Battery diagnosis device and battery diagnosis method

Abstract

The invention discloses a battery diagnosis device and a battery diagnosis method. The battery diagnosis apparatus includes: a processor configured to control a stimulus applying device to intermittently apply a second electrical stimulus greater than a first electrical stimulus to a target cell during a state change period until an electrical state of the target cell changes from an initial state to a target state; and a communication unit configured to obtain current time series data during the state change period and voltage time series data representing a change history of a full cell voltage of the target cell during a rest period of the second electrical stimulation applied in 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 a positive electrode loading amount representing an amount of positive electrode active material per unit area of a positive electrode of the target cell.

Description

Technical Field

[0001] The present disclosure relates to a technique for non-destructively diagnosing the state of a battery.

[0002] This application claims the priority of Korean Patent Application No. 10-2023-0133644, filed in Korea on October 6, 2023, the disclosure of which is incorporated herein by reference. Background Art

[0003] In recent years, the demand for portable electronic products such as laptop computers, cameras, and mobile phones has increased rapidly, and with the widespread development of electric vehicles, energy storage accumulators for energy storage, robots, and satellites, many studies are being conducted on high-performance batteries that can be repeatedly recharged.

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

[0005] Although many studies are being conducted on these batteries in terms of increasing capacity and density, improvements in lifespan and safety are also important. To improve battery safety, the current state of the battery must be accurately diagnosed.

[0006] Accurately diagnosing the internal state of a battery is crucial for the safety and long lifespan of the battery. To diagnose the internal state of a battery without disassembling it, relationship data showing the correspondence between capacity and voltage (which can be referred to as a full cell profile, etc.) is mainly used.

[0007] Conventionally, a full cell profile has been obtained by repeating the process of measuring the voltage and capacity of a battery at short intervals while applying a constant electrical stimulus (e.g., constant current charging or discharging) to the battery. However, in order to minimize polarization (or overpotential) that causes a decrease in diagnostic accuracy, the level of the electrical stimulus applied to the target cell must be reduced, which has the limitation that it takes too much time to obtain a full cell profile. At the same time, although advanced electrical stimuli are advantageous in terms of shortening time, since advanced electrical stimuli are accompanied by severe polarization phenomena, the accuracy of diagnostic results cannot be guaranteed. Summary of the Invention

[0008] Technical Problem

[0009] The present disclosure is designed to solve the problems of the related art, and thus the present disclosure aims to provide a battery diagnosis device and a battery diagnosis method, which can obtain relationship data representing the correspondence between the capacity and the voltage of a target cell by using a method of intermittently applying a high-level electrical stimulus to the target cell, and diagnose the degradation state of the positive electrode of the target cell (for example, the positive electrode loading amount, the positive electrode capacity loss rate, etc. explained later) based on the obtained relationship data.

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

[0011] Technical Solution

[0012] In one aspect of the present disclosure, there is provided a battery diagnosis device, including: 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 until the electrical state of the target cell changes from an initial state to a target state, the target cell being a battery cell to be diagnosed; and a communication unit configured to obtain current time series data representing the change history of the current of the target cell during the state change period, and voltage time series data representing the change history of the full cell voltage of the target cell during the rest period of the second electrical stimulus applied during the state change period. The processor is configured to: generate a measured full cell profile representing the correspondence between the capacity and the full cell voltage of the target cell based on the current time series data and the voltage time series data, and estimate the positive electrode loading amount by analyzing the measured full cell profile, the positive electrode loading amount representing the amount of positive electrode active material per unit area of the positive electrode of the target cell.

[0013] The first electrical stimulus may be an electrical stimulus such that the difference between the OCV and the CCV in the target cell is equal to or less than a reference value. The second electrical stimulus may be an electrical stimulus such that the difference between the OCV and the CCV in the target cell is greater than the reference value.

[0014] The first electrical stimulus may be charging at a first current rate, and the second electrical stimulus may be charging at a second current rate greater than the first current rate.

[0015] The first electrical stimulus may be discharging at a first current rate, and the second electrical stimulus may be discharging at a second current rate greater than the first current rate.

[0016] The voltage time series data may be measured values of the full cell voltage during the rest period of the second electrical stimulus, and the measured values are arranged in chronological order as the OCV of the target cell.

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

[0018] 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 a start time point of the rest period of the second electrical stimulation.

[0019] The processor may be configured to determine a positive electrode capacity loss rate of a target cell based on an estimated value of a positive electrode load amount.

[0020] The processor may be configured to limit at least one of an allowable voltage range and an allowable SOC range of the target cell based on the estimated value of the positive electrode load amount.

[0021] In yet another aspect of the present disclosure, a charging station including the battery diagnosis device is further provided.

[0022] In still another aspect of the present disclosure, a cloud server including the battery diagnosis device is further provided.

[0023] In still another aspect of the present disclosure, a battery diagnosis method is further provided, including: 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 an electrical state of the target cell changes from an initial state to a target state, where the target cell is a battery cell to be diagnosed; obtaining current time series data representing a change history of a current of the target cell during the state change period, and voltage time series data representing a change history of a full cell voltage of the target cell during a rest period of the second electrical stimulation applied during the state change period; generating a measured full cell profile representing a correspondence between a capacity and a full cell voltage of the target cell based on the current time series data and the voltage time series data; and estimating a positive electrode load amount by analyzing the measured full cell profile, where the positive electrode load amount represents an amount of positive electrode active material per unit area of a positive electrode of the target cell.

[0024] The voltage time series data may be measured values of the full cell voltage during the rest period of the second electrical stimulation, and the measured values are arranged in chronological order as an OCV of the target cell.

[0025] The battery diagnosis method may further include determining a positive electrode capacity loss rate of the target cell based on the estimated value of the positive electrode load amount.

[0026] The battery diagnosis method may further include limiting at least one of an allowable voltage range and an allowable SOC range of the target cell based on the estimated value of the positive electrode load amount.

[0027] Beneficial effects

[0028] According to at least one embodiment of the present disclosure, relationship data representing the correspondence between the capacity and voltage of a target cell can be obtained by using a method of intermittently applying a high-level electrical stimulation to the target cell, and based on the obtained relationship data, the state of degradation of the positive electrode of the target cell (such as the positive electrode load amount, positive electrode capacity loss rate, etc., explained later) can be diagnosed.

[0029] That is, by using high-level electrical stimulation to change the electrical state of the target cell, the time required to obtain the relationship data can be shortened, and at the same time, a decrease in diagnostic accuracy caused by excessive polarization due to the intermittent application of electrical stimulation can be prevented.

[0030] The effects of the present disclosure are not limited to the above effects, and those skilled in the art will clearly understand these and other effects according to the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0032] Figure 1 is a diagram exemplarily showing the configurations of an electric vehicle and a charging station including a battery diagnostic circuit according to the present disclosure.

[0033] Figure 2 is a graph referred to for respectively describing examples of a reference positive electrode profile line and a reference negative electrode profile line.

[0034] Figure 3a and Figure 3b is a graph referred to for exemplarily describing the process of obtaining a measured full-cell profile line of a target cell.

[0035] Figures 4 to 6 is a diagram referred to for describing an example of the process of generating a comparative full-cell profile line for comparison with a measured full-cell profile line according to an embodiment of the present disclosure.

[0036] Figures 7 to 9 is a diagram referred to for describing another example of the process of generating a comparative full-cell profile line for comparison with a measured full-cell profile line according to an embodiment of the present disclosure.

[0037] Figure 10 is a flowchart referred to for exemplarily describing a battery diagnostic method according to a first embodiment of the present disclosure.

[0038] Figure 11 is a flowchart referred to for exemplarily describing a battery diagnostic method according to a second embodiment of the present disclosure.

[0039] Figure 12 is a diagram referred to for describing the process of correcting the voltage time series data performed in step S1122 of Figure 11 . DETAILED DESCRIPTION

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

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

[0042] Terms including ordinal numbers such as "first", "second", etc. are used to distinguish one element from another among the respective elements, but are not intended to limit the elements by the terms.

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

[0044] Furthermore, throughout the specification, it should also be understood that when an element is referred to as "connected to" another element, it can be directly connected to the other element or an intermediate element may exist.

