Battery diagnosis device and battery diagnosis method

Abstract

The invention discloses a battery diagnosis apparatus and a battery diagnosis method. The battery diagnosis apparatus includes: a processor configured to control a stimulus applying device to intermittently apply a second electrical stimulus greater than a first electrical stimulus to a target cell during a state change period; and a communication unit configured to obtain current time series data during a state change period and voltage time series data representing a change history of a total battery voltage of the target cell during a rest period of the second electrical stimulation given in the state change period. The processor generates a measured full battery curve based on the current time-series data and the voltage time-series data, and analyzes the measured full battery curve to estimate a cathode participation origin.

Description

Technical Field

[0001] This disclosure relates to techniques for non-destructively diagnosing the state of a battery.

[0002] This application claims priority to Korean Patent Application No. 10-2023-0154883, filed on November 9, 2023, and Korean Patent Application No. 10-2023-0133644, filed on October 6, 2023, the disclosures of which are incorporated herein by reference. Background Technology

[0003] Recently, there has been a rapid increase in demand for portable electronic products such as laptops, cameras and mobile phones, and with the widespread development of electric vehicles, energy storage devices, robots and satellites, there is a lot of research being done on high-performance batteries that can be repeatedly recharged.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries have little or no memory effect, so they receive more attention than nickel-based batteries because their advantages are that they can be recharged whenever convenient, have a very low self-discharge rate, and high energy density.

[0005] While much research has been conducted on these batteries in terms of increasing capacity and density, improvements in lifespan and safety are also important. To improve battery safety, it is essential to accurately diagnose the current state of the battery.

[0006] Accurate diagnosis of the internal state of a battery is crucial for its safety and longevity. To diagnose the internal state of a battery without disassembly, relational data showing the correspondence between capacity and voltage (which may be referred to as a full-cell profile, etc.) is primarily used.

[0007] Conventionally, full-cell profiles are obtained by repeatedly measuring the battery's voltage and capacity at short intervals while applying constant electrical stimulation (e.g., constant current charging or discharging). However, to minimize polarization (or overpotential) that reduces diagnostic accuracy, the level of electrical stimulation applied to the target cell must be reduced, which has the limitation of taking too long to obtain full-cell profiles. Meanwhile, while high levels of electrical stimulation are advantageous in terms of shortening the time required, it is impossible to guarantee the accuracy of diagnostic results because high levels of electrical stimulation are accompanied by severe polarization. Summary of the Invention

[0008] Technical issues

[0009] This disclosure is designed to address problems in the related art, and therefore relates to providing a battery diagnostic apparatus and a battery diagnostic method that can obtain relational data representing the correspondence between the capacity and voltage of a target cell by using a method of intermittently applying high-level electrical stimulation to a target cell, and diagnose the negative electrode degradation state of the target cell (such as the negative electrode participation start point, which will be described later) based on the obtained relational data.

[0010] These and other objects and advantages of this disclosure may be understood from the following detailed description and will become more fully apparent from the exemplary embodiments of this disclosure. Moreover, it will be readily understood that the objects and advantages of this disclosure can be achieved by the means and combinations thereof shown in the appended claims.

[0011] Technical solution

[0012] In one aspect of this disclosure, a battery diagnostic apparatus is provided, comprising: a processor configured to: control a stimulation application device to intermittently apply a second electrical stimulation greater than a first electrical stimulation to the target cell during a state-change period prior to the electrical state of the target cell being changed from an initial state to a target state; and a communication unit configured to acquire current time-series data representing the history of current changes in the target cell during the state-change period and voltage time-series data representing the history of changes in the full-cell voltage of the target cell during a rest period of the second electrical stimulation given in the state-change period. The processor is configured to: generate a measured full-cell curve representing the correspondence between the capacity of the target cell and the full-cell voltage based on the current time-series data and the voltage time-series data, and estimate the negative electrode participation start point as a parameter representing the charge / discharge performance of the negative electrode of the target cell by analyzing the measured full-cell curve.

[0013] The first electrical stimulation can be an electrical stimulation that causes the difference between OCV and CCV to be equal to or less than the reference value in the target cell. The second electrical stimulation can be an electrical stimulation that causes the difference between OCV and CCV to be greater than the reference value in the target cell.

[0014] The first electrical stimulation can be performed using a first current rate, and the second electrical stimulation can be performed using a second current rate greater than the first current rate.

[0015] The first electrical stimulation may be a discharge using a first current rate, and the second electrical stimulation may be a discharge using a second current rate greater than the first current rate.

[0016] Voltage time series data can be measurements of the full cell voltage during the rest period of the second electrical stimulation, arranged in chronological order as the OCV of the target cell.

[0017] The processor can be configured to control the stimulation application device to initiate a rest period of the second electrical stimulation whenever the current integral value changes the threshold integral value.

[0018] The processor can be configured to control the stimulation application device to resume the application of the second electrical stimulation when a reference time has elapsed from the start time of the rest period of the second electrical stimulation.

[0019] The processor can be configured to determine the performance degradation factor of the target unit based on the estimated negative electrode participation start point.

[0020] The processor can be configured to limit at least one of the allowable voltage range and allowable SOC range of the target unit based on the estimated negative electrode participation start point.

[0021] In another aspect of this disclosure, a charging station is also provided, which includes a battery diagnostic device.

[0022] In another aspect of this disclosure, a cloud server is also provided, including a battery diagnostic device.

[0023] In another aspect of this disclosure, a battery diagnostic method is also provided, comprising: controlling a stimulation application device to intermittently apply a second electrical stimulus greater than a first electrical stimulus to a target cell during a state change period until the electrical state of the target cell, which is a battery cell to be diagnosed, is changed from an initial state to a target state; obtaining current time series data representing the history of current changes in the target cell during the state change period and voltage time series data representing the history of full-cell voltage changes in the target cell during a rest period of the second electrical stimulus given in the state change period; generating a measured full-cell curve representing the correspondence between the capacity of the target cell and the full-cell voltage based on the current time series data and the voltage time series data; and estimating the negative electrode participation start point as a parameter representing the charging / discharging performance of the negative electrode of the target cell by analyzing the measured full-cell curve.

[0024] Voltage time series data can be measurements of the full cell voltage during the rest period of the second electrical stimulation, which are arranged in chronological order as the OCV of the target cell.

[0025] Battery diagnostic methods may also include determining the performance degradation factor of a target cell based on an estimated negative electrode participation initiation.

[0026] Battery diagnostic methods may also include limiting at least one of the allowable voltage range and allowable SOC range of a target cell based on an estimated negative electrode engagement start point.

[0027] Beneficial effects

[0028] According to at least one embodiment of the present disclosure, relational data representing the correspondence between the capacity and voltage of the target cell can be obtained by using a method of intermittently applying high-level electrical stimulation to the target cell, and the negative electrode deterioration state of the target cell (the negative electrode participation start point described later) can be diagnosed based on the obtained relational data.

[0029] In other words, by using high levels of electrical stimulation to alter the electrical state of the target monomer, the time required to obtain relational data can be shortened, while also preventing a decrease in diagnostic accuracy due to overpolarization caused by intermittent application of electrical stimulation.

[0030] The effects of this disclosure are not limited to those described above, and those skilled in the art will clearly understand these and other effects from the appended claims. Attached Figure Description

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

[0032] Figure 1 This is an exemplary diagram showing the configuration of a charging station and an electric vehicle including a battery diagnostic circuit according to this disclosure.

[0033] Figure 2 These are the reference curves used to describe examples of the reference positive electrode curve and the reference negative electrode curve, respectively.

[0034] Figure 3a and Figure 3b This is a graph used to illustrate the process of obtaining a measurement full-cell curve for a target single cell.

[0035] Figures 4 to 6 The figure is a reference to an example illustrating the process of generating a comparative full-cell curve for comparison with a measured full-cell curve according to embodiments of the present disclosure.

[0036] Figures 7 to 9 This is a diagram illustrating another example of a process for generating a comparative full-cell curve for comparison with a measured full-cell curve, according to embodiments of the present disclosure.

[0037] Figure 10 This is an exemplary flowchart describing the battery diagnostic method according to a first embodiment of the present disclosure.

[0038] Figure 11 This is an exemplary flowchart describing the battery diagnostic method according to a second embodiment of the present disclosure.

[0039] Figure 12 It is described in Figure 11The diagram referenced in step S1122, which involves the process of correcting the voltage time series data. Detailed Implementation

[0040] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Before the description, it should be understood that the terminology used in the specification and appended claims should not be construed as limited to its general and dictionary meanings, but rather is interpreted based on the principle that allows the inventors to appropriately define the terminology for best explanation, and on the meanings and concepts corresponding to the technical aspects of the present disclosure.

[0041] Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of this disclosure. It should be understood that other equivalents and modifications may be made thereto without departing from the scope of this disclosure.

[0042] Ordinal terms such as “first” and “second” are used to distinguish one element from another among various elements, but are not intended to limit elements by terminology.

[0043] Unless the context clearly indicates otherwise, the terms "comprising" and "including" are used in this specification to specify the presence of the stated element, but do not exclude the presence or addition of one or more other elements. Additionally, as used herein, the term "...unit" refers to at least one processing unit of function or operation, which may be implemented by hardware and software, individually or in combination.

[0044] Furthermore, throughout the specification, it should be understood that when an element is referred to as being “connected” to another element, it can be directly connected to the other element, or there can be an intermediate element.

[0045] Figure 1 This is an exemplary diagram showing the configuration of a charging station and an electric vehicle including a battery diagnostic circuit according to this disclosure.

[0046] refer to Figure 1 The electric vehicle 1 includes a vehicle controller 2, a battery pack 10, an inverter 30, and a motor 40. The charging terminal P+ and discharging terminal P- of the battery pack 10 can be electrically connected to the charging station 300 via a charging cable or the like.

[0047] The vehicle controller 2 (e.g., ECU: Electronic Control Unit) is configured to send a key-on signal to the battery management system 100 in response to a user switching a start button (not shown) located in the electric vehicle 1 to the on position. The vehicle controller 2 is also configured to send a key-off signal to the battery management system 100 in response to a user switching the start button to the off position. The charging station 300 can communicate with the vehicle controller 2 and supplies charging power selected from constant power, constant current, and constant voltage through the charging terminal P+ and discharging terminal P- of the battery pack 10.

[0048] The battery pack 10 includes a battery 11, a relay 20, and a battery management system 100.

