a diagram schematically illustrating the charging and discharging behavior of a battery cell according to an embodiment of the present disclosure.

[0032] Figure 3 and Figure 4This is a schematic diagram illustrating the charge and discharge amounts of a first cell according to an embodiment of the present disclosure.

[0033] Figure 5 and Figure 6 This is a diagram schematically illustrating the charge and discharge amounts of a second cell according to an embodiment of the present disclosure.

[0034] Figure 7 This is a diagram schematically illustrating an exemplary configuration of a battery pack according to another embodiment of the present disclosure.

[0035] Figure 8 This is a schematic diagram illustrating a lithium precipitation detection method according to another embodiment of the present disclosure. Detailed Implementation

[0036] It should be understood that the terms used in this specification and the appended claims should not be construed as limited to their general and dictionary meanings, but rather interpreted based on their meanings and concepts corresponding to the technical aspects of this disclosure, while allowing the inventors to define the terms appropriately for the best illustration.

[0037] Therefore, the descriptions presented herein are merely preferred examples for illustrative purposes only and are not intended to limit the scope of this disclosure. It should be understood that other equivalents and modifications can be made to this disclosure without departing from its scope.

[0038] In addition, in describing this disclosure, a detailed description of a known element or function is omitted here when it is considered to obscure the key subject matter of the disclosure.

[0039] Ordinal terms such as “first” and “second” can be used to distinguish one element from another among various elements, but are not intended to limit these elements.

[0040] Throughout this specification, when a part is referred to as “comprising” or “including” any element, it means that the part may further include other elements, without excluding other elements, unless otherwise specifically stated.

[0041] Furthermore, throughout this specification, when a part is referred to as being “connected” to another part, it is not limited to the case where they are “directly connected” but also includes the case where they are “indirectly connected” by means of another element inserted between them.

[0042] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0043] Figure 1 This is a schematic diagram illustrating a lithium precipitation detection device 100 according to an embodiment of the present disclosure.

[0044] refer to Figure 1 The lithium precipitation detection device 100 may include a measurement unit 110 and a control unit 120.

[0045] The measurement unit 110 can be configured to calculate the amount of charge of the battery cell 10 during charging and the amount of discharge of the battery cell 10 during discharging.

[0046] Here, battery cell 10 refers to a physically separable, independent unit having a negative terminal and a positive terminal. For example, a lithium-ion battery or a lithium polymer battery can be considered as battery cell 10.

[0047] Specifically, the measurement unit 110 can be configured to calculate the amount of charge by integrating the charging current from the start time of charging to the end time of charging. Furthermore, the measurement unit 110 can be configured to calculate the amount of discharge by integrating the discharging current from the start time of discharging to the end time of discharging.

[0048] Figure 2 This is a diagram schematically illustrating the charging and discharging behavior of a battery cell 10 according to an embodiment of the present disclosure.

[0049] exist Figure 2 In this embodiment, the battery cell 10 can begin charging at time point t1 and end charging at time point t2. During the charging process from time point t1 to time point t2, the measurement unit 110 can calculate the first charge amount (ΔI) by integrating the charging current of the battery cell 10. C1 In the following text, battery cell 10 can be kept in an idle state from time point t2 to time point t3.

[0050] The battery cell 10 can begin discharging at time point t3 and end discharging at time point t4. During the discharge process from time point t3 to time point t4, the measurement unit 110 can calculate the first discharge quantity (ΔI) by integrating the discharge current of the battery cell 10. D1 In the following text, battery cell 10 can be kept in an idle state from time point t4 to time point t5.

[0051] Battery cell 10 can begin charging at time point t5 and end charging at time point t6. During the charging process from time point t5 to time point t6, measurement unit 110 can calculate the second charge amount (ΔI) by integrating the charging current of battery cell 10. C2 In the following text, battery cell 10 can be kept in an idle state from time point t6 to time point t7.

[0052] Battery cell 10 can begin discharging at time point t7 and end discharging at time point t8. During the discharge process from time point t7 to time point t8, measurement unit 110 can calculate the second discharge quantity (ΔI) by integrating the discharge current of battery cell 10. D2 In the following text, battery cell 10 can be kept in an idle state from time point t8.

[0053] The control unit 120 can be configured to estimate the state of charge (SOC) of the battery cell 10 during the charging and discharging processes.

[0054] Preferably, the control unit 120 can estimate the state of charge (SOC) of the battery cell 10 at the charging start time, charging end time, discharging start time, and discharging end time.

