Battery diagnostic device and battery diagnostic method

Abstract

A battery diagnostic device and a battery diagnostic method are disclosed. A battery diagnostic device according to one embodiment of the present invention includes a processor configured to control a stimulus application device to intermittently apply a second electrical stimulus greater than a first electrical stimulus to a target cell during a state change period, and a communication unit configured to acquire current time series data during the state change period and voltage time series data showing the history of changes in the full cell voltage of the target cell during the pause period of the second electrical stimulus applied during the state change period. The processor generates a measured full cell profile of the target cell based on the current time series data and the voltage time series data, and analyzes the measured full cell profile to estimate the positive electrode loading amount 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. 10-2023-0133644, filed on 6 October 2023, and all contents disclosed in the specification and drawings of said application are incorporated herein by reference. [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] Accurately diagnosing the internal condition of a battery is essential for its safety and longevity. When diagnosing the internal condition of a battery without disassembly, relational data showing the correspondence between capacity and voltage (which may be called a "full-cell profile," etc.) is primarily used.

[0007] Traditionally, a full cell profile is obtained by repeatedly measuring the battery voltage and capacity at short intervals while applying a constant electrical stimulation (e.g., constant current charging or discharging) to the battery. However, in order to minimize polarization (or overvoltage) that causes a decrease in diagnostic accuracy, the level of electrical stimulation applied to the target cell must be reduced, which imposes a constraint that makes it excessively time-consuming to obtain a full cell profile. Conversely, while high levels of electrical stimulation are advantageous in terms of saving time, they are accompanied by severe polarization phenomena, making it impossible to guarantee the accuracy of the diagnostic results. [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention was devised to solve the above-mentioned problems, and aims to provide a battery diagnostic device and battery diagnostic method that can acquire relational data showing the correspondence between the capacity and voltage of a target cell by intermittently applying a high level of electrical stimulation to the target cell, and diagnose the degradation state of the positive electrode of the target cell (positive electrode loading amount, positive electrode capacity loss rate, etc., described later) based on the acquired relational data.

[0009] 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]

[0010] According to one aspect of the present invention, a battery diagnostic device includes a processor configured to control a stimulation application device to intermittently apply a second electrical stimulation greater than a first electrical stimulation to a target cell, which is a battery cell to be diagnosed, during a state change period until the electrical state of the target cell changes from an initial state to a target state, and a communication unit configured to acquire current time-series data indicating a change history of the current of the target cell during the state change period and voltage time-series data indicating a change history of the full cell voltage of the target cell during a rest period of the second electrical stimulation applied during the state change period. The processor is configured to generate a measured full cell profile indicating a correspondence relationship between the capacity of the target cell and the full cell voltage based on the current time-series data and the voltage time-series data. The processor is configured to analyze the measured full cell profile and estimate a positive electrode loading amount, which means the amount of positive electrode active material per unit area of the positive electrode of the target cell.

[0011] The first electrical stimulation may be an electrical stimulation that induces a difference between an OCV (Open Circuit Voltage) and a CCV (Closed Circuit Voltage) below a reference value in the target cell. The second electrical stimulation may be an electrical stimulation that induces a difference between an OCV and a CCV exceeding the reference value in the target cell.

[0012] The first electrical stimulation may be charging using a first current rate, and the second electrical stimulation may be charging using a second current rate greater than the first current rate.

[0013] The first electrical stimulation may be discharging using a first current rate, and the second electrical stimulation may be discharging using a second current rate greater than the first current rate.

[0014] The voltage time-series data may be data in which measured values of the full cell voltage during the rest period of the second electrical stimulation are arranged in time order as the OCV of the target cell.

[0015] The processor may be configured to control the stimulation application device to start the pause period of the second electrical stimulation each time the integrated value of the current changes by a critical integrated value.

[0016] The processor may be configured to control the stimulation application device to resume the application of the second electrical stimulation when a reference time has elapsed since the start of the pause period of the second electrical stimulation.

[0017] The processor may be configured to determine the positive electrode capacity loss rate of the target cell based on the estimated value of the positive electrode loading amount.

[0018] The processor may be configured to limit at least one of the allowable voltage range and the allowable SOC (State of Charge) range for the target cell based on the estimated value of the positive electrode loading amount.

[0019] A charging station according to another aspect of the present invention includes a battery diagnostic device according to an aspect of the present invention.

[0020] A cloud server according to still another aspect of the present invention includes a battery diagnostic device according to an aspect of the present invention.

