Battery diagnostic method and battery diagnostic device

Abstract

The battery diagnostic method and battery diagnostic device are started. The battery diagnostic method according to the present invention includes the steps of: performing an intermittent application process of electrical stimulation to a battery cell; acquiring state history data of the battery cell corresponding to the state change period from a first state to a second state by the intermittent application process; generating a measured full cell profile showing the correspondence between the capacity and voltage of the battery cell based on the state history data; and analyzing the measured full cell profile to generate first diagnostic information including at least one diagnostic factor relating to the charge / discharge performance of the target cell.

Description

[Technical Field]

[0001] This invention relates to a technique for diagnosing the condition of a battery in a non-destructive manner.

[0002] This application claims priority based on Korean Patent Application No. 10-2023-0154875 filed on 9 November 2023, Korean Patent Application No. 10-2024-0057162 filed on 29 April 2024, and Korean Patent Application No. 10-2023-0133644 filed on 6 October 2023, and all contents disclosed in the specifications and drawings of said applications are incorporated into this application. [Background technology]

[0003] In recent years, demand for portable electronic products such as laptop computers, video cameras, and mobile phones has grown rapidly, and as development of electric vehicles, energy storage batteries, robots, and artificial satellites intensifies, research into high-performance batteries that can be repeatedly charged and discharged is becoming increasingly active.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among these, lithium batteries are attracting attention because they exhibit almost no memory effect compared to nickel-based batteries, allowing for flexible charging and discharging, and they have advantages such as a very low self-discharge rate and high energy density.

[0005] While various studies are being conducted on such batteries from the perspective of increasing capacity and density, improving lifespan and safety is also important. To improve battery safety, the current condition of the battery must be accurately diagnosed.

[0006] Accurate diagnosis of the internal state of a battery cell can be said to be essential for improving the safety and extending the service life of battery cells. When diagnosing the internal state of a battery cell without disassembly, relational data indicating the correspondence between capacity and voltage (which may be referred to as a "full-cell profile" or the like) is mainly used.

[0007] Conventionally, a full-cell profile is obtained by repeating, at short intervals, the process of measuring the voltage and capacity of a battery cell while a constant electric stimulation (for example, constant current charging or discharging) is applied to the battery cell. However, in order to minimize polarization (or overvoltage) that causes a decrease in diagnostic accuracy, it is necessary to lower the level of electric stimulation applied to the battery cell as much as possible, which results in the constraint that obtaining a full-cell profile takes an excessive amount of time. Conversely, although a high level of electric stimulation is advantageous in terms of shortening time, it is accompanied by severe polarization, so the accuracy of the diagnostic result cannot be guaranteed. Summary of the Invention Problem to be Solved by the Invention

[0008] The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a battery diagnostic method and a battery diagnostic apparatus that perform an intermittent application process of electric stimulation in which application and removal of electric stimulation are alternately repeated, and acquire relational data that directly or indirectly indicates the correspondence between the capacity and voltage of a battery cell. Polarization induced in a battery cell during an application period of electric stimulation naturally decreases during a rest period of electric stimulation. Therefore, even if the electric stimulation used in the intermittent application process has a high level, the actual charge-discharge characteristics of the battery cell can be sufficiently reflected in the acquired relational data.

[0009] Furthermore, the present invention aims to provide a battery diagnostic method and a battery diagnostic device that can generate diagnostic information regarding the charge and discharge performance of a battery cell based on relational data obtained by performing an intermittent application process.

[0010] Other objects and advantages of the present invention can be understood from the following description and more clearly from the embodiments of the present invention. Furthermore, the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0011] A battery diagnostic method according to one aspect of the present invention includes the steps of: acquiring state history data of a battery cell corresponding to the state change period from a first state to a second state by an intermittent application process of electrical stimulation to the battery cell; generating a measured full cell profile showing the correspondence between the capacity and voltage of the battery cell based on the state history data; and analyzing the measured full cell profile to generate first diagnostic information including at least one diagnostic factor relating to the charge and discharge performance of the battery cell.

[0012] Electrical stimulation can be a current stimulus that induces a momentary voltage change exceeding a threshold in the battery cell.

[0013] The electrical stimulation may be a current stimulation that induces an overvoltage exceeding a threshold in the battery cell when the electrical stimulation is continuously applied over a predetermined period of time.

[0014] The electrical stimulation may be a charging current having a predetermined current rate.

[0015] The electrical stimulation may be a discharge current having a predetermined current rate.

[0016] The state history data may include voltage values ​​indicating the voltage of the battery cell, measured at least once during each rest period of the electrical stimulation applied during the state change period.

[0017] The intermittent application process may include a process of removing the electrical stimulation to the battery cell each time the integrated current value of the battery cell changes by a critical integrated value during the application of electrical stimulation, thereby giving the battery cell a resting period.

[0018] The intermittent application process may further include a process of resuming the application of electrical stimulation when the duration of the rest period reaches a reference time.

[0019] The first diagnostic information may include at least one of the following as diagnostic factors, which indicates the charge / discharge performance of the positive electrode of the battery cell: the positive electrode engagement start point, the positive electrode engagement end point, the positive electrode scale factor, and the positive electrode loading amount.

[0020] The battery diagnostic method may further include the step of applying mathematical operations to first diagnostic information to generate second diagnostic information that includes at least one degradation parameter relating to the positive electrode or available lithium of the battery cell.

[0021] The first diagnostic information may include at least one of the following as diagnostic factors, indicating the charge / discharge performance of the negative electrode of the battery cell: the negative electrode engagement start point, the negative electrode engagement end point, the negative electrode scale factor, and the negative electrode loading amount.

[0022] The battery diagnostic method may further include the step of applying mathematical operations to first diagnostic information to generate second diagnostic information that includes at least one degradation parameter relating to the negative electrode of the battery cell.

[0023] The battery diagnostic method may further include the step of updating charge / discharge tolerance information indicating at least one of the allowable voltage range, SOC (State of Charge) range, and current range for the battery cell, based on at least one of the first diagnostic information and the second diagnostic information.

[0024] A battery diagnostic device according to another aspect of the present invention includes a data acquisition unit configured to acquire state history data of a battery cell corresponding to the state change period from a first state to a second state by an intermittent application process of electrical stimulation to the battery cell, and a processor configured to generate a measured full cell profile showing the correspondence between the capacity and voltage of the battery cell based on the state history data. The processor is configured to analyze the measured full cell profile and generate first diagnostic information including at least one diagnostic factor relating to the charge / discharge performance of the battery cell.

[0025] The intermittent application process may include a process of removing the electrical stimulation to the battery cell each time the integrated current value of the battery cell changes by a critical integrated value during the application of electrical stimulation, thereby giving the battery cell a resting period.

[0026] The intermittent application process may further include a process of resuming the application of electrical stimulation when the duration of the rest period reaches a reference time.

[0027] The first diagnostic information may include at least one of the following as diagnostic factors, which indicates the charge / discharge performance of the positive electrode of the battery cell: the positive electrode engagement start point, the positive electrode engagement end point, the positive electrode scale factor, and the positive electrode loading amount.

[0028] The first diagnostic information may include at least one of the following as diagnostic factors, indicating the charge / discharge performance of the negative electrode of the battery cell: the negative electrode engagement start point, the negative electrode engagement end point, the negative electrode scale factor, and the negative electrode loading amount.

[0029] A charging station according to yet another aspect of the present invention includes a battery diagnostic device according to one aspect of the present invention.

[0030] A cloud server according to yet another aspect of the present invention includes a battery diagnostic device according to one aspect of the present invention. [Effects of the Invention]

[0031] According to one aspect of the present invention, by applying an intermittent electrical stimulus to a battery cell, relational data showing the correspondence between the capacity and voltage of the battery cell can be obtained, and diagnostic information indicating the charge and discharge performance of the battery cell can be generated based on the obtained relational data.

[0032] This not only prevents a decrease in diagnostic accuracy due to excessive polarization, even when using high levels of electrical stimulation to change the electrical state of battery cells, but also reduces the time required to acquire relevant data.

[0033] The effects of the present invention are not limited to those described above, and other effects of the present invention not mentioned herein will be clearly understood by those skilled in the art from the claims.

[0034] The drawings accompanying this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, are intended to further facilitate understanding of the technical concept of the invention; therefore, the present invention shall not be construed as being limited solely to what is shown in the drawings. [Brief explanation of the drawing]

[0035] [Figure 1] This is a diagram for reference to illustrate a battery diagnostic device according to one embodiment of the present invention. [Figure 2] These graphs are used to illustrate examples of both the reference positive electrode profile and the reference negative electrode profile. [Figure 3a] This graph is used to illustrate the process of obtaining a full cell profile of a battery cell. [Figure 3b] This graph is used to illustrate the process of obtaining a full cell profile of a battery cell. [Figure 4]This figure is a reference to illustrate an example of the process for generating a comparative full-cell profile used for comparison with a measured full-cell profile according to one embodiment of the present invention. [Figure 5] This figure is a reference to illustrate an example of the process for generating a comparative full-cell profile used for comparison with a measured full-cell profile according to one embodiment of the present invention. [Figure 6] This figure is a reference to illustrate an example of the process for generating a comparative full-cell profile used for comparison with a measured full-cell profile according to one embodiment of the present invention. [Figure 7] This figure is referenced to illustrate another example of the process for generating a comparative full-cell profile used for comparison with a measured full-cell profile according to one embodiment of the present invention. [Figure 8] This figure is referenced to illustrate another example of the process for generating a comparative full-cell profile used for comparison with a measured full-cell profile according to one embodiment of the present invention. [Figure 9] This figure is referenced to illustrate another example of the process for generating a comparative full-cell profile used for comparison with a measured full-cell profile according to one embodiment of the present invention. [Figure 10] This flowchart is for reference in order to provide an overview of the battery diagnostic method according to the first embodiment of the present invention. [Figure 11] This flowchart is for reference in order to outline the battery diagnostic method according to a second embodiment of the present invention. [Figure 12] This figure is a reference to illustrate the voltage history data correction process performed in step S1122 of Figure 11. [Modes for carrying out the invention]

[0036] Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and in the claims shall not be interpreted in their general and dictionary sense, but in accordance with the principle that inventors can appropriately define the concepts of terms in order to best describe their invention, and shall be interpreted in the sense and concepts corresponding to the technical idea of ​​the present invention.

[0037] Therefore, the embodiments described herein and the configurations shown in the drawings represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the invention. It should be understood that there are various equivalents and modifications that can substitute for them at the time of filing this application.

[0038] Terms that include ordinal numbers, such as "1st," "2nd," etc., are used to distinguish one of several components from other components, and these terms do not limit the components themselves.

[0039] Throughout the specification, when a part "comprises" or "includes" a component, this does not exclude other components unless otherwise specified, but rather means that it may further include other components. Furthermore, terms such as <~unit> in the specification mean a unit that processes at least one function or operation, which may be implemented in hardware, software, or a combination of hardware and software.

[0040] Furthermore, when a part of the specification is described as being "connected" to another part, this includes not only "direct connections" but also "indirect connections" mediated by other elements.

[0041] Figure 1 is a reference diagram illustrating a battery diagnostic device according to one embodiment of the present invention.

[0042] Referring to Figure 1, the battery system 1 includes a system controller 2, a battery pack 10, an inverter 30, and an electrical load 40. The charge / discharge terminals P+ and P- of the battery pack 10 can be electrically connected to the charging station 300 via a charging cable or the like.

[0043] The system controller 2 (for example, the ECU (Electronic Control Unit)) is configured to transmit a key-on signal to the battery management system 100 in response to the user switching the engine start button (not shown) on the battery system 1 to the ON position. The system controller 2 is also configured to transmit a key-off signal to the battery management system 100 in response to the user switching the engine start button to the OFF position. The charging station 300 communicates with the system controller 2 and can supply charging power selected from constant power, constant current, and constant voltage through the charge / discharge terminals P+ and P- of the battery pack 10.