[0049] Battery 11 includes at least one battery cell BC. Figure 1 In the example, battery 11 is shown as comprising a plurality of battery cells (BC1 to BC2) connected in series. N (N is a natural number of 2 or greater). Multiple battery cells (BC1 to BC2). N ( ) can be supplied with the same electrochemical specifications. In the following, when multiple cell units (BC1 to BC) are described... N When common features are present, the reference numeral "BC" will be assigned to the battery cell. The charging station 300 can perform the charging and discharging cycles required for diagnosing the battery cell BC by cooperating with the inverter 30, which has a discharge function.

[0050] There are no particular restrictions on the type of battery cell BC, as long as it is an electrochemical element capable of repeated charging and discharging. Battery cell BC is the target for charging station diagnostics.

[0051] Relay 20 is connected in series to battery 11 via a power path connecting battery 11 and inverter 30. Figure 1 In the diagram, relay 20 is shown connected between the positive terminal of battery 11 and the charging / discharging terminal P+. Relay 20 is controlled to turn on and off in response to a switching signal from battery management system 100. Relay 20 can be a mechanical contactor that turns on and off via the magnetic force of a coil, or a semiconductor switch such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor).

[0052] Inverter 30 is provided to convert DC current from battery 11 included in battery pack 10 into AC current in response to commands from battery management system 100 or vehicle controller 2. The AC current power from inverter 30 is used to drive motor 40. For example, a three-phase AC current motor can be used as motor 40. Components in electric vehicle 1 that receive discharge power from battery 11 (such as inverter 30 and motor 40) can be collectively referred to as electrical loads.

[0053] The battery management system 100 includes a sensing unit 110 and a control circuit 130. The battery management system 100 may also include a communication circuit 150.

[0054] The sensing unit 110 includes a voltage sensor 111. The sensing unit 110 may also include a current sensor 112.

[0055] Voltage sensor 111 is connected to the positive and negative terminals of battery cell BC and is configured to detect the voltage across battery cell BC (also referred to as the "full cell voltage") and generate a voltage signal representing the detected value of the voltage. Voltage sensor 111 can be implemented as one or a combination of two or more known voltage sensing elements, such as a voltage measurement IC.

[0056] A current sensor 112 is connected in series to the battery 11 via the current path between the battery 11 and the inverter 30. The current sensor 112 is configured to detect the current flowing through the battery 11 (also referred to as the "charging and discharging current") and generate a current signal representing the detected value of the current. This is due to multiple battery cells (BC1 to BC2). N The current sensors 112 and 113 are connected in series, so the current flowing in battery 11 is the same as the current flowing in battery cell BC. The current sensor 112 can be implemented as one or a combination of two or more known current sensing elements such as shunt resistors, Hall effect elements, etc.

[0057] The communication circuit 150 is configured to support wired or wireless communication between the control circuit 130 and the vehicle controller 2. Wired communication may be, for example, CAN (Controller Area Network) communication, and wireless communication may be, for example, ZigBee or Bluetooth communication. The type of communication protocol is not particularly limited, as long as it supports both wired and wireless communication between the control circuit 130 and the vehicle controller 2. The communication circuit 150 may include an output device (e.g., a display, a speaker) that provides information received from the control circuit 130 and / or the vehicle controller 2 in a user- (driver-readable) format.

[0058] The control circuit 130 is operatively coupled to the relay 20, the voltage sensor 111, and the communication circuit 150. The operative coupling of the two components means that they are directly or indirectly connected to enable the transmission and reception of signals in one or both directions.

[0059] Control circuit 130 can collect voltage signals from voltage sensor 111 and current signals from current sensor 112. In this specification, the term "detection signal" can refer only to the voltage signal or to both the voltage and current signals. That is, control circuit 130 can use an ADC (analog-to-digital converter) provided therein to convert each analog signal collected from sensors 111 and 112 into a digital value and record the digital value. Alternatively, each of voltage sensor 111 and current sensor 112 may include an ADC and send the digital value to control circuit 130.

[0060] The control circuit 130 may be referred to as a "battery controller" and may be implemented in hardware using at least one of an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a microprocessor, or an electrical unit for performing other functions.

[0061] Memory 131 may include at least one type of storage medium, such as flash memory, hard disk, solid-state drive (SSD), silicon disk drive (SDD), multimedia card micro, random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or programmable read-only memory (PROM). Memory 131 may store data and programs required for the computational operations of control circuitry 130. Memory 131 may also store data representing the results of computational operations performed by control circuitry 130.

[0062] When relay 20 is turned on, battery 11 enters charging or discharging mode. If relay 20 is turned off while battery 11 is being used in charging or discharging mode, battery 11 switches to idle mode.

[0063] Control circuit 130 can activate relay 20 in response to a key-on signal. Control circuit 130 can deactivate relay 20 in response to a key-off signal. The key-on signal is a signal requesting a switch from a rest mode to a charging or discharging mode. The key-off signal is a signal requesting a switch from a charging or discharging mode to a rest mode. Alternatively, vehicle controller 2 can be responsible for activating / deactivating relay 20 instead of control circuit 130.

[0064] In this specification, time-series data for a parameter indicates the parameter's history of change over time. Furthermore, a curve (or bend) representing the correspondence between any two parameters obtained at the same time point within the same time period can be a mapping of two time-series data points for the two parameters, such that they can be expressed as a two-dimensional graph, or it can be a polynomial equation obtained by applying predetermined bend fitting logic to a set of time-series data points from two mappings. Here, the degree of the highest term in the polynomial equation can be predetermined.

[0065] The battery diagnostic device 302 includes a communication unit 310, a processor 320, and a memory unit 330.

[0066] Charging station 300 may include a stimulus application device 301 and a battery diagnostic device 302. Alternatively, the battery diagnostic device 302 may be configured independently of charging station 300. For example, battery diagnostic device 302 may be provided as included in a cloud server (not shown). The cloud server may be placed remotely from charging station 300. In this case, communication unit 310 of battery diagnostic device 302 can perform diagnostic processes on the target cell through remote communication with stimulus application device 301 and / or electric vehicle 1.

[0067] The battery diagnostic device 302 may be included in the battery pack 10, and in this case, the battery management system 100 may be omitted from the battery pack 10. In other words, the processor 320 may be responsible for all functions of the control circuit 130 of the battery management system 100. For example, the communication unit 310 may be included as a sub-component of the processor 320 and may be responsible for all functions of the communication circuit 150 of the battery management system 100. Furthermore, the communication unit 310 may collect voltage measurement information and current measurement information from the sensing unit 110.

[0068] The stimulation application device 301 may include a charger that provides charging power for the normal charging of the battery pack 10. The stimulation application device 301 may apply various electrical stimuli to the individual battery cells BC, either alone or in cooperation with the inverter 30, to diagnose the individual battery cells BC.

[0069] The communication unit 310 is configured to support wired or wireless communication between the processor 320 and the vehicle controller 2. The communication unit 310 can send the diagnostic results of the battery cell BC performed by the processor 320 to the electric vehicle 1.

[0070] In terms of hardware, the processor 320 can be implemented using at least one of an ASIC (Application-Specific Integrated Circuit), a DSP (Digital Signal Processor), a DSPD (Digital Signal Processing Device), a PLD (Programmable Logic Device), an FPGA (Field Programmable Gate Array), a microprocessor, and an electrical unit for performing other functions.

[0071] Memory unit 330 may include at least one type of storage medium, such as flash memory, hard disk, solid-state drive (SSD), silicon disk drive (SDD), multimedia card micro, random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or programmable read-only memory (PROM). Memory unit 330 may store data and programs required for diagnostic processes executed by processor 320. Memory unit 330 may store data representing the results of computational operations performed by processor 320. Memory unit 330 may store datasets and software used for diagnosing the degradation state of battery cell BC.

[0072] Figure 2 These are the reference graphs used to describe examples of each of the reference positive and reference negative electrode curves. Figure 2 In the graph, the horizontal axis (X-axis) represents capacity (Ah), and the vertical axis (Y-axis) represents voltage.

[0073] refer to Figure 2 The memory unit 330 can store a reference positive electrode curve Rp and a reference negative electrode curve Rn. The reference cell can be a coin-shaped cell including a positive half-cell and a negative half-cell, or it can be a three-electrode cell. In the following text, the reference cell and the positive electrode of the positive half-cell will be described in equivalent terms, and the reference cell and the negative electrode of the negative half-cell will be described in equivalent terms.

[0074] The reference positive electrode curve Rp can be a curve representing the relationship between the capacity of a reference cell and its positive electrode voltage. The positive electrode voltage of the reference cell refers to the potential difference between the potential of the reference electrode (not shown) and the potential of the positive electrode of the reference cell. The positive electrode curve can also be called the positive half-cell curve.

[0075] The reference negative electrode curve Rn can be a curve representing the relationship between the capacity of a reference cell and its negative electrode voltage. The negative electrode voltage of the reference cell refers to the potential difference between the potential of the reference electrode and the potential of the negative electrode. The negative electrode curve can also be called the negative electrode half-cell curve.

[0076] The potential of the reference electrode can be, for example, the redox potential of lithium. The positive electrode voltage can be simply referred to as the positive electrode potential, and the negative electrode voltage can be simply referred to as the negative electrode potential.

[0077] Each of the positive and negative voltages can be either an open-circuit voltage (OCV) or a closed-circuit voltage (CCV).

[0078] A first charging protocol or a first discharging protocol may be used to obtain the open-circuit voltage of each of the positive and negative terminals of the reference cell. The first charging protocol may be an intermittent charging method in which constant current charging using a first current rate and pauses are performed alternately. The first discharging protocol may be an intermittent discharging method in which constant current discharging using a first current rate and pauses are performed alternately. The first current rate (e.g., 0.05C) may be predetermined to be greater than a second current rate (e.g., 3.0C), as described later.

[0079] For example, whenever the constant current charging time of the first charging protocol elapses for a set time or the charging capacity of the reference cell increases by a set capacity, the charging of the reference cell can be paused for a predetermined pause time, and then constant current charging can be resumed. The charging capacity can be calculated by periodically or non-periodically accumulating sampled values ​​of the charging current.

[0080] As another example, whenever the discharge time of the constant current discharge via the first discharge protocol elapses for a set time or the discharge capacity of the reference cell decreases by a set capacity, the discharge of the reference cell can be stopped for a predetermined pause time, and then the constant current discharge can be resumed. The discharge capacity can be calculated by periodically or non-periodically accumulating the sampled values ​​of the discharge current (i.e., the measured values ​​of the cell current).