[0021] A battery diagnostic method according to still another aspect of the present invention includes: controlling a stimulation application device to intermittently apply a second electrical stimulation greater than a first electrical stimulation to a target cell during a state change period until the electrical state of the target cell, which is a battery cell to be diagnosed, changes from an initial state to a target state; obtaining current time-series data indicating the change history of the current of the target cell during the state change period and voltage time-series data indicating the change history of the full cell voltage of the target cell during the pause period of the second electrical stimulation given during the state change period; generating a measured full cell profile indicating the correspondence between the capacity of the target cell and the full cell voltage based on the current time-series data and the voltage time-series data; and analyzing the measured full cell profile to estimate the positive electrode loading amount, which means the amount of positive electrode active material per unit area of the positive electrode of the target cell.

[0022] Voltage time-series data may consist of data where the measured full cell voltage during the resting phase of the second electrical stimulation is arranged chronologically as the OCV of the target cell.

[0023] The battery diagnostic method may further include the step of determining the positive electrode capacity loss rate of the target cell based on an estimate of the positive electrode loading amount.

[0024] The battery diagnostic method may further include a step of limiting at least one of the allowable voltage range and the allowable SOC range for the target cell based on an estimate of the positive electrode loading amount. [Effects of the Invention]

[0025] According to one aspect of the present invention, a method is used in which a high level of electrical stimulation is intermittently applied to the target cell to obtain relational data showing the correspondence between the capacitance and voltage of the target cell, and the degradation state of the positive electrode of the target cell (positive electrode loading amount, positive electrode capacitance loss rate, etc., described later) can be diagnosed based on the obtained relational data.

[0026] In other words, by using high levels of electrical stimulation to change the electrical state of the target cell, the time required to acquire relevant data can be shortened, and the intermittent application of electrical stimulation can prevent a decrease in diagnostic accuracy due to excessive polarization.

[0027] 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.

[0028] The drawings accompanying this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, are intended to facilitate a better understanding of the technical concept of the invention. Therefore, the present invention is not to be construed as being limited solely to what is shown in the drawings. [Brief explanation of the drawing]

[0029] [Figure 1] This diagram illustrates the configuration of an electric vehicle and a charging station including 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 the full cell profile of the target cell. [Figure 3b] This graph is used to illustrate the process of obtaining the full cell profile of the target 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 time series data correction process performed in step S1122 of Figure 11. [Modes for carrying out the invention]

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Figure 1 is an illustrative diagram showing the configuration of an electric vehicle and a charging station including a battery diagnostic device according to one embodiment of the present invention.

[0036] Referring to Figure 1, the electric vehicle 1 includes a vehicle controller 2, a battery pack 10, an inverter 30, and an electric motor 40. The charge and 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.

[0037] The vehicle controller 2 (for example, an 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 electric vehicle 1 to the ON position. The vehicle 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 vehicle 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.

[0038] The battery pack 10 includes a battery 11, a relay 20, and a battery management system 100.

[0039] Battery 11 includes at least one battery cell BC. Figure 1 shows multiple battery cells BC1~BC connected in series to battery 11. NThe 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 to 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.

[0040] The type of battery cell BC is not particularly limited, as long as it is an electrochemical element capable of repeated charging and discharging. Battery cells BC are subject to diagnosis by charging stations.

[0041] 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).

[0042] The inverter 30 is configured to respond to commands from the battery management system 100 or the vehicle controller 2 and convert the DC current from the battery 11 contained in the battery pack 10 into AC current. The electric motor 40 is driven using the AC power from the inverter 30. For example, a three-phase AC motor may be used as the electric motor 40. The components within the electric vehicle 1 that receive the discharge power from the battery 11, including the inverter 30 and the electric motor 40, may be referred to as an electrical load.

[0043] 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.

[0044] The sensing unit 110 includes a voltage sensor 111. The sensing unit 110 may further include a current sensor 112.

[0045] The voltage sensor 111 is connected to the positive and negative terminals of the battery cell BC and is configured to detect the voltage across both ends of the battery cell BC (which may also be called the "full-cell voltage") and to generate a voltage signal indicating the detected value of the voltage. The voltage sensor 111 can be implemented using one or more combinations of known voltage detection elements such as a voltage measurement IC.

[0046] The current sensor 112 is connected in series with the battery 11 through a current path between the battery 11 and the inverter 30. The current sensor 112 is configured to detect the current flowing through the battery 11 (which may also be called the "charge / discharge current") and to generate a current signal indicating the detected value of the current. 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 sensing elements such as a shunt resistor or a Hall effect element.