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

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

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

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

[0049] The battery 11 includes at least one battery cell BC. In Figure 1 FIG., the battery 11 is exemplarily shown as including a plurality of battery cells (BC1 to BC N , where N is a natural number of 2 or greater). The plurality of battery cells (BC1 to BC N ) may be provided with the same electrochemical specifications. Hereinafter, when describing features common to the plurality of battery cells (BC1 to BC N ), the reference numeral "BC" will be given to the battery cell. The charging station 300 can perform the charge and discharge cycles required for diagnosing the battery cell BC by cooperating with an inverter 30 having a discharging function.

[0050] The type of the battery cell BC is not particularly limited as long as it is an electrochemical element capable of being repeatedly charged and discharged. The battery cell BC is the diagnostic target of the charging station.

[0051] The relay 20 is serially electrically connected to the battery 11 through a power path connecting the battery 11 and the inverter 30. In Figure 1 FIG., the relay 20 is shown as being connected between the positive terminal of the battery 11 and the charging and discharging terminal P+. The relay 20 is controlled to be turned on and off in response to a switching signal from the battery management system 100. The relay 20 may be a mechanical contactor turned on and off by the magnetic force of a coil, or a semiconductor switch such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

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

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

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

[0055] 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 the two ends of the battery cell BC (also referred to as "full cell voltage") and generate a voltage signal representing the detected value of the voltage. The voltage sensor 111 may be implemented as one or a combination of two or more known voltage detection elements such as a voltage measurement IC.

[0056] The current sensor 112 is serially connected to the battery 11 through the current path between the battery 11 and the inverter 30. The current sensor 112 is configured to detect the current flowing through the battery 11 (also referred to as "charge and discharge current") and generate a current signal representing the detected value of the current. Since multiple battery cells (BC1 to BC N ) are connected in series, the current flowing in the battery 11 is the same as the current flowing in the battery cell BC. The current sensor 112 may be implemented as one or a combination of two or more known current detection elements such as a shunt resistor, a Hall effect element, etc.

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

[0058] The processor 130 is operably coupled to the relay 20, the voltage sensor 111, and the communication circuit 150. The operable coupling of any two components means that the two components are directly or indirectly connected so as to enable signal transmission and reception in one direction or two directions.

[0059] Processor 130 may collect a voltage signal from voltage sensor 111 and a current signal from current sensor 112. In this specification, the detection signal may be a term that only refers to the voltage signal, or a term that collectively refers to the voltage signal and the current signal. That is, processor 130 may use an ADC (analog-to-digital converter) provided therein to convert each analog signal collected from sensors 111 and 112 into a digital value and record the digital value. Alternatively, each of voltage sensor 111 and current sensor 112 may include an ADC therein and send the digital value to processor 130.

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

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

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

[0063] Processor 130 may turn on relay 20 in response to a key-on signal. Processor 130 may turn off relay 20 in response to a key-off signal. The key-on signal is a signal requesting a switch from the rest mode to the charging or discharging mode. The key-off signal is a signal requesting a switch from the charging or discharging mode to the rest mode. Alternatively, vehicle controller 2 may be responsible for turning on / off relay 20 instead of processor 130.

[0064] In this specification, the time-series data of a specific parameter indicates the change history of the parameter over time. Additionally, a profile (or curve) representing the correspondence of any two parameters obtained at the same timing within the same time period can be a mapping of the two time-series data of the two parameters, such that they can be represented in the form of a two-dimensional graph, or can be a polynomial equation obtained by applying a predetermined curve fitting logic to a set of the two mapped time-series data. Here, the degree of the highest term of the polynomial equation can be predetermined.

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

[0066] 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 arranged to be included in a cloud server (not shown). The cloud server may be placed far from the charging station 300. In this case, the communication unit 310 of the battery diagnostic device 302 may perform the diagnostic process of the target cell by remote communication with the stimulation application device 301 and / or the electric vehicle 1.

[0067] 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 various electrical stimulations to the battery cell BC alone or in cooperation with the inverter 30 for diagnosing the battery cell BC.

[0068] 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 may send the result of the diagnosis of the battery cell BC executed by the processor 320 to the electric vehicle 1.

[0069] In terms of hardware, the processor 320 may be implemented using at least one of an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), a DSPD (Digital Signal Processing Device), a PLD (Programmable Logic Device), an FPGA (Field Programmable Gate Array), a microprocessor, and an electrical unit for performing other functions.

[0070] The memory unit 330 may include at least one type of storage medium such as a flash memory type, a hard disk type, a solid state drive (SSD) type, a silicon disk drive (SDD) type, a multimedia card micro type, a random access memory (RAM), a static random access memory (SRAM), a read only memory (ROM), an electrically erasable programmable read only memory (EEPROM), or a programmable read only memory (PROM). The memory unit 330 may store data and programs required for diagnostic processes executed by the processor 320. The memory unit 330 may store data representing the results of computational operations of the processor 320. The memory unit 330 may store a data set and software for diagnosing the degradation state of the battery cell BC.

[0071] Figure 2 is a graph that is referred to for describing an example of each of the reference positive electrode profile and the reference negative electrode profile. In Figure 2 the graph of, the horizontal axis (X-axis) represents the capacity (Ah), and the vertical axis (Y-axis) represents the voltage.

[0072] Reference Figure 2 , the memory unit 330 may store the reference positive electrode profile Rp and the reference negative electrode profile Rn. The reference cell may be a button-type cell including a positive electrode half-cell and a negative electrode half-cell, or may be a three-electrode cell. Hereinafter, the positive electrode and the positive electrode half-cell of the reference cell will be described in equivalent terms, and the negative electrode and the negative electrode half-cell of the reference cell will be described in equivalent terms.

[0073] The reference positive electrode profile Rp may be a profile representing the correspondence between the positive electrode voltage and the capacity of the 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 referred to as the positive electrode half-cell profile.

[0074] The reference negative electrode profile Rn may be a profile representing the correspondence between the negative electrode voltage and the capacity of the 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 referred to as the negative electrode half-cell profile.

[0075] Each of the positive electrode voltage and the negative electrode voltage may be an open circuit voltage (OCV) or a closed circuit voltage (CCV).

[0076] The open circuit voltage of each of the positive electrode and the negative electrode of the reference cell may be obtained using a first charging protocol or a first discharging protocol. The first charging protocol may be an intermittent charging method in which constant current charging using a first current rate and rest are alternately performed. The first discharging protocol may be an intermittent discharging method in which constant current discharging using a first current rate and rest are alternately performed.

[0077] For example, whenever the charging time of constant current charging through the first charging protocol has elapsed a set time or the charging capacity of the reference cell has increased by a set capacity, the charging of the reference cell can be stopped for a predetermined remaining time and then constant current charging can be resumed. The charging capacity can be calculated by periodically or aperiodically accumulating sampled values of the charging current.

[0078] As another example, whenever the discharging time of constant current discharging through the first discharging protocol has elapsed a set time or the discharging capacity of the reference cell has decreased by a set capacity, the discharging of the reference cell can be stopped for a predetermined remaining time and then constant current discharging can be resumed. The discharging capacity can be calculated by periodically or aperiodically accumulating sampled values of the discharging current (i.e., measured values of the cell current).

[0079] At this time, a plurality of rest periods can be provided while the first charging protocol or the first discharging protocol is in progress, and the open circuit voltages of the positive and negative electrodes of the reference cell measured at specific timings within each rest period can be respectively recorded as the positive electrode voltage and the negative electrode voltage of the reference cell.

[0080] When compared with the open circuit voltage, the second charging protocol or the second discharging protocol can be used to obtain the closed circuit voltage of each of the positive and negative electrodes of the reference cell. The second charging protocol can be a constant current charging method using a second current rate. The second discharging protocol can be a constant current discharging method using a second current rate. For example, when the reference cell is continuously charged through the second charging protocol or continuously discharged through the second discharging protocol, the periodically or aperiodically measured closed circuit voltages of the positive and negative electrodes of the reference cell can be recorded as the positive electrode voltage and the negative electrode voltage of the reference cell.

[0081] In this specification, the first electrical stimulation can refer to an electrical stimulation that makes the difference between the OCV and the CCV in the battery cell equal to or less than a reference value, and the second electrical stimulation refers to an electrical stimulation that makes the difference between the OCV and the CCV in the battery cell greater than the reference value.

[0082] For example, the first electrical stimulation can be charging using a first current rate, and the second electrical stimulation can be charging using a second current rate greater than the first current rate.