[0044] The battery pack 10 includes a battery 11 and may further include at least one of a relay 20 and a battery management system 100.

[0045] Battery 11 includes at least one battery cell BC. Figure 1 shows multiple battery cells BC1~BC connected in series to battery 11. N The diagram illustrates the inclusion of multiple battery cells BC1~BC (where N is a natural number greater than or equal to 2). N These may be configured to have the same electrochemical specifications. Below are multiple battery cells BC1~BC N When explaining common features, the battery cell is denoted with the reference designation "BC". The charging station 300, together with the inverter 30 which has a discharge function, can perform the charge-discharge cycles necessary for diagnosing the battery cell BC.

[0046] The type of battery cell BC is not particularly limited, as long as it is an electrochemical element that can be repeatedly charged and discharged. Battery cells BC are subject to diagnosis by charging stations.

[0047] The relay 20 is electrically connected in series with the battery 11 through a power path that connects the battery 11 and the inverter 30. Figure 1 illustrates that the relay 20 is connected between the positive terminal and the charge / discharge terminal P+ of the battery 11. The relay 20 is controlled to turn on or off in response to a switching signal from the battery management system 100. The relay 20 may be a mechanical contactor that is switched on or off by the magnetic force of a coil, or it may be a semiconductor switch such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

[0048] The inverter 30 is configured to respond to commands from the battery management system 100 or the system controller 2 and convert the DC current from the battery 11 contained in the battery pack 10 into AC current. The electrical load 40 is driven using the AC power from the inverter 30. For example, a three-phase AC motor may be used as the electrical load 40. The components within the battery system 1 that receive the discharge power from the battery 11, including the inverter 30 and the electrical load 40, may be referred to as the electrical load.

[0049] The battery management system 100 includes a sensing unit 110 and a control circuit 130. The battery management system 100 may further include a communication circuit 150.

[0050] The sensing unit 110 includes a voltage sensor 111. The sensing unit 110 may further include a current sensor 112.

[0051] The voltage sensor 111 is connected to the positive and negative terminals of the battery cell BC and is configured to measure the voltage across both ends of the battery cell BC (which may also be called "full-cell voltage" or "cell voltage") and generate a voltage signal indicating the measured voltage. The voltage sensor 111 can be implemented using one or more known voltage measuring elements such as a voltage measuring IC.

[0052] The current sensor 112 is connected in series to the battery 11 through a current path between the battery 11 and the inverter 30. The current sensor 112 is configured to measure the current flowing through the battery 11 (which may also be called the "charge / discharge current") and to generate a current signal indicating the measured value. Multiple battery cells BC1~BC N Since they are connected in series, the current flowing through battery 11 is equal to the current flowing through battery cell BC. The current sensor 112 can be implemented using one or more combinations of known current measuring elements such as a shunt resistor or a Hall effect element.

[0053] The communication circuit 150 is configured to support wired or wireless communication between the control circuit 130 and the system controller 2. Wired communication may be, for example, CAN (Controller Area Network) communication, and wireless communication may be, for example, ZigBee® or Bluetooth® communication. Of course, the type of communication protocol is not particularly limited as long as it supports wired or wireless communication between the control circuit 130 and the system controller 2. The communication circuit 150 may include an output device (e.g., display, speaker) that provides information received from the control circuit 130 and / or the system controller 2 in a form that is recognizable to the user (driver).

[0054] The control circuit 130 is operably coupled to the relay 20, the voltage sensor 111, and the communication circuit 150. The operably coupled nature of the two components means that they are directly or indirectly connected to enable the transmission and reception of signals in one direction or bidirectionally.

[0055] The control circuit 130 can collect voltage signals from the voltage sensor 111 and current signals from the current sensor 112. In this specification, the term "measured signal" may refer to voltage signals only, or to voltage signals and current signals collectively. That is, the control circuit 130 can use an internally provided ADC (Analog to Digital Converter) to convert and store the respective analog signals collected from the sensors (voltage sensor 111, current sensor 112) as digital values. Alternatively, the voltage sensor 111 and current sensor 112 may each contain an internal ADC and transmit digital values ​​to the control circuit 130.

[0056] The control circuit 130 may be called a "battery controller" and may be implemented in hardware using at least one of the following: ASICs (application-specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), microprocessors, or other electrical units for performing functions.

[0057] The memory 131 may include at least one form of storage medium, such as flash memory, hard disk, SSD (Solid State Disk), SDD (Solid Disk Drive), multimedia microcard, RAM (Random Access Memory), SRAM (Static RAM), ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable ROM), or PROM (Programmable ROM). The memory 131 can store data and programs required for the arithmetic operations of the control circuit 130. The memory 131 can store data indicating the results of the arithmetic operations of the control circuit 130.

[0058] The control circuit 130 can control the charging and discharging of battery cells BC according to the charge / discharge tolerance information described later (including at least one of the tolerance voltage range, tolerance SOC range, and tolerance current range). For example, if the full cell voltage of battery cell BC exceeds the tolerance voltage range or the SOC of battery cell BC exceeds the SOC range, the control circuit 130 will prohibit the relay 20 from turning on, and otherwise may allow the relay 20 to turn on. The control circuit 130 can also control the relay 20 and / or inverter 30 so that the magnitude of the current flowing through battery cell BC does not exceed the tolerance current range.

[0059] When relay 20 is turned on, battery 11 enters either charging mode or discharging mode. When relay 20 is turned off while battery 11 is in charging mode or discharging mode, battery 11 switches to hibernation mode.

[0060] The control circuit 130 can turn on the relay 20 in response to a key-on signal. The control circuit 130 can turn off the relay 20 in response to a key-off signal. The key-on signal is a signal that requests a switch from standby to charging or discharging. The key-off signal is a signal that requests a switch from charging or discharging to standby. Alternatively, the on / off control of the relay 20 may be handled by the system controller 2 instead of the control circuit 130.

[0061] In this specification, historical data for a parameter represents the history of its changes over time. Furthermore, a profile (or curve) showing the correspondence between two parameters obtained at the same time intervals during the same period (e.g., "voltage" and "capacitance" or "voltage" and "current") may be a mapping of the historical data of the two parameters so that it can be represented in the form of a two-dimensional graph, or it may be a polynomial equation obtained by applying a predetermined curve-fitting logic to the two mapped sets of historical data. Here, the degree of the highest-order term in the polynomial may be predetermined.

[0062] The battery diagnostic device 302 includes a data acquisition unit 310, a processor 320, and a memory unit 330.

[0063] The charging station 300 may include a stimulation application device 301 and a battery diagnostic device 302, as shown in Figure 1. Of course, the battery diagnostic device 302 may be implemented to operate independently of the charging station 300. For example, the battery diagnostic device 302 may be provided in a form included in a cloud server (not shown). The cloud server may be located remotely from the charging station 300. In this case, the data acquisition unit 310 of the battery diagnostic device 302 may perform a diagnostic process on the battery cell BC through remote communication with the stimulation application device 301 and / or the battery system 1. Hereinafter, the battery cell BC to be diagnosed may also be simply referred to as the "target cell".

[0064] Alternatively, the battery diagnostic device 302 may be included in the battery pack 10 as a replacement for the battery management system 100, and the battery management system 100 may be omitted from the battery pack 10. In this case, the processor 320 may be responsible for all the functions of the control circuit 130 of the battery management system 100, and the data acquisition unit 310 may be responsible for all the functions of the communication circuit 150 of the battery management system 100. Furthermore, the data acquisition unit 310 may be implemented to include a sensing unit 110.

[0065] The stimulation application device 301 may include a charger that provides charging power for normal charging of the battery pack 10. The stimulation application device 301 may, alone or together with the inverter 30, apply or remove at least one form of electrical stimulation to the battery cell BC for diagnostic purposes.

[0066] The data acquisition unit 310 is configured to support wired or wireless communication between the processor 320 and the system controller 2. The data acquisition unit 310 can transmit the results of diagnostics performed on the battery cell BC by the processor 320 to the battery system 1. The data acquisition unit 310 may be included as a subordinate component of the processor 320.

[0067] The processor 320 may be implemented in hardware using at least one of the following: ASICs, DSPs, DSPDs, PLDs, FPGAs, microprocessors, or other electrical units for performing functions.

[0068] The memory unit 330 may include at least one form of storage medium, such as flash memory, hard disk, SSD, SDD, multimedia microcard, RAM, SRAM, ROM, EEPROM, or PROM. The memory unit 330 may store data and programs necessary for the diagnostic process performed by the processor 320. The memory unit 330 may store data indicating the results of the arithmetic operations performed by the processor 320. The memory unit 330 may store datasets and software used to diagnose the degradation state of the battery cell BC.

[0069] Figure 2 is a graph used to illustrate examples of the reference positive electrode profile and the reference negative electrode profile. In the graph in Figure 2, the horizontal axis (X axis) represents capacitance (Ah), and the vertical axis (Y axis) represents voltage.

[0070] Referring to Figure 2, the memory unit 330 can store a reference positive electrode profile Rp and a reference negative electrode profile Rn. The reference cell may be a coin-type cell containing a positive electrode half-cell and a negative electrode half-cell, or it may be a tri-electrode cell. Hereinafter, the positive electrode and positive electrode half-cell of the reference cell will be described as equivalent terms, and the negative electrode and negative electrode half-cell of the reference cell will be described as equivalent terms.

[0071] The reference positive electrode profile Rp may be a profile that shows the correspondence between the positive electrode voltage and capacitance of a reference cell. The positive electrode voltage of the reference cell refers to the potential difference between the potential of a reference electrode (not shown) and the potential of the positive electrode of the reference cell. The positive electrode profile may also be called the positive electrode half-cell profile.

[0072] The reference negative electrode profile Rn may be a profile that shows the correspondence between the negative electrode voltage and capacitance of a reference cell. 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 of the reference cell. The negative electrode profile may also be called the negative electrode half-cell profile.

[0073] The potential of the reference electrode may be, for example, the oxidation-reduction potential of lithium. The positive electrode voltage may simply be called the positive electrode potential, and the negative electrode voltage may simply be called the negative electrode potential.

[0074] The positive and negative voltages can be either open-circuit voltages (OCV) or closed-circuit voltages (CCV), respectively.

[0075] To obtain the closed-circuit voltages of the positive and negative electrodes of a reference cell, a first charging protocol or a first discharging protocol may be used. The first charging protocol may be a constant-current charging method using a first current rate. The first discharging protocol may be a constant-current discharging method using a first current rate (e.g., 0.05C). As an example, while the reference cell is continuously charged by the first charging protocol or continuously discharged by the first discharging protocol, the closed-circuit voltages of the positive and negative electrodes of the reference cell, measured periodically or aperiodicly, may be stored as the positive and negative electrode voltages of the reference cell.

[0076] On the other hand, a second charging protocol or a second discharging protocol may be used to obtain the open-circuit voltages of the positive and negative electrodes of the reference cell. The second charging protocol may be an intermittent charging method in which constant current charging and pauses are alternated using a second current rate (e.g., 3.0C). The second discharging protocol may be an intermittent discharging method in which constant current discharge and pauses are alternated using a second current rate.

[0077] For example, when the charging time by constant current charging in the second charging protocol has elapsed for a set time, or each time the charging capacity of the reference cell has increased by a set capacity, charging of the reference cell may be suspended for a predetermined pause time, after which constant current charging may be resumed. The charging capacity may be calculated by periodically or aperiodically integrating sample values ​​of the charging current.

[0078] As another example, the discharge of the reference cell may be paused for a predetermined period of time after the discharge time of the second discharge protocol's constant current discharge has elapsed for a set time or after the discharge capacity of the reference cell has decreased by a set capacity, and then the constant current discharge may be resumed. The discharge capacity may be calculated by periodically or aperiodicly integrating sample values ​​of the discharge current (i.e., measured values ​​of the cell current).