[0055] For example, the control unit 120 can use an extended Kalman filter to estimate the state of charge (SOC) of the battery cell 10. For this purpose, the measurement unit 110 can be configured to further measure the open-circuit voltage (OCV) of the battery cell 10. Additionally, the control unit 120 can estimate the SOC at each time point based on the OCV measured by the measurement unit 110 at each of the charging start time, charging end time, discharging start time, and discharging end time.

[0056] As another example, the control unit 120 may use an extended Kalman filter to estimate the SOC at the start of charging and the start of discharging, and use coulomb counting to estimate the SOC at the end of charging and the end of discharging based on the amount of charge and discharge calculated by the measurement unit 110.

[0057] exist Figure 2 In this embodiment, for ease of explanation, it is assumed that the State of Charge (SOC) of battery cell 10 is maintained at the same level during the periods from time t2 to time t3 and from time t4 to time t5 when battery cell 10 is kept in an idle state. Control unit 120 can estimate the SOC of battery cell 10 at time t1 as SOC1, and can estimate the SOC of battery cell 10 at time t2 as SOC4. Control unit 120 can estimate the SOC of battery cell 10 at time t3 as SOC4, and can estimate the SOC of battery cell 10 at time t4 as SOC2. Control unit 120 can estimate the SOC of battery cell 10 at time t5 as SOC2, and can estimate the SOC of battery cell 10 at time t6 as SOC3. Control unit 120 can estimate the SOC of battery cell 10 at time t7 as SOC3, and can estimate the SOC of battery cell 10 at time t8 as SOC2.

[0058] The control unit 120 can be configured to determine whether lithium deposition has occurred in the battery cell 10 based on the estimated SOC, charge amount, and discharge amount.

[0059] Specifically, the control unit 120 can be configured to compare the magnitude of the charge and discharge.

[0060] For example, in Figure 2 In one embodiment, the control unit 120 can compare the first charge amount (ΔI) C1 ) and the first discharge quantity (ΔI) D1 The size of the second charge (ΔI) can also be compared. Furthermore, the control unit 120 can compare the second charge amount (ΔI) with the second charge amount (ΔI). C2 ) and second discharge quantity (ΔI) D2 ) size.

[0061] In addition, the control unit 120 can be configured to determine whether lithium deposition has occurred in the battery cell 10 based on the comparison result.

[0062] Specifically, when the discharge exceeds the charge, the control unit 120 can be configured to determine that lithium has been deposited.

[0063] For example, when the discharge amount is less than the charge amount, the control unit 120 can determine that lithium has not been deposited on the surface of the negative electrode of the battery cell 10. Conversely, when the discharge amount exceeds the charge amount, the control unit 120 can determine that lithium has been deposited on the surface of the negative electrode of the battery cell 10.

[0064] Typically, during the manufacturing process of the battery cell 10, the negative electrode capacity is set to be greater than the positive electrode capacity. The value obtained by dividing the total capacity of the negative electrode by the total capacity of the positive electrode is called the N / P ratio, and the N / P ratio has a significant impact on the safety and capacity of the battery and therefore typically has a value of 1 or greater. Preferably, the battery cell 10 is manufactured such that the N / P ratio exceeds 1.

[0065] The lithium deposition detection apparatus 100 according to an embodiment of the present disclosure has the advantage of determining the change behavior of the N / P ratio by comparing the charging and discharging amounts of the battery cell 10 during operation, and quickly determining whether lithium deposition has occurred based on the change behavior of the N / P ratio. Therefore, the advantage is that it can quickly determine whether lithium deposition has occurred without analyzing the thickness change caused by the swelling of the battery cell 10 or performing a volcano analysis (analyzing the Q-dV / dQ curve representing the correspondence between capacity (Q) and differential voltage (dV / dQ) or the V-dQ / dV curve representing the correspondence between voltage (V) and differential capacity (dQ / dV)).

[0066] Meanwhile, the control unit 120 provided in the lithium deposition detection device 100 may optionally include processors, application-specific integrated circuits (ASICs), another chipset, logic circuits, registers, communication modems, and data processing devices known in the art to execute the various control logics performed in this disclosure. Furthermore, when the control logic is implemented in software, the control unit 120 may be implemented as a collection of program modules. In this case, the program modules may be stored in memory and executed by the control unit 120. The memory may be located within or outside the control unit 120 and may be connected to the control unit 120 by various known means.

[0067] Furthermore, the lithium deposition detection device 100 may further include a storage unit 130. The storage unit 130 may store data or programs necessary for the operation and function of each component of the lithium deposition detection device 100, data generated during the execution of operations or functions, etc. The storage unit 130 is not particularly limited in its type, as long as it is a known information storage device capable of recording, erasing, updating, and retrieving data. As examples, the information storage device may include RAM, flash memory, ROM, EEPROM, registers, etc. Additionally, the storage unit 130 may store program code, defining processes that can be executed by the control unit 120.

