JP2018190502A - Secondary battery system - Google Patents

Abstract

In a secondary battery system including a lithium ion secondary battery, high-rate deterioration is more appropriately suppressed. When a high rate deterioration trigger is larger than a reference value, an ECU 100 suppresses a charging / discharging current of a battery 10 as compared with a case where the high rate deterioration trigger is smaller than a reference value. ECU 100 stores a correspondence relationship between initial DC resistance Rohm0 indicating the DC resistance in the initial state of battery 10 and temperature TB of battery 10 as initial state map MP. ECU 100 obtains DC resistance Rohm of battery 10 from the measurement result of AC impedance measured by AC impedance measurement device 30. The ECU 100 estimates a high rate deterioration trigger using a difference (shift amount ΔRohm) between the acquired DC resistance Rohm and the initial DC resistance Rohm0 corresponding to the temperature TB detected by the temperature sensor 63. [Selection] Figure 6

Description

  The present disclosure relates to a secondary battery system, and more particularly, to a technique for estimating the degree of deterioration of a secondary battery (lithium ion secondary battery) having an electrode body impregnated with an electrolyte containing lithium ions. .

  2. Description of the Related Art In recent years, with the spread of electric vehicles such as hybrid vehicles and electric vehicles, secondary battery systems including a lithium ion secondary battery as a traveling battery have become widespread. Generally, in a lithium ion secondary battery (hereinafter also abbreviated as “secondary battery”), the concentration distribution of lithium ions in the electrode body (hereinafter also abbreviated as “salt concentration distribution”) during charging / discharging (charging or discharging). It is known that a bias occurs, thereby increasing the internal resistance of the secondary battery. Since the deviation of the salt concentration distribution becomes particularly noticeable during charging / discharging with a large current, such deterioration is also referred to as “high-rate deterioration”.

  In order to appropriately control charging / discharging of a lithium ion secondary battery in accordance with the degree of high-rate deterioration (degree of progress, hereinafter also referred to as “high-rate deterioration degree”), a technique for estimating the high-rate deterioration degree has been proposed. . For example, in Japanese Patent Application Laid-Open No. 2013-044580 (Patent Document 1), an internal resistance increase rate of a secondary battery is calculated, and the calculated internal resistance increase rate and an internal resistance increase due to aged deterioration of the secondary battery obtained in advance. A technique for estimating a high-rate deterioration degree by obtaining a difference from a rate is disclosed.

JP2013-045580A JP 2006-065832 A

  By controlling charging / discharging of the secondary battery according to the high rate deterioration degree of the secondary battery, further progress of the high rate of the secondary battery can be suppressed (prevented). For example, when the high rate deterioration level is equal to or higher than a predetermined value (more strictly speaking, when a minute change before the high rate deterioration is detected), The charge / discharge current of the secondary battery is suppressed as compared with the case where no change is detected. Thereby, further progress of high-rate deterioration can be suppressed.

  As described above, in Patent Document 1, the internal resistance increase rate of the secondary battery and the internal resistance increase rate due to aging of the secondary battery are calculated. According to Patent Document 1, the internal resistance increase rate of the secondary battery (the internal resistance increase rate as a whole) is obtained by superposing the internal resistance increase rate due to aging and the internal resistance increase rate due to high-rate deterioration. Under the assumption that there is, the internal resistance increase rate due to high rate deterioration is estimated by subtracting the internal resistance increase rate due to aging from the internal battery resistance increase rate (total internal resistance increase rate) of the secondary battery. (See, for example, paragraph [0042] of Patent Document 1).

  However, the above-described estimation method disclosed in Patent Document 1 is a method for indirectly estimating the high rate deterioration level. Therefore, there is room for improvement in the estimation accuracy of the high rate deterioration degree, and there is room for improvement in terms of suppressing the high rate deterioration.

  The present disclosure has been made to solve the above-described problem, and an object of the present disclosure is to provide a technique capable of more appropriately suppressing high-rate deterioration in a secondary battery system including a lithium ion secondary battery. It is to be.