[0079] In this case, multiple pauses may be introduced during the second charging protocol or the first discharging protocol, and the open-circuit voltages of the positive and negative electrodes of the reference cell, measured at specific timings within each pause, may be stored as the positive and negative electrode voltages of the reference cell.

[0080] In this specification, a low level of electrical stimulation may be referred to as "first electrical stimulation," and a high level of electrical stimulation may be referred to as "second electrical stimulation."

[0081] Assuming the battery cell is in a new condition, the first electrical stimulus can refer to a current stimulus that induces a momentary voltage change below a threshold (e.g., the difference between OCV and CCV) in the battery cell, and the second electrical stimulus can refer to a current stimulus that induces a momentary voltage change above a threshold in the battery cell. The momentary voltage change is due to Ohm's law, which is based on the internal resistance of the battery cell and the current flowing through it, and can represent the difference between the voltage of the battery cell immediately before the application of the electrical stimulus (i.e., OCV) and the voltage of the battery cell immediately after the application (i.e., CCV). If the electrical stimulus is a charge-inducing stimulus, the momentary voltage change can be called a "voltage rise". Conversely, if the electrical stimulus is a discharge-inducing stimulus, the momentary voltage change can be called a "voltage drop".

[0082] Alternatively, assuming the battery cell is in a new condition, the first electrical stimulus may refer to a current stimulus that induces an overvoltage below a threshold in the battery cell when applied continuously for a predetermined time, and the second electrical stimulus may refer to a current stimulus that induces an overvoltage above a threshold in the battery cell when applied continuously for a predetermined time. The overvoltage when a certain electrical stimulus is applied continuously for a predetermined time may be represented by the difference between the change in OCV and the change in CCV over the same period of time.

[0083] For example, the first electrical stimulation may be a charging current having a predetermined current rate (e.g., a first current rate), and the second electrical stimulation may be a charging current having a current rate (e.g., a second current rate) that corresponds to a higher level than the first electrical stimulation.

[0084] As another example, the first electrical stimulus may be a discharge current having a predetermined current rate (e.g., a first current rate), and the second electrical stimulus may be a discharge current having a current rate (e.g., a second current rate) that corresponds to a higher level than the first electrical stimulus.

[0085] The implementation of the first charging protocol or the first discharging protocol may mean the continuous application of the first electrical stimulus to the battery cell. The implementation of the second charging protocol or the second discharging protocol may mean the intermittent application of the second electrical stimulus to the battery cell.

[0086] For the sake of explanation, we will assume that the horizontal axis in Figures 2 to 9 represents the charging capacity.

[0087] At least one of the two profiles (reference positive electrode profile Rp and reference negative electrode profile Rn) can be aligned along the horizontal axis so that the combined result of a portion of the common capacity range between the two profiles (5 to 50 Ah in Figure 2) matches the reference full-cell profile R. Figure 2 illustrates a case where the reference negative electrode profile Rn is shifted to the right and aligned with the starting point of the reference positive electrode profile Rp (corresponding to a capacity of 0) as the reference point.

[0088] Figure 2 shows that the ends of the reference positive electrode profile Rp and the ends of the reference negative electrode profile Rn are misaligned. In other words, the capacitance range of the reference positive electrode profile Rp and the capacitance range of the reference negative electrode profile Rn do not coincide, but only partially overlap. Therefore, the reference full cell profile R represents the full cell voltage of the reference cell in a portion of the capacitance range common to the reference positive electrode profile Rp and the reference negative electrode profile Rn. That is, the reference full cell profile R is an example of a full cell voltage profile obtained by directly subtracting a portion of the reference negative electrode profile Rn from a portion of the reference positive electrode profile Rp.

[0089] The reference full cell profile R can show the correspondence between the capacity and full cell voltage of a new battery cell that has been verified as good. In other words, the reference cell has the same level of positive and negative electrode performance as a new battery cell that has been verified as good. The positive and negative electrode performance of any battery cell can be collectively referred to as "charge / discharge performance".

[0090] A new battery cell refers to a battery cell in its original, new condition. The new condition can be considered the same concept as the BOL (Beginning of Life) state. For example, a battery can be considered in the BOL state until its cumulative charge / discharge capacity from the time of manufacture reaches a predetermined set capacity, and after that, it can be considered in the MOL (Middle of Life) state.

[0091] The reference full cell profile R can show the correspondence between the voltage and capacitance of the reference cell, at least within the voltage range of interest (e.g., 3.0 to 4.0 V). The lower and upper limits of the voltage range of interest may be the first set voltage (3.0 V in Figure 2) and the second set voltage (4.0 V in Figure 2).

[0092] The State of Charge (SOC) can be set to 0% when the full cell voltage of any battery cell, including the reference cell, is the same as the first set voltage. The SOC can be set to 100% when the full cell voltage of any battery cell, including the reference cell, is the same as the second set voltage. According to Figure 2, the reference cell can go from a completely discharged state (SOC 0%) to a fully charged state (SOC 100%) with a charge capacity of 45Ah.

[0093] In this specification, the positive electrode engagement start point on the positive electrode profile of any battery cell represents the positive electrode voltage and positive electrode capacitance (or positive electrode SOC) when the full cell voltage of the battery cell matches the first set voltage. Similarly, the negative electrode engagement start point on the negative electrode profile of the battery cell represents the negative electrode voltage and negative electrode capacitance (or negative electrode SOC) when the full cell voltage of the battery cell matches the first set voltage. Therefore, the voltage difference between the positive electrode engagement start point and the negative electrode engagement start point may be the same as the first set voltage.

[0094] Furthermore, the positive electrode involvement termination point on the positive electrode profile of any battery cell indicates the positive electrode voltage and positive electrode capacitance (or positive electrode SOC) when the full cell voltage of the battery cell matches the second set voltage. Similarly, the negative electrode involvement termination point on the negative electrode profile of the battery cell indicates the negative electrode voltage and negative electrode capacitance (or negative electrode SOC) when the full cell voltage of the battery cell matches the second set voltage. Therefore, the voltage difference between the positive electrode involvement termination point and the negative electrode involvement termination point may be the same as the second set voltage.

[0095] In this specification, the positive electrode capacity (capacity value) of a particular point on the positive electrode profile of any battery cell may mean the capacity difference between the particular point and either of the endpoints on either side of the positive electrode profile. The positive electrode SOC of a particular point on the positive electrode profile of any battery cell may mean the ratio of the capacity difference between the particular point and either of the endpoints on either side of the positive electrode profile (e.g., a low-capacity point) to the capacity difference between the endpoints on either side of the positive electrode profile. The capacity difference between the endpoints on either side of the positive electrode profile may be referred to as the total positive electrode capacity.

[0096] Similarly, the negative electrode capacity (capacity value) at a specific point on the negative electrode profile of any battery cell may represent the capacity difference between that specific point and either of the endpoints on either side of the negative electrode profile (or positive electrode profile). The negative electrode SOC at a specific point on the negative electrode profile of any battery cell may represent the ratio of the capacity difference between that specific point and either of the endpoints on either side of the negative electrode profile (e.g., a low-capacity point) to the capacity difference between the endpoints on either side of the negative electrode profile (or positive electrode profile). The capacity difference between the endpoints on either side of the negative electrode profile may be referred to as the total negative electrode capacity.

[0097] The memory unit 330 can pre-store information indicating the voltages of the reference positive electrode involvement start point (pi0), reference positive electrode involvement end point (pf0), reference negative electrode involvement start point (ni0), and reference negative electrode involvement end point (nf0). The reference positive electrode involvement start point (pi0) and reference positive electrode involvement end point (pf0) are the positive electrode involvement start point and positive electrode involvement end point on the reference positive electrode profile Rp, respectively. The reference negative electrode involvement start point (ni0) and reference negative electrode involvement end point (nf0) are the negative electrode involvement start point and negative electrode involvement end point on the reference negative electrode profile Rn, respectively.

[0098] The voltage difference between the reference positive electrode engagement start point (pi0) and the reference negative electrode engagement start point (ni0) may be the same as the first set voltage (e.g., 3.0V). The voltage difference between the reference positive electrode engagement end point (pf0) and the reference negative electrode engagement end point (nf0) may be the same as the second set voltage (e.g., 4.0V).

[0099] Figures 3a and 3b are graphs used to illustrate the process of obtaining the measured full cell profile of the target cell.

[0100] The graph shown in Figure 3a illustrates an example of the change in the full cell voltage of a target cell over time due to the intermittent application of electrical stimulation (e.g., the second electrical stimulation described above). The target cell is a battery cell that is to be diagnosed by a battery diagnostic device. The target cell may be a new battery cell that needs to be verified as good or bad, or a battery cell that has deteriorated since being verified as good and is no longer new. In the following, the reference designation BC will also be used for the target cell.

[0101] The processor 320 can control the stimulation device 301 to intermittently apply electrical stimulation to the target cell BC.

[0102] The process of controlling the stimulation device 301 for the diagnosis of the target cell BC may be performed during the state change period until the electrical state of the target cell BC (e.g., the full cell voltage corresponding to the OCV) changes from a first state (e.g., a first set voltage) to a second state (e.g., a second set voltage).

[0103] Referring to the graph in Figure 3a, the full cell voltage of the target cell BC shows an increasing trend with a repeating sawtooth pattern. Each sawtooth voltage increase segment is generated by the application of electrical stimulation, and the voltage decrease segment is generated by the interruption of electrical stimulation. In other words, the voltage decrease segment shows the change in the full cell voltage of the target cell BC over the rest period.

[0104] During the state change period, the processor 320 may repeatedly store the measured current of the target cell BC and generate current history data.

[0105] The processor 320 can control the stimulation application device 301 to initiate a pause in electrical stimulation whenever a predetermined pause condition is met within the state change period. That is, the electrical stimulation application process can be temporarily interrupted when a pause condition is met. As an example, at least one of the following can be set as a pause condition: (i) the integrated current value changes by a critical integrated value, (ii) the state of clock (SOC) changes by a critical SOC, and (iii) the time during which the electrical stimulation is applied reaches a critical time. For example, if the total integrated current value during the state change period is 40 Ah and the critical integrated value is 2 Ah, then a total of 20 pauses may be applied during the state change period.

[0106] The processor 320 can determine at least one of the critical integrated value, critical SOC, and critical time based on the full charge capacity, SOH (State of Health), or previous diagnostic results (e.g., capacity value at the negative electrode termination point, negative electrode loss rate) of the target cell BC. At least one of the critical integrated value, critical SOC, and critical time may have a predetermined positive (or negative) correspondence with the full charge capacity, SOH, or previous diagnostic results, and such correspondence data (data table for rest period control) can be pre-stored in the memory unit 330. According to the predetermined positive (or negative) correspondence, as the full charge capacity, SOH, or previous diagnostic results decrease, at least one of the critical integrated value, critical SOC, and critical time also decreases. As a result, the more the target cell BC deteriorates over time, the shorter the intervals between rest periods within the state change period become. This prevents a decrease in the number of data points included in the voltage history data, which shows the time-dependent change history of the full cell voltage during the rest periods of the state change period.

[0107] The processor 320 may obtain at least one of the following from the data table for rest period control: full charge capacity, SOH or critical integrated value mapped to the previous diagnostic result, critical SOC, and critical time. The processor 320 may use at least one of the critical integrated value, critical SOC, and critical time obtained from the data table for rest period control to control the intermittent application process of electrical stimulation over the state change period.

[0108] The processor 320 can control the stimulation device 301 to resume the application of electrical stimulation when a reference time has elapsed from the start of the rest period of electrical stimulation. The reference time can be predetermined to allow sufficient time for the polarization caused by the electrical stimulation to dissipate. For example, the reference time, which is the length of the rest period, may be the time required for the polarization at the start of the rest period to be less than 10%.