[0047] The communication circuit 150 is configured to support wired or wireless communication between the control circuit 130 and the vehicle controller 2. Wired communication may be, for example, CAN (Controller Area Network) communication, and wireless communication may be, for example, ZigBee® or Bluetooth® communication. 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 vehicle 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 vehicle controller 2 in a form that is recognizable to the user (driver).

[0048] 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.

[0049] 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 "detection signal" may refer to the voltage signal only, or it may be a general term referring to both the voltage signal and the current signal. 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 the current sensor 112 may each contain an ADC internally and transmit digital values ​​to the control circuit 130.

[0050] 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.

[0051] 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). Memory 131 can store data and programs required for the arithmetic operations of the control circuit 130. Memory 131 can store data indicating the results of the arithmetic operations of the control circuit 130.

[0052] 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.

[0053] 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 vehicle controller 2 instead of the control circuit 130.

[0054] In this specification, time-series data of a parameter represents the history of its change over time. Furthermore, a profile (or curve) showing the correspondence between two parameters obtained at the same time intervals during the same period may be a mapping of the time-series data of the two parameters so that it can be represented in the form of a two-dimensional graph, or a polynomial equation obtained by applying a predetermined curve-fitting logic to the two mapped sets of time-series data. Here, the degree of the highest-order term in the polynomial may be predetermined.

[0055] The battery diagnostic device 302 includes a communication unit 310, a memory unit 330, and a processor 320.

[0056] The charging station 300 may include a stimulation application device 301 and a battery diagnostic device 302. Alternatively, the battery diagnostic device 302 may be configured 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 communication unit 310 of the battery diagnostic device 302 may perform a diagnostic process on the target cell through remote communication with the stimulation application device 301 and / or the electric vehicle 1.

[0057] 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 apply a variety of electrical stimuli to the battery cell BC for diagnosis of the battery cell BC, either alone or together with the inverter 30.

[0058] The communication unit 310 is configured to support wired or wireless communication between the processor 320 and the vehicle controller 2. The communication unit 310 can transmit the results of diagnostics performed on the battery cell BC by the processor 320 to the electric vehicle 1.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] The positive and negative voltages can be either open-circuit voltages (OCV) or closed-circuit voltages (CCV), respectively.

[0066] To obtain the open-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 an intermittent charging method in which constant current charging and pauses are performed alternately using a first current rate. The first discharging protocol may be an intermittent discharging method in which constant current discharge and pauses are performed alternately using a first current rate. The first current rate (e.g., 0.05C) may be predetermined to be greater than the second current rate (e.g., 3.0C) described later.

[0067] For example, when the charging time by constant current charging in the first 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.

[0068] As another example, the discharge of the reference cell may be paused for a predetermined period of time after the discharge time of the first 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).

[0069] In this case, multiple pauses may be introduced during the progress of the first 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.

[0070] On the other hand, a second charging protocol or a second discharging protocol can be used to obtain the closed-circuit voltages of the positive and negative electrodes of the reference cell. The second charging protocol may be a constant-current charging method using a second current rate. The second discharging protocol may be a constant-current discharging method using a second current rate. As an example, while the reference cell is continuously charged by the second charging protocol or continuously discharged by the second discharging protocol, the closed-circuit voltages of the positive and negative electrodes of the reference cell, measured periodically or aperiodicly, can be stored as the positive and negative electrode voltages of the reference cell.

[0071] In this specification, the first electrical stimulation refers to an electrical stimulation that induces a difference between OCV and CCV below a reference value in a battery cell, and the second electrical stimulation refers to an electrical stimulation that induces a difference between OCV and CCV above a reference value in a battery cell.

[0072] For example, the first electrical stimulation may be charging using a first current rate, and the second electrical stimulation may be charging using a second current rate that is higher than the first current rate.

[0073] As another example, the first electrical stimulation could be a discharge using a first current rate, and the second electrical stimulation could be a discharge using a second current rate that is higher than the first current rate.

[0074] The implementation of the first charging protocol or the first discharging protocol may mean the application of a first electrical stimulus to the battery cell. The implementation of the second charging protocol or the second discharging protocol may mean the application of a second electrical stimulus to the battery cell.

[0075] For the sake of explanation, we will assume that the horizontal axis in Figures 2 to 9 represents the charging capacity.

[0076] 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.