[0081] At this time, multiple pause periods can be provided while the first charging protocol or the first discharging protocol is in progress, and the open-circuit voltages of the positive and negative terminals of the reference cell measured at a specific timing point within each pause period can be recorded as the positive and negative terminal voltages of the reference cell, respectively.

[0082] When compared with the open-circuit voltage, the closed-circuit voltage of each of the positive and negative electrodes of the reference cell can be obtained using a second charging protocol or a second discharging protocol. The second charging protocol can be a constant-current charging method using a second current rate. The second discharging protocol can be a constant-current discharging method using a second current rate. For example, while the reference cell is being continuously charged using the second charging protocol or while the reference cell is being continuously discharged using the second discharging protocol, the closed-circuit voltages of the positive and negative electrodes of the reference cell, measured periodically or non-periodically, can be recorded as the positive and negative electrode voltages of the reference battery.

[0083] In this specification, the first electrical stimulation refers to the electrical stimulation that causes the difference between OCV and CCV to be equal to or less than the reference value in the battery cell, and the second electrical stimulation refers to the electrical stimulation that causes the difference between OCV and CCV to be greater than the reference value in the battery cell.

[0084] For example, the first electrical stimulation can be charged with a first current rate, and the second electrical stimulation can be charged with a second current rate greater than the first current rate.

[0085] As another example, the first electrical stimulation can discharge at a first current rate, and the second electrical stimulation can discharge at a second current rate greater than the first current rate.

[0086] Implementing a first charging protocol or a first discharging protocol may mean applying a first electrical stimulus to a battery cell. Implementing a second charging protocol or a second discharging protocol may mean applying a second electrical stimulus to a battery cell.

[0087] For ease of explanation, let's assume the horizontal axis represents... Figures 2 to 9 The charging capacity in the middle.

[0088] At least one of the reference positive electrode curve Rp and the reference negative electrode curve Rn can be aligned along the horizontal axis such that the common capacity range of the two curves (Rp, Rn) is ( Figure 2 The synthesis results of a portion of the 5Ah to 50Ah cells matched the reference full-cell curve R. Figure 2 An example is shown in which the reference negative electrode curve Rn is aligned to the right based on the starting point of the reference positive electrode curve Rp (the point corresponding to capacity 0).

[0089] from Figure 2 As can be seen, the two ends of the reference positive electrode curve Rp and the reference negative electrode curve Rn are offset from each other. In other words, the capacity ranges of the reference positive electrode curve Rp and the reference negative electrode curve Rn do not match and only partially overlap. Therefore, the reference full-cell curve R indicates the full-cell voltage of a reference cell within a portion of the common capacity range of the reference positive electrode curve Rp and the reference negative electrode curve Rn. In other words, the reference full-cell curve R is an example of a full-cell voltage curve obtained by directly subtracting a portion of the reference negative electrode curve Rn from a portion of the reference positive electrode curve Rp.

[0090] The reference full-cell curve R represents the relationship between the full-cell voltage and capacity of a new battery cell that has been verified as a good product. In other words, the reference cell has the same level of positive and negative electrode performance as the new battery cell that has been verified as a good product. The positive and negative electrode performance of any battery cell can be collectively referred to as "charge / discharge performance".

[0091] A new battery cell refers to a battery cell that is in a new state. New state is the same concept as BOL (Start of Life). For example, the time before the accumulated charge / discharge capacity reaches the set capacity from the time of manufacture completion can be called BOL, and the time from when the accumulated charge / discharge capacity reaches the set capacity can be called MOL (Mid-Life).

[0092] The reference full-cell curve R can represent the correspondence between the voltage and capacity of a reference cell within at least the voltage range of interest (e.g., 3.0 to 4.0 V). The lower and upper limits of the voltage range of interest can be a first set voltage ( Figure 2 3.0V in the middle) and the second set voltage ( Figure 2 (4.0V in the middle).

[0093] If the total cell voltage, including the reference cell, is equal to a first set voltage, then the State of Charge (SOC) can be set to 0%. When the total cell voltage, including the reference cell, is equal to a second set voltage, the SOC can be set to 100%. Figure 2 The reference cell can reach a charging capacity of 45Ah from a fully discharged state (SOC 0%) to a fully charged state (SOC 100%).

[0094] In this specification, when the full-cell voltage of a corresponding battery cell matches the first set voltage, the positive electrode participation start point on the positive electrode curve of any battery cell represents the positive electrode voltage and positive electrode capacity (or positive electrode SOC). Furthermore, when the full-cell voltage of a corresponding battery cell matches the first set voltage, the negative electrode participation start point on the negative electrode curve of the corresponding battery cell indicates the negative electrode voltage and negative electrode capacity (or negative electrode SOC). Therefore, the voltage difference between the positive electrode participation start point and the negative electrode participation start point can be equal to the first set voltage.

[0095] Furthermore, when the full-cell voltage of the corresponding battery cell matches the second set voltage, the positive electrode participation endpoint on the positive electrode curve of any battery cell indicates the positive electrode voltage and positive electrode capacity (or positive electrode SOC). Similarly, when the full-cell voltage of the corresponding battery cell matches the second set voltage, the negative electrode participation endpoint on the negative electrode curve of the corresponding battery cell indicates the negative electrode voltage and negative electrode capacity (or negative electrode SOC). Therefore, the voltage difference between the positive electrode participation endpoint and the negative electrode participation endpoint can be equal to the second set voltage.

[0096] In this specification, the positive electrode capacity (capacity value) at a specific point on the positive electrode curve of a given battery cell can refer to the capacity difference between either of the two endpoints of the positive electrode curve and the specific point. The positive electrode SOC at a specific point on the positive electrode curve of any battery cell can refer to the ratio of the capacity difference between either of the two endpoints of the positive electrode curve (e.g., the low capacity point) and the specific point to the capacity difference between the two endpoints of the positive electrode curve. The capacity difference between the two endpoints of the positive electrode curve can be referred to as the total positive electrode capacity.

[0097] Similarly, the negative electrode capacity (capacity value) at a specific point on the negative electrode curve of any battery cell can refer to the capacity difference between either of the two endpoints of the negative electrode curve (or positive electrode curve) and that specific point. The negative electrode SOC at a specific point on the negative electrode curve of any battery cell can refer to the ratio of the capacity difference between either of the two endpoints of the negative electrode curve (or positive electrode curve) (e.g., the low capacity point) and that specific point to the capacity difference between the two endpoints of the negative electrode curve. The capacity difference between the two endpoints of the negative electrode curve can be referred to as the total negative electrode capacity.

[0098] In memory cell 330, information indicating the voltage at each of the following points can be pre-recorded: the reference positive electrode participation start point (pi0), the reference positive electrode participation end point (pf0), the reference negative electrode participation start point (ni0), and the reference negative electrode participation end point (nf0). The reference positive electrode participation start point (pi0) and the reference positive electrode participation end point (pf0) are the positive electrode participation start point and positive electrode participation end point on the reference positive electrode curve Rp, respectively. The reference negative electrode participation start point (ni0) and the reference negative electrode participation end point (nf0) are the negative electrode participation start point and negative electrode participation end point on the reference negative electrode curve Rn, respectively.

[0099] The voltage difference between the reference positive electrode participation start point (pi0) and the reference negative electrode participation start point (ni0) can be equal to a first set voltage (e.g., 3.0V). The voltage difference between the reference positive electrode participation end point (pf0) and the reference negative electrode participation end point (nf0) can be equal to a second set voltage (e.g., 4.0V).

[0100] Figure 3a and Figure 3b This is a diagram used to illustrate the process of obtaining a measurement full-cell curve of a target cell.

[0101] Figure 3a The graph depicted illustrates an example of the change in the full-cell voltage of a target cell over time due to intermittent application of a second electrical stimulus. The target cell is a battery cell undergoing diagnosis by a battery diagnostic device. A target cell can be a new battery cell requiring verification of its product quality, or a battery cell that has been verified as a product quality but is no longer considered new due to degradation. In the following text, the target cell is also designated by the reference numeral BC.

[0102] Reference Figure 3a The processor 320 can control the stimulation application device 301 to intermittently apply a second electrical stimulus greater than the first electrical stimulus to the target monomer BC.

[0103] The process of controlling the stimulation application device 301 to diagnose the target cell BC can be performed during the state change period before the electrical state (e.g., full cell voltage) of the target cell BC is changed from an initial state (e.g., a first set voltage) to a target state (e.g., a second set voltage).

[0104] refer to Figure 3a The graph shows that the full-cell voltage of the target cell BC exhibits an upward trend while repeating a sawtooth pattern. Each sawtooth voltage rise segment is caused by the application of a second electrical stimulus, and the voltage drop segment is caused by the interruption of the second electrical stimulus. In other words, the voltage drop segment represents the change in the full-cell voltage of the target cell BC during each rest period.

[0105] During the state change period, the processor 320 can repeatedly record the current measurement value of the target cell BC to generate current time series data.

[0106] Whenever a predetermined rest condition is met during a state change period, the processor 320 can control the stimulation application device 301 to initiate a rest period for the second electrical stimulation. In other words, the application of the second electrical stimulation can be temporarily stopped when the rest condition is met. For example, at least one of the following can be preset as a rest condition: (i) the current integral value changes the threshold integral value, (ii) the state of charge (SOC) changes the threshold SOC, and (iii) the duration of application of the second electrical stimulation reaches a threshold time. For example, if the total current integral value during the state change period is 40 Ah and the threshold integral value is 2 Ah, a total of 20 rest periods can be permitted during the state change period.

[0107] Processor 320 can determine at least one of a threshold integral value, a threshold SOC, and a threshold time based on the full-charge capacity, SOH, or previous diagnostic results (e.g., the potential and / or capacity value at the negative electrode participation endpoint) of the target cell BC. At least one of the threshold integral value, threshold SOC, and threshold time can have a predetermined positive (or negative) correspondence with the full-charge capacity, SOH, or previous diagnostic results, and relational data (a data table for controlling rest periods) defining this correspondence can be pre-stored in memory unit 330. Due to the predetermined positive (or negative) correspondence, as the full-charge capacity, SOH, or previous diagnostic results decrease, at least one of the threshold integral value, threshold SOC, and threshold time also decreases. As a result, as the target cell BC deteriorates over time, rest periods are given at shorter intervals within the state-change period, thus preventing a reduction in the number of data points included in the voltage time-series data—which indicates the history of changes in the full cell voltage over time during the rest periods of the state-change period.