[0109] During each pause in electrical stimulation, the full cell voltage of the target cell BC is measured at least once. For example, the processor 320 may store the measured full cell voltage at the end of each pause in electrical stimulation as the OCV of the target cell BC. Alternatively, during each pause in electrical stimulation, the full cell voltage may be measured at least three times, and the processor 320 may estimate the OCV of the target cell BC for each pause based on the three measured full cell voltages for each pause.

[0110] As a result, voltage history data can be generated by storing OCV multiple times with time differences over the state change period. Each OCV point (D) is shown in Figure 3a. OCV ) is an example of an arbitrary data point in the voltage history data.

[0111] The inventors have found through numerous experiments that the voltage history data generated using the second electrical stimulus in the intermittent application method described above has a high degree of consistency with the voltage history data generated when the first electrical stimulus is actually continuously applied to the target cell BC.

[0112] The advantages of the diagnostic method, which involves intermittently applying the second electrical stimulus instead of continuously applying the first electrical stimulus, will be explained below.

[0113] Assume the following conditions are relevant to the diagnosis of target cell BC.

[0114] (i) First electrical stimulation = 0.05C charging (ii) Second electrical stimulation = 3.0C charging (iii) Length of the rest period of the second electrical stimulation = 12 minutes (iv) Total capacity change during the state change period = 80% of the full charge capacity (FCC) of the target cell BC (v) Critical integrated value = 3% of the full charge capacity of the target cell BC

[0115] Therefore, the time required for the target cell BC to change from the first state to the second state due to the continuous application of the first electrical stimulation is 1 / 0.05 × 80% = 16 hours.

[0116] In comparison, the time required for the charge capacity of the target cell BC to increase by the critical cumulative value due to the second electrical stimulation is 0.03 / 3 × 80% = 0.008 hours. Also, since a rest period is granted each time the charge capacity increases by 3%, a total of 26 rest periods are granted during the state change period. Therefore, the time required for the target cell BC to change from the first state to the second state due to the intermittent application of the second electrical stimulation is (0.008 hours + 0.2 hours) × 26 = 5.4 hours.

[0117] In other words, compared to a continuous application method for the first electrical stimulation, an intermittent application method for the second electrical stimulation is advantageous in shortening the time required to acquire a full cell profile.

[0118] In the graph in Figure 3b, the horizontal axis (X-axis) represents capacitance (Ah), and the vertical axis (Y-axis) represents voltage.

[0119] Referring to Figure 3b, the processor 320 can generate a measured full-cell profile M that shows the correspondence between the capacitance of the target cell BC and the full-cell voltage (which may also be called "full-cell voltage"). The measured full-cell profile may also be called a QV profile or Q-OCV profile.

[0120] Here, the full cell voltage is the voltage across the target cell BC, and is distinct from the positive and negative electrode voltages mentioned above. In other words, the full cell voltage of the target cell BC can be said to be the difference between the positive and negative electrode voltages of the target cell BC.

[0121] To generate the measured full cell profile M, state history data mapped to state change periods may be used. The state history data includes the voltage history data described above and may further include current history data or capacitance history data.

[0122] More specifically, each data point in the current history data and voltage history data is indexed in chronological order. Therefore, the processor 320 can sequentially integrate the data points of the current history data to generate capacitance history data. Furthermore, the processor 320 can apply a curve fitting algorithm to a set of multiple Q-OCV pairs obtained by mapping the capacitance history data and voltage history data to generate a measured full cell profile M. The reference full cell profile R, reference positive electrode profile Rp, reference negative electrode profile Rn, and measured full cell profile M may be polynomials with a predetermined order for the highest-order term.

[0123] Similar to the reference full cell profile R, the measured full cell profile M can show the correspondence between the capacitance and OCV of the target cell BC over at least the voltage range of interest (e.g., 3.0 to 4.0 V).

[0124] In terms of charge and discharge performance, there is inevitably a certain degree of difference between the reference cell and the target cell BC. Therefore, as shown in Figure 3b, there is also a certain degree of difference between the measured full cell profile M and the reference full cell profile R.

[0125] For example, at the same capacity value, the voltage of the measured full cell profile M is higher than the voltage of the reference full cell profile 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. It is obvious that as the target cell BC deteriorates through repeated charging and discharging, the difference between the measured full cell profile M and the reference full cell profile R will gradually increase. As shown in Figure 3b, unlike the reference cell explained with reference to Figure 2, the target cell BC requires a charging capacity of 40Ah to reach the second set voltage from the first set voltage, which is 5Ah less than the 50Ah charging capacity of the reference cell under the same conditions.

[0126] On the other hand, while Ah is used as the unit for the horizontal axis in the graphs of Figures 2 and 3b, other units may be used. For example, instead of Ah, the unit for the horizontal axis could be a percentage (%) representing SOC (State of Charge).

[0127] Once a measured full cell profile M is generated, the processor 320 may be configured to compare the measured full cell profile M with at least one comparison full cell profile. Here, the comparison full cell profile may be the result of generating an adjusted positive electrode profile and an adjusted negative electrode profile by adjusting the reference positive electrode profile Rp and reference negative electrode profile Rn stored in the memory unit 330, respectively, and then combining (combining) the adjusted positive electrode profile and the adjusted negative electrode profile.

[0128] In other words, if the reference full cell profile R is the result of subtracting a portion of the reference negative electrode profile Rn from a portion of the reference positive electrode profile Rp, then the comparative full cell profile can be said to be the result of subtracting a portion of the adjusted negative electrode profile from a portion of the adjusted positive electrode profile.

[0129] The processor 320 may generate at least one comparison full cell profile by directly adjusting the reference positive electrode profile Rp and the reference negative electrode profile Rn. Alternatively, at least one comparison full cell profile may be pre-allocated and stored in the memory unit 330 based on the reference positive electrode profile Rp and the reference negative electrode profile Rn. In this case, the processor 320 may obtain the comparison full cell profile by accessing the memory unit 330 and reading it.

[0130] The processor 320 can generate multiple comparison full cell profiles from the reference positive electrode profile Rp and the reference negative electrode profile Rn by repeating an adjustment process in which the reference positive electrode profile Rp and the reference negative electrode profile Rn are each adjusted to multiple levels and then combined. The comparison full cell profiles may also be referred to as "adjusted reference full cell profiles".

[0131] The processor 320 may identify one comparison full cell profile from among several comparison full cell profiles that has the smallest error with the measured full cell profile M. Subsequently, the processor 320 may determine that the adjusted positive electrode profile and adjusted negative electrode profile mapped to the identified comparison full cell profile are the positive electrode profile and negative electrode profile of the target cell BC.

[0132] In this regard, various methods known at the time of filing of the present invention can be used to determine the error between two profiles that can each be represented in a two-dimensional coordinate system. For example, the integral of the absolute value over the region between the two profiles, or the RMSE (Root Mean Square Error), can be used as the error between the two profiles.

[0133] According to this configuration of the present invention, various state information about the target cell BC can be obtained based on the finally determined adjusted positive electrode profile and adjusted negative electrode profile. The finally determined adjusted positive electrode profile and adjusted negative electrode profile may be mapped to a comparative full cell profile mapped to the minimum error. In particular, the comparative full cell profile obtained from the finally determined adjusted positive electrode profile and adjusted negative electrode profile can be said to be in close agreement with the measured full cell profile M in terms of general shape, etc.

[0134] Therefore, according to one embodiment of the present invention, the positive electrode profile and negative electrode profile of the target cell BC can be obtained without disassembling the target cell BC or without manufacturing it in a three-electrode cell configuration.

[0135] If the target cell BC is a new battery cell, it can be more easily used to diagnose whether a defect has occurred in the target cell BC, and if so, what type of defect it is, by analyzing the adjusted positive electrode profile and adjusted negative electrode profile.

[0136] If the target cell BC is verified as a good product and is in use, the degree of degradation of the target cell BC can be determined for each degradation item through the adjusted positive electrode profile and adjusted negative electrode profile.

[0137] Furthermore, according to one embodiment of the present invention, the positive electrode profile and negative electrode profile of the target cell BC can be obtained in a simple manner. The present invention can be implemented even if only one reference positive electrode profile Rp and one reference negative electrode profile Rn are stored in the memory unit 330. In other words, it is not necessary for multiple reference positive electrode profiles Rp and / or multiple reference negative electrode profiles Rn to be stored in the memory unit 330. Therefore, the memory unit 330 does not need to have a large storage capacity, and many prior tests to secure multiple reference positive electrode profiles Rp and / or multiple reference negative electrode profiles Rn are not required.

[0138] The following describes the analysis process of the measured full cell profile M for estimating the negative electrode loading amount, one of the parameters involved in the current charge / discharge performance of the target cell BC, with reference to Figures 4 to 9. The negative electrode loading amount of any battery cell refers to the amount of negative electrode active material per unit area of ​​the negative electrode of the battery cell, and its unit is mAh / cm². 2 or mg / cm 2 It is possible.

[0139] Figures 4 to 6 are diagrams to illustrate an example of the process for generating a comparative full-cell profile used for comparison with a measured full-cell profile according to one embodiment of the present invention.

[0140] The comparative full-cell profile generation process, as described with reference to Figures 4 to 6, is performed in the following order: a first routine (see Figure 4) to set four points (positive electrode involvement start point, positive electrode involvement end point, negative electrode involvement start point, and negative electrode involvement end point) corresponding to the voltage range of interest; a second routine (see Figure 5) to perform profile shifting; and a third routine (see Figure 6) to perform capacitance scaling. In other words, the comparative full-cell profile generation process according to one embodiment of the present invention includes the first to third routines.

[0141] First, referring to Figure 4, the reference positive electrode profile Rp and the reference negative electrode profile Rn are the same as those shown in Figure 2.

[0142] The processor 320 determines the positive electrode involvement start point (pi), positive electrode involvement end point (pf), negative electrode involvement start point (ni), and negative electrode involvement end point (nf) on the reference positive electrode profile Rp and reference negative electrode profile Rn.

[0143] Either the positive electrode involvement start point (pi) or the negative electrode involvement start point (ni) depends on the other.

[0144] As an example, the processor 320 may divide the positive electrode voltage range from the start point to the end point (or second set voltage) of the reference positive electrode profile Rp into a plurality of minute voltage intervals, and then determine the boundary point between two adjacent minute voltage intervals as the positive electrode involvement start point (pi). Each minute voltage interval may have a predetermined size (e.g., 0.01V). Subsequently, the processor 320 may determine the negative electrode involvement start point (ni) as a point on the reference negative electrode profile Rn that is lower than the positive electrode involvement start point (pi) by a first set voltage (e.g., 3V).

[0145] As another example, the processor 320 may divide the negative voltage range from the start to the end point of the reference negative electrode profile Rn into a plurality of minute voltage intervals of a predetermined size, and then determine the boundary point between two adjacent minute voltage intervals as the negative electrode involvement start point (ni). Subsequently, the processor 320 may search for a point in the reference positive electrode profile Rp that is greater than the negative electrode involvement start point (ni) by a first set voltage, and determine the searched point as the positive electrode involvement start point (pi).

[0146] Either the positive electrode-involved termination point (pf) or the negative electrode-involved termination point (nf) depends on the other.

[0147] As an example, the processor 320 may divide the voltage range from the second set voltage to the endpoint of the reference positive electrode profile Rp into a plurality of minute voltage intervals of a predetermined size, and then determine the boundary point between two adjacent minute voltage intervals as the positive electrode involvement endpoint (pf). Subsequently, the processor 320 may determine the negative electrode involvement endpoint (nf) as a point on the reference negative electrode profile Rn that is lower than the positive electrode involvement endpoint (pf) by the second set voltage (e.g., 4V).

[0148] As another example, the processor 320 may divide the negative voltage range from the start to the end point of the reference negative profile Rn into a plurality of minute voltage intervals of a predetermined size, and then determine the boundary point between two adjacent minute voltage intervals as the negative electrode involvement termination point (nf). Subsequently, the processor 320 may search the reference positive profile Rp for a point that is greater than the negative electrode involvement termination point (nf) by a second set voltage, and determine the found point as the positive electrode involvement termination point (pf).