[0077] 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.

[0078] 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".

[0079] 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).

[0080] 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.

[0081] In this specification, the positive electrode engagement start point on the positive electrode profile of any battery cell represents the positive electrode voltage 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 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.

[0082] Furthermore, the positive electrode involvement termination point on the positive electrode profile of any battery cell indicates the positive electrode voltage 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 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.

[0083] 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.

[0084] 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).

[0085] Figures 3a and 3b are graphs used to illustrate the process of obtaining the measured full cell profile of the target cell.

[0086] 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 a second electrical stimulus. The target cell is a battery cell that is being 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.

[0087] Referring to Figure 3a, the processor 320 can control the stimulation application device 301 to intermittently apply a second electrical stimulus greater than the first electrical stimulus to the target cell BC.

[0088] 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., full cell voltage) changes from an initial state (e.g., first set voltage) to a target state (e.g., second set voltage).

[0089] 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 the second electrical stimulus, and the voltage decrease segment is generated by the interruption of the second electrical stimulus. In other words, the voltage decrease segments show the change in the full cell voltage of the target cell BC over the rest period.

[0090] During the state change period, the processor 320 may repeatedly store the measured current of the target cell BC and generate current time-series data.

[0091] The processor 320 can control the stimulation application device 301 to initiate a pause period for the second electrical stimulation whenever a predetermined pause condition is met during the state change period. That is, the process of applying the second electrical stimulation 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 application of the second electrical stimulation is maintained 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 pause periods may be applied during the state change period.

[0092] 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 capacity loss rate) of the target cell BC. At least one of the critical integrated value, critical SOC, and critical time may have a predetermined 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. Due to the predetermined negative correspondence, at least one of the critical integrated value, critical SOC, and critical time decreases as the full charge capacity, SOH, or previous diagnostic results decrease. 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 time series data, which shows the time-series history of the full cell voltage during the rest periods of the state change period.

[0093] 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 the second electrical stimulus over the state change period.

[0094] The processor 320 can control the stimulation device 301 to resume the application of the second electrical stimulation when a reference time has elapsed from the start of the pause period of the second electrical stimulation. The reference time can be predetermined to the extent that the polarization caused by the second electrical stimulation is sufficiently resolved. For example, the reference time, which is the length of the pause period, may be the time required for the polarization at the start of the pause period to be 10% or less.

[0095] During each pause of the second 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 of the second electrical stimulation as the OCV of the target cell BC. Alternatively, during each pause of the second 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.

[0096] As a result, OCV is stored multiple times with time differences over the state change period, which can generate voltage time-series data. Each OCV point (D) is shown in Figure 3a. OCV ) is an example of a data point in voltage time series data.

[0097] The inventors have observed through numerous experiments that the voltage time series data generated using the above method with the second electrical stimulus has a high degree of consistency with the voltage time series data generated when the first electrical stimulus is actually applied to the target cell BC.

[0098] 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.

[0099] Assume the following conditions are relevant to the diagnosis of target cell BC.

[0100] (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 In this case, the time required for the target cell BC to change from its initial state to the target state due to the continuous application of the first electrical stimulation is 1 / 0.05 × 80% = 16 hours.

[0101] 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 applied each time the charge capacity increases by 3%, a total of 26 rest periods are applied during the state change period. Therefore, the time required for the target cell BC to change from the initial state to the target state due to the intermittent application of the second electrical stimulation is (0.008 hours + 0.2 hours) × 26 = 5.4 hours.

[0102] 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.

[0103] In the graph in Figure 3b, the horizontal axis (X-axis) represents capacitance (Ah), and the vertical axis (Y-axis) represents voltage.

[0104] 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.

[0105] 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.

[0106] Current time-series data and voltage time-series data mapped to the state change period can be used to generate the measured full cell profile M.

[0107] More specifically, each data point in the current time series data and voltage time series data is indexed in chronological order. Therefore, the processor 320 can sequentially integrate the data points of the current time series data to generate capacitance time series data. Furthermore, the processor 320 can apply a curve fitting algorithm to a set of multiple Q-OCV pairs obtained by mapping the capacitance time series data and the voltage time series 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.

[0108] 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).

[0109] 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.

[0110] 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.

[0111] 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).

[0112] 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 adjusting the reference positive electrode profile Rp and reference negative electrode profile Rn stored in the memory unit 330, respectively, to generate an adjusted positive electrode profile and an adjusted negative electrode profile, and then combining (combining) the adjusted positive electrode profile and the adjusted negative electrode profile.