[0068] For example, the storage unit 130 can store the charge and discharge amounts calculated by the measurement unit 110. Furthermore, the storage unit 130 can store the state of charge (SOC) of the battery cell 10 estimated by the control unit 120.

[0069] More specifically, when the SOC at the start of charging and the SOC at the end of discharging are the same, and the SOC at the end of charging and the SOC at the start of discharging are the same, the control unit 120 can be configured to determine whether lithium deposition has occurred by comparing the amount of discharge and the amount of charge.

[0070] For example, in Figure 2 In this embodiment, the depth of discharge (DOD) during the charging process from time point t5 to time point t6 and the discharging process from time point t7 to time point t8 can be the same. Specifically, the DOD during the charging process and the DOD during the discharging process can be the same, namely "SOC3 - SOC2".

[0071] That is, when the DOD is the same during the charging and discharging processes, the control unit 120 can directly compare the discharge amount and the charge amount calculated by the measurement unit 110. In addition, when the discharge amount exceeds the charge amount, the control unit 120 can determine that lithium metal has been deposited in the negative electrode of the battery cell 10.

[0072] On the other hand, Figure 2In this embodiment, the DOD during the charging process from time point t1 to time point t2 and the DOD during the discharging process from time point t3 to time point t4 can be different. Specifically, since the DOD during the charging process is "SOC4 – SOC1" and the DOD during the discharging process is "SOC4 - SOC2", the DOD during the charging process and the DOD during the discharging process can differ by as much as "SOC2 – SOC1".

[0073] Therefore, when the DOD during charging and discharging are different, it is not possible to accurately determine whether lithium deposition has occurred in the battery cell 10 by directly comparing the charging and discharging amounts. This is because the DOD during charging is greater than the DOD during discharging, and even when lithium metal is deposited on the negative electrode of the battery cell 10, the discharge amount may be calculated as less than the charging amount.

[0074] Therefore, when the SOC at the start of charging and the SOC at the end of discharging are different, or when the SOC at the end of charging and the SOC at the start of discharging are different, the control unit 120 can be configured to correct the discharge amount and the charge amount, and determine whether lithium deposition has occurred based on the comparison result of the corrected discharge amount and the corrected charge amount.

[0075] For example, in Figure 2 In this embodiment, the time point t1, which is the start time of charging, and the time point t4, which is the end time of discharging, can be different from each other. In this case, when based on a direct comparison of the first charge amount (ΔI)... C1 ) and the first discharge quantity (ΔI) D1 Using the result of the first charge amount (ΔI) to determine whether lithium precipitation has occurred may yield inaccurate results. Therefore, the control unit 120 can correct the first charge amount (ΔI) separately. C1 ) and the first discharge quantity (ΔI) D1 ).

[0076] Specifically, the control unit 120 can be configured to calculate the SOC deviation between the SOC at the start of charging and the SOC at the end of charging, and to correct the charging amount based on the calculated SOC deviation.

[0077] For example, in Figure 2 In this embodiment, the control unit 120 can calculate the formula "SOC4 - SOC1" to calculate the charging SOC deviation between the SOC at time point t1 and the SOC at time point t2. Additionally, the control unit 120 can calculate "the first charge amount (ΔI)". C1 The formula “) ÷ (SOC4 - SOC1)” is used to correct the first charge (ΔI). C1 ).

[0078] Additionally, the control unit 120 can be configured to calculate the discharge SOC deviation between the SOC at the start time of discharge and the SOC at the end time of discharge, and to correct the discharge amount based on the calculated discharge SOC deviation.

[0079] For example, in Figure 2 In this embodiment, the control unit 120 can calculate the discharge SOC deviation between the SOC at time point t3 and the SOC at time point t4 using the formula "SOC4 – SOC2". Additionally, the control unit 120 can calculate the first discharge quantity (ΔI) D1 The formula “) ÷ (SOC4 – SOC2)” is used to correct the first discharge quantity (ΔI). D1 ).

[0080] In addition, the control unit 120 can determine whether lithium deposition has occurred based on the result of comparing the magnitude of the corrected first charge and the corrected first discharge.

[0081] For example, when the corrected first discharge amount exceeds the corrected first charge amount, the control unit 120 can determine that lithium has been deposited in the battery cell 10. Conversely, if the corrected first discharge amount is less than or equal to the corrected first charge amount, the control unit 120 can determine that lithium has not been deposited in the battery cell 10.