[0149] Once the determination of the positive electrode involvement start point (pi), positive electrode involvement end point (pf), negative electrode involvement start point (ni), and negative electrode involvement end point (nf) is complete, the processor 320 shifts at least one of the reference positive electrode profile Rp and reference negative electrode profile Rn to the left or right along the horizontal axis.

[0150] Referring to Figure 5, the processor 320 may shift the reference positive electrode profile Rp to the left (towards lower capacitance), or shift the reference negative electrode profile Rn to the right (towards higher capacitance), or both, so that the capacitance value at the positive electrode engagement start point (pi) matches the capacitance value at the negative electrode engagement start point (ni).

[0151] Alternatively, the processor 320 may shift the reference positive profile Rp to the left, or the reference negative profile Rn to the right, or both, so that the capacitance value of the positive-involved endpoint (pf) matches the capacitance value of the negative-involved endpoint (nf).

[0152] Figure 5 illustrates a situation where only the reference positive electrode profile Rp is shifted to the left to generate an adjusted reference positive electrode profile Rp', resulting in the capacitance value at the positive electrode involvement start point (pi') matching the capacitance value at the negative electrode involvement start point (ni). The adjusted reference positive electrode profile Rp' is the result of applying an adjustment process to the reference positive electrode profile Rp that shifts it to the left by the voltage difference between the positive electrode involvement start point (pi) and the negative electrode involvement start point (ni). Therefore, the two points (pi, pi') differ only in capacitance value, while their voltages are equal. Similarly, the two points (pf, pf') also differ only in capacitance value, while their voltages are equal.

[0153] Once an adjusted profile (Rp', Rn) is obtained in which at least one of the reference positive profile Rp and the reference negative profile Rn is shifted, the processor 320 scales at least one capacity range of the adjusted profile (Rp', Rn).

[0154] As shown in the example in Figure 5, the processor 320 performs an additional adjustment process to contract or expand at least one of the adjusted reference positive electrode profile Rp' and reference negative electrode profile Rn along the horizontal axis.

[0155] Referring to Figure 6, the processor 320 may shrink or expand the adjusted reference cathode profile Rp' so that the size of the capacitance range between two points (pi', pf') in the adjusted reference cathode profile Rp' matches the size of the capacitance range of the measured full cell profile M, thereby generating the adjusted reference cathode profile Rp''. In this case, one of the two points (pi', pf') (pi') may be fixed. This ensures that the capacitance difference between the two points (pi', pf) in the adjusted reference cathode profile Rp'' matches the capacitance range of the measured full cell profile M.

[0156] Furthermore, the processor 320 may shrink or expand the reference negative electrode profile Rn so that the size of the capacitance range between two points (ni, nf) in the reference negative electrode profile Rn matches the size of the capacitance range of the measured full cell profile M, thereby generating an adjusted reference negative electrode profile Rn'. In this case, one of the two points (ni, nf) (ni) may be fixed. This ensures that the capacitance difference between two points (ni, nf') in the adjusted reference negative electrode profile Rn' matches the capacitance range of the measured full cell profile M.

[0157] In Figure 6, the adjusted reference positive electrode profile Rp'' is the result of contracting the adjusted reference positive electrode profile Rp' shown in Figure 5, and the adjusted reference negative electrode profile Rn' is the result of expanding the reference negative electrode profile Rn shown in Figure 5.

[0158] The positive electrode involvement endpoint (pf) on the adjusted reference positive electrode profile Rp'' corresponds to the positive electrode involvement endpoint (pf) on the adjusted reference positive electrode profile Rp'. The negative electrode involvement endpoint (nf') on the adjusted reference negative electrode profile Rn' corresponds to the negative electrode involvement endpoint (nf) on the reference negative electrode profile Rn.

[0159] The volume difference between the positive electrode involvement start point (pi') and the positive electrode involvement end point (pf) of the adjusted reference positive electrode profile Rp'' corresponds to the size of the volume range of the measured full cell profile M. Similarly, the volume difference between the negative electrode involvement start point (ni) and the negative electrode involvement end point (nf') of the adjusted reference negative electrode profile Rn' corresponds to the size of the volume range of the measured full cell profile M.

[0160] Furthermore, the capacitance range between two points (pi', pf') of the adjusted reference positive electrode profile Rp'' matches the capacitance range between two points (ni, nf') of the adjusted reference negative electrode profile Rn'. The processor 320 can generate a comparative full cell profile S by subtracting the profile between the two points (pi, pf') of the adjusted reference positive electrode profile Rp'' from the profile between the two points (ni, nf') of the adjusted reference negative electrode profile Rn'.

[0161] The processor 320 can calculate the error (profile error) between the comparison full cell profile S and the measured full cell profile M.

[0162] The processor 320 may map at least two of the following to each other and store them in the memory unit 330: the adjusted reference positive electrode profile Rp'', the adjusted reference negative electrode profile Rn', the positive electrode involvement start point (pi'), the positive electrode involvement end point (pf''), the negative electrode involvement start point (ni), the negative electrode involvement end point (nf'), the positive electrode scale factor, the negative electrode scale factor, the comparison full cell profile S, and the profile error.

[0163] The positive electrode scale factor may represent the ratio of the capacitance difference between the ends of the adjusted reference positive electrode profile Rp'' to the capacitance difference between the ends of the reference positive electrode profile Rp. Alternatively, the positive electrode scale factor may represent the ratio of the capacitance difference between two points (pi', pf'') to the capacitance difference between two points (pi0, pf0). Alternatively, the positive electrode scale factor may represent the ratio of the positive electrode capacitance difference between two points (pi', pf'') to the positive electrode capacitance difference between two points (pi0, pf0). Alternatively, the positive electrode scale factor may 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).

[0164] The negative electrode scale factor may represent the ratio of the capacitance difference between the ends of the adjusted reference negative electrode profile Rn' to the capacitance difference between the ends of the reference negative electrode profile Rn. Alternatively, the negative electrode scale factor may represent the ratio of the capacitance difference between two points (ni, nf') to the capacitance difference between two points (ni0, nf0). Alternatively, the negative electrode scale factor may represent the ratio of the negative electrode capacitance difference between two points (ni, nf') to the negative electrode capacitance difference between two points (ni0, nf0). Alternatively, the negative electrode scale factor may 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).

[0165] On the other hand, as described above, when the positive electrode voltage range of the reference positive electrode profile Rp is divided into multiple minute voltage intervals, the boundary point between two adjacent minute voltage intervals can be set as the positive electrode involvement start point (pi).

[0166] For example, if the positive electrode voltage range of the reference positive electrode profile Rp is divided into 100 minute voltage ranges, there may be 100 boundary points that can be set as the positive electrode involvement start point (pi). Also, if the voltage range above the second set voltage in the reference positive electrode profile Rp is divided into 40 minute voltage ranges, there may be 40 boundary points that can be set as the positive electrode involvement end point (pf). In this case, up to 4000 different comparison full cell profiles can be generated.

[0167] Of course, it is easily understood by those skilled in the art that the number of comparative full-cell profiles that can be generated increases as the size of the minute voltage interval decreases, and conversely, the number of comparative full-cell profiles that can be generated decreases as the size of the minute voltage interval increases.

[0168] After identifying the minimum profile error among the multiple comparison full-cell profiles generated as described above, the processor 320 may obtain information mapped to the minimum profile error (for example, at least one of the following: positive electrode involvement start point, positive electrode involvement end point, negative electrode involvement start point, negative electrode involvement end point, positive electrode scale factor, negative electrode scale factor) from the memory unit 330.

[0169] Figures 7-9 are diagrams that illustrate other examples of the process for generating a comparative full-cell profile used for comparison with a measured full-cell profile by one embodiment of the present invention. For reference, the embodiments in Figures 7-9 are independent of the embodiments in Figures 4-6. Therefore, terms and reference numerals used in common in the descriptions of the embodiments in Figures 4-6 and Figures 7-9 should be understood as being limited to each respective embodiment.

[0170] The comparative full-cell profile generation process, as described with reference to Figures 7 to 9, is performed in the following order: a fourth routine (see Figure 7) for performing capacity scaling, a fifth routine (see Figure 8) for setting four points (positive electrode involvement start point, positive electrode involvement end point, negative electrode involvement start point, negative electrode involvement end point), and a sixth routine (see Figure 9) for performing profile shifting. That is, the comparative full-cell profile generation process according to other embodiments of the present invention includes the fourth to sixth routines.

[0171] Referring to Figure 7, the processor 320 applies the positive and negative scale factors selected from the scaling numerical range to the reference positive profile Rp and reference negative profile Rn, respectively, to generate the adjusted reference positive profile Rp' and adjusted reference negative profile Rn'.

[0172] The scaling numerical range is predetermined or can vary depending on the ratio of the volume range size of the measured full-cell profile M to the volume range size of the reference full-cell profile R. For example, if the positive and negative scale factors can be selected from values ​​spaced 0.1% apart within the scaling numerical range (e.g., 90-99%) (i.e., 90%, 90.1%, 90.2%, ..., 98.9%, 99%), then 91 values ​​can be selected as the positive and negative scale factors, respectively. In this case, 91 × 91 = 8281 adjustment levels (combinations of positive and negative scale factors) can generate up to 8281 adjusted profile pairs. An adjusted profile pair means a combination of an adjusted positive profile and an adjusted negative profile.

[0173] The adjusted reference positive electrode profile Rp' and adjusted reference negative electrode profile Rn' shown in Figure 7 illustrate the results of applying positive and negative electrode scale factors of less than 100%, respectively, to the reference positive electrode profile Rp and reference negative electrode profile Rn.

[0174] Since the positive and negative electrode scale factors are less than 100%, the adjusted reference positive electrode profile Rp' is the reference positive electrode profile Rp contracted along the horizontal axis, and the adjusted reference negative electrode profile Rn' is the reference negative electrode profile Rn contracted along the horizontal axis. For ease of understanding, the starting points of the reference positive electrode profile Rp and reference negative electrode profile Rn are fixed, and only the remaining parts are shown as a general representation scaled to the left along the horizontal axis.

[0175] Referring to Figure 8, the processor 320 determines the positive electrode involvement start point (pi'), positive electrode involvement end point (pf'), negative electrode involvement start point (ni'), and negative electrode involvement end point (nf') on the adjusted reference positive electrode profile Rp' and the adjusted reference negative electrode profile Rn'.

[0176] Either the positive electrode involvement start point (pi') or the negative electrode involvement start point (ni') may depend on the other. Similarly, either the positive electrode involvement end point (pf') or the negative electrode involvement end point (nf') may depend on the other. Furthermore, either the positive electrode involvement start point (pi') or the positive electrode involvement end point (pf') may be set based on the other.

[0177] In other words, once any one of the positive electrode involvement start point (pi'), positive electrode involvement end point (pf'), negative electrode involvement start point (ni'), and negative electrode involvement 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 size of the capacitance range of the measured full cell profile M (for example, 45Ah - 5Ah = 40Ah in Figure 3b).

[0178] As an example, the processor 320 may divide the positive voltage range from the start point to the end point (or second set voltage) of the adjusted reference positive profile Rp' into a plurality of minute voltage intervals, and then determine the boundary point between two adjacent minute voltage intervals as the positive involvement start point (pi'). Subsequently, the processor 320 may determine the negative involvement start point (ni') as a point on the adjusted reference negative profile Rn' that is less than the positive involvement start point (pi') by a first set voltage (e.g., 3V).

[0179] As another example, the processor 320 may divide the negative voltage range from the start to the end of the adjusted reference negative profile Rn' into a plurality of minute voltage intervals of a predetermined size, and then determine the boundary point between two adjacent minute voltage intervals as the negative involvement start point (ni'). Subsequently, the processor 320 may search the reference positive profile Rp for a point that is greater than the negative involvement start point (ni') by a first set voltage, and determine the found point as the positive involvement start point (pi').