[0113] 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.

[0114] 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 based on the reference positive electrode profile Rp and the reference negative electrode profile Rn and stored in the memory unit 330. In this case, the processor 320 may obtain the comparison full cell profile by accessing the memory unit 330 and reading it.

[0115] 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".

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] The following describes the analysis process of the measured full cell profile M for estimating the positive electrode loading amount of the target cell BC, referring to Figures 4 to 9. The positive electrode loading amount of any battery cell refers to the amount of positive electrode active material per unit area of ​​the positive electrode of the battery cell, and its unit is mAh / cm². 2 or mg / cm 2 It is possible.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] Either the positive electrode involvement start point (pi) or the negative electrode involvement start point (ni) depends on the other.

[0129] 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 set the boundary point between two adjacent minute voltage intervals as the positive electrode engagement start point (pi). Each minute voltage interval may have a predetermined size (e.g., 0.01V). Subsequently, the processor 320 may set a point on the reference negative electrode profile Rn that is less than the positive electrode engagement start point (pi) by a first set voltage (e.g., 3V) as the negative electrode engagement start point (ni).

[0130] As another example, the processor 320 may divide the negative voltage range from the start to the end of the reference negative profile Rn into a plurality of minute voltage intervals of a predetermined size, and then set 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 profile Rp that is greater than the negative electrode involvement start point (ni) by a first set voltage, and set the found point as the positive electrode involvement start point (pi).

[0131] Either the positive electrode-involved termination point (pf) or the negative electrode-involved termination point (nf) depends on the other.

[0132] 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 set the boundary point between two adjacent minute voltage intervals as the positive electrode involvement endpoint (pf). Subsequently, the processor 320 may set a point on the reference negative electrode profile Rn that is lower than the positive electrode involvement endpoint (pf) by a second set voltage (e.g., 4V) as the negative electrode involvement endpoint (nf).

[0133] As another example, the processor 320 may divide the negative voltage range from the start to the end of the reference negative profile Rn into a plurality of minute voltage intervals of a predetermined size, and then set 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 set the found point as the positive electrode involvement termination point (pf).

[0134] 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.

[0135] 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).

[0136] 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).

[0137] 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 engagement start point (pi') matching the capacitance value at the negative electrode engagement 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 engagement start point (pi) and the negative electrode engagement 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.

[0138] 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).

[0139] 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.

[0140] Referring to Figure 6, the processor 320 may shrink or expand the adjusted reference cathode profile Rp' to generate the adjusted reference cathode profile Rp'' such 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. 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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'.

[0146] The processor 320 can calculate the error (profile error) between the comparison full cell profile S and the measured full cell profile M.

[0147] 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. 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). 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).

[0148] 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).

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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'.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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'.

[0159] 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.

[0160] 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).

[0161] 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 set the boundary point between two adjacent minute voltage intervals as the positive involvement start point (pi'). Subsequently, the processor 320 may set the negative involvement start point (ni') at 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).

[0162] 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 set 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 set the found point as the positive involvement start point (pi').

[0163] 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 set 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 set the found point as the negative electrode involvement endpoint (nf').

[0164] As yet 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 set the boundary point between two adjacent minute voltage intervals as the negative involvement termination point (nf'). Subsequently, the processor 320 may search for a point in the adjusted reference positive profile Rp' that is greater than the negative involvement termination point (nf') by a second set voltage, and set the found point as the positive involvement termination point (pf').

[0165] If 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 determined, the processor 320 may additionally determine the remaining three points based on the determined point.

[0166] As an example, once the positive electrode involvement start point (pi') is determined, the processor 320 may set a point on the adjusted reference positive electrode profile Rp' having a capacitance value that is 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 as the positive electrode involvement end point (pf'). 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 set the found point as the negative electrode involvement start point (ni'). Furthermore, the processor 320 may set a point on the adjusted reference negative electrode profile Rn' having a capacitance value that is 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 as the negative electrode involvement end point (nf').

[0167] As another example, once the positive electrode involvement termination point (pf') is determined, the processor 320 may set 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') as the positive electrode involvement start point (pi'). 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 set the found point as the negative electrode involvement termination point (nf'). Furthermore, the processor 320 may set 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') as the negative electrode involvement start point (ni').