[0082] That is, when the DOD during charging and the DOD during discharging are different, the lithium deposition detection device 100 can more accurately determine whether lithium deposition has occurred based on the corrected discharge amount and the corrected charge amount.

[0083] Figure 3 and Figure 4 This is a schematic diagram illustrating the charge and discharge amounts of a first cell according to an embodiment of the present disclosure.

[0084] Specifically, Figure 3 This is a graph showing the charge and discharge amounts according to the C-rate (current rate) when the first cell is in the BOL (Life Start) state. Figure 4 This is a graph showing the charge and discharge amounts according to the C-rate when the first cell is in the MOL (Mid-Life) state. Here, the first cell can be charged from 3% SOC to 98% SOC and discharged from 98% SOC to 3% SOC.

[0085] Here, the charging and discharging C-rate can be set by the control unit 120 within the range of 1 C and 0.05 C. Preferably, the charging and discharging C-rate can be set within the range of 0.5 C and 0.05 C.

[0086] refer to Figure 3When the first monomer is in the BOL state, the charge amount can always be greater than the discharge amount. That is, when the charging C-rate and discharging C-rate are 0.4 C, 0.3 C, 0.2 C, and 0.1 C, respectively, the charge amount can be greater than or equal to the discharge amount. Therefore, the control unit 120 can determine that lithium metal has not been deposited in the first monomer in the BOL state.

[0087] On the other hand, reference Figure 4 When the first monomer is in the MOL state, and the charging C-rate and discharging C-rate are both 0.1 C, the discharge amount can exceed the charging amount. In this case, because the discharge amount exceeds the charging amount, the control unit 120 can determine that lithium metal has been deposited in the first monomer in the MOL state.

[0088] Figure 5 and Figure 6 This is a diagram schematically illustrating the charge and discharge amounts of a second cell according to an embodiment of the present disclosure.

[0089] Specifically, Figure 5 This is a graph showing the charge and discharge amounts according to the C-rate when the second cell is in the BOL state. Figure 6 This is a graph showing the charge and discharge amounts according to the C-rate when the second cell is in the MOL state. Here, the second cell can be charged from 3% SOC to 98% SOC and discharged from 98% SOC to 3% SOC.

[0090] refer to Figure 5 When the second monomer is in the BOL state, the charge amount can always be greater than the discharge amount. That is, when the charging C-rate and discharging C-rate are 0.4 C, 0.3 C, 0.2 C, and 0.1 C, respectively, the charge amount can be greater than or equal to the discharge amount. Therefore, the control unit 120 can determine that lithium metal has not been deposited in the second monomer in the BOL state.

[0091] On the other hand, reference Figure 6 When the second monomer is in the MOL state, the discharge amount can exceed the charge amount when the charging C-rate and discharging C-rate are 0.3 C, 0.2 C, or 0.1 C. In this case, because the discharge amount exceeds the charge amount, the control unit 120 can determine that lithium metal has been deposited in the second monomer in the MOL state.

[0092] Because the battery cell 10 is manufactured to have an N / P ratio of 1 or greater (preferably greater than 1), during low-current (e.g., 0.1 C) charging and discharging, the charge amount in the battery cell 10 in the BOL state can always be equal to or greater than the discharge amount. On the other hand, in the battery cell 10 in the deteriorated MOL state, metallic lithium can be deposited on the surface of the negative electrode, and during low-current charging and discharging with the deposited metallic lithium, the discharge amount can conversely be greater than the charge amount. Therefore, the lithium deposition detection device 100 can quickly and accurately detect whether lithium deposition has occurred by comparing the charge and discharge amounts of the battery cell 10.

[0093] For example, the control unit 120 can be configured to set the charging C-rate and discharging C-rate to be the same.

[0094] refer to Figures 3 to 6 In one embodiment, the amount of charge can vary with the charging C-rate, and the amount of discharge can vary with the discharging C-rate.

[0095] As a specific example, in Figure 3 In some embodiments, when the first monomer is charged at 0.2 C or 0.1 C and discharged at 0.4 C, the discharge amount can exceed the charge amount. That is, even if lithium is not deposited in the first monomer in the BOL state, the discharge amount can exceed the charge amount due to the difference between the charging C-rate and the discharging C-rate.

[0096] Therefore, when detecting whether lithium precipitation has occurred, the control unit 120 can set the charging C-rate and the discharging C-rate to be the same, thereby preventing false detection of lithium precipitation caused by the difference in C-rate.

[0097] The control unit 120 can be configured to send the charging C-rate and discharging C-rate of the battery cell 10 to a charging and discharging device 2 capable of charging and discharging the battery cell 10.