[0083] As another example, the first electrical stimulation can be discharging using a first current rate, and the second electrical stimulation can be discharging using a second current rate greater than the first current rate.

[0084] Implementing the first charging protocol or the first discharging protocol can mean continuously applying the first electrical stimulation to the battery cell. Implementing the second charging protocol or the second discharging protocol can mean intermittently applying the second electrical stimulation to the battery cell.

[0085] For the sake of illustration, assume that Figures 2 to 9 the horizontal axis represents the charge capacity.

[0086] At least one of the reference positive electrode profile Rp and the reference negative electrode profile Rn can be aligned along the horizontal axis such that the composite result of a part of the common capacity range ( Figure 2 5 to 50 Ah in) of the two profiles (Rp, Rn) matches the reference full cell profile R. Figure 2 An example is shown in which the reference negative electrode profile Rn is aligned to be shifted to the right based on the starting point (the point corresponding to a capacity of 0) of the reference positive electrode profile Rp.

[0087] From Figure 2 it can be found that the two ends of the reference positive electrode profile Rp and the reference negative electrode profile Rn are offset from each other. In other words, the capacity ranges of the reference positive electrode profile Rp and the reference negative electrode profile Rn do not match and only partially overlap. Therefore, the reference full cell profile R indicates the full cell voltage of the reference cell in a part of the common capacity range of the reference positive electrode profile Rp and the reference negative electrode profile Rn. In other words, the reference full cell profile R is an example of a full cell voltage profile obtained by directly subtracting a part of the reference negative electrode profile Rn from a part of the reference positive electrode profile Rp.

[0088] The reference full cell profile R can represent the correspondence between the capacity and the full cell voltage of a new battery cell verified as a good product. In other words, the reference cell has the same level of positive electrode performance and negative electrode performance as a new battery cell verified as a good product. The positive electrode performance and negative electrode performance of any battery cell can be collectively referred to as "charge / discharge performance".

[0089] The reference full cell profile R can represent the correspondence between the voltage and the capacity of the reference cell within at least the voltage range of interest (for example, 3.0 V to 4.0 V). The lower limit and the upper limit of the voltage range of interest can be the first set voltage ( Figure 2 3.0 V in) and the second set voltage ( Figure 2 4.0 V in).

[0090] If the full cell voltage of any battery cell - including the reference cell - is equal to the first set voltage, the SOC can be set to 0%. When the full cell voltage of any battery cell - including the reference cell - is equal to the second set voltage, the SOC can be set to 100%. According to Figure 2 , the reference cell can reach the fully charged state (SOC 100%) from the fully discharged state (SOC 0%) through a charge capacity of 45 Ah.

[0091] In this specification, the positive electrode participation start point on the positive electrode profile line of any battery cell represents the positive electrode voltage when the full cell voltage of the corresponding battery cell matches the first set voltage. In addition, the negative electrode participation start point on the negative electrode profile line of the corresponding battery cell indicates the negative electrode voltage when the full cell voltage of the corresponding battery cell matches the first set voltage. Therefore, the voltage difference between the positive electrode participation start point and the negative electrode participation start point can be equal to the first set voltage.

[0092] In addition, the positive electrode participation end point on the positive electrode profile line of any battery cell indicates the positive electrode voltage when the full cell voltage of the corresponding battery cell matches the second set voltage. In addition, the negative electrode participation end point on the negative electrode profile line of the corresponding battery cell indicates the negative electrode voltage when the full cell voltage of the corresponding battery cell matches the second set voltage. Therefore, the voltage difference between the positive electrode participation end point and the negative electrode participation end point can be equal to the second set voltage.

[0093] In the memory unit 330, information indicating the voltage at each of the reference positive electrode participation start point (pi0), reference positive electrode participation end point (pf0), reference negative electrode participation start point (ni0), and reference negative electrode participation end point (nf0) can be pre-recorded. The reference positive electrode participation start point (pi0) and the reference positive electrode participation end point (pf0) are the positive electrode participation start point and the positive electrode participation end point on the reference positive electrode profile line Rp, respectively. The reference negative electrode participation start point (ni0) and the reference negative electrode participation end point (nf0) are the negative electrode participation start point and the negative electrode participation end point on the reference negative electrode profile line Rn, respectively.

[0094] The voltage difference between the reference positive electrode participation start point (pi0) and the reference negative electrode participation start point (ni0) can be equal to the first set voltage (e.g., 3.0V). The voltage difference between the reference positive electrode participation end point (pf0) and the reference negative electrode participation end point (nf0) can be equal to the second set voltage (e.g., 4.0V).

[0095] Figure 3a and Figure 3b are curves that are referred to for exemplarily describing the process of obtaining the measured full cell profile line of the target cell.

[0096] Figure 3a The curves depicted in show an example of the change over time of the full cell voltage of the target cell due to the intermittent application of the second electrical stimulus. The target cell is the battery cell to be diagnosed by the battery diagnostic device. The target cell can be a new battery cell that needs to be verified whether it is a good product, or a battery cell that is no longer a new product due to deterioration after being verified as a good product. Hereinafter, the target cell is also denoted by the reference numeral BC.

[0097] Reference Figure 3a, the processor 320 may control the stimulation application device 301 to intermittently apply a second electrical stimulation greater than the first electrical stimulation to the target monomer BC.

[0098] The process for controlling the stimulation application device 301 to diagnose the target monomer BC may be performed during a state change period until the electrical state (e.g., full monomer voltage) of the target monomer BC changes from an initial state (e.g., a first set voltage) to a target state (e.g., a second set voltage).

[0099] Reference Figure 3a In the curve graph in, the full monomer voltage of the target monomer BC has an upward trend when in a repetitive sawtooth form. Each sawtooth voltage rise segment is caused by the application of the second electrical stimulation, and the voltage drop segment is caused by the interruption of the second electrical stimulation. That is, the voltage drop section represents the change in the full monomer voltage of the target monomer BC during each rest period.

[0100] During the state change period, the processor 320 may repeatedly record the current measurement values of the target monomer BC to generate current time series data.

[0101] The processor 320 may control the stimulation application device 301 to initiate a rest period of the second electrical stimulation whenever a predetermined rest condition is met within the state change period. In other words, when the rest condition is met, the process of applying the second electrical stimulation may be temporarily stopped. For example, at least one of (i) the current integral value changes the threshold integral value, (ii) the SOC changes the threshold SOC, and (iii) the time for which the application of the second electrical stimulation is maintained reaches the threshold time may be preset as the rest condition. For example, if the total current integral value during the state change period is 40 Ah and the threshold integral value is 2 Ah, then a total of 20 rest periods may be permitted during the state change period.

[0102] The processor 320 may determine at least one of a threshold integration value, a threshold SOC, and a threshold time based on the full charge capacity, SOH, or previous diagnostic results of the target single cell BC (e.g., the capacity value at the end point of negative electrode participation, the negative electrode capacity loss rate). At least one of the threshold integration value, the threshold SOC, and the threshold time may have a predetermined negative correspondence with the full charge capacity, SOH, or previous diagnostic results, and the relationship data (data table for controlling the rest period) defining the correspondence may be pre-stored in the memory unit 330. Due to the predetermined negative correspondence, as the full charge capacity, SOH, or previous diagnostic results decrease, at least one of the threshold integration value, the threshold SOC, and the threshold time also decreases. Therefore, as the target single cell BC deteriorates over time, the rest period is applied at short time intervals during the state change period, so that the number of data points included in the voltage time series data can be prevented from decreasing, and the voltage history data indicates the change history of the full cell voltage over time during the rest period of the state change period.

[0103] The processor 320 may obtain at least one of the threshold integration value, the threshold SOC, and the threshold time mapped to the full charge capacity, SOH, or previous diagnostic results from the data table for rest period control. The processor 320 may use at least one of the threshold integration value, the threshold SOC, and the threshold time obtained from the data table for rest period control to control the intermittent application process of the second electrical stimulation during the state change period.

[0104] When a reference time has elapsed since the start time point of the rest period of the second electrical stimulation, the processor 320 may control the stimulation application device 301 to resume the application of the second electrical stimulation. The reference time may be predetermined such that the polarization caused by the second electrical stimulation can be sufficiently resolved. For example, the reference time as the time length of the rest period may be the time required for the polarization at the start time point of the rest period to become 10% or less.