[0108] Processor 320 may obtain at least one of a threshold integral value, threshold SOC, and threshold time mapped to full charge capacity, SOH, or previous diagnostic results from a data sheet for use in rest period control. Processor 320 may use at least one of the threshold integral value, threshold SOC, and threshold time obtained from the data sheet for rest period control to control the intermittent application process of the second electrical stimulation during the state change period.

[0109] When a reference time has elapsed since the start of the rest period of the second electrical stimulation, the processor 320 can control the stimulation application device 301 to resume the application of the second electrical stimulation. The reference time can be predetermined such that the polarization caused by the second electrical stimulation can be sufficiently neutralized. For example, the reference time, which is the length of the rest period, can be the time required for the polarization at the start of the rest period to become 10% or less.

[0110] During each rest period of the second electrical stimulation, the full-cell voltage of the target cell BC is measured at least once. As an example, the processor 320 can record the measured full-cell voltage at the end of each rest period of the second electrical stimulation as the OCV of the target cell BC. As another example, the full-cell voltage can be measured at least three times during each rest period of the second electrical stimulation, and the processor 320 can estimate the OCV of the target cell BC for each rest period based on the three full-cell voltage measurements for each rest period.

[0111] Therefore, voltage time series data can be generated by recording OCV multiple times with time differences during the state change period. Figure 3a Each OCV point (D) marked in the middle OCV () is an example representing data points of voltage time series data.

[0112] The inventors of this disclosure have recognized through multiple experiments that the voltage time series data generated using the second electrical stimulation in the manner described above has a high degree of consistency with the voltage time series data generated when the first electrical stimulation is actually applied to the target monomer BC.

[0113] From this point onward, the advantages of diagnostic methods based on the intermittent application of a second electrical stimulus rather than the continuous application of a first electrical stimulus will be described.

[0114] The following conditions are assumed to be relevant to the diagnosis of the target monomer BC.

[0115] (i) First electrical stimulation = charging at 0.05C

[0116] (ii) Second electrical stimulation = charging at 3.0C

[0117] (iii) The length of the rest period after the second electrical stimulation = 12 minutes

[0118] (iv) Total capacity change during the state change period = 80% of the full charge capacity (FCC) of the target cell BC.

[0119] (v) Threshold integral value = 3% of the full charge capacity of the target cell BC

[0120] Then, by continuously applying the first electrical stimulation, the time taken for the target monomer BC to change from the initial state to the target state is 1 / 0.05*80%=16 hours.

[0121] In contrast, the time taken for the target cell BC to increase its charging capacity by the threshold integral value through the second electrical stimulation is 0.03 / 3 * 80% = 0.008 hours. Furthermore, since a rest period is permitted whenever the charging capacity increases by 3%, a total of 26 rest periods are permitted during the state-changing period. Therefore, the time taken for the target cell BC to change from its initial state to its target state through intermittent application of the second electrical stimulation is (0.008 hours + 0.2 hours) * 26 = 5.4 hours.

[0122] In other words, compared with the method of continuously applying the first electrical stimulation, the method of intermittently applying the second electrical stimulation is beneficial to shortening the time to obtain the full cell curve.

[0123] exist Figure 3b In the graph, the horizontal axis (X-axis) represents capacity (Ah), and the vertical axis (Y-axis) represents voltage.

[0124] refer to Figure 3b The processor 320 can generate a measured full-cell curve M representing the correspondence between the capacity and voltage (also known as the full-cell voltage) of the target cell BC. The measured full-cell curve can also be referred to as the QV curve or Q-OCV curve.

[0125] Here, the full-cell voltage is the voltage across the target cell BC, and it differs from the positive and negative electrode voltages mentioned above. In other words, the full-cell voltage of the target cell BC can be considered as the difference between the positive and negative electrode voltages of the target cell BC.

[0126] To generate the full-cell measurement curve M, current time series data and voltage time series data mapped to the state change period can be used.

[0127] In detail, each data point of the current time series data and voltage time series data is indexed in chronological order. Therefore, processor 320 can generate capacity time series data by sequentially integrating the data points of the current time series data. Furthermore, processor 320 can generate the measured full-cell curve M by applying a curved line fitting algorithm to a set of multiple Q-OCV pairs mapped between the capacity time series data and voltage time series data. The reference full-cell curve R, the reference positive electrode curve Rp, the reference negative electrode curve Rn, and the measured full-cell curve M can be polynomial equations, where the order of the highest term is predetermined.

[0128] Similar to the reference full-cell curve R, the measured full-cell curve M can represent the correspondence between the capacity of the target cell BC and the OCV over at least the voltage range of interest (e.g., 3.0 to 4.0 V).

[0129] Because there are inevitably some differences in the charge / discharge performance between the reference cell and the target cell BC, there are also some differences between the measured full-cell curve M and the reference full-cell curve R, such as... Figure 3b As shown.

[0130] For example, at the same capacity value, the voltage of the measured full-cell curve M is higher than the voltage of the reference full-cell curve R. This is due to manufacturing defects in the target cell BC, loss of positive electrode capacity, loss of negative electrode capacity, and / or loss of available lithium. Clearly, as the target cell BC deteriorates through repeated charge / discharge cycles, the difference between the measured full-cell curve M and the reference full-cell curve R will gradually increase. According to... Figure 3b , and reference Figure 2 The target cell BC requires 40Ah of charging capacity to reach the full cell voltage from the first set voltage to the second set voltage, which is 5Ah less than the 50Ah charging capacity of the reference cell under the same conditions.

[0131] At the same time, Figure 2 and Figure 3b In the graph, Ah is used as the unit on the horizontal axis, but this unit can be expressed in other forms. For example, the unit on the horizontal axis could be a percentage (%), which represents SOC (State of Charge) instead of Ah.

[0132] When generating the full-cell measurement curve M, the processor 320 can be configured to compare the full-cell measurement curve M with at least one comparative full-cell curve. Here, the comparative full-cell curve can be generated by adjusting each of the reference positive curve Rp and the reference negative curve Rn stored in the memory unit 330 to generate an adjusted positive curve and an adjusted negative curve, and then synthesizing (combining) the results of the adjusted positive curve and the adjusted negative curve.

[0133] In other words, when the reference full-cell curve R is the result of subtracting a portion of the reference negative curve Rn from a portion of the reference positive curve Rp, the comparison of the full-cell curves can be considered as the result of subtracting a portion of the adjusted negative curve from a portion of the adjusted positive curve.

[0134] Processor 320 can generate at least one comparative full-cell curve by directly adjusting the reference positive electrode curve Rp and the reference negative electrode curve Rn. Alternatively, at least one comparative full-cell curve can be pre-defined based on the reference positive electrode curve Rp and the reference negative electrode curve Rn and stored in memory unit 330. In this case, processor 320 can also obtain the comparative full-cell curve by accessing memory unit 330 and reading the comparative full-cell curve.

[0135] The processor 320 can generate multiple comparative full-cell curves from the reference positive electrode curve Rp and the reference negative electrode curve Rn by repeatedly adjusting each of the reference positive electrode curve Rp and the reference negative electrode curve Rn to several levels and then synthesizing their adjustment process. The comparative full-cell curves can also be referred to as "adjusted reference full-cell curves".

[0136] The processor 320 can specify any one of multiple comparative full-cell curves that has the minimum error relative to the measured full-cell curve M. The processor 320 can then determine that the adjusted positive and adjusted negative electrode curves mapped to the specified comparative full-cell curve are the positive and negative electrode curves of the target cell BC.

[0137] In this regard, various methods known at the time of filing of this application can be used to determine the error between two curves, each of which can be represented in a two-dimensional coordinate system. For example, the integral of the absolute value of the area between two curves, or RMSE (root mean square error), can be used as the error between the two curves.

[0138] According to this configuration, various state information about the target cell BC can be obtained based on the finally determined adjusted positive and negative electrode curves. The finally determined adjusted positive and negative electrode curves can be mapped to a comparative full-cell curve mapped with minimal error. In particular, the comparative full-cell curve obtained by the finally determined adjusted positive and negative electrode curves can be almost identical to the measured full-cell curve M in shape, etc.

[0139] Therefore, according to this disclosure, even without disassembling the target cell BC or manufacturing the target cell BC in the form of a 3-electrode battery, the positive and negative electrode curves of the target cell BC can be obtained.

[0140] If the target cell BC is a new battery cell, it is easier to analyze and utilize the adjusted positive and negative electrode curves to diagnose whether a defect has occurred in the target cell BC, and if so, what type of defect it is.

[0141] If the battery cell is used after the target cell BC has been verified as a good product, it is possible to determine how much the target cell BC has deteriorated for each degradation item by means of the adjusted positive and negative electrode curves.

[0142] Furthermore, according to embodiments of this disclosure, the positive and negative electrode curves of the target monomer BC can be obtained in a simple manner. This disclosure can be implemented even if only one reference positive electrode curve Rp and one reference negative electrode curve Rn are stored in the memory cell 330. That is, it is not necessary to store multiple reference positive electrode curves Rp and / or multiple reference negative electrode curves Rn in the memory cell 330. Therefore, a high storage capacity of the memory cell 330 is not required, and the extensive preliminary testing required to ensure multiple reference positive electrode curves Rp and / or multiple reference negative electrode curves Rn is not necessary.

[0143] In the following text, see references Figures 4 to 9 This describes the process of analyzing and measuring the full-cell curve M to estimate one of the parameters involved in the current charge / discharge performance of the target cell BC (e.g., the negative electrode participation start).

[0144] Figures 4 to 6 This is a diagram illustrating an example of the process of generating a comparative full-cell curve for comparison with a measured full-cell curve, according to embodiments of the present disclosure.

[0145] Reference Figures 4 to 6 The described process for generating comparative full-cell curves is used to set four points (positive electrode participation start point, positive electrode participation end point, negative electrode participation start point, negative electrode participation end point) as a first routine corresponding to the voltage range of interest (see [link to documentation]). Figure 4 The second routine used to perform curve shifting (see...) Figure 5 ) and a third routine for performing capacity scaling (see Figure 6 The process is performed in the order of the first routine to the third routine, according to embodiments of the present disclosure.