[0098] Here, the charging and discharging device 2 can be connected to the battery cell 10 and configured to charge the battery cell 10 according to the charging C-rate set by the control unit 120. Additionally, the charging and discharging device 2 can be configured to discharge the battery cell 10 according to the discharging C-rate set by the control unit 120.

[0099] When the discharge amount is less than or equal to the charge amount and the difference between the discharge amount and the charge amount is less than or equal to a preset standard value, the control unit 120 can be configured to reduce the charging C-rate and the discharging C-rate and send the reduced charging C-rate and the reduced discharging C-rate to the charging and discharging device 2.

[0100] For example, in Figure 4 In this embodiment, it is assumed that the control unit 120 sets the charging C-rate and discharging C-rate to 0.2C, and the difference between the charging amount and the discharging amount calculated by the measurement unit 110 is equal to or less than a standard value. The control unit 120 can reduce the charging C-rate and discharging C-rate to 0.1C, which is less than 0.2C, and send information about the reduced charging C-rate and reduced discharging C-rate to the charging and discharging device 2.

[0101] Additionally, the control unit 120 can be configured to determine again whether lithium deposition has occurred based on the amount of charge of the battery cell 10 during charging at a reduced charging C-rate and the amount of discharge of the battery cell 10 during discharging at a reduced discharging C-rate.

[0102] In the previous embodiment, the charging and discharging device 2 can receive a charging C-rate and a discharging C-rate reduced to 0.1 C from the control unit 120, and discharge the battery cell 10 at the received charging C-rate (0.1 C) and the received discharging C-rate (0.1 C). Based on 0.1 C, the discharge amount of the battery cell 10 exceeds the charge amount, so the control unit 120 can determine that lithium has been deposited in the first cell in the MOL state.

[0103] As another example, in Figure 6 In this embodiment, it is assumed that the control unit 120 sets the charging C-rate and discharging C-rate to 0.5 C, and the difference between the charge amount and discharge amount calculated by the measurement unit 110 is equal to or less than a standard value. The control unit 120 can reduce the charging C-rate and discharging C-rate to 0.4 C, which is less than 0.5 C, and send information about the reduced charging C-rate and discharging C-rate to the charging and discharging device 2. The charging and discharging device 2 can receive the reduced charging C-rate and discharging C-rate to 0.4 C from the control unit 120, and charge and discharge the battery cell 10 at the received charging C-rate (0.4 C) and discharging C-rate (0.4 C). Based on 0.4 C, the discharge amount of the battery cell 10 is less than or equal to the charge amount, but the difference between the discharge amount and the charge amount can still be less than or equal to the standard value.

[0104] The control unit 120 can reduce the charging C-rate and discharging C-rate to 0.3 C, which is less than 0.4 C, and send information about the reduced charging C-rate and discharging C-rate to the charging and discharging device 2. The charging and discharging device 2 can receive the reduced charging C-rate and discharging C-rate to 0.3 C from the control unit 120, and charge and discharge the battery cell 10 at the received charging C-rate (0.3 C) and discharging C-rate (0.3 C). Based on 0.3 C, since the discharge amount of the battery cell 10 exceeds the charge amount, the control unit 120 can determine that lithium is deposited in the second cell in the MOL state.

[0105] That is, when the difference between the discharge amount and the charge amount is less than or equal to a standard value, the lithium deposition detection device 100 can determine whether lithium deposition has occurred again while reducing the charging C-rate and the discharging C-rate. Therefore, the lithium deposition detection device 100 has the advantages of rapidly detecting whether lithium deposition has occurred at a relatively high C-rate in the initial stage, and accurately detecting whether lithium deposition has occurred while reducing the C-rate when the difference between the discharge amount and the charge amount is less than or equal to a standard value.

[0106] Additionally, when the discharge amount is less than or equal to the charge amount and the first difference between the discharge amount and the charge amount is greater than or equal to a standard value, the control unit 120 may reduce the charging C-rate and the discharging C-rate and then recalculate the second difference between the discharge amount and the charge amount. If the second difference is also greater than or equal to the standard value but less than the first difference, the control unit 120 may again reduce the charging C-rate and the discharging C-rate and then calculate the third difference between the discharge amount and the charge amount.

[0107] If the difference between the amount of discharge and the amount of charge caused by the charging C-rate and the discharging C-rate is greater than or equal to the standard value, but the difference between the amount of discharge and the amount of charge calculated based on the reduced charging C-rate and the reduced discharging C-rate tends to gradually decrease, then the control unit 120 can compare the amount of discharge and the amount of charge while reducing the charging C-rate and the discharging C-rate.