[0105] During each rest period of the second electrical stimulation, the full cell voltage of the target single cell BC is measured at least once. As an example, the processor 320 may record the measured value of the full cell voltage at the end time point of each rest period of the second electrical stimulation as the OCV of the target single cell BC. As another example, the full cell voltage may be measured at least three times during each rest period of the second electrical stimulation, and the processor 320 may estimate the OCV of the target single cell BC for each rest period based on the three full cell voltage measurement values of each rest period.

[0106] Therefore, the voltage time series data can be generated by recording the OCV multiple times with a time difference during the state change period. Figure 3a Each OCV point marked in (D OCV(0) is an example of a data point representing voltage time series data.

[0107] The inventors of the present disclosure have recognized through multiple experiments that the voltage time series data generated by using the second electrical stimulation in the above manner has high consistency with the voltage time series data generated when the first electrical stimulation is actually applied to the target monomer BC.

[0108] From now on, the advantages of the diagnostic method based on the intermittent application of the second electrical stimulation instead of the continuous application of the first electrical stimulation will be described.

[0109] Assume that the conditions related to the diagnosis of the target monomer BC are as follows.

[0110] (i) First electrical stimulation = charge at 0.05 C

[0111] (ii) Second electrical stimulation = charge at 3.0 C

[0112] (iii) Length of the rest period of the second electrical stimulation = 12 minutes

[0113] (iv) Total capacity change during the state change period = 80% of the full charge capacity (FCC) of the target monomer BC

[0114] (v) Threshold integral value = 3% of the full charge capacity of the target monomer BC

[0115] Then, the time taken to change the target monomer BC from the initial state to the target state by continuously applying the first electrical stimulation is 1 / 0.05 * 80% = 16 hours.

[0116] In contrast, the time taken to increase the charge capacity of the target monomer BC by the threshold integral value by the second electrical stimulation is 0.03 / 3 * 80% = 0.008 hours. Moreover, since a rest period is permitted every time the charge capacity increases by 3%, a total of 26 rest periods are permitted during the state change period. Therefore, the time taken to change the target monomer BC from the initial state to the target state by intermittently applying the second electrical stimulation is (0.008 hours + 0.2 hours) * 26 = 5.4 hours.

[0117] In other words, compared with the method of continuously applying the first electrical stimulation, the method of intermittently applying the second electrical stimulation is beneficial for shortening the time required to obtain the full monomer profile.

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

[0119] Refer to Figure 3b, the processor 320 may generate a measured full cell profile M representing the correspondence between the capacity and voltage of the target cell BC (also referred to as the "full cell voltage"). The measured full cell profile may also be referred to as the Q-V profile or the Q-OCV profile.

[0120] Here, the full cell voltage is the voltage across the two ends of the target cell BC and is different from the above-mentioned positive electrode voltage and negative electrode voltage. In other words, the full cell voltage of the target cell BC can be regarded as the difference between the positive electrode voltage and the negative electrode voltage of the target cell BC.

[0121] To generate the measured full cell profile M, current time series data and voltage time series data mapped to the state change period can be used.

[0122] Specifically, each data point of the current time series data and the voltage time series data is indexed in chronological order. Therefore, the processor 320 can generate capacity time series data by sequentially integrating the data points of the current time series data. In addition, the processor 320 can generate the measured full cell profile M by applying a curve fitting algorithm to a set of multiple Q-OCV pairs obtained through the mapping between the capacity time series data and the voltage time series data. The reference full cell profile R, the reference positive electrode profile Rp, the reference negative electrode profile Rn, and the measured full cell profile M can be polynomial equations, where the order of the highest term is predetermined.

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

[0124] Since there are inevitably some differences in the charge / discharge performance between the reference cell and the target cell BC, there are also some differences between the measured full cell profile M and the reference full cell profile R, as Figure 3b shown.

[0125] For example, at the same capacity value, the voltage of the measured full cell profile M is higher than the voltage of the reference full cell profile R, which is caused by manufacturing defects of the target cell BC, loss of positive electrode capacity, loss of negative electrode capacity, and / or loss of available lithium. Obviously, as the target cell BC deteriorates through repeated charge / discharge, the difference between the measured full cell profile M and the reference full cell profile R will gradually increase. According to Figure 3b , different from the reference Figure 2 cell described, the full cell voltage of the target cell BC requires a charging capacity of 40 Ah to reach the second set voltage from the first set voltage, which is 5 Ah less than the 50 Ah charging capacity of the reference cell under the same conditions.

[0126] Meanwhile, inFigure 2 and Figure 3b In the curve graphs of Figure 2 and Figure 3b , Ah is used as the unit on the horizontal axis, but this unit can be expressed in other forms. For example, the unit on the horizontal axis can be a percentage %, which represents the SOC (state of charge), rather than Ah.

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

[0128] In other words, when the reference full cell profile R is the result of subtracting a part of the reference negative electrode profile Rn from a part of the reference positive electrode profile Rp, the comparison full cell profile can be regarded as the result of subtracting a part of the adjusted negative electrode profile from a part of the adjusted positive electrode profile.

[0129] The processor 320 can 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 can be pre - ensured 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 can also obtain the comparison full cell profile by accessing the memory unit 330 and reading the comparison full cell profile.

[0130] The processor 320 can generate multiple comparison full cell profiles according to the reference positive electrode profile Rp and the reference negative electrode profile Rp by repeatedly adjusting each of the reference positive electrode profile Rp and the reference negative electrode profile Rp to several levels and then synthesizing their adjustment processes. The comparison full cell profile can also be referred to as the "adjusted reference full cell profile".

[0131] The processor 320 can specify any one of the multiple comparison full cell profiles that has the minimum error relative to the measured full cell profile M. Then, the processor 320 can determine that the adjusted positive electrode profile and the adjusted negative electrode profile mapped to the specified comparison full cell profile are the positive electrode profile and the negative electrode profile of the target cell BC.

[0132] Regarding this, various methods known at the time of filing this application can be adopted to determine the error between two profiles, and each of the two profiles can be represented in a two - dimensional coordinate system. For example, the integral of the absolute value of the area between the two profiles or the RMSE (root mean square error) can be used as the error between the two profiles.

[0133] According to this configuration of the present disclosure, various state information regarding the target single cell BC can be obtained based on the finally determined adjusted positive electrode profile and the adjusted negative electrode profile. The finally determined adjusted positive electrode profile and the adjusted negative electrode profile can be mapped to a relatively complete single cell profile mapped with the smallest error. In particular, the relatively complete single cell profile obtained through the finally determined adjusted positive electrode profile and the adjusted negative electrode profile can be almost the same in shape as the measured complete single cell profile M and so on.

[0134] Therefore, according to the present disclosure, even without disassembling the target single cell BC or manufacturing the target single cell BC in the form of a three-electrode battery, the positive electrode profile and the negative electrode profile of the target single cell BC can be obtained.

[0135] If the target single cell BC is a new battery single cell, it is easier to analyze and utilize the adjusted positive electrode profile and the adjusted negative electrode profile to diagnose whether there are defects in the target single cell BC, and if there are defects, to diagnose what type of defects they are.

[0136] If the battery single cell is used after the target single cell BC is verified as a good product, it is possible to determine how much the target single cell BC has deteriorated for each deterioration item through the adjusted positive electrode profile and the adjusted negative electrode profile.

[0137] In addition, according to an embodiment of the present disclosure, the positive electrode profile and the negative electrode profile of the target single cell BC can be obtained in a simple manner. Even if only one reference positive electrode profile Rp and one reference negative electrode profile Rn are stored in the memory unit 330, the present disclosure can be implemented. That is, it is not necessary to store multiple reference positive electrode profiles Rp and / or multiple reference negative electrode profiles Rn in the memory unit 330. Therefore, the storage capacity of the memory unit 330 does not need to be high, and a large number of preliminary tests required to ensure multiple reference positive electrode profiles Rp and / or multiple reference negative electrode profiles Rn are not required.

[0138] Hereinafter, with reference to Figures 4 to 9 , the process of analyzing the measured complete single cell profile M to estimate the positive electrode loading amount of the target single cell BC will be described. The positive electrode loading amount of any battery single cell is a term indicating the amount of positive electrode active material per unit area of the positive electrode of the battery single cell, and its unit can be mAh / cm 2 or mg / cm 2 .