[0146] First, refer to Figure 4 The reference positive electrode curve Rp and the reference negative electrode curve Rn are compared with Figure 2 The same as those shown.

[0147] The processor 320 determines the positive electrode participation start point (pi), positive electrode participation end point (pf), negative electrode participation start point (ni), and negative electrode participation end point (nf) on the reference positive electrode curve Rp and the reference negative electrode curve Rn.

[0148] The positive electrode participation start point (pi) or the negative electrode participation start point (ni) depends on the other.

[0149] As an example, processor 320 can divide the positive voltage range from the start point to the end point (or second set voltage) of the reference positive curve Rp into multiple small voltage segments, and then set the boundary point of two adjacent small voltage segments as the positive participation start point (pi). Each small voltage segment can have a predetermined size (e.g., 0.01V). Next, processor 320 can set the point on the reference negative curve Rn that is smaller than the positive participation start point (pi) by a first set voltage (e.g., 3V) as the negative participation start point (ni).

[0150] As another example, processor 320 can divide the negative voltage range from the start point to the end point of the reference negative voltage curve Rn into multiple small voltage segments of a predetermined size, and then set the boundary point of two adjacent small voltage segments as the negative participation start point (ni). Next, processor 320 can search for a point from the reference positive voltage curve Rp that is larger than the negative participation start point (ni), and set the searched point as the positive participation start point (pi).

[0151] The positive electrode participation endpoint (pf) or the negative electrode participation endpoint (nf) depends on the other.

[0152] As an example, processor 320 can divide the voltage range from the second set voltage to the endpoint of the reference positive curve Rp into a plurality of small voltage segments of predetermined size, and then set the boundary point of two adjacent small voltage segments among the plurality of small voltage segments as the positive participation endpoint (pf). Next, processor 320 can set the point on the reference negative curve Rn that is lower than the positive participation endpoint (pf) by the second set voltage (e.g., 4V) as the negative participation endpoint (nf).

[0153] As another example, processor 320 can divide the negative voltage range from the start point to the end point of the reference negative voltage curve Rn into multiple small voltage segments of a predetermined size, and then set the boundary point between two adjacent small voltage segments as the negative participation endpoint (nf). Next, processor 320 can search for a point from the reference positive voltage curve Rp that is larger than the negative participation endpoint (nf) by a second predetermined voltage, and set the searched point as the positive participation endpoint (pf).

[0154] If the positive electrode participation start point (pi), positive electrode participation end point (pf), negative electrode participation start point (ni), and negative electrode participation end point (nf) are completely determined, then the processor 320 will shift at least one of the reference positive electrode curve Rp and the reference negative electrode curve Rn to the left or right along the horizontal axis.

[0155] refer to Figure 5 The processor 320 can shift the reference positive curve Rp to the left (towards lower capacity) or shift the reference negative curve Rn to the right (towards higher capacity), or both, so that the capacity values ​​of the positive participation start point (pi) and the negative participation start point (ni) are matched.

[0156] Alternatively, the processor 320 may shift the reference positive curve Rp to the left or shift the reference negative curve Rn to the right or both, so that the capacity values ​​of the positive participation endpoint (pf) and the negative participation endpoint (nf) are matched.

[0157] Figure 5 This illustrates the case where only the positive electrode curve Rp is shifted to the left to generate an adjusted reference positive electrode curve (Rp'), and thus, the capacity value at the positive electrode participation start point (pi') matches the capacity value at the negative electrode participation start point (ni). The adjusted reference positive electrode curve (Rp') is the result of applying an adjustment process to the reference positive electrode curve Rp, which involves shifting the voltage difference between the positive electrode participation start point (pi) and the negative electrode participation start point (ni) to the left. Therefore, the two points (pi, pi') differ only in capacity value and have the same voltage. Similarly, the two points (pf, pf') also differ only in capacity value and have the same voltage.

[0158] If at least one of the reference positive curve Rp and the reference negative curve Rn is shifted, the adjustment result curve (Rp', Rn) is ensured, then the processor 320 scales the capacity range of at least one of the adjustment result curves (Rp', Rn).

[0159] according to Figure 5 In the example shown, processor 320 performs an additional adjustment process to shrink or expand at least one of the adjusted reference positive curve (Rp') and reference negative curve Rn along the horizontal axis.

[0160] refer to Figure 6The processor 320 can generate an adjusted reference positive electrode curve (Rp") by shrinking or expanding the adjusted reference positive electrode curve (Rp'), such that the capacity range between two points (pi', pf') of the adjusted reference positive electrode curve (Rp') matches the capacity range of the measured full-cell curve M. In this case, either point (pi') can be fixed. Therefore, the capacity difference between the two points (pi', pf") of the adjusted reference positive electrode curve (Rp") can match the capacity range of the measured full-cell curve M.

[0161] Furthermore, the processor 320 can generate an adjusted reference negative electrode curve (Rn') by shrinking or expanding the reference negative electrode curve Rn, such that the capacity range between the two points (ni, nf) of the reference negative electrode curve Rn matches the capacity range of the measured full-cell curve M. In this case, either point (ni) can be fixed. Therefore, the capacity difference between the two points (ni, nf') of the adjusted reference negative electrode curve (Rn') can match the capacity range of the measured full-cell curve M.

[0162] exist Figure 6 In the middle, the adjusted reference positive electrode curve (Rp") is the contraction... Figure 5 The results shown are the adjusted reference positive electrode curve (Rp'), and the adjusted reference negative electrode curve (Rn') is an extended... Figure 5 The results of the reference negative electrode curve Rn are shown.

[0163] The positive electrode participation endpoint (pf") on the adjusted reference positive electrode curve (Rp") corresponds to the positive electrode participation endpoint (pf) on the adjusted reference positive electrode curve (Rp'). The negative electrode participation endpoint (nf') on the adjusted reference negative electrode curve (Rn') corresponds to the negative electrode participation endpoint (nf) on the reference negative electrode curve Rn.

[0164] The capacity difference between the positive electrode participation start point (pi') and the positive electrode participation end point (pf") of the adjusted reference positive electrode curve (Rp") corresponds to the size of the capacity range of the full-cell measurement curve M. Similarly, the capacity difference between the negative electrode participation start point (ni) and the negative electrode participation end point (nf') of the adjusted reference negative electrode curve (Rn') corresponds to the size of the capacity range of the full-cell measurement curve M.

[0165] Furthermore, the capacity range of the two points (pi', pf') of the adjusted reference positive electrode curve (Rp") matches the capacity range of the two points (ni, nf') of the adjusted reference negative electrode curve (Rn'). The processor 320 can generate a comparison full-cell curve S by subtracting the curve between the two points (pi, pf') of the adjusted reference positive electrode curve (Rp") from the curve between the two points (ni, nf') of the adjusted reference negative electrode curve (Rn').

[0166] The processor 320 can calculate the error (curve error) between the comparison value of the full-cell curve S and the measured full-cell curve M.

[0167] The processor 320 can map at least two of the following to each other: the adjusted reference positive electrode curve (Rp"), the adjusted reference negative electrode curve (Rn'), the positive electrode participation start point (pi'), the positive electrode participation end point (pf"), the negative electrode participation start point (ni), the negative electrode participation end point (nf'), the positive electrode scaling factor, the negative electrode scaling factor, the comparison full cell curve S, and the curve error, and record them in the memory unit 330.

[0168] The positive electrode scaling factor can represent the ratio of the capacity difference between the two ends of the adjusted reference positive electrode curve (Rp") to the capacity difference between the two ends of the reference positive electrode curve Rp. Alternatively, the positive electrode scaling factor can represent the ratio of the capacity difference between two points (pi', pf") to the capacity difference between two points (pi0, pf0). Alternatively, the positive electrode scaling factor can represent the ratio of the positive electrode capacity difference between two points (pi', pf") to the positive electrode capacity difference between two points (pi0, pf0). Alternatively, the positive electrode scaling factor can represent the ratio of the positive electrode SOC difference between two points (pi', pf") to the positive electrode SOC difference between two points (pi0, pf0).

[0169] The negative electrode scaling factor can represent the ratio of the capacity difference between the two ends of the adjusted reference negative electrode curve (Rn') to the capacity difference between the two ends of the reference negative electrode curve Rn. Alternatively, the negative electrode scaling factor can represent the ratio of the capacity difference between two points (ni, nf') to the capacity difference between two points (ni0, nf0). Alternatively, the negative electrode scaling factor can represent the ratio of the negative electrode capacity difference between two points (ni, nf') to the negative electrode capacity difference between two points (ni0, nf0). Alternatively, the negative electrode scaling factor can represent the ratio of the negative electrode SOC difference between two points (ni, nf') to the negative electrode SOC difference between two points (ni0, nf0).

[0170] Meanwhile, as mentioned above, when the positive voltage range of the reference positive curve Rp is divided into multiple small voltage segments, the boundary point of two adjacent small voltage segments among the multiple small voltage segments can be set as the positive participation start point (pi).

[0171] For example, if the positive voltage range of the reference positive electrode curve Rp is divided into 100 smaller voltage ranges, then 100 boundary points can be set as the positive electrode participation start point (pi). Furthermore, if the voltage range in the reference positive electrode curve Rp that is greater than or equal to a second set voltage is divided into 40 smaller voltage ranges, then 40 boundary points can be set as the positive electrode participation end point (pf). In this case, at least 4,000 different comparative full-cell curves can be generated.

[0172] Of course, those skilled in the art will readily understand that as the size of the small voltage segment decreases, the maximum number of comparative full-cell curves that can be generated increases, and conversely, as the size of the small voltage segment increases, the maximum number of comparative full-cell curves that can be generated decreases.

[0173] The processor 320 can identify the minimum curve error among the multiple comparison full-cell curves generated as described above, and then obtain information mapped to the minimum curve error from the memory unit 330 (e.g., at least one of positive electrode participation start point, positive electrode participation end point, negative electrode participation start point, negative electrode participation end point, positive electrode scaling factor, and negative electrode scaling factor).

[0174] Figures 7 to 9 This is a diagram referenced to further illustrate the process of generating a comparative full-cell curve for comparison with a measured full-cell curve, according to embodiments of the present disclosure. For reference, Figures 7 to 9 The embodiments shown are independent of Figures 4 to 6 The illustrated embodiment. Therefore, it is commonly used to describe Figures 4 to 6 The illustrated embodiments and Figures 7 to 9 The terminology or reference numerals in the embodiments shown should be understood to be limited to each embodiment.