[0108] That is, if the difference between the charge amount and the discharge amount also tends to decrease as the charging C-rate and the discharging C-rate are reduced, then since it can be determined that lithium metal is deposited during low-current charging and discharging, the control unit 120 can compare the charge amount and the discharge amount while reducing the charging C-rate and the discharging C-rate.

[0109] For example, in Figure 4In this embodiment, it is assumed that the charging C-rate and discharging C-rate are initially set to 0.4 C. When the charging and discharging C-rate is 0.4 C, the discharge amount may be less than the charging amount, and a first difference between the discharge amount and the charging amount may be greater than or equal to a standard value. The control unit 120 can reduce the charging C-rate and discharging C-rate to 0.3 C and compare the discharge amount and the charging amount. When the charging and discharging C-rate is 0.3 C, the discharge amount is less than the charging amount, and a second difference between the discharge amount and the charging amount is greater than or equal to a standard value. However, because the second difference is lower than the first difference, the control unit 120 can reduce the charging C-rate and discharging C-rate to 0.2 C and compare the discharge amount and the charging amount again. When the charging and discharging C-rate is 0.2 C, the discharge amount is less than the charging amount, and a third difference between the discharge amount and the charging amount is less than or equal to a standard value. However, because the third difference is lower than the second difference, the control unit 120 can reduce the charging C-rate and discharging C-rate to 0.1 C and compare the discharge amount and the charging amount again. When the charging and discharging C-rate is 0.1 C, because the discharge amount exceeds the charging amount, the control unit 120 can determine that lithium metal has been deposited in the battery cell 10.

[0110] That is, when the discharge amount is less than the charge amount, but the difference between the discharge amount and the charge amount tends to decrease as the charging and discharging C- rate decreases, the lithium precipitation detection device 100 has the advantage of determining whether lithium metal has been precipitated while reducing the charging and discharging C- rate.

[0111] The lithium deposition detection device 100 according to this disclosure can be applied to a BMS (Battery Management System). That is, a BMS according to this disclosure may include the aforementioned lithium deposition detection device 100. In this configuration, at least some components of the lithium deposition detection device 100 can be implemented by supplementing or adding functions included in a conventional BMS. For example, the measurement unit 110, control unit 120, and storage unit 130 of the lithium deposition detection device 100 can be implemented as components of a BMS.

[0112] Furthermore, the lithium deposition detection device 100 according to this disclosure can be disposed in the battery pack 1. That is, the battery pack 1 according to this disclosure may include the aforementioned lithium deposition detection device 100 and at least one battery cell 10. In addition, the battery pack 1 may further include electrical equipment (relays, fuses, etc.) and a housing.

[0113] Figure 7 This is a diagram schematically illustrating an exemplary configuration of battery pack 1 according to another embodiment of the present disclosure.

[0114] refer to Figure 7 The battery pack 1 may include a single battery cell 10 and a lithium deposition detection device 100.

[0115] The positive terminal of the battery cell 10 can be connected to the positive terminal (P+) of the battery pack 1, and the negative terminal of the battery cell 10 can be connected to the negative terminal (P-) of the battery pack 1.

[0116] The measurement unit 110 can be connected to a first sensing line SL1, a second sensing line SL2, and a third sensing line SL3. Specifically, the measurement unit 110 can be connected to the positive terminal of the battery cell 10 via the first sensing line SL1, and can be connected to the negative terminal of the battery cell 10 via the second sensing line SL2. The measurement unit 110 can measure the voltage of the battery cell 10 based on the voltage measured at each of the first sensing line SL1 and the second sensing line SL2.

[0117] Additionally, the measurement unit 110 can be connected to the current measurement unit A via the third sensing line SL3. For example, the current measurement unit A can be an ammeter or a shunt resistor capable of measuring the charging and discharging currents of the battery cell 10. The measurement unit 110 can calculate the charge amount by measuring the charging current of the battery cell 10 via the third sensing line SL3. Furthermore, the measurement unit 110 can calculate the discharge amount by measuring the discharging current of the battery cell 10 via the third sensing line SL3.

[0118] The charging and discharging device 2 may have one end connected to the positive terminal (P+) of the battery pack 1 and the other end connected to the negative terminal (P-) of the battery pack 1. Therefore, the positive terminal of the battery cell 10, the positive terminal (P+) of the battery pack 1, the charging and discharging device 2, the negative terminal (P-) of the battery pack 1, and the negative terminal of the battery cell 10 can be electrically connected.

[0119] Additionally, the charging and discharging device 2 can be connected to communicate with the control unit 120. The charging and discharging device 2 can charge the battery cell 10 according to the charging C-rate received from the control unit 120 and discharge the battery cell 10 according to the discharging C-rate received from the control unit 120.