[0139] Figures 4 to 6 is a diagram exemplifying the process of generating a relatively complete single cell profile for comparison with the measured complete single cell profile according to an embodiment of the present disclosure.

[0140] With reference to Figures 4 to 6The process for generating a relatively complete cell profile is as follows: The first routine for setting four points (the positive participation start point, the positive participation end point, the negative participation start point, and the negative participation end point) corresponding to the voltage range of interest (see Figure 4 ), the second routine for performing profile shift (see Figure 5 ), and the third routine for performing capacity scaling (see Figure 6 ). That is, the process for generating a relatively complete cell profile according to an embodiment of the present disclosure includes the first to third routines.

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

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

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

[0144] As an example, the processor 320 can divide the positive voltage range from the start point to the end point (or the second set voltage) of the reference positive profile Rp into multiple small voltage segments, and then set the boundary point between two adjacent small voltage segments among the multiple small voltage segments as the positive participation start point (pi). Each small voltage segment can have a predetermined size (e.g., 0.01V). Next, the processor 320 can set the point on the reference negative profile Rn that is smaller than the positive participation start point (pi) by the first set voltage (e.g., 3V) as the negative participation start point (ni).

[0145] As another example, the processor 320 can divide the negative voltage range from the start point to the end point of the reference negative profile Rn into multiple small voltage segments of a predetermined size, and then set the boundary point between two adjacent small voltage segments among the multiple small voltage segments as the negative participation start point (ni). Next, the processor 320 can search for the point on the reference positive profile Rp that is larger than the negative participation start point (ni) by the first set voltage and set the searched point as the positive participation start point (pi).

[0146] Either the positive participation end point (pf) or the negative participation end point (nf) depends on the other.

[0147] As an example, the processor 320 may divide the voltage range from the second set voltage to the end point of the reference positive cutting line Rp into a plurality of small voltage segments of a predetermined size, and then set the boundary point between two adjacent small voltage segments among the plurality of small voltage segments as the positive participation end point (pf). Next, the processor 320 may set the point on the reference negative cutting line Rn that is smaller than the positive participation end point (pf) by the second set voltage (e.g., 4V) as the negative participation end point (nf).

[0148] As another example, the processor 320 may divide the negative voltage range from the starting point to the end point of the reference negative cutting line Rn into a plurality of small voltage segments of a predetermined size, and then set the boundary point between two adjacent small voltage segments among the plurality of small voltage segments as the negative participation end point (nf). Next, the processor 320 may search for a point on the reference positive cutting line Rp that is larger than the negative participation end point (nf) by the second set voltage, and set the searched point as the positive participation end point (pf).

[0149] If the positive participation starting point (pi), the positive participation end point (pf), the negative participation starting point (ni), and the negative participation end point (nf) are completely determined, the processor 320 shifts at least one of the reference positive cutting line Rp and the reference negative cutting line Rn to the left or right along the horizontal axis.

[0150] Reference Figure 5 , the processor 320 may shift the reference positive cutting line Rp to the left (towards low capacity) or shift the reference negative cutting line Rn to the right (towards high capacity) or shift both of them, so that the capacity values of the positive participation starting point (pi) and the negative participation starting point (ni) match.

[0151] Alternatively, the processor 320 shifts the reference positive cutting line Rp to the left or shifts the reference negative cutting line Rn to the right or shifts both of them, so that the capacity values of the positive participation end point (pf) and the negative participation end point (nf) match.

[0152] Figure 5 Shows a case where only the reference positive cutting line Rp is shifted to the left to generate an adjusted reference positive cutting line (Rp'), and thus the capacity value of the positive participation starting point (pi') matches the capacity value of the negative participation starting point (ni). The adjusted reference positive cutting line (Rp') is the result of applying the adjustment process of shifting the voltage difference between the positive participation starting point (pi) and the negative participation starting point (ni) to the left to the reference positive cutting line Rp. Therefore, the two points (pi, pi') are only different in capacity value and have the same voltage. The two points (pf, pf') are also only different in capacity value and have the same voltage.

[0153] If an adjusted result profile line (Rp’, Rn) in which at least one of a reference positive electrode profile line Rp and a reference negative electrode profile line Rn is shifted is ensured, the processor 320 scales a capacity range of at least one of the adjusted result profile lines (Rp’, Rn).

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

[0155] Reference Figure 6 , the processor 320 can generate an adjusted reference positive electrode profile line (Rp’’) by contracting or expanding the adjusted reference positive electrode profile line (Rp’) such that a size of a capacity range between two points (pi’, pf’) of the adjusted reference positive electrode profile line (Rp’) matches a size of a capacity range of the measured full cell profile line M. At this time, any one of the two points (pi’, pf’) (pi’) can be fixed. Accordingly, a capacity difference between two points (pi’, pf’’) of the adjusted reference positive electrode profile line (Rp’’) can match the capacity range of the measured full cell profile line M.

[0156] In addition, the processor 320 can generate an adjusted reference negative electrode profile line (Rn’) by contracting or expanding the reference negative electrode profile line Rn such that a size of a capacity range between two points (ni, nf) of the reference positive electrode profile line Rn matches a size of a capacity range of the measured full cell profile line M. At this time, any one of the two points (ni, nf) (ni) can be fixed. Accordingly, a capacity difference between two points (ni, nf’) of the adjusted reference negative electrode profile line (Rn’) can match the capacity range of the measured full cell profile line M.

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

[0158] A positive electrode participation end point (pf’’) on the adjusted reference positive electrode profile line (Rp’’) corresponds to a positive electrode participation end point (pf) on the adjusted reference positive electrode profile line (Rp’). A negative electrode participation end point (nf’) on the adjusted reference negative electrode profile line (Rn’) corresponds to a negative electrode participation end point (nf) on the reference negative electrode profile line Rn.

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

[0160] In addition, the capacity ranges of the two points (pi’, pf’’) of the adjusted reference positive electrode profile (Rp’’) match the capacity ranges of the two points (ni, nf’) of the adjusted reference negative electrode profile (Rn’). The processor 320 can generate a comparison full cell profile S by subtracting the profile between the two points (pi, pf’) of the adjusted reference positive electrode profile (Rp’’) from the profile between the two points (ni, nf’) of the adjusted reference negative electrode profile (Rn’).

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

[0162] The processor 320 can map at least two of the adjusted reference positive electrode profile (Rp’’), the adjusted reference negative electrode profile (Rn’), the positive electrode participation start point (pi’), the positive electrode participation end point (pf’’), the negative electrode participation start point (ni), the negative electrode participation end point (nf’), the positive electrode scaling factor, the negative electrode scaling factor, the comparison full cell profile S, and the profile error to each other and record them in the memory unit 330. The positive electrode scaling factor can represent the ratio of the capacity difference between the two points (pi’, pf’’) to the capacity difference between the two points (pi0, pf0). The negative electrode scaling factor can represent the ratio of the capacity difference between the two points (ni, nf’) to the capacity difference between the two points (ni0, nf0).

[0163] Meanwhile, as described above, when the positive electrode voltage range of the reference positive electrode profile Rp is divided into multiple small voltage sections, the boundary points of two adjacent small voltage sections among the multiple small voltage sections can be set as the positive electrode participation start point (pi).

[0164] For example, if the positive electrode voltage range of the reference positive electrode profile Rp is divided into 100 small voltage ranges, there can be 100 boundary points that can be set as the positive electrode participation start point (pi). In addition, if the voltage range greater than or equal to the second set voltage in the reference positive electrode profile Rp is divided into 40 small voltage ranges, there can be 40 boundary points that can be set as the positive electrode participation end point (pf). In this case, at least 4000 different comparison full cell profiles can be generated.

[0165] Of course, those skilled in the art will readily understand that as the size of the small voltage section decreases, the maximum number of comparative full monomer profiles that can be generated increases, and conversely, as the size of the small voltage section increases, the maximum number of comparative full monomer profiles that can be generated decreases.

[0166] The processor 320 can identify the minimum value among the profile errors of the generated plurality of comparative full monomer profiles as described above, and then obtain information (such as at least one of the positive electrode participation start point, positive electrode participation end point, negative electrode participation start point, negative electrode participation end point, positive electrode scaling factor, and negative electrode scaling factor) mapped to the minimum profile error from the memory unit 330.