[0168] As yet another example, once the negative electrode involvement start point (ni') is determined, the processor 320 may set a point on the adjusted reference negative electrode profile Rn' having a capacitance value that is 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 as the negative electrode involvement end point (nf'). Alternatively, the processor 320 may 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 set the found point as the positive electrode involvement start point (pi'). Furthermore, the processor 320 may set a point on the adjusted reference positive electrode profile Rp' having a capacitance value that is 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 as the positive electrode involvement end point (pf').

[0169] As yet another example, once the negative electrode involvement termination point (nf') is determined, the processor 320 may set 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') as the negative electrode involvement start point (ni'). 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 set the found point as the positive electrode involvement termination point (pf'). The processor 320 may also set 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') as the positive electrode involvement start point (pi').

[0170] 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').

[0171] 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.

[0172] 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''.

[0173] The processor 320 can calculate the error (profile error) between the comparison full cell profile U and the measured full cell profile M.

[0174] 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.

[0175] 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.

[0176] The processor 320 can extract the positive electrode scale factor from the information mapped to the minimum profile error. Based on the extracted positive electrode scale factor, the processor 320 can estimate the positive electrode loading amount of the target cell BC.

[0177] Specifically, the processor 320 can estimate the positive electrode loading amount of the target cell BC based on the positive electrode scale factor and the reference positive electrode loading amount. Here, the reference positive electrode capacity can be a value preset as the total positive electrode capacity of the reference cell. The reference positive electrode loading amount is a predetermined value indicating the positive electrode active material amount (or available capacity) per unit area of the positive electrode of the reference cell.

[0178] Specifically, the processor 320 can determine an estimated value of the positive electrode loading amount of the target cell BC using the following Equation 1.

[0179]

Equation

[0180] In Equation 1, P t_loading is the estimated value of the positive electrode loading amount of the target cell BC, P t_scale is the positive electrode scale factor, and P r_loading indicates the reference positive electrode loading amount.

[0181] The processor 320 can determine the positive electrode capacity loss rate of the target cell BC based on the estimated value of the positive electrode loading amount of the target cell BC. The following Equation 2 can be used to determine the positive electrode capacity loss rate.

[0182]

Equation

[0183] In Equation 2, L P_Q indicates the positive electrode capacity loss rate of the target cell BC. That is, the positive electrode capacity loss rate of the target cell BC can indicate the ratio of the decrease in the positive electrode loading amount of the target cell BC to the reference positive electrode loading amount.

[0184] Instead of Equation 2, the following Equation 3 can be used to determine the positive electrode capacity loss rate.

[0185]

Equation

[0186] In formula 3, N r_f The negative electrode involvement endpoint of the reference cell (reference code nf0 in Figure 2) is the capacitance value, N r_i P is the volume value at the negative electrode involvement start point of the reference cell (reference symbol ni0 in Figure 2), P r_f P is the capacitance value at the positive electrode involvement endpoint of the reference cell (reference symbol pf0 in Figure 2), P t_f This indicates the capacitance value at the positive electrode involvement termination point of the target cell BC (for example, reference symbol pf'' in Figure 6).

[0187] The processor 320 can limit at least one of the allowable voltage range and allowable SOC range for the target cell BC based on an estimate of the positive electrode loading amount of the target cell BC. Relational data showing a predetermined positive correlation between the positive electrode loading amount and the limiting level can be pre-stored in the memory unit 330. That is, according to the relational data, a decrease in the positive electrode loading amount causes 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 of that range and lowering the upper limit.

[0188] Let's 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%.

[0189] 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.

[0190] In step S1010, the processor 320 controls the stimulation application device 301 to intermittently apply a second electrical stimulus, which is greater than the first electrical stimulus, to the target cell BC during the state change period from the initial state to the target state.

[0191] In step S1020, the processor 320 uses the communication unit 310 to acquire current time series data showing the history of current changes in the target cell BC during the state change period, and voltage time series data showing the history of full cell voltage changes in the target cell BC during the pause period of the second electrical stimulation applied during the state change period. The voltage time series data is the measured value of the full cell voltage at the end of each pause period (Figure 3aD OCV (See reference) may include.

[0192] The communication unit 310 can collect current time-series data and voltage time-series data generated by the electric vehicle 1 from the electric vehicle 1 after the end of the state change period.

[0193] Alternatively, the communication unit 310 may periodically collect measurement data from the electric vehicle 1 showing at least one measurement of the current and full cell voltage of the target cell BC over the state change period. In this case, each measurement collected multiple times over the state change period may be stored in the memory unit 330 in chronological order. The processor 320 may generate current time-series data and voltage time-series data from the set of measurement values ​​collected over the state change period.