[0120] Figure 8 This is a schematic diagram illustrating a lithium precipitation detection method according to another embodiment of the present disclosure.

[0121] Preferably, each step of the lithium precipitation detection method can be performed by the lithium precipitation detection device 100. In the following text, for ease of explanation, content overlapping with the foregoing will be omitted or briefly described.

[0122] refer to Figure 8 The lithium precipitation detection method may include a charge / discharge calculation step (S100), a SOC estimation step (S200), and a lithium precipitation judgment step (S300).

[0123] The charge / discharge calculation step (S100) is a step that calculates the charge amount of the battery cell 10 during the charging process and the discharge amount of the battery cell 10 during the discharging process, and can be executed by the measurement unit 110.

[0124] For example, the measuring unit 110 can calculate the amount of charge by accumulating the charging current during the charging process, and calculate the amount of discharge by accumulating the discharging current during the discharging process. Preferably, the charging C-rate during the charging process and the discharging C-rate during the discharging process can be the same.

[0125] The SOC estimation step (S200) is a step of estimating the SOC of the battery cell 10 during the charging and discharging processes, and can be executed by the control unit 120.

[0126] For example, the control unit 120 can estimate the state of charge (SOC) of the battery cell 10 at each of the charging start time, charging end time, discharging start time, and discharging end time. During the SOC estimation process, an extended Kalman filter and / or ampere counting can be applied.

[0127] The lithium deposition determination step (S300) is a step to determine whether lithium deposition has occurred in the battery cell 10 based on the estimated SOC, charge amount and discharge amount, and can be executed by the control unit 120.

[0128] Specifically, the control unit 120 can determine whether the SOC at the start of charging and the SOC at the end of discharging are the same, and whether the SOC at the end of charging and the SOC at the start of discharging are the same.

[0129] For example, when the SOC at the start of charging and the SOC at the end of discharging are the same, and the SOC at the end of charging and the SOC at the start of discharging are the same, the control unit 120 can determine whether lithium deposition has occurred in the battery cell 10 based on a direct comparison of the discharge amount and the charge amount calculated by the measurement unit 110.

[0130] As another example, when the State of Charge (SOC) at the start of charging and the State of Charge (SOC) at the end of discharging are different, or when the SOC at the end of charging and the SOC at the start of discharging are different, the control unit 120 can correct the charge and discharge amounts calculated by the measurement unit 110. Specifically, the control unit 120 can correct the charge amount based on the SOC deviation during charging and correct the discharge amount based on the SOC deviation during discharging. Furthermore, the control unit 120 can determine whether lithium deposition has occurred in the battery cell 10 based on a direct comparison of the corrected charge amount and the corrected discharge amount.

[0131] The lithium precipitation detection method has the advantage of quickly and accurately diagnosing whether lithium metal has been deposited by comparing the amount of charge and discharge during the charging and discharging process of the battery cell 10.

[0132] The embodiments of this disclosure described above can be implemented not only by apparatus and methods, but also by a program that implements the functions corresponding to the configurations of the embodiments of this disclosure, or by a recording medium on which the program is recorded. The program or recording medium can be readily implemented by those skilled in the art from the above description of the embodiments.

[0133] This disclosure has been described in detail. However, it should be understood that the detailed description and specific examples are given by way of illustration only while indicating preferred embodiments of this disclosure, as various changes and modifications within the scope of this disclosure will become apparent to those skilled in the art from the detailed description.

[0134] Furthermore, many substitutions, modifications and alterations can be made to the above-described disclosure by those skilled in the art without departing from the technical aspects of this disclosure, and this disclosure is not limited to the above embodiments and drawings, and each embodiment can be selectively combined in part or in whole to allow various modifications.

[0135] (See attached image labels)

[0136] 1: Battery pack

[0137] 2: Charging and discharging equipment

[0138] 10: Battery cell

[0139] 100: Lithium Precipitation Detection Device

[0140] 110: Measurement Unit

[0141] 120: Control Unit

[0142] 130: Storage unit

Claims

1. A lithium precipitation detection device, comprising: A measurement unit configured to calculate the amount of charge of a single battery cell during charging and to calculate the amount of discharge of a single battery cell during discharging; as well as A control unit is configured to estimate the state of charge (SOC) of the battery cell during the charging and discharging processes, and to determine whether lithium deposition has occurred in the battery cell based on the estimated SOC, the amount of charge, and the amount of discharge. The control unit is configured to: compare the charge amount and the discharge amount, and determine, based on the comparison result, whether lithium deposition has occurred in the battery cell. The control unit is further configured to: compare the discharge amount and the charge amount when the SOC at the start of charging time is the same as the SOC at the end of discharging time and the SOC at the end of charging time is the same as the SOC at the start of discharging time; and determine that lithium precipitation has occurred when the discharge amount exceeds the charge amount.