[0167] Figures 7 to 9 is a diagram for another example of the process of generating a comparative full monomer profile for comparison with a measured full monomer profile according to an embodiment of the present disclosure. For reference, Figures 7 to 9 The embodiment shown in Figures 4 to 6 is independent of the embodiment shown in Figures 4 to 6 Therefore, the terms or reference numerals commonly used to describe the embodiment shown in Figures 7 to 9 and the embodiment shown in

[0168] should be understood to be limited to each embodiment. Figures 7 to 9 The process of generating a comparative full monomer profile to be explained with reference to Figure 7 is carried out in the following order: the fourth routine for performing capacity scaling (see Figure 8 ), the fifth routine for setting four points (the positive electrode participation start point, positive electrode participation end point, negative electrode participation start point, and negative electrode participation end point) (see Figure 9 ), and the sixth routine for performing profile shift (see

[0169] That is, the process of generating a comparative full monomer profile according to another embodiment of the present disclosure includes the fourth to sixth routines. Figure 7 Referring to

[0170] The scaling value range can be predetermined or can vary according to the ratio (R) of the size of the measured capacity range of the full cell profile M to the size of the capacity range of the reference full cell profile. As an example, assume that the positive electrode scaling factor and the negative electrode scaling factor can be selected from among values spaced 0.1% apart within the scaling value range (e.g., 90 to 99%), i.e., 90%, 90.1%, 90.2%, … 98.9%, 99%. In this case, up to 8281 pairs of adjusted profiles can be generated according to 91×91 = 8281 adjustment levels (combinations of the positive electrode scaling factor and the negative electrode scaling factor). The adjusted profile pair refers to the combination of the adjusted positive electrode profile and the adjusted negative electrode profile.

[0171] Reference Figure 7 , the adjusted reference positive electrode profile (Rp’) and the adjusted reference negative electrode profile (Rn’) respectively show the results of applying the positive electrode scaling factor and the negative electrode scaling factor to the reference positive electrode profile Rp and the reference negative electrode profile Rn.

[0172] Since the positive electrode scaling factor and the negative electrode scaling factor are less than 100%, the adjusted reference positive electrode profile (Rp’) is obtained by shrinking the reference positive electrode profile Rp along the horizontal axis, and the adjusted reference negative electrode profile (Rn’) is also obtained by shrinking the reference negative electrode profile Rn along the horizontal axis. For ease of understanding, the reference positive electrode profile Rp and the reference negative electrode profile Rn are shown in a form where their starting points are fixed respectively and the remaining parts shrink to the left along the horizontal axis.

[0173] Reference Figure 8 , the processor 320 determines the positive electrode participation starting point (pi’), the positive electrode participation ending point (pf’), the negative electrode participation starting point (ni’), and the negative electrode participation ending point (nf’) on the adjusted reference positive electrode profile (Rp’) and the adjusted reference negative electrode profile (Rp’).

[0174] Either the positive electrode participation starting point (pi’) or the negative electrode participation starting point (ni’) can depend on the other. Also, either the positive electrode participation ending point (pf’) or the negative electrode participation ending point (nf’) can depend on the other. In addition, either the positive electrode participation starting point (pi’) or the positive electrode participation ending point (pf’) can be set based on the other.

[0175] That is, if any one of the positive electrode participation starting point (pi’), the positive electrode participation ending point (pf’), the negative electrode participation starting point (ni’), and the negative electrode participation ending 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 measured capacity range of the full cell profile M (e.g., Figure 3b 45Ah - 5Ah = 40Ah in

[0176] As an example, the processor 320 can divide the positive voltage range from the starting point to the ending point (or the second set voltage) of the adjusted reference positive dissection line (Rp’) into a plurality of small voltage segments, and then set the boundary point between two adjacent small voltage segments among the plurality of small voltage segments as the positive participation starting point (pi’). Next, the processor 320 can set the point on the adjusted reference negative dissection line (Rn) that is smaller than the positive participation starting point (pi’) by a first set voltage (e.g., 3V) as the negative participation starting point (ni’).

[0177] As another example, the processor 320 can divide the negative voltage range from the starting point to the ending point of the adjusted reference negative dissection line (Rn’) into a plurality of small voltage segments of a predetermined size, and then set the boundary point between two adjacent small voltage segments among the plurality of small voltage segments as the negative participation starting point (ni’). Next, the processor 320 can search for a point on the adjusted reference positive dissection line (Rp) that is larger than the negative participation starting point (ni’) by the first set voltage, and set the searched point as the positive participation starting point (pi’).

[0178] As yet another example, the processor 320 can divide the voltage range from the second set voltage to the ending point of the adjusted reference positive dissection line (Rp’) into a plurality of small voltage segments of a predetermined size, and then set the boundary point between two adjacent small voltage segments among the plurality of small voltage segments as the positive participation ending point (pf’). Next, the processor 320 can search for a point on the adjusted reference negative dissection line (Rn’) that is smaller than the positive participation ending point (pf’) by a second set voltage (e.g., 4V), and set the searched point as the negative participation ending point (nf’).

[0179] As yet another example, the processor 320 can divide the negative voltage range from the starting point to the ending point of the adjusted reference negative dissection line (Rn’) into a plurality of small voltage segments of a predetermined size, and then set the boundary point between two adjacent small voltage segments among the plurality of small voltage segments as the negative participation ending point (nf’). Next, the processor 320 can search for a point on the adjusted reference positive dissection line (Rp’) that is larger than the negative participation ending point (nf’) by the second set voltage, and set the searched point as the positive participation ending point (pf’).

[0180] If any one of the positive participation starting point (pi’), the positive participation ending point (pf’), the negative participation starting point (ni’), and the negative participation ending point (nf’) is determined, the processor 320 can additionally determine the remaining three points based on the determined point.

[0181] For example, if the positive electrode participation starting point (pi') is first determined, the processor 320 may set, as the positive electrode participation ending point (pf'), a point on the adjusted reference positive electrode profile line (Rp') that has a capacitance value greater than the size of the capacitance range of the measured full cell profile line M with respect to the capacitance value of the positive electrode participation starting point (pi'). In addition, the processor 320 may search, from the adjusted reference negative electrode profile line (Rn'), for a point that is lower than the positive electrode participation starting point (pi') by a first set voltage, and set the searched point as the negative electrode participation starting point (ni'). In addition, the processor 320 may set, as the negative electrode participation ending point (nf'), a point on the adjusted reference negative electrode profile line (Rn') that has a capacitance value greater than the size of the capacitance range of the measured full cell profile line M with respect to the capacitance value of the negative electrode participation starting point (ni').

[0182] As another example, when the positive electrode participation ending point (pf') is first determined, the processor 320 may set, as the positive electrode participation starting point (pi'), a point on the adjusted reference positive electrode profile line (Rp') that has a capacitance value smaller than the size of the capacitance range of the measured full cell profile line M with respect to the capacitance value of the positive electrode participation ending point (pf'). In addition, the processor 320 may search, from the adjusted reference negative electrode profile line (Rn'), for a point that is lower than the positive electrode participation ending point (pf') by a second set voltage, and set the searched point as the negative electrode participation ending point (nf'). Additionally, the processor 320 may set, as the negative electrode participation starting point (ni'), a point on the adjusted reference negative electrode profile line (Rn') that has a capacitance value smaller than the size of the capacitance range of the measured full cell profile line M with respect to the capacitance value of the negative electrode participation ending point (nf').

[0183] As yet another example, when the negative electrode participation starting point (ni') is determined, the processor 320 may set, as the negative electrode participation ending point (nf'), a point on the adjusted reference negative electrode profile line (Rn') that has a capacitance value greater than the size of the capacitance range of the measured full cell profile line M with respect to the capacitance value of the negative electrode participation starting point (ni'). In addition, the processor 320 may search, from the adjusted reference positive electrode profile line (Rp'), for a point that is higher than the negative electrode participation starting point (ni') by a first set voltage, and set the searched point as the positive electrode participation starting point (pi'). In addition, the processor 320 may set, as the positive electrode participation ending point (pf'), a point on the adjusted reference positive electrode profile line (Rp') that has a capacitance value greater than the size of the capacitance range of the measured full cell profile line M with respect to the capacitance value of the positive electrode participation starting point (pi').