[0194] 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 capacitance of the target cell BC and the full cell voltage, based on the current time series data and the voltage time series data.

[0195] In step S1040, the processor 320 analyzes the measured full cell profile and estimates the positive electrode loading amount of the target cell BC (see Equation 1). The positive electrode loading amount refers to the amount of positive electrode active material per unit area of ​​the positive electrode.

[0196] In step S1050, the processor 320 determines the positive electrode capacity loss rate of the target cell BC based on the estimated positive electrode loading amount (see Equation 2).

[0197] In step S1060, the processor 320 limits 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.

[0198] In the method shown in Figure 10, only one of step S1050 and step S1060 may be performed.

[0199] In step S1070, the processor 320 may transmit the diagnostic results of the target cell BC to the electric vehicle 1 using the communication unit 310. The diagnostic results include at least one of the following: positive electrode loading amount, positive electrode capacitance loss rate, limited allowable voltage range, and limited allowable SOC range.

[0200] 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.

[0201] In step S1110, the processor 320 controls the stimulation application device 301 to intermittently apply a second electrical stimulus, which is greater than the first electrical stimulus, to the target cell BC during the state change period from the initial state to the target state.

[0202] In step S1120, the processor 320 uses the communication unit 310 to acquire current time series data showing the history of current changes in the target cell BC during the state change period, and voltage time series data showing the history of full cell voltage changes in the target cell BC during the pause period of the second electrical stimulation applied during the state change period.

[0203] Unlike the first embodiment described above, the voltage time series data acquired in step S1120 is the measured value of the full cell voltage at the end of each rest period (D in Figure 3a). OCV (See reference) This includes full cell voltage measurements taken at least three times before the end of each rest period.

[0204] In step S1122, the processor 320 applies OCV estimation logic to the voltage time series data acquired in step S1120 to generate corrected voltage time series data. 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 time series 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 time series data acquired in step S1120 will contain 3X full cell voltage measurements, and the corrected voltage time series data will contain X OCV values.

[0205] 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 current time series data and the corrected voltage time series data.

[0206] In step S1140, the processor 320 analyzes the measured full cell profile and estimates the positive electrode loading amount of the target cell BC (see Equation 1).

[0207] In step S1150, the processor 320 determines the positive electrode capacity loss rate of the target cell BC based on the estimated positive electrode loading amount (see Equation 2).

[0208] In step S1160, the processor 320 limits 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.

[0209] In the method shown in Figure 11, only one of step S1150 and step S1160 may be performed.

[0210] In step S1170, the processor 320 may transmit the diagnostic results of the target cell BC to the electric vehicle 1 via the communication unit 310. The diagnostic results include at least one of the following: positive electrode loading amount, positive electrode capacitance loss rate, limited allowable voltage range, and limited allowable SOC range.

[0211] Figure 12 is a reference diagram to illustrate the voltage time series data correction process performed in step S1122 of Figure 11.

[0212] Reference numeral 1200 in Figure 12 indicates one of the voltage drop segments shown in Figure 3a. t when the rest period is sufficiently long R This indicates the point in time when the reference time has elapsed from the start of the rest period. R The part up to t is a solid line, R The following sections are indicated by dotted lines for clarity.

[0213] Referring to Figure 12, during each rest period, the target cell BC is placed in an unloaded state with neither charging nor discharging.

[0214] Under no-load conditions, the full cell voltage of the target cell BC gradually converges toward the OCV corresponding to the state of charge (SOC) of the target cell BC. The behavior of the full cell voltage of the target cell BC during a specific resting period may be equivalent to the voltage response of a primary RC circuit as shown in Equation 4 below.

[0215]

number

[0216] In formula 4, t is the elapsed time from the start of a specific resting period, V full (t) is the full cell voltage at t, V OCV This is the actual OCV, V S τ is the full cell voltage at the start of a specific resting period, and τ is the time constant determined by the internal resistance and capacitance of the target cell BC.

[0217] In equation 4, V full(t) is measurable, V OCV , V S And τ are unknowns. Since there are three unknowns, the OCV for a particular resting period is the V measured at three different timings. full It can be estimated based on (t). Equation 5 below can be used to estimate OCV for each resting period.

[0218]

number

[0219] In equation 5, t1, t2, and t3 are the timings for a series of measurements of the full cell voltage. The time difference between t1 and t2 may be the same as the time difference between t2 and t3.