[0180] As yet another example, the processor 320 may divide the voltage range from the second set voltage to the endpoint of the adjusted reference positive electrode profile Rp' into a plurality of minute voltage intervals of a predetermined size, and then determine the boundary point between two adjacent minute voltage intervals as the positive electrode involvement endpoint (pf'). Subsequently, the processor 320 may search for a point in the adjusted reference negative electrode profile Rn' that is less than the positive electrode involvement endpoint (pf') by the second set voltage (e.g., 4V), and determine the found point as the negative electrode involvement endpoint (nf').

[0181] As yet another example, the processor 320 may divide the negative voltage range from the start to the end of the adjusted reference negative electrode profile Rn' into a plurality of minute voltage intervals of a predetermined size, and then determine the boundary point between two adjacent minute voltage intervals as the negative electrode involvement termination point (nf'). Subsequently, the processor 320 may search for a point in the adjusted reference positive electrode profile Rp' that is greater than the negative electrode involvement termination point (nf') by a second set voltage, and determine the found point as the positive electrode involvement termination point (pf').

[0182] If one of the positive electrode involvement start point (pi'), positive electrode involvement end point (pf'), negative electrode involvement start point (ni'), and negative electrode involvement end point (nf') is determined, the processor 320 may additionally determine one of the remaining three points based on the determined point.

[0183] For example, once the positive electrode involvement start point (pi') is determined, the processor 320 may determine the positive electrode involvement end point (pf') as a point on the adjusted reference positive electrode profile Rp' that has a capacitance value greater than the capacitance value of the positive electrode involvement start point (pi') by the size of the capacitance range of the measured full cell profile M. Alternatively, the processor 320 may search for a point on the adjusted reference negative electrode profile Rn' that is lower than the positive electrode involvement start point (pi') by a first set voltage, and determine the searched point as the negative electrode involvement start point (ni'). Furthermore, the processor 320 may determine the negative electrode involvement end point (nf') as a point on the adjusted reference negative electrode profile Rn' that has a capacitance value greater than the capacitance value of the negative electrode involvement start point (ni') by the size of the capacitance range of the measured full cell profile M.

[0184] As another example, once the positive electrode involvement termination point (pf') is determined, the processor 320 may determine the positive electrode involvement start point (pi') as a point on the adjusted reference positive electrode profile Rp' having a capacitance value smaller by the size of the capacitance range of the measured full cell profile M than the capacitance value of the positive electrode involvement termination point (pf'). Alternatively, the processor 320 may search for a point on the adjusted reference negative electrode profile Rn' that is lower by a second set voltage than the positive electrode involvement termination point (pf'), and determine the found point as the negative electrode involvement termination point (nf'). Furthermore, the processor 320 may determine the negative electrode involvement start point (ni') as a point on the adjusted reference negative electrode profile Rn' having a capacitance value smaller by the size of the capacitance range of the measured full cell profile M than the capacitance value of the negative electrode involvement termination point (nf').

[0185] As yet another example, once the negative electrode involvement start point (ni') is determined, the processor 320 may determine the negative electrode involvement end point (nf') to be a point on the adjusted reference negative electrode profile Rn' that has a capacitance value greater than the capacitance value of the negative electrode involvement start point (ni') by the size of the capacitance range of the measured full cell profile M. The processor 320 may also search for a point on the adjusted reference positive electrode profile Rp' that is higher than the negative electrode involvement start point (ni') by a first set voltage, and determine the found point as the positive electrode involvement start point (pi'). The processor 320 may also determine the positive electrode involvement end point (pf') to be a point on the adjusted reference positive electrode profile Rp' that has a capacitance value greater than the capacitance value of the positive electrode involvement start point (pi') by the size of the capacitance range of the measured full cell profile M.

[0186] As yet another example, once the negative electrode involvement termination point (nf') is determined, the processor 320 may determine the negative electrode involvement start point (ni') as a point on the adjusted reference negative electrode profile Rn' having a capacitance value smaller by the size of the capacitance range of the measured full cell profile M than the capacitance value of the negative electrode involvement termination point (nf'). The processor 320 may also search for a point on the adjusted reference positive electrode profile Rp' that is higher by a second set voltage than the negative electrode involvement termination point (nf'), and determine the searched point as the positive electrode involvement termination point (pf'). Furthermore, the processor 320 may determine the positive electrode involvement start point (pi') as a point on the adjusted reference positive electrode profile Rp' having a capacitance value smaller by the size of the capacitance range of the measured full cell profile M than the capacitance value of the positive electrode involvement termination point (pf').

[0187] Once the determination of the positive electrode involvement start point (pi'), positive electrode involvement end point (pf'), negative electrode involvement start point (ni'), and negative electrode involvement end point (nf') is complete based on the pairs of positive electrode scale factors and negative electrode scale factors, the processor 320 may shift at least one of the adjusted reference positive electrode profile Rp' and adjusted reference negative electrode profile Rn' to the left or right along the horizontal axis so that the capacitance value of the positive electrode involvement start point (pi') matches the capacitance value of the negative electrode involvement start point (ni'), or so that the capacitance value of the positive electrode involvement end point (pf') matches the capacitance value of the negative electrode involvement end point (nf').

[0188] The adjusted reference negative electrode profile Rn'' shown in Figure 9 is obtained by shifting only the adjusted reference negative electrode profile Rn' shown in Figure 8 to the right. As a result, the capacitance value at the positive electrode engagement start point (pi') and the capacitance value at the negative electrode engagement start point (ni") coincide on the horizontal axis. Related to this, the capacitance difference between the positive electrode engagement start point (pi') and the positive electrode engagement end point (pf') is equal to the capacitance difference between the negative electrode engagement start point (ni') and the negative electrode engagement end point (nf'). Therefore, once the capacitance value at the positive electrode engagement start point (pi') and the capacitance value at the negative electrode engagement start point (ni") coincide, the capacitance value at the positive electrode engagement end point (pf') and the capacitance value at the negative electrode engagement end point (nf') will also coincide on the horizontal axis.

[0189] Referring to Figure 9, the processor 320 may generate a comparison full cell profile U by subtracting a partial profile between two points (pi', pf') of the adjusted reference positive electrode profile Rp' from a partial profile between two points (ni'', nf'') of the adjusted reference negative electrode profile Rn''.

[0190] The processor 320 can calculate the error (profile error) between the comparison full cell profile U and the measured full cell profile M.

[0191] The processor 320 may map at least two of the following to each other and store them in the memory unit 330: the adjusted reference positive electrode profile Rp', the adjusted reference negative electrode profile Rn'', the positive electrode involvement start point (pi'), the positive electrode involvement end point (pf'), the negative electrode involvement start point (ni''), the negative electrode involvement end point (nf''), the positive electrode scale factor, the negative electrode scale factor, the comparison full cell profile U, and the profile error.

[0192] As described above, the processor 320 can generate a corresponding comparison full cell profile for each pair of positive and negative scale factors selected from the scaling numerical range. Since there are multiple pairs of positive and negative scale factors, it is obvious that multiple comparison full cell profiles will also be generated. After identifying the minimum profile error among the multiple comparison full cell profiles, the processor 320 can obtain information mapped to the minimum profile error from the memory unit 330.

[0193] The processor 320 can determine the negative electrode loading amount of the target cell BC from the information mapped to the minimum profile error. The processor 320 can estimate the negative electrode loading amount of the target cell BC based on the extracted negative electrode scale factor. For reference, at least one of a positive electrode engagement start point, a positive electrode engagement end point, a negative electrode engagement start point, a negative electrode engagement end point, a positive electrode scale factor, and a negative electrode scale factor of the target cell BC in a new state may be already stored in the memory unit 330 by performing the above-described analysis process when the target cell BC is in the new state.

[0194] The processor 320 can determine at least one degradation parameter (e.g., negative electrode loading amount) based on the information mapped to the minimum profile error. Table 1 below summarizes the degradation parameters and the mathematical formulas used to determine each degradation parameter.

[0195]

Table 1

[0196] Each of the variables described in Table 1 is a diagnostic factor that can be determined by the above-described analysis process. The definitions of the degradation parameters and variables in Table 1 are as follows.

[0197] <Degradation Parameters> P SOH : Positive electrode SOH of target cell BC N SOH : Negative electrode SOH of target cell BC L SOH : Available lithium SOH of target cell BC F SOH : Full cell SOH of target cell BC P LOSS : Positive electrode loss rate of target cell BC N LOSS : Negative electrode loss rate of target cell BC L LOSS : Available lithium loss rate of target cell BC FLOSS : Full cell loss rate of target cell BC P loading_MOL : Positive electrode loading amount of target cell BC N loading_MOL : Amount of negative electrode loading for target cell BC

[0198] The positive electrode loading amount of any battery cell refers to 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 amount of any battery cell refers to 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 amount is mAh / cm². 2 or mg / cm 2 It is possible. In Table 1, P loading_ref This indicates the reference positive electrode loading amount, N loading_ref The reference negative electrode loading amount is a predetermined value indicating the amount of positive electrode active material (or usable capacity) per unit area of ​​the positive electrode of the reference cell. The reference positive electrode loading amount may be the value obtained by dividing the reference positive electrode capacity by the reference positive electrode area. Here, the reference positive electrode capacity may be a value predetermined as the total positive electrode capacity of the reference cell. The reference positive electrode area may be a value predetermined as the area of ​​the positive electrode of the reference cell. The reference negative electrode loading amount is a predetermined value indicating the amount of negative electrode active material (or usable capacity) per unit area of ​​the negative electrode of the reference cell. The reference negative electrode loading amount may be the value obtained by dividing the reference negative electrode capacity by the reference negative electrode area. Here, the reference negative electrode capacity may be a value predetermined as the total negative electrode capacity of the reference cell. The reference negative electrode area may be a value predetermined as the area of ​​the negative electrode of the reference cell.

[0199] <Variable> pi BOL : Positive electrode capacity (positive electrode SOC) at the point of positive electrode involvement in the target cell BC in the BOL state. pi MOL : The current positive electrode involvement start point (e.g., pi' shown in Figure 6) of the target cell BC, and the positive electrode capacity (positive electrode SOC). pf BOL : Positive electrode capacity (positive electrode SOC) at the positive electrode involvement termination point of the target cell BC in the BOL state. pfMOL : The positive electrode capacity (positive electrode SOC) of the target cell BC at its current positive electrode involvement endpoint (e.g., pf) shown in Figure 6. ni BOL : The negative electrode capacity (negative electrode SOC) at the point of negative electrode involvement in the target cell BC in the BOL state. ni MOL : The negative electrode capacity (negative electrode SOC) at the current negative electrode involvement start point of the target cell BC (e.g., ni shown in Figure 6) nf BOL : Negative electrode capacity (negative electrode SOC) at the negative electrode involvement termination point of the target cell BC in the BOL state. nf MOL : The negative electrode capacity (negative electrode SOC) of the current negative electrode involvement endpoint of the target cell BC (e.g., nf' shown in Figure 6) ps BOL : Positive electrode scale factor of target cell BC in BOL state ps MOL : Current positive electrode scale factor of target cell BC ns BOL : Negative electrode scale factor of target cell BC in BOL state ns MOL : The current negative electrode scale factor of target cell BC

[0200] The process of determining diagnostic factors for target cell BC may be repeated periodically or aperiodically throughout the entire lifespan of the target cell BC.

[0201] As the available lithium capacity, total positive electrode capacity, and / or total negative electrode capacity of any given battery cell decrease, the positive electrode capacity at the point where positive electrode involvement begins (positive electrode SOC) of that battery cell may gradually increase. The amount of available lithium of any given battery cell may be a parameter that indicates the total amount of lithium that can contribute to the charging and discharging of that battery cell. The amount of available lithium may gradually decrease from its new state due to side reactions that occur inside the battery cell during charging and discharging.