[0184] As another example, when the negative electrode participation end point (nf’) is determined, the processor 320 may set a point on the adjusted reference negative electrode profile line (Rn’) having a capacity value smaller than the size of the capacity range of the measured full cell profile line M of the negative electrode participation end point (nf’) as the negative electrode participation start point (ni’). In addition, the processor 320 may search for a point on the adjusted reference positive electrode profile line (Rp’) that is higher than the negative electrode participation end point (nf’) by a second set voltage, and set the searched point as the positive electrode participation end point (pf’). Additionally, the processor 320 may set a point on the adjusted reference positive electrode profile line (Rp’) having a capacity value smaller than the size of the capacity range of the measured full cell profile line M of the positive electrode participation end point (pf’) as the positive electrode participation start point (pi’).

[0185] If the positive electrode participation start point (pi’), the positive electrode participation end point (pf’), the negative electrode participation start point (ni’), and the negative electrode participation end point (nf’) are fully determined based on the positive electrode scaling factor and the negative electrode scaling factor, the processor 320 may shift at least one of the adjusted reference positive electrode profile line (Rp’) and the adjusted reference negative electrode profile line (Rn’) left or right along the horizontal axis so that the capacity values of the positive electrode participation start point (pi’) and the negative electrode participation start point (ni’) match or the capacity values of the positive electrode participation end point (pf’) and the negative electrode participation start point (nf’) match.

[0186] Figure 9 The adjusted reference negative electrode profile line (Rn’’) shown in is obtained by shifting only the Figure 8 adjusted reference negative electrode profile line (Rn’) shown in to the right. Accordingly, the capacity values of the positive electrode participation start point (pi’) and the negative electrode participation start point (ni’’) match each other. Correlatively, the capacity difference between the positive electrode participation start point (pi’) and the positive electrode participation end point (pf’) is equal to the capacity difference between the negative electrode participation start point (ni’) and the negative electrode participation end point (nf’). Therefore, if the capacity values of the positive electrode participation start point (pi’) and the negative electrode participation start point (ni’’) match each other, the capacity values of the positive electrode participation end point (pf’) and the negative electrode participation end point (nf’) also match each other.

[0187] Reference Figure 9 , the processor 320 may generate a comparison full cell profile line U by subtracting the partial profile line between two points (pi’, pf’) of the adjusted reference positive electrode profile line (Rp’) from the partial profile line between two points (ni’’, nf’’) of the adjusted reference negative electrode profile line (Rn’’).

[0188] The processor 320 may calculate the error (profile line error) between the comparison full cell profile line U and the measured full cell profile line M.

[0189] The processor 320 may map at least two of the adjusted reference positive profile line (Rp’), the adjusted reference negative profile line (Rn’’), the positive participation start point (pi’), the positive participation end point (pf’), the negative participation start point (ni’’), the negative participation end point (nf’’), the positive scaling factor, the negative scaling factor, the comparison full cell profile line U, and the profile error to each other and record them in the memory unit 330.

[0190] As described above, the processor 320 may generate a comparison full cell profile line corresponding to each pair of the positive scaling factor and the negative scaling factor selected from the scaling value range. Since there are multiple pairs of the positive scaling factor and the negative scaling factor, it is obvious that multiple comparison profile lines will also be generated. The processor 320 may identify the minimum value among the profile errors of the multiple comparison full cell profile lines, and then obtain the information mapped to the minimum profile error from the memory unit 330.

[0191] The processor 320 may extract the positive scaling factor from the information mapped to the minimum profile error. The processor 320 may estimate the positive load amount of the target cell BC based on the extracted positive scaling factor.

[0192] Specifically, the processor 320 may estimate the positive load amount of the target cell BC based on the positive scaling factor and the reference positive load amount. Here, the reference positive load amount is the total positive capacity of the reference cell, and may be a predetermined value. The reference positive load amount is a predetermined value representing the amount (or available capacity) of the positive active material per unit area of the positive electrode of the reference cell.

[0193] Specifically, the processor 320 may use the following formula 1 to determine the estimated value of the positive load amount of the target cell BC.

[0194] <Formula 1>

[0195]

[0196] In formula 1, P t_loading represents the estimated value of the positive load amount of the target cell BC, P t_scale represents the positive scaling factor, and P r_loading represents the reference positive load amount.

[0197] The processor 320 may determine the positive capacity loss rate of the target cell BC based on the estimated value of the positive load amount of the target cell BC. The following formula 2 may be used to determine the positive capacity loss rate.

[0198] <Formula 2>

[0199]

[0200] In Formula 2, L P_Q represents the positive electrode capacity loss rate of the target monomer BC. That is, the positive electrode capacity loss rate of the target monomer BC can represent the ratio of the reduction in the positive electrode loading of the target monomer BC to the reference positive electrode loading.

[0201] In addition to Formula 2, the following Formula 3 can also be used to determine the positive electrode capacity loss rate.

[0202] <Formula 3>

[0203]

[0204] In Formula 3, N r_f represents the capacity value of the negative electrode of the reference monomer participating in the end point ( Figure 2 the symbol nf0 in), N r_i represents the capacity value of the negative electrode of the reference monomer participating in the starting point ( Figure 2 the symbol ni0 in), P r_f represents the capacity value of the positive electrode of the reference monomer participating in the end point ( Figure 2 the symbol pf0 in), and P t_f represents the capacity value of the positive electrode of the target monomer BC participating in the end point (for example, Figure 6 the symbol pf'' in).

[0205] The processor 320 can limit at least one of the allowable voltage range and the allowable SOC range of the target monomer BC based on an estimated value of the positive electrode loading of the target monomer BC. Relationship data indicating a predetermined positive correlation between the positive electrode loading and the limit level can be pre-stored in the memory unit 330. That is, according to the relationship data, a decrease in the positive electrode loading causes a decrease in at least one of the allowable voltage range and the allowable SOC range. The decreasing range means at least one of the lower limit of the increasing range and the upper limit of the decreasing range.

[0206] For example, assume that the allowable voltage range and the allowable SOC range are 2.5 V to 4.5 V and 5% to 95% respectively. If the positive electrode loading is estimated to be 90% of the reference positive electrode loading, the allowable voltage range can be reduced to 2.75 V to 4.05 V, and the allowable SOC range can be reduced to 5.5% to 85.5%.

[0207] Figure 10 is a flowchart exemplarily depicting a battery diagnosis method according to a first embodiment of the present disclosure. According to Figure 10 the method can be executed by a battery diagnosis device.

[0208] At step S1010, the processor 320 controls the stimulation application device 301 to intermittently apply a second electrical stimulation greater than the first electrical stimulation to the target cell BC during a state change period until the electrical state of the target cell BC changes from an initial state to a target state.

[0209] In step S1020, the processor 320 uses the communication unit 310 to obtain current time series data representing the change history of the current of the target cell BC during the state change period and voltage time series data representing the change history of the full cell voltage of the target cell BC during the rest period of the second electrical stimulation applied during the state change period. The voltage time series data may include measured values of the full cell voltage at the end time point of each rest period (see Figure 3a D of OCV ).

[0210] The communication unit 310 may collect the current time series data and the voltage time series data generated by the electric vehicle 1 from the electric vehicle 1 after the state change period ends.

[0211] Alternatively, the communication unit 310 may periodically collect measurement data representing at least one of the current and the full cell voltage of the target cell BC from the electric vehicle 1 during the state change period. In this case, each measurement value collected multiple times during the state change period may be recorded in the memory unit 330 in chronological order. The processor 320 may generate the current time series data and the voltage time series data based on the set of measurement values collected during the state change period.

[0212] In step S1030, the processor 320 generates a measured full cell profile indicating the correspondence between the capacity of the target cell BC and the full cell voltage based on the current time series data and the voltage time series data (see Figure 3b M in

[0213] ). In step S1040, the processor 320 analyzes the measured full cell profile to estimate the positive electrode loading amount of the target cell BC (see Equation 1). The positive electrode loading amount represents the amount of the positive electrode active material per unit area of the positive electrode of the target cell.

[0214] In step S1050, the processor 320 determines the positive electrode capacity loss rate of the target cell BC based on the estimated value of the positive electrode loading amount (see Equation 2).