[0220] The processor 320 takes three full cell voltage measurements (V) per hibernation period. full (t1), V full (t2), V full (t3)) a single OCV value (D OCV_C By repeating the process of replacing with ) for all rest periods, the voltage time series data acquired in step S1120 can be converted into corrected voltage time series data for step S1130.

[0221] For reference, D OCV D is a measurement of the full cell voltage at the end of the resting period (before polarization is completely resolved), while D OCV_C This is the full cell voltage (i.e., V) when polarization is completely eliminated. OCV This is an estimate of D. OCV_C is D OCV It can be said that this is closer to the actual OCV of the target cell BC.

[0222] The embodiments of the present invention described above are not limited to apparatus and methods, but can also be implemented through a program that realizes the functions corresponding to the configuration of the embodiments of the present invention, or through a storage medium on which such program is stored. The program or storage medium can be easily implemented by those skilled in the art based on the description of the embodiments described above.

[0223] 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.

[0224] 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 processor configured to control a stimulation application device to intermittently apply a second electrical stimulus, which is greater than the first electrical stimulus, to the target cell, which is a battery cell to be diagnosed, during the state change period from the initial state to the target state. The system includes a communication unit configured to acquire current time-series data showing the history of current changes in the target cell during the state change period, and voltage time-series data showing the history of full cell voltage changes in the target cell during the pause period of the second electrical stimulation applied during the state change period. The aforementioned processor, Based on the current time series data and the voltage time series data, a measured full cell profile is generated that shows the correspondence between the capacity of the target cell and the full cell voltage. A battery diagnostic device configured to analyze the measured full cell profile and estimate the positive electrode loading amount, which represents the amount of positive electrode active material per unit area of ​​the positive electrode of the target cell.

2. The first electrical stimulation is an electrical stimulation that induces a difference between the open-circuit voltage and the closed-circuit voltage below a reference value in the target cell. The battery diagnostic device according to claim 1, wherein the second electrical stimulation is an electrical stimulation that induces a difference between the open-circuit voltage and the closed-circuit voltage exceeding the reference value in the target cell.

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

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

5. The aforementioned voltage time series data is The battery diagnostic device according to claim 1, wherein the measured values ​​of the full cell voltage during the rest period of the second electrical stimulation are data arranged in chronological order as the open-circuit voltage of the target cell.

6. The aforementioned processor, The battery diagnostic device according to claim 1, configured to control the stimulation application device so that a pause period for the second electrical stimulation is initiated each time the current integration value of the current changes by a critical integration value.

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

8. The aforementioned processor, A battery diagnostic device according to any one of claims 1 to 7, configured to determine the positive electrode capacity loss rate of the target cell based on the estimated positive electrode loading amount.

9. The aforementioned processor, The battery diagnostic device according to any one of claims 1 to 7, configured to limit at least one of the allowable voltage range and the allowable charge rate range for the target cell based on the estimated value of the positive electrode loading amount.

10. A charging station including a battery diagnostic device according to any one of claims 1 to 7.

11. A cloud server including a battery diagnostic device according to any one of claims 1 to 7.

12. The steps include controlling the stimulation application device to intermittently apply a second electrical stimulus, which is greater than the first electrical stimulus, to the target cell, which is a battery cell to be diagnosed, during the state change period from the initial state to the target state, and The steps include obtaining current time series data showing the history of changes in the current of the target cell during the state change period, and voltage time series data showing the history of changes in the full cell voltage of the target cell during the pause period of the second electrical stimulation applied during the state change period, The steps include generating a measured full cell profile showing the correspondence between the capacity of the target cell and the full cell voltage based on the current time series data and the voltage time series data, A battery diagnostic method comprising the steps of analyzing the measured full cell profile and estimating the positive electrode loading amount, which means the amount of positive electrode active material per unit area of ​​the positive electrode of the target cell.

13. The aforementioned voltage time series data is The battery diagnostic method according to claim 12, wherein the measured values ​​of the full cell voltage during the rest period of the second electrical stimulation are data arranged in chronological order as the open-circuit voltage of the target cell.

14. The battery diagnostic method according to claim 12 or 13, further comprising the step of determining the positive electrode capacity loss rate of the target cell based on the estimated positive electrode loading amount.

15. The battery diagnostic method according to claim 12 or 13, further comprising the step of limiting at least one of the allowable voltage range and the allowable charge rate range for the target cell based on the estimated value of the positive electrode loading amount.

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