2. A lithium precipitation detection device, comprising: A measurement unit configured to calculate the amount of charge of a single battery cell during charging and to calculate the amount of discharge of a single battery cell during discharging; as well as A control unit is configured to estimate the state of charge (SOC) of the battery cell during the charging and discharging processes, and to determine whether lithium deposition has occurred in the battery cell based on the estimated SOC, the amount of charge, and the amount of discharge. The control unit is configured to: compare the charge amount and the discharge amount, and determine, based on the comparison result, whether lithium deposition has occurred in the battery cell. The control unit is configured to: correct the discharge amount and the charge amount when the SOC at the start of charging is different from the SOC at the end of discharging or when the SOC at the end of charging is different from the SOC at the start of discharging; compare the corrected discharge amount and the corrected charge amount; and determine that lithium precipitation has occurred when the corrected discharge amount exceeds the corrected charge amount.

3. The lithium precipitation detection device according to claim 2, in, The control unit is configured to: calculate the charging SOC deviation between the SOC at the start of charging and the SOC at the end of charging, and correct the charging amount based on the calculated charging SOC deviation. The control unit is configured to: calculate the discharge SOC deviation between the SOC at the discharge start time and the SOC at the discharge end time, and correct the discharge amount based on the calculated discharge SOC deviation.

4. The lithium precipitation detection device according to claim 1 or 2, in, The control unit is configured to send the charging C-rate and discharging C-rate of the battery cell to a charging and discharging device capable of charging and discharging the battery cell.

5. The lithium precipitation detection device according to claim 4, in, The control unit is configured to: reduce the charging C-rate and the discharging C-rate when the discharge amount is equal to or less than the charging amount and the difference between the discharge amount and the charging amount is equal to or less than a preset standard value, and send the reduced charging C-rate and the reduced discharging C-rate to the charging and discharging device.

6. The lithium precipitation detection device according to claim 5, in, The control unit is configured to determine again whether lithium deposition has occurred based on the amount of charge of the battery cell during charging at a reduced charging C-rate and the amount of discharge of the battery cell during discharging at a reduced discharging C-rate.

7. The lithium precipitation detection device according to claim 4, in, The control unit is configured to set the charging C-rate and the discharging C-rate to be the same.

8. The lithium precipitation detection device according to claim 1 or 2, in, The measurement unit is configured to calculate the amount of charge by integrating the charging current from the start time of charging to the end time of charging, and The measurement unit is configured to calculate the discharge quantity by integrating the discharge current from the start time of discharge to the end time of discharge.

9. A battery pack comprising a lithium deposition detection device according to any one of claims 1 to 8.

10. A method for detecting lithium precipitation, comprising: The charging / discharging calculation steps include calculating the charging amount of a single battery cell during the charging process and calculating the discharging amount of the single battery cell during the discharging process. The SOC estimation step estimates the SOC of the battery cell during the charging and discharging processes. as well as The lithium deposition determination step determines whether lithium deposition has occurred in the battery cell based on the estimated SOC, the charge amount, and the discharge amount. The lithium deposition determination step further includes comparing the charge amount and the discharge amount, and determining whether lithium deposition has occurred in the battery cell based on the comparison result. The lithium precipitation determination step further includes: when the SOC at the start of charging is the same as the SOC at the end of discharging and when the SOC at the end of charging is the same as the SOC at the start of discharging, comparing the discharge amount and the charging amount; and when the discharge amount exceeds the charging amount, determining that lithium precipitation has occurred.

11. A method for detecting lithium precipitation, comprising: The charging / discharging calculation steps include calculating the charging amount of a single battery cell during the charging process and calculating the discharging amount of the single battery cell during the discharging process. The SOC estimation step estimates the SOC of the battery cell during the charging and discharging processes. as well as The lithium deposition determination step determines whether lithium deposition has occurred in the battery cell based on the estimated SOC, the charge amount, and the discharge amount. The lithium deposition determination step further includes comparing the charge amount and the discharge amount, and determining whether lithium deposition has occurred in the battery cell based on the comparison result. The lithium precipitation determination step further includes: when the SOC at the start of charging is different from the SOC at the end of discharging, or when the SOC at the end of charging is different from the SOC at the start of discharging, correcting the discharge amount and the charge amount; comparing the corrected discharge amount and the corrected charge amount; and when the corrected discharge amount exceeds the corrected charge amount, determining that lithium precipitation has occurred.

Images