[0215] In step S1060, the processor 320 restricts at least one of the allowable voltage range and the allowable SOC range of the target cell BC based on the estimated value of the positive electrode loading amount.

[0216] In accordance with Figure 10In the method, only one of steps S1050 and S1060 can be executed.

[0217] In step S1070, the processor 320 may use the communication unit 310 to send the diagnostic result of the target cell BC to the electric vehicle 1. The diagnostic result includes at least one of a positive electrode load amount, a positive electrode capacity loss rate, a restricted allowable voltage range, and a restricted allowable SOC range.

[0218] Figure 11 is a flowchart exemplarily depicting a battery diagnostic method according to a second embodiment of the present disclosure. According to Figure 11 the method can be executed by a battery diagnostic device.

[0219] At step S1110, the processor 320 controls the stimulation application device 301 to intermittently apply a second electric stimulation greater than the first electric stimulation to the target cell BC during a state change period until the electrical state of the target cell BC changes from an initial state to a target state.

[0220] In step S1120, the processor 320 uses the communication unit 310 to obtain current time series data representing the change history of the current of the target cell BC during the state change period and voltage time series data representing the change history of the full cell voltage of the target cell BC during the rest period of the second electric stimulation applied during the state change period.

[0221] Different from the above according to the first embodiment, the voltage time series data obtained in step S1120 includes measured values of the full cell voltage measured three or more times before the end of each rest period, rather than the measured value of the full cell voltage at the end of each rest period (see Figure 3a D in OCV )

[0222] In step S1122, the processor 320 applies the OCV estimation logic to the voltage time series data obtained in step S1120 to generate corrected voltage time series data. The OCV estimation logic can be provided to replace a set of measured values of the three full cell voltages of each rest period included in the voltage time series data obtained in step S1120 with a single OCV value. Thus, if a total of X rest periods are permitted during the state change period and the full cell voltage is measured three times for each rest period, those skilled in the art will readily understand that the voltage time series data obtained in step S1120 will include 3X full cell voltage measurement values, and the corrected voltage time series data will include X OCV values.

[0223] In step S1130, the processor 320 generates a measured full-cell profile indicating the correspondence between the capacity of the target cell BC and the full-cell voltage based on the current time-series data and the corrected voltage time-series data (see M in Figure 3b ).

[0224] In step S1140, the processor 320 analyzes the measured full-cell profile to estimate the positive electrode load amount of the target cell BC (see Equation 1).

[0225] In step S1150, the processor 320 determines the positive electrode capacity loss rate of the target cell BC based on the estimated value of the positive electrode load amount (see Equation 2).

[0226] In step S1160, the processor 320 restricts at least one of the allowable voltage range and the allowable SOC range of the target cell BC based on the estimated value of the positive electrode load amount.

[0227] In the method according to Figure 11 , only one of steps S1150 and S1160 can be executed.

[0228] In step S1170, the processor 320 can send the diagnostic result of the target cell BC to the electric vehicle 1 through the communication unit 310. The diagnostic result includes at least one of the positive electrode load amount, the positive electrode capacity loss rate, the restricted allowable voltage range, and the restricted allowable SOC range.

[0229] Figure 12 is referred to describe the process of correcting the voltage time-series data performed in step S1122 of Figure 11 .

[0230] Figure 12 The symbol 1200 in Figure 3a indicates one of the voltage drop segments shown in R . When the rest period is long enough, t R indicates the time point at which the reference time has elapsed since the start time point of the rest period. The part up to t R is depicted as a solid line, and the part after t

[0231] Refer to Figure 12 . During each rest period, the target cell BC is placed in a no-load state where there is neither charging nor discharging.

[0232] During the no-load state, the full-cell voltage of the target cell BC gradually converges to the OCV corresponding to the SOC of the target cell BC. The behavior of the full-cell voltage of the target cell BC during a specific rest period can be equivalent to the voltage response of a primary RC circuit, such as Equation 4 below.

[0233] <Formula 4>

[0234]

[0235] In Formula 4, t is the time elapsed since the start time point of a specific rest period, and V full (t) is the full cell voltage at t, V OCV is the actual OCV, V S is the full cell voltage at the start time point of the specific rest period, and τ is the time constant determined by the internal resistance and capacity of the target cell BC.

[0236] In Formula 4, V full (t) is measurable, so V OCV , V S and τ are unknown. Since there are three unknown values, the OCV of a specific rest period can be estimated based on V full (t) measured at three different timings during the specific rest period. The following Formula 5 can be used to estimate the OCV of each rest period.

[0237] <Formula 5>

[0238]

[0239] In Formula 5, t1, t2, and t3 are the sequential measurement timings of the full cell voltage. The time difference between t1 and t2 can be the same as the time difference between t2 and t3.

[0240] The processor 320 can convert the voltage time series data obtained in step S1120 into the corrected voltage time series data of step S1130 by repeating the process of replacing the three full cell voltage measurement values (V OCV_C ), V full (t1), V full (t2), V full (t3)) of each rest period with a single OCV value (D

[0241] As a reference, D OCV is the measured value of the full cell voltage at the end time point of the rest period (before the polarization is completely resolved), while D OCV_C is the estimated value of the full cell voltage in the state where the polarization is completely resolved (i.e., V OCV ). Therefore, it can be considered that D OCV_C is closer to the actual OCV of the target cell BC than D OCV .

[0242] The embodiments of the present disclosure described above are not only implemented by the device and method, but also can be implemented by a program that executes functions corresponding to the configurations of the embodiments of the present disclosure or a recording medium having the program recorded thereon, and based on the disclosure of the previously described embodiments, those skilled in the art can easily implement such an implementation manner.

[0243] Although the present disclosure has been described above with respect to a limited number of embodiments and drawings, the present disclosure is not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes can be made thereto within the technical scope of the present disclosure and the equivalent scope of the appended claims.

[0244] In addition, since those skilled in the art can make many substitutions, modifications, and changes to the present disclosure without departing from the technical aspects of the present disclosure, the present disclosure is not limited by the above-described embodiments and drawings, and some or all of the embodiments can be selectively combined to allow various modifications.

Claims

1. A battery diagnosis device, comprising: 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 during a state change period until an electrical state of the target cell changes from an initial state to a target state, the target cell being a battery cell to be diagnosed; and a communication unit configured to obtain current time series data representing a change history of a current of the target cell during the state change period, and voltage time series data representing a change history of a full-cell voltage of the target cell during a rest period of the second electrical stimulation applied during the state change period, wherein the processor is configured to: generate a measured full-cell profile representing a correspondence between a capacity of the target cell and the full-cell voltage based on the current time series data and the voltage time series data, and estimate a positive electrode loading amount by analyzing the measured full-cell profile, the positive electrode loading amount representing an amount of a positive electrode active material per unit area of a positive electrode of the target cell.

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

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

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

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

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

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

8. The battery diagnostic device according to claim 1, wherein, The processor is configured to determine a positive electrode capacity loss rate of the target cell based on an estimated value of the positive electrode loading amount.

9. The battery diagnosis device according to claim 1, wherein, The processor is configured to limit at least one of an allowable voltage range and an allowable SOC range of the target cell based on the estimated value of the positive electrode loading amount.

10. A charging station, comprising the battery diagnosis device according to any one of claims 1 to 9.

11. A cloud server, comprising the battery diagnosis device according to any one of claims 1 to 9.

12. A battery diagnosis method, comprising: Control 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 an electrical state of the target cell changes from an initial state to a target state, where the target cell is a battery cell to be diagnosed; Obtain current time series data representing a change history of a current of the target cell during the state change period, and voltage time series data representing a change history of a full cell voltage of the target cell during a rest period of the second electrical stimulation applied during the state change period; Generate a measured full cell profile representing a correspondence between a capacity of the target cell and the full cell voltage based on the current time series data and the voltage time series data; And Estimate a positive electrode loading amount by analyzing the measured full cell profile, where the positive electrode loading amount represents an amount of a positive electrode active material per unit area of a positive electrode of the target cell.

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

14. The battery diagnosis method according to claim 12, further comprising: Determine a positive electrode capacity loss rate of the target cell based on an estimated value of the positive electrode loading amount.

15. The battery diagnosis method according to claim 12, further comprising: Restrict at least one of an allowable voltage range and an allowable SOC range of the target cell based on an estimated value of the positive electrode loading amount.

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