[0175] The generation will refer to Figures 7 to 9 The process of comparing full-cell curves can be performed by following the fourth routine of capacity scaling (see [link]). Figure 7 The fifth routine sets four points (positive electrode participation start point, positive electrode participation end point, negative electrode participation start point, and negative electrode participation end point) (see...). Figure 8 ) and the sixth routine for performing curve shifting (see Figure 9 The process of generating a comparison full-cell curve according to another embodiment of this disclosure includes the fourth to sixth routines.

[0176] refer to Figure 7The processor 320 generates an adjusted reference positive curve (Rp') and an adjusted reference negative curve (Rn') by applying positive and negative scaling factors selected from the scaling value range to the reference positive curve Rp and the reference negative curve (Rn), respectively.

[0177] The scaling range can be predetermined or it can vary depending on the ratio of the capacity range of the measured full-cell curve M to the capacity range of the reference full-cell curve (R). As an example, assuming the positive and negative scaling factors can be selected from values ​​at intervals of 0.1% within the scaling range (e.g., 90% to 99%) (i.e., 90%, 90.1%, 90.2%, ... 98.9%, 99%), 91 values ​​can be selected as the positive and negative scaling factors, respectively. In this case, based on 91 × 91 = 8,281 adjustment levels (combinations of the positive and negative scaling factors), a maximum of 8,281 adjusted curve pairs can be generated. An adjusted curve pair refers to a combination of an adjusted positive curve and an adjusted negative curve.

[0178] refer to Figure 7 The adjusted reference positive electrode curve (Rp') and the adjusted reference negative electrode curve (Rn') show the results of applying the positive electrode scaling factor and the negative electrode scaling factor to the reference positive electrode curve Rp and the reference negative electrode curve Rn, respectively.

[0179] Since the positive and negative scaling factors are less than 100%, the adjusted reference positive curve (Rp') is obtained by shrinking the reference positive curve Rp along the horizontal axis, and the adjusted reference negative curve (Rn') is also obtained by shrinking the reference negative curve Rn along the horizontal axis. For ease of understanding, the reference positive curve Rp and the reference negative curve Rn are shown with their starting points fixed and the remaining portions shrunk to the left along the horizontal axis.

[0180] refer to Figure 8 The processor 320 determines the positive electrode participation start point (pi'), positive electrode participation end point (pf'), negative electrode participation start point (ni'), and negative electrode participation end point (nf') on the adjusted reference positive electrode curve (Rp') and the adjusted reference negative electrode curve (Rn').

[0181] One of the positive electrode participation start point (pi') or the negative electrode participation start point (ni') can depend on the other. Furthermore, one of the positive electrode participation end point (pf') or the negative electrode participation end point (nf') can depend on the other. Moreover, one of the positive electrode participation start point (pi') or the positive electrode participation end point (pf') can be set based on the other.

[0182] In other words, if any one of the positive electrode participation start point (pi'), positive electrode participation end point (pf'), negative electrode participation start point (ni'), and negative electrode participation end point (nf') is set, the remaining three points can be automatically set by the first set voltage, the second set voltage, and / or the capacity range of the measured full-cell curve M (e.g., Figure 3b (45Ah - 5Ah = 40Ah).

[0183] As an example, processor 320 can divide the positive voltage range from the start point to the end point (or the second set voltage) of the adjusted reference positive curve (Rp') into multiple small voltage segments, and then set the boundary point of two adjacent small voltage segments as the positive participation start point (pi'). Next, processor 320 can set the point on the adjusted reference negative curve (Rn') that is lower than the positive participation start point (pi') by a first set voltage (e.g., 3V) as the negative participation start point (ni').

[0184] As another example, processor 320 can divide the negative voltage range from the start point to the end point of the adjusted reference negative voltage curve (Rn') into multiple small voltage segments of predetermined size, and then set the boundary point of two adjacent small voltage segments as the negative participation start point (ni'). Next, processor 320 can search for a point on the reference positive voltage curve (Rp) that is larger than the negative participation start point (ni') by a first predetermined voltage, and select the searched point as the positive participation start point (pi').

[0185] As another example, processor 320 can divide the voltage range from the second set voltage to the endpoint of the adjusted reference positive curve (Rp') into a plurality of small voltage segments of predetermined size, and then set the boundary point of two adjacent small voltage segments among the plurality of small voltage segments as the positive participation endpoint (pf'). Next, processor 320 can search for a point in the adjusted reference negative curve (Rn') that is smaller than the second set voltage (e.g., 4V) than the positive participation endpoint (pf'), and set the searched point as the negative participation endpoint (nf').

[0186] As another example, processor 320 can divide the negative voltage range from the start point to the end point of the reference negative voltage curve (Rn') into multiple small voltage segments of predetermined size, and then set the boundary point of two adjacent small voltage segments as the negative participation endpoint (nf'). Next, processor 320 can search from the adjusted reference positive voltage curve (Rp') for a point that is a second predetermined voltage larger than the negative participation endpoint (nf'), and set the searched point as the positive participation endpoint (pf').

[0187] If any one of the positive electrode participation start point (pi'), positive electrode participation end point (pf'), negative electrode participation start point (ni'), and negative electrode participation end point (nf') is determined, the processor 320 can additionally determine the remaining three points based on the determined point.

[0188] For example, if the positive electrode participation start point (pi') is determined first, the processor 320 can set the point on the adjusted reference positive electrode curve (Rp') with a capacity value that is larger than the capacity range of the measured full-cell curve M by the capacity value of the positive electrode participation start point (pi') and set it as the positive electrode participation end point (pf'). Furthermore, the processor 320 can search for a point on the adjusted reference negative electrode curve (Rn') with a voltage lower than the positive electrode participation start point (pi') and set the searched point as the negative electrode participation start point (ni'). Additionally, the processor 320 can set the point on the adjusted reference negative electrode curve (Rn') with a capacity value that is larger than the capacity range of the measured full-cell curve M by the capacity value of the negative electrode participation start point (ni') and set it as the negative electrode participation end point (nf').

[0189] As another example, when first determining the positive electrode participation endpoint (pf'), the processor 320 can set a point on the adjusted reference positive electrode curve (Rp') with a capacity value that is smaller than the capacity range of the full-cell curve M measured by the positive electrode participation endpoint (pf') as the positive electrode participation start point (pi'). Furthermore, the processor 320 can search for a point on the adjusted reference negative electrode curve (Rn') with a voltage lower than the positive electrode participation endpoint (pf') and set the searched point as the negative electrode participation endpoint (nf'). Additionally, the processor 320 can set a point on the adjusted reference negative electrode curve (Rn') with a capacity value that is smaller than the capacity range of the full-cell curve M measured by the negative electrode participation endpoint (nf') as the negative electrode participation start point (ni').

[0190] As another example, when determining the negative electrode participation start point (ni'), the processor 320 can set the point on the adjusted reference negative electrode curve (Rn') whose capacity value is greater than the capacity value of the full-cell curve M by a factor of 100 (ni') to be the negative electrode participation end point (nf'). Furthermore, the processor 320 can search for a point on the adjusted reference positive electrode curve (Rp') that is higher than the negative electrode participation start point (ni') by a first set voltage, and set the searched point as the positive electrode participation start point (pi'). Additionally, the processor 320 can set the point on the adjusted reference positive electrode curve (Rp') whose capacity value is greater than the capacity value of the full-cell curve M by a factor of 100 (pi') to be the positive electrode participation end point (pf').

[0191] As another example, when determining the negative electrode participation endpoint (nf'), the processor 320 can set a point on the adjusted reference negative electrode curve (Rn') whose capacity value is smaller than the capacity value of the negative electrode participation endpoint (nf') within the capacity range of the measured full-cell curve M as the negative electrode participation start point (ni'). Furthermore, the processor 320 can search for a point on the adjusted reference positive electrode curve (Rp') that is higher than the negative electrode participation endpoint (nf') by a second set voltage, and set the searched point as the positive electrode participation endpoint (pf'). Additionally, the processor 320 can set a point on the adjusted reference positive electrode curve (Rp') with a capacity value smaller than the capacity value of the measured full-cell curve M within the capacity range of the positive electrode participation endpoint (pf') as the positive electrode participation start point (pi').

[0192] If the positive electrode participation start point (pi'), positive electrode participation end point (pf'), negative electrode participation start point (ni'), and negative electrode participation end point (nf') are determined entirely based on the pairing of positive and negative electrode scaling factors, then the processor 320 may shift at least one of the adjusted reference positive electrode curve (Rp') and the adjusted reference negative electrode curve (Rn') to the left or right along the horizontal axis, such that the capacity values ​​of the positive electrode participation start point (pi') and the negative electrode participation start point (ni') match or the capacity values ​​of the positive electrode participation end point (pf') and the negative electrode participation end point (nf') match.

[0193] Figure 9 The adjusted reference negative electrode curve (Rn") shown is obtained by only using Figure 8 The adjusted reference negative electrode curve (Rn') shown is obtained by shifting it to the right. Therefore, the capacity values ​​of the positive electrode participation start point (pi') and the negative electrode participation start point (ni") are matched on the horizontal axis. Correspondingly, the capacity difference between the positive electrode participation start point (pi') and the positive electrode participation end point (pf') is equal to the capacity difference between the negative electrode participation start point (ni') and the negative electrode participation end point (nf'). Therefore, if the capacity values ​​of the positive electrode participation start point (pi') and the negative electrode participation start point (ni') are matched, then the capacity values ​​of the positive electrode participation end point (pf') and the negative electrode participation end point (nf') are also matched.

[0194] refer to Figure 9 The processor 320 can generate a comparison full-cell curve U by subtracting the portion of the curve between two points (ni" and nf") of the adjusted reference positive curve (Rp') from the portion of the curve between two points (pi' and pf') of the adjusted reference negative curve (Rn").

[0195] The processor 320 can calculate and compare the error (curve error) between the full-cell curve U and the measured full-cell curve M.

[0196] The processor 320 may map at least two of the adjusted reference positive curve (Rp'), adjusted reference negative curve (Rn"), positive participation start point (pi'), positive participation end point (pf'), negative participation start point (ni"), negative participation end point (nf"), positive scaling factor, negative scaling factor, compare the full cell curve U and the curve error, and record them in the memory unit 330.