[0202] Using these characteristics, the processor 320 can determine whether or not a loss of available lithium has occurred in the target cell BC, based on the estimated starting point of the positive electrode involvement of the target cell BC, due to a loss of at least one of the available lithium amount and the total positive electrode capacity.

[0203] The processor 320 may diagnose that available lithium loss has occurred in response to an increase in the positive electrode capacitance (or positive electrode SOC) at the positive electrode engagement initiation point from its value in the new state.

[0204] There may be situations where the change from the new state of the positive electrode capacity (or positive electrode SOC) at the positive electrode engagement start point and the negative electrode capacity (or negative electrode SOC) at the negative electrode engagement end point of the target cell BC is less than a predetermined set value. If so, the processor 320 may determine that the greater the increase from the new state of the new state of the negative electrode capacity (or negative electrode SOC) at the negative electrode engagement start point, the greater the change from the new state of the target cell BC at the negative electrode engagement start point, compared to the loss of available lithium.

[0205] The processor 320 may limit at least one of the allowable voltage range and allowable SOC range for the target cell BC based on the estimated positive electrode engagement start point for the target cell BC. Relational data showing a predetermined positive correlation between the amount of change (e.g., increase) of the positive electrode capacitance (or positive electrode SOC) from the new state at the positive electrode engagement start point and the limit level may be pre-stored in the memory unit 330. That is, according to the relational data, a decrease or increase in the capacitance value (positive electrode capacitance or positive electrode SOC) at the positive electrode engagement start point may cause a reduction in at least one of the allowable voltage range and allowable SOC range. Reducing a range means at least one of raising the lower limit and lowering the upper limit of that range. Assume the allowable voltage range and allowable SOC range are 2.5 to 4.5V and 5 to 95%, respectively. If the positive electrode capacitance at the point of positive electrode involvement is estimated to be 110% of the value in the BOL state, the allowable voltage range may be reduced to 2.75 to 4.05 V, and the allowable SOC range may be reduced to 5.5 to 85.5%.

[0206] The processor 320 may diagnose that a capacity loss has occurred in the positive electrode of the target cell BC in response to a decrease in the positive electrode capacity (or positive electrode SOC) at the positive electrode involvement termination point from its value in a new state.

[0207] The processor 320 may limit at least one of the allowable voltage range and allowable SOC range for the target cell BC based on the positive electrode involvement termination point. Relational data showing a predetermined positive correlation between the change (e.g., decrease) in the positive electrode capacitance (or positive electrode SOC) from the new state at the positive electrode involvement termination point and the limiting level may be pre-stored in the memory unit 330. That is, according to the relational data, a decrease in the capacitance value (positive electrode capacitance, positive electrode SOC) at the positive electrode involvement termination point may cause a reduction in at least one of the allowable voltage range and allowable SOC range. Assume the allowable voltage range and allowable SOC range are 2.5 to 4.5 V and 5 to 95%, respectively. If the positive electrode involvement termination point is estimated to be 90% of the value in the BOL state, the allowable voltage range may be reduced to 2.75 to 4.05 V and the allowable SOC range may be reduced to 5.5 to 85.5%.

[0208] The processor 320 may limit at least one of the allowable voltage range and allowable SOC range for the target cell BC based on the estimated positive electrode scale factor of the target cell BC. Relational data showing a predetermined positive correlation between the positive electrode scale factor from the BOL state (e.g., the amount of decrease) and the limiting level may be pre-stored in the memory unit 330. That is, according to the relational data, a decrease in the positive electrode scale factor may cause a reduction in at least one of the allowable voltage range and allowable SOC range. Assume the allowable voltage range and allowable SOC range are 2.5 to 4.5 V and 5 to 95%, respectively. If the current positive electrode scale factor of the target cell BC is ps MOL The positive electrode scale factor ps in new condition BOL If estimated to be 90%, the allowable voltage range may be reduced to 2.75–4.05V, and the allowable SOC range may be reduced to 5.5–85.5%.

[0209] The processor 320 may limit at least one of the allowable voltage range and allowable SOC range for the target cell BC based on an estimated positive electrode loading amount for the target cell BC. Relational data showing a predetermined positive correlation between the positive electrode loading amount and the limiting level may be pre-stored in the memory unit 330. That is, according to the relational data, a decrease in the positive electrode loading amount may cause a reduction in at least one of the allowable voltage range and allowable SOC range. Assume the allowable voltage range and allowable SOC range are 2.5 to 4.5 V and 5 to 95%, respectively. If the positive electrode loading amount is estimated to be 90% of the reference positive electrode loading amount, the allowable voltage range may be reduced to 2.75 to 4.05 V and the allowable SOC range may be reduced to 5.5 to 85.5%.

[0210] The processor 320 may limit at least one of the allowable voltage range and allowable SOC range for the target cell BC based on the negative electrode engagement start point of the target cell BC. Relational data showing a predetermined positive correlation between the change (e.g., decrease) in the negative electrode capacitance (or negative electrode SOC) from the new state at the negative electrode engagement start point and the limiting level may be pre-stored in the memory unit 330. That is, according to the relational data, a decrease or increase in the capacitance value (negative electrode capacitance, or negative electrode SOC) at the negative electrode engagement start point may cause a reduction in at least one of the allowable voltage range and allowable SOC range. Assume the allowable voltage range and allowable SOC range are 2.5 to 4.5 V and 5 to 95%, respectively. If the current negative electrode capacitance at the negative electrode engagement start point is estimated to be 90% of the value in the BOL state, the allowable voltage range may be reduced to 2.75 to 4.05 V and the allowable SOC range may be reduced to 5.5 to 85.5%.

[0211] The processor 320 may diagnose that a capacitance loss has occurred in the negative electrode of the target cell BC in response to a decrease in the negative electrode capacitance (or negative electrode SOC) at the negative electrode involvement termination point from its value in the new state. Based on the estimated negative electrode involvement termination point for the target cell BC, the processor 320 may limit at least one of the allowable voltage range and allowable SOC range for the target cell BC. Relational data showing a predetermined positive correlation between the amount of change (e.g., decrease) of the negative electrode capacitance (or negative electrode SOC) at the negative electrode involvement termination point from the new state and the limiting level may be pre-stored in the memory unit 330. That is, according to the relational data, a decrease in the capacitance value (negative electrode capacitance, negative electrode SOC) at the negative electrode involvement termination point may cause a reduction in at least one of the allowable voltage range and allowable SOC range. Assume the allowable voltage range and allowable SOC range are 2.5 to 4.5 V and 5 to 95%, respectively. If the current negative electrode involvement termination point is estimated to be 90% of the BOL state value, the allowable voltage range may be reduced to 2.75–4.05V, and the allowable SOC range may be reduced to 5.5–85.5%.

[0212] The processor 320 may limit at least one of the allowable voltage range and allowable SOC range for the target cell BC based on the estimated negative electrode scale factor of the target cell BC. Relational data showing a predetermined positive correlation between the amount of decrease in the negative electrode scale factor from the BOL state and the limiting level may be pre-stored in the memory unit 330. That is, according to the relational data, a decrease in the negative electrode scale factor may cause a reduction in at least one of the allowable voltage range and allowable SOC range. Assume the allowable voltage range and allowable SOC range are 2.5 to 4.5 V and 5 to 95%, respectively. If the current negative electrode scale factor of the target cell BC is ns MOL The negative electrode scale factor ns in new condition BOLIf estimated to be 90%, the allowable voltage range may be reduced to 2.75-4.05V and the allowable SOC range may be reduced to 5.5-85.5%. The processor 320 may limit at least one of the allowable voltage range and allowable SOC range for the target cell BC based on the estimated amount of negative electrode loading of the target cell BC. Relational data showing a predetermined positive correlation between the amount of decrease in negative electrode loading from the BOL state and the limiting level may be pre-stored in the memory unit 330. That is, according to the relational data, a decrease in negative electrode loading can cause a reduction in at least one of the allowable voltage range and allowable SOC range. Assume the allowable voltage range and allowable SOC range are 2.5-4.5V and 5-95%, respectively. If the current negative electrode loading amount N loading_MOL N is the value of the BOL state. loading_BOL If estimated to be 90%, the allowable voltage range may be reduced to 2.75–4.05V, and the allowable SOC range may be reduced to 5.5–85.5%.

[0213] Figure 10 is a flowchart for illustrative purposes to explain the battery diagnostic method according to the first embodiment of the present invention. The method shown in Figure 10 can be performed by a battery diagnostic device 302.

[0214] In step S1010, the processor 320 performs a process of intermittently applying electrical stimulation to the target cell BC. Specifically, the processor 320 can control the stimulation application device 301 to intermittently apply electrical stimulation (e.g., a second electrical stimulation) to the target cell BC during the state change period from the first state to the second state of the target cell BC.

[0215] The intermittent application process of electrical stimulation may be a process in which periods of electrical stimulation application and rest periods are repeated. That is, the intermittent application process includes at least two application processes and at least two rest periods. When the integrated current value of the target cell BC changes by a critical integrated value during the application of electrical stimulation by each application process, the electrical stimulation to the target cell BC may be removed (output interrupted) and a rest period may be granted. When the duration of the rest period by each rest process reaches a reference time, the application process of electrical stimulation may be resumed.

[0216] Step S1010 may also be performed by the battery management system 100 or the system controller 2 instead of the processor 320, in which case step S1010 can be omitted from the method shown in Figure 10.

[0217] In step S1020, the processor 320 uses the data acquisition unit 310 to acquire state history data of the target cell BC corresponding to the state change period. The state history data includes voltage history data and may further include current history data or capacitance history data.

[0218] Voltage history data may include voltage values ​​representing the full cell voltage of the target cell BC, measured at least once during each pause in the electrical stimulation applied during the state change period. That is, voltage history data may show the history of changes in the full cell voltage of the target cell BC over the state change period. Voltage history data may include the measured value of the full cell voltage of the target cell BC at the end of each pause (D in Figure 3a). OCV (See reference) may include. The data acquisition unit 310 may collect state history data generated by the battery system 1 from the battery system 1 after the end of the state change period.

[0219] Alternatively, the data acquisition unit 310 may periodically collect measurement data from the battery system 1 over the state change period, showing at least one measurement value of the current and full cell voltage of the target cell BC. In this case, each measurement value collected multiple times over the state change period may be stored in the memory unit 330 in chronological order. The processor 320 may generate state history data from the set of measurement values ​​collected over the state change period.

[0220] In step S1030, the processor 320 generates a measured full cell profile (see reference numeral M in Figure 3b) that shows the correspondence between the capacity of the target cell BC and the full cell voltage, based on the state history data.

[0221] In step S1040, the processor 320 analyzes the measured full cell profile and generates first diagnostic information that includes at least one diagnostic factor relating to the charge-discharge performance of the target cell BC.

[0222] The first diagnostic information may include at least one of the following as diagnostic factors, indicating the charge-discharge performance of the positive electrode of the target cell BC: the positive electrode engagement start point, the positive electrode engagement end point, the positive electrode scale factor, and the positive electrode loading amount. The positive electrode loading amount refers to the amount of positive electrode active material per unit area of ​​the positive electrode.

[0223] The first diagnostic information may include at least one of the following as diagnostic factors, indicating the charge-discharge performance of the negative electrode of the target cell BC: the negative electrode engagement start point, the negative electrode engagement end point, the negative electrode scale factor, and the negative electrode loading amount. The negative electrode loading amount refers to the amount of negative electrode active material per unit area of ​​the negative electrode.

[0224] In step S1050, the processor 320 applies at least one mathematical operation to the first diagnostic information to generate second diagnostic information for the target cell BC. The second diagnostic information may include at least one degradation parameter relating to at least one of the positive electrode, negative electrode, and available lithium (see Table 1, etc.).

[0225] The second diagnostic information may include whether or not available lithium loss occurs in the target cell BC and / or the rate of available lithium loss, determined based on the positive electrode involvement start point of the first diagnostic information.