[0197] As described above, the processor 320 may generate a comparison full cell curve corresponding to each pair of the positive scaling factor and the negative scaling factor selected from the scaling value range. Since the pairs of the positive scaling factor and the negative scaling factor are plural, it is obvious that the comparison curves will also be generated in plural. The processor 320 may identify the minimum value among the curve errors of the plurality of comparison full cell curves, and then obtain the information mapped to the minimum curve error from the memory unit 330.

[0198] The processor 320 may extract at least the negative participation start point ( Figure 6 ni' of Figure 9 or ni" of

[0199] from the information mapped to the minimum curve error. As a reference, when the target cell BC is in a new state, at least one of the positive participation start point, positive participation end point, negative participation start point, negative participation end point, positive scaling factor, and negative scaling factor may have been recorded in the memory unit 330 by performing the above analysis process when the target cell BC is in a new state.

[0200]

[0201] Each variable listed in Table 1 is a diagnostic factor that can be determined by the above analysis process. The definitions of the degradation parameters and variables in Table 1 may be as follows. <Degradation parameter>

[0202] P SOH : Positive SOH (State of Health) of the target cell BC

[0203] N SOH : Negative SOH of the target cell BC

[0204] L SOH : Available lithium SOH of the target cell BC

[0205] F SOH : Full cell SOH of the target cell BC

[0206] P LOSS: Cathode loss rate of target single cell BC

[0207] N LOSS Negative electrode loss rate of target monomer BC

[0208] L LOSS Available lithium loss rate of target monomer BC

[0209] F LOSS : Total cell loss rate of target single cell BC

[0210] P loading_MOL : Cathode loading of target cell BC

[0211] N loading_MOL The negative electrode loading of the target single cell BC

[0212] As any battery cell deteriorates, at least one of the following parameters for that cell—total positive electrode capacity, total negative electrode capacity, available lithium, and total full cell capacity—will gradually decrease from its value at the BOL (Baltic Oxide) state. Total full cell capacity can be represented as the capacity difference between the two endpoints of the full cell curve. For example, total full cell capacity can mean the full charge capacity (FCC). Available lithium can represent the total amount of lithium that can contribute to the charging and discharging of the battery cell. SOH It can represent the retention rate of the total positive electrode capacity. N SOH It can represent the retention rate of the total negative electrode capacity. L SOH It can indicate the maintenance rate of available lithium. F SOH It can represent the retention rate of the total full battery capacity.

[0213] P SOH and P LOSS The sum of N SOH and N LOSS The sum of L SOH and L LOSS The sum and F SOH and F LOSS The sum of these can all equal 1. F LOSS It can be equal to P LOSS and L LOSS sum.

[0214] The positive electrode loading of any battery cell represents the amount of positive electrode active material (or usable capacity) per unit area of ​​the positive electrode of the battery cell. The negative electrode loading of any battery cell represents the amount of negative electrode active material (or usable capacity) per unit area of ​​the negative electrode of the battery cell. The unit of loading can be mAh / cm². 2 or mg / cm 2 In Table 1, P loading_ref This indicates the reference positive electrode load, and N loading_refThe reference negative electrode loading is a predetermined value representing the amount of positive electrode active material (or available capacity) per unit area of ​​the positive electrode of the reference monomer. The reference positive electrode loading can be a value obtained by dividing the reference positive electrode capacity by the reference positive electrode area. Here, the reference positive electrode capacity can be a value preset as the total positive electrode capacity of the reference monomer. The reference positive electrode area can be a value preset as the area of ​​the positive electrode of the reference monomer. The reference negative electrode loading is a predetermined value representing the amount of negative electrode active material (or available capacity) per unit area of ​​the negative electrode of the reference monomer. The reference negative electrode loading can be a value obtained by dividing the reference negative electrode capacity by the reference negative electrode area. Here, the reference negative electrode capacity can be a value preset as the total negative electrode capacity of the reference monomer. The reference negative electrode area can be a value preset as the area of ​​the negative electrode of the reference monomer.

[0215] <variable>

[0216] pi BOL When the target single cell BC is in the BOL state, the positive electrode capacity (positive electrode SOC) at the starting point of the positive electrode participation.

[0217] pi MOL The current positive electrode participation starting point of the target monomer BC (e.g., Figure 6 The positive electrode capacity (positive electrode SOC) of pi' shown in the figure.

[0218] pf BOL When the target single cell BC is in the BOL state, the positive electrode participates in the final positive electrode capacity (positive electrode SOC).

[0219] pf MOL The current positive electrode of the target cell BC participates in the endpoint (e.g., Figure 6 The positive electrode capacity (positive electrode SOC) shown is pf".

[0220] ni BOL When the target monomer BC is in the BOL state, the negative electrode capacity (negative electrode SOC) at the negative electrode participation starting point.

[0221] ni MOL The current negative electrode participation starting point of the target monomer BC (e.g., Figure 6 The negative electrode capacity (negative electrode SOC) of ni shown in the figure.

[0222] nf BOL When the target monomer BC is in the BOL state, the negative electrode participates in the final negative electrode capacity (negative electrode SOC).

[0223] nf MOL The current negative electrode of the target monomer BC participates in the endpoint (e.g., Figure 6 The negative electrode capacity (negative electrode SOC) of nf' shown in the figure.

[0224] ps BOL : Positive scaling factor when the target single cell BC is in the BOL state

[0225] ps MOL : Current positive scaling factor of target cell BC

[0226] ns BOL Negative scaling factor when the target single unit BC is in the BOL state.

[0227] ns MOL : Current negative pole scaling factor of target single cell BC

[0228] As the available lithium capacity, total positive electrode capacity, and / or total negative electrode capacity of any single battery cell decrease, the negative electrode capacity at the point of negative electrode participation (negative electrode SOC) of the battery cell can exhibit a gradual change (increasing or decreasing) characteristic. The available lithium content of any single battery cell can be a parameter representing the total amount of lithium that can contribute to the charging and discharging of the battery cell. Due to side reactions and other processes occurring within the battery cell during charging and discharging, the available lithium content can gradually decrease from a new state of product.

[0229] Based on these characteristics, processor 320 can determine the performance degradation factor of the target cell BC due to the loss of at least one of the available lithium and the total cathode capacity, based on the estimation of the negative electrode participation start point of the target cell BC. The performance degradation factor can indicate whether there is a loss of available lithium, whether there is a capacity loss of the cathode, and / or whether there is a capacity loss of the negative electrode.

[0230] The processor 320 can determine the performance degradation factor associated with the amount of reduction in negative capacity at the current time of negative participation starting point based on a predetermined positive correlation between the amount of reduction in negative capacity (or negative SOC) indicating the negative participation starting point from the new product state and the performance degradation factor.

[0231] There may be cases where the change in positive electrode capacity (or positive electrode SOC) at the positive electrode participation start point and negative electrode capacity (or negative electrode SOC) at the negative electrode participation end point from the new product state is less than a predetermined set value. If so, the processor 320 can determine that the capacity loss of at least one of the positive and negative electrodes contributes more to the change in the negative electrode participation start point of the target monomer BC from the new product state than the loss of available lithium, because the increase in negative electrode capacity (or negative electrode SOC) at the negative electrode participation start point from the new product state is greater.

[0232] There may be a situation where the change in negative electrode capacity (or negative electrode SOC) at the negative electrode participation starting point of the target monomer BC from the new product state is less than a predetermined value. If so, the processor 320 can determine that the loss of available lithium is greater because the reduction in negative electrode capacity (or negative electrode SOC) at the negative electrode participation ending point of the target monomer BC from the new product state is greater.

[0233] The process of identifying diagnostic factors for a target monomer BC can be repeated periodically or non-periodically throughout the lifetime of the target monomer BC.

[0234] Processor 320 can limit at least one of the allowable voltage range and allowable SOC range of target cell BC based on the estimated negative electrode participation start point of target cell BC. Relationship data indicating a predetermined positive correlation between the amount of change (e.g., reduction) in negative electrode capacity from the negative electrode participation start point of the new product state and the limit level can be pre-stored in memory unit 330. That is, according to the relationship data, a decrease or increase in the capacity value (negative electrode capacity or negative electrode SOC) of the negative electrode participation start point can lead to a decrease in at least one of the allowable voltage range and allowable SOC range. A decrease in range means at least one of increasing the lower limit of the range and decreasing the upper limit of the range.

[0235] For example, suppose the permissible voltage range and permissible SOC range are 2.5V to 4.5V and 5% to 95%, respectively. If the negative electrode capacity at the starting point is estimated to be 90% of the value under BOL conditions, the permissible voltage range can be reduced to 2.75V to 4.05V, and the permissible SOC range can be reduced to 5.5% to 85.5%.

[0236] Figure 10 This is an exemplary flowchart describing a battery diagnostic method according to a first embodiment of the present disclosure. Figure 10 The method can be performed by a battery diagnostic device.

[0237] In step S1010, the processor 320 controls the stimulation application device 301 to intermittently apply a second electrical stimulus greater than the first electrical stimulus to the target monomer BC during the state change period until the electrical state of the target monomer BC is changed from the initial state to the target state.

[0238] In step S1020, the processor 320 uses the communication unit 310 to obtain current time-series data representing the history of current changes in the target cell BC during the state-change period and voltage time-series data representing the history of full-cell voltage changes in the target cell BC during the rest period of the second electrical stimulation given in the state-change period. The voltage time-series data may include measurements of the full-cell voltage at the end of each rest period (see [link to relevant documentation]). Figure 3a DOCV ).

[0239] The communication unit 310 can collect the current time series data and voltage time series data generated by the electric vehicle 1 from the electric vehicle 1 after the state change period ends.

[0240] Alternatively, the communication unit 310 may periodically collect measurement data from the electric vehicle 1 during state-change periods, representing at least one measurement of the current of the target cell BC and the total battery voltage. In this case, each measurement collected multiple times during the state-change period may be recorded in the memory unit 330 in chronological order. The processor 320 may generate current time-series data and voltage time-series data from this set of measurements collected during the state-change period.

[0241] In step S1030, the processor 320 generates a measured full-cell curve indicating the correspondence between the capacity of the target cell BC and the full-cell voltage based on the current time-series data and the voltage time-series data (see [link to full-cell curve]). Figure 3b M in (the middle part).

[0242] In step S1040, the processor 320 analyzes the full cell curve M to estimate the negative electrode participation start point of the target cell BC.

[0243] In step S1050, the processor 320 determines the performance degradation factor of the target monomer BC based on the estimated negative electrode participation start point.