[0226] The second diagnostic information may include whether or not positive electrode capacity loss occurs in the target cell BC and / or the positive electrode loss rate, determined based on the positive electrode involvement termination point, positive electrode scale factor, and / or positive electrode loading amount of the first diagnostic information.

[0227] The second diagnostic information may include whether or not there is a loss of available lithium in the target cell BC, whether or not positive electrode capacity loss occurs, whether or not negative electrode capacity loss occurs, and / or negative electrode loss rate, determined based on the negative electrode involvement start point, negative electrode involvement end point, and / or negative electrode scale factor of the first diagnostic information.

[0228] The second diagnostic information may include the negative electrode loss rate (which may also be called the "negative electrode capacity loss rate") of the target cell BC, which is determined based on the negative electrode loading amount of the first diagnostic information.

[0229] In step S1060, the processor 320 updates charge / discharge tolerance condition information indicating at least one of the voltage range, SOC range, and current range that are permissible for the target cell BC, based on at least one of the first diagnostic information and the second diagnostic information.

[0230] As an example, the processor 320 may determine updated charge / discharge tolerance information by limiting (e.g., downward adjusting) at least one of the voltage range, SOC range, and current range of the target cell BC of the previously known charge / discharge tolerance information, based on at least one degradation parameter (e.g., negative electrode loading amount) of the first diagnostic information.

[0231] In step S1070, the processor 320 may transmit the diagnostic results of the target cell BC to the battery system 1 using the data acquisition unit 310. The diagnostic results include at least one of the first diagnostic information, the second diagnostic information, and the updated charge / discharge tolerance condition information.

[0232] In the method shown in Figure 10, at least one of steps S1050, S1060, and S1070 can be omitted from the method shown in Figure 10.

[0233] Figure 11 is a flowchart for illustrative purposes to explain the battery diagnostic method according to a second embodiment of the present invention. The method shown in Figure 11 can be performed by a battery diagnostic device 302.

[0234] In step S1110, the processor 320 performs a process of intermittently applying electrical stimulation to the target cell BC.

[0235] In step S1120, the processor 320 uses the data acquisition unit 310 to acquire state history data corresponding to the state change period.

[0236] Unlike step S1020 in Figure 10 according to the first embodiment described above, the voltage history data of the state history data acquired in step S1120 includes measurements of the full cell voltage taken three or more times for each idle period during the state change period.

[0237] In step S1122, the processor 320 applies OCV estimation logic to the voltage history data of the state history data acquired in step S1120 to generate corrected state history data. The OCV estimation logic may be configured to replace the set of three full cell voltage measurements for each rest period included in the voltage history data acquired in step S1120 with a single OCV value. Therefore, if a total of X rest periods are given during the state change period, and the full cell voltage is measured three times for each rest period, it will be easily understood by those skilled in the art that the voltage history data acquired in step S1120 will contain 3X full cell voltage measurements, and the corrected voltage history data will contain X OCV values.

[0238] In step S1130, the processor 320 generates a measured full cell profile (see reference numeral M in Figure 3b) that shows the correspondence between the capacitance of the target cell BC and the full cell voltage, based on the corrected state history data.

[0239] In step S1140, the processor 320 analyzes the measured full cell profile and generates first diagnostic information that includes at least one diagnostic factor relating to the charge-discharge performance of the target cell BC.

[0240] In step S1150, the processor 320 applies at least one mathematical operation to the first diagnostic information to generate second diagnostic information for the target cell BC.

[0241] In step S1160, the processor 320 updates charge / discharge tolerance condition information indicating at least one of the voltage range, SOC range, and current range that are permissible for the target cell BC, based on at least one of the first diagnostic information and the second diagnostic information.

[0242] In step S1170, the processor 320 may transmit the diagnostic results of the target cell BC to the battery system 1 via the data acquisition unit 310.

[0243] In the method shown in Figure 11, steps S1110, S1140, S1150, S1160, and S1170 may be substantially identical to steps S1010, S1040, S1050, S1060, and S1070 of the method shown in Figure 10, respectively. In the method shown in Figure 11, at least one of steps S1150, S1160, and S1170 can be omitted from the method shown in Figure 11.

[0244] Figure 12 is a diagram to be referenced to illustrate the voltage history data correction process performed in step S1122 of Figure 11.

[0245] Reference numeral 1200 in Figure 12 indicates one of the voltage drop segments shown in Figure 3a. Rindicates the time point when a reference time has elapsed from the start time point of a rest period. t R The portion up to is indicated by a solid line, and t R The portion after is distinguished and indicated by a dotted line.

[0246] Referring to FIG. 12, during each rest period, the target cell BC is placed in a no-load state where neither charging nor discharging occurs.

[0247] In the no-load state, 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 a primary RC circuit as shown in Mathematical Formula 1 below.

[0248] [Mathematical Formula 1] [Numerical]

[0249] In Mathematical Formula 1, t is the elapsed time from the start time point of a specific rest period, V full (t) is the full-cell voltage at time t, V OCV is the actual OCV, V S is the full-cell voltage at the start time point of the specific rest period, and τ is the time constant determined by the internal resistance and capacitance of the target cell BC.

[0250] In Mathematical Formula 1, V full (t) can be measured, and V OCV , V S and τ are unknowns. Since there are three unknowns, the OCV for a specific rest period can be estimated based on V full (t) measured at three different timings. For estimating the OCV for each rest period, Mathematical Formula 2 below can be used.

[0251] [Mathematical Formula 2] [Numerical]

[0252] In Equation 2, t1, t2 and t3 are a series of measurement timings for full-cell voltage. The time difference between t1 and t2 may be the same as the time difference between t2 and t3. On the other hand, in the illustration of FIG. 12, t R and t3 are different, but t R and t3 may be the same. In this case, V full (t3)=D OCV .

[0253] The processor 320 may determine D OCV in the same manner as V OCV_C calculated through Equation 2.

[0254] The processor 320 repeats, for all rest periods, the process of replacing three full-cell voltage measurement values (V full (t1), V full (t2), V full (t3)) for each rest period with a single OCV value (D OCV_C ), whereby the voltage history data acquired in step S1120 can be converted into corrected voltage history data for step S1130. The corrected voltage history data includes X number of OCV values. The processor 320 may apply curve fitting logic to the corrected voltage history data to generate a measured full-cell profile M.

[0255] For reference, D OCV is a measured value of the full-cell voltage at the end of the rest period (before polarization is completely eliminated), while D OCV_C is an estimated value of the full-cell voltage in a state where polarization is completely eliminated (that is, V OCV ). Therefore, it can be said that D OCV_C is closer to the actual OCV of the target cell BC than D OCV is.

[0256] The above-described embodiments of the present invention are not implemented only by the apparatus and method, and can also be implemented through a program that implements functions corresponding to the configuration of the embodiments of the present invention or a storage medium storing the program. Such a program or storage medium can be easily implemented by those skilled in the art based on the description of the above embodiments.

[0257] As described above, the present invention has been explained with limited embodiments and drawings, but it goes without saying that the present invention is not limited thereto, and that various modifications and variations are possible within the equivalent scope of the technical idea and claims of the present invention by persons with ordinary skill in the art to which the present invention pertains.

[0258] Furthermore, the present invention described above can be substituted, modified, and altered in various ways by a person with ordinary skill in the art to which the present invention pertains, without departing from the technical spirit of the invention, and is not limited by the embodiments described above and the accompanying drawings. All or part of each embodiment can be selectively combined to form a variety of modifications.

Claims

1. A step of acquiring state history data of a battery cell corresponding to the state change period from a first state to a second state by an intermittent application process of electrical stimulation to the battery cell, The steps include generating a measured full cell profile showing the correspondence between the capacity and voltage of the battery cell based on the state history data, A battery diagnostic method comprising the steps of: analyzing the measured full cell profile and generating first diagnostic information including at least one diagnostic factor relating to the charge / discharge performance of the battery cell.

2. The battery diagnostic method according to claim 1, wherein the electrical stimulation is a current stimulation that induces a momentary voltage change exceeding a threshold in the battery cell.

3. The battery diagnostic method according to claim 1, wherein the electrical stimulation is a current stimulation that induces an overvoltage exceeding a threshold in the battery cell when the electrical stimulation is continuously applied over a predetermined period of time.

4. The battery diagnostic method according to claim 1, wherein the electrical stimulation is a charging current having a predetermined current rate.

5. The battery diagnostic method according to claim 1, wherein the electrical stimulation is a discharge current having a predetermined current rate.

6. The battery diagnostic method according to claim 1, wherein the state history data includes a voltage value indicating the voltage of the battery cell measured at least once during each of the pauses in the electrical stimulation applied during the state change period.

7. The battery diagnostic method according to claim 1, wherein the intermittent application process includes a process of removing the electrical stimulation to the battery cell each time the integrated current value of the battery cell changes by a critical integrated value during the application of the electrical stimulation, such that a rest period is given to the battery cell.

8. The battery diagnostic method according to claim 7, wherein the intermittent application process further includes a process of resuming the application of the electrical stimulation when the duration of the rest period reaches a reference time.

9. The battery diagnostic method according to claim 1, wherein the first diagnostic information includes at least one of the following as diagnostic factors: a positive electrode engagement start point, a positive electrode engagement end point, a positive electrode scale factor, and a positive electrode loading amount, which indicate the charge-discharge performance of the positive electrode of the battery cell.

10. The battery diagnostic method according to claim 9, further comprising the step of applying mathematical operations to the first diagnostic information to generate second diagnostic information including at least one degradation parameter relating to the positive electrode or available lithium of the battery cell.

11. The battery diagnostic method according to claim 1, wherein the first diagnostic information includes at least one of the following as diagnostic factors: a negative electrode involvement start point, a negative electrode involvement end point, a negative electrode scale factor, and a negative electrode loading amount, which indicate the charge and discharge performance of the negative electrode of the battery cell.

12. The battery diagnostic method according to claim 11, further comprising the step of applying mathematical operations to the first diagnostic information to generate second diagnostic information including at least one degradation parameter relating to the negative electrode of the battery cell.

13. The battery diagnostic method according to claim 10 or 12, further comprising the step of updating charge / discharge tolerance information indicating at least one of the voltage range, SOC range, and current range that are permissible for the battery cell, based on at least one of the first diagnostic information and the second diagnostic information.

14. A data acquisition unit is configured to acquire state history data of the battery cell corresponding to the state change period from a first state to a second state by an intermittent application process of electrical stimulation to the battery cell. A processor configured to generate a measured full cell profile showing the correspondence between the capacity and voltage of the battery cell based on the state history data, A battery diagnostic device comprising a processor configured to analyze the measured full cell profile and generate first diagnostic information including at least one diagnostic factor relating to the charge / discharge performance of the battery cell.

15. The battery diagnostic device according to claim 14, wherein the intermittent application process includes a process of removing the electrical stimulation to the battery cell each time the integrated current value of the battery cell changes by a critical integrated value during the application of the electrical stimulation, such that a rest period is given to the battery cell.

16. The battery diagnostic device according to claim 15, wherein the intermittent application process further includes a process of resuming the application of the electrical stimulation when the duration of the rest period reaches a reference time.

17. The battery diagnostic device according to claim 14, wherein the first diagnostic information includes at least one of the following as diagnostic factors: a positive electrode engagement start point, a positive electrode engagement end point, a positive electrode scale factor, and a positive electrode loading amount, which indicate the charge-discharge performance of the positive electrode of the battery cell.

18. The battery diagnostic device according to claim 14, wherein the first diagnostic information includes at least one of the following as diagnostic factors: a negative electrode involvement start point, a negative electrode involvement end point, a negative electrode scale factor, and a negative electrode loading amount, which indicate the charge and discharge performance of the negative electrode of the battery cell.

19. A charging station comprising a battery diagnostic device according to any one of claims 14 to 18.

20. A cloud server including a battery diagnostic device according to any one of claims 14 to 18.

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