[0244] In step S1060, processor 320 limits at least one of the allowable voltage range and allowable SOC range of target cell BC based on the estimated negative electrode participation start point. Alternatively, the allowable current of target cell BC may be limited (reduced).

[0245] According to Figure 10 In the method, at least one of steps S1050 and S1060 can be omitted.

[0246] In step S1070, the processor 320 may use the communication unit 310 to send the diagnostic results of the target cell BC to the electric vehicle 1. The diagnostic results include at least one of the following: negative electrode participation start point, performance degradation factor, limited permissible voltage range, and limited permissible SOC range.

[0247] Figure 11 This is a flowchart illustrating, exemplarily, a battery diagnostic method according to a second embodiment of the present disclosure. Figure 11 The method can be performed by a battery diagnostic device.

[0248] In step S1110, the processor 320 controls the stimulation application device 301 to intermittently apply a second electrical stimulus greater than the first electrical stimulus to the target monomer BC during the state change period until the electrical state of the target monomer BC is changed from the initial state to the target state.

[0249] In step S1120, the processor 320 uses the communication unit 310 to obtain current time series data representing the history of current changes in the target cell BC during the state change period and voltage time series data representing the history of full cell voltage changes in the target cell BC during the rest period of the second electrical stimulation given during the state change period.

[0250] Unlike the first embodiment described above, the voltage time series data obtained in step S1120 includes measurements of the full cell voltage taken three or more times during each rest period.

[0251] In step S1122, the processor 320 applies OCV estimation logic to the voltage time series data acquired in step S1120 to generate corrected voltage time series data. OCV estimation logic can be provided to replace a set of measurements of three full-cell voltages for each rest period included in the voltage time series data acquired in step S1120 with a single OCV value. Therefore, if a total of X rest periods are permitted during the state change period and the full-cell voltage is measured three times for each rest period, those skilled in the art will readily understand that the voltage time series data acquired in step S1120 will include 3X full-cell voltage measurements, and the corrected voltage time series data will include X OCV values.

[0252] In step S1130, processor 320 generates a measured full-cell curve indicating the correspondence between the capacity of the target cell BC and the full-cell voltage based on current time-series data and corrected voltage time-series data (see [link to full-cell curve]). Figure 3b M in (the middle part).

[0253] In step S1140, processor 320 analyzes and measures the full cell curve M to estimate the negative electrode participation start point of the target cell BC.

[0254] In step S1150, the processor 320 determines the performance degradation factor of the target monomer BC based on the estimated negative electrode participation start point.

[0255] In step S1160, processor 320 limits at least one of the allowable voltage range and allowable SOC range of target cell BC based on the estimated negative electrode participation start point. Alternatively, the allowable current of target cell BC may be limited (reduced).

[0256] According to Figure 11In the method, at least one of steps S1150 and S1160 may be omitted.

[0257] In step S1170, the processor 320 can send the diagnostic results of the target cell BC to the electric vehicle 1 via the communication unit 310. The diagnostic results include at least one of the following: negative electrode participation start, performance degradation factor, limited permissible voltage range, and limited permissible SOC range.

[0258] Figure 12 It is described in Figure 11 The diagram referenced in step S1122, which involves the process of correcting the voltage time series data.

[0259] Figure 12 The symbol 1200 indicates Figure 3a One of the voltage drop segments described herein. t R Indicates the time point elapsed from the start time of the rest period to the reference time. Until t R The portion is depicted as a solid line, and t R The subsequent part is depicted as a dashed line.

[0260] refer to Figure 12 During each rest period, the target cell BC is placed in a no-load state—neither charging nor discharging.

[0261] During the no-load period, the full-cell voltage of the target cell BC gradually converges toward the OCV corresponding to the SOC of the target cell BC. The behavior of the full-cell voltage of the target cell BC during a specific rest period can be equivalent to the voltage response of the primary RC circuit, as shown in Equation 1 below.

[0262] <Formula 1>

[0263]

[0264] In Formula 1, t is the time elapsed from the start point of a specific rest period, and V is the time elapsed from the start point of the rest period. full (t) is the full cell voltage at point t, V OCV It is the actual OCV, V S It is the full cell voltage at the start of a specific rest period, and τ is a time constant determined by the internal resistance and capacitance of the target cell BC.

[0265] In Formula 1, V full (t) is measurable, therefore V OCV 、V S And τ are unknown. Since there are three unknowns, V can be determined based on measurements at three different timing points within a specific rest period. full(t) is used to estimate the OCV for a specific rest period. Formula 2 below can be used to estimate the OCV for each rest period.

[0266] <Formula 2>

[0267]

[0268] In Formula 2, t1, t2, and t3 are the timing parameters for the sequential measurement of the full-cell voltage. The time difference between t1 and t2 can be the same as the time difference between t2 and t3. Meanwhile, in Figure 12 In the middle, t R t3 is shown as different, but t R =t3 is also possible. In this case, V full (t3) = D OCV .

[0269] Processor 320 can be coupled with V calculated by Formula 2 OCV Determine D in the same way OCV_C .

[0270] Processor 320 can reuse a single OCV value (D) for all rest periods. OCV_C Replace the three full-cell voltage measurements (V) for each rest period. full (t1), V full (t2), V full The process (t3) transforms the voltage time series data obtained in step S1120 into the corrected voltage time series data of step S1130. The corrected voltage time series data contains X OCV values. The processor 320 can apply curve fitting logic to the corrected voltage time series data to generate a measurement full-cell curve M.

[0271] For reference, D OCV It is the measured value of the full cell voltage at the end of the rest period (before the polarization is completely resolved), while D OCV_C The full cell voltage (i.e., V) is the voltage when polarization is completely eliminated. OCV The estimated value of D. Therefore, it can be considered that D... OCV_C Compared to D OCV The actual OCV is closer to that of the target monomer BC.

[0272] The embodiments of the present disclosure described above are not implemented solely by means of apparatus and methods, but can be implemented by a program that performs functions corresponding to the configuration of the embodiments of the present disclosure or by a recording medium on which the program is recorded, and such implementation can be readily achieved by those skilled in the art from the disclosure of the previously described embodiments.

[0273] While this disclosure has been described above with respect to a limited number of embodiments and accompanying drawings, this disclosure is not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes can be made to it within the technical aspects of this disclosure and within the equivalent scope of the appended claims.

[0274] Furthermore, since those skilled in the art can make many substitutions, modifications and changes to the above-described disclosure without departing from the technical aspects of this disclosure, this disclosure is not limited to the above embodiments and drawings, and some or all of the embodiments can be selectively combined to allow for various modifications.

Claims

1. A battery diagnostic device, comprising: A processor configured to control a stimulation application device to intermittently apply a second electrical stimulus greater than the first electrical stimulus to the target cell during a state change period prior to the electrical state of the target cell, which is the battery cell to be diagnosed, being changed from an initial state to a target state. as well as A communication unit configured to acquire current time-series data representing the history of current changes in the target cell during the state change period and voltage time-series data representing the history of full-cell voltage changes in the target cell during a rest period of the second electrical stimulation given in the state change period. The processor is configured as follows: Based on the current time series data and the voltage time series data, a measured full-cell curve representing the correspondence between the capacity of the target cell and the full-cell voltage is generated, and The negative electrode participation start point is estimated by analyzing the measured full-cell curve as a parameter representing the charge / discharge performance of the negative electrode of the target cell.

2. The battery diagnostic device according to claim 1, wherein, The first electrical stimulation is an electrical stimulation that causes the difference between the OCV and CCV in the target monomer to be equal to or less than a reference value, and The second electrical stimulation is an electrical stimulation that causes the difference between the OCV and the CCV in the target monomer to be greater than the reference value.

3. The battery diagnostic device according to claim 1, wherein, The first electrical stimulation is performed by charging using a first current rate, and The second electrical stimulation is performed by charging with a second current rate greater than the first current rate.

4. The battery diagnostic device according to claim 1, wherein, The first electrical stimulation is performed by discharging using a first current rate, and The second electrical stimulation is achieved by discharging a second current rate greater than the first current rate.

5. The battery diagnostic device according to claim 1, wherein, The voltage time series data are measurements of the full cell voltage during the rest period of the second electrical stimulation, and the measurements are arranged in chronological order as the OCV of the target cell.

6. The battery diagnostic device according to claim 1, wherein, The processor is configured to control the stimulation application device to initiate a rest period of the second electrical stimulation whenever the current integral value of the current changes the threshold integral value.

7. The battery diagnostic device according to claim 6, wherein, The processor is configured to control the stimulation application device to resume the application of the second electrical stimulation after a reference time has elapsed from the start time of the rest period of the second electrical stimulation.

8. The battery diagnostic device according to claim 1, wherein, The processor is configured to determine the performance degradation factor of the target monomer based on the estimated negative electrode participation start point.

9. The battery diagnostic device according to claim 1, wherein, The processor is configured to limit at least one of the allowable voltage range and allowable SOC range of the target cell based on the estimated negative electrode participation start point.

10. A charging station comprising a battery diagnostic device according to any one of claims 1-9.

11. A cloud server comprising a battery diagnostic device according to any one of claims 1-9.

12. A battery diagnostic method, comprising: The stimulation application device controls the application of a second electrical stimulus, greater than the first electrical stimulus, to the target cell during a state change period before the electrical state of the target cell, which is the cell to be diagnosed, is changed from an initial state to a target state. Obtain current time series data representing the history of current changes in the target cell during the state change period and voltage time series data representing the history of full cell voltage changes in the target cell during the rest period of the second electrical stimulation given in the state change period. A measured full-cell curve representing the correspondence between the capacity of the target cell and the full-cell voltage is generated based on the current time series data and the voltage time series data. as well as By analyzing the measured full-cell curve, the negative electrode participation start point is estimated as a parameter representing the charge / discharge performance of the negative electrode of the target cell.

13. The battery diagnostic method according to claim 12, wherein, The voltage time series data are measurements of the full cell voltage during the rest period of the second electrical stimulation, and the measurements are arranged in chronological order as the OCV of the target cell.

14. The battery diagnostic method according to claim 12, further comprising: The performance degradation factor of the target monomer is determined based on the estimated negative electrode participation starting point.

15. The battery diagnostic method according to claim 12, further comprising: The target cell's permissible voltage range and permissible SOC range are limited based on the estimated negative electrode participation start point.

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