  A secondary battery system according to an aspect of the present disclosure includes a secondary battery, a temperature sensor, a measurement device, and a control device. The secondary battery has an electrode body impregnated with an electrolytic solution containing lithium ions. The temperature sensor detects the temperature of the secondary battery. The measuring device is configured to be able to measure the AC impedance of the secondary battery. When the high-rate deterioration trigger indicating the factor causing the deterioration (high-rate deterioration) of the secondary battery caused by the uneven distribution of the lithium ion concentration in the electrode body is larger than the predetermined value, the high-rate deterioration trigger is the predetermined value. The charging / discharging current of the secondary battery is suppressed as compared with the case of smaller than that. The control device stores a correspondence relationship between the initial DC resistance indicating the DC resistance of the secondary battery in the initial state of the secondary battery and the temperature of the secondary battery. The control device acquires the DC resistance of the secondary battery from the measurement result of the AC impedance of the secondary battery measured by the measuring device. The control device estimates a high rate deterioration trigger using a difference between the acquired DC resistance and an initial DC resistance corresponding to the temperature detected by the temperature sensor.

  According to the said structure, the DC resistance of a secondary battery is acquired from the measurement result of AC impedance. Further, by referring to the correspondence relationship (for example, a map), an initial DC resistance corresponding to the temperature detected by the temperature sensor is obtained. Although details will be described later, a high rate deterioration trigger of the secondary battery is reflected in the difference between the DC resistance and the initial DC resistance. Therefore, the estimation accuracy of the high rate deterioration degree can be improved by estimating the high rate deterioration trigger using the above difference. Therefore, it is possible to more appropriately suppress high rate deterioration.

  According to the present disclosure, in a secondary battery system including a lithium ion secondary battery, high rate deterioration can be more appropriately suppressed.

It is a block diagram which shows roughly the whole structure of the hybrid vehicle by which the secondary battery system which concerns on this Embodiment is mounted. It is a figure which shows the structure of an alternating current impedance measuring apparatus in detail. It is a figure for demonstrating the complex impedance plot of the measurement result of alternating current impedance. It is a figure for demonstrating the influence of the high-rate degradation and aging degradation to the circular arc on a complex impedance plot. It is a figure which shows an example of the initial state map in this Embodiment. It is a flowchart which shows the deterioration estimation process of the battery in this Embodiment.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  In the embodiments described below, a configuration in which a secondary battery system according to the present disclosure is mounted on a hybrid vehicle will be described as an example. However, the vehicle on which the secondary battery system according to the present disclosure can be mounted is not limited to a hybrid vehicle, and may be an electric vehicle or a fuel vehicle. Moreover, the use of the secondary battery system according to the present disclosure is not limited to a vehicle, and may be a stationary one, for example.

[Embodiment]
<Configuration of secondary battery system>
FIG. 1 is a block diagram schematically showing an overall configuration of a hybrid vehicle equipped with a secondary battery system according to the present embodiment. The vehicle 9 includes a secondary battery system 1, motor generators (MG) 910 and 920, a power split device 930, an engine 940, and drive wheels 950. The secondary battery system 1 includes a battery 10, a relay 20, an AC impedance measuring device 30, a system main relay (SMR) 40, a power control unit (PCU) 50, and a voltage sensor. 61, a current sensor 62, a temperature sensor 63, and an electronic control unit (ECU) 100.

  Each of motor generators 910 and 920 is, for example, a three-phase AC rotating electric machine. Motor generator 910 is coupled to the crankshaft of engine 940 via power split device 930. The motor generator 910 rotates the crankshaft of the engine 940 using the electric power of the battery 10 when starting the engine 940. Motor generator 910 can also generate power using the power of engine 940. The AC power generated by the motor generator 910 is converted into DC power by the PCU 50 and charged to the battery 10. In addition, the AC power generated by the motor generator 910 may be supplied to the motor generator 920.

  Motor generator 920 rotates the drive shaft using at least one of the electric power from battery 10 and the electric power generated by motor generator 910. The motor generator 920 can also generate electric power by regenerative braking. The AC power generated by the motor generator 920 is converted into DC power by the PCU 50 and charged to the battery 10.

  Power split device 930 includes, for example, a planetary gear mechanism (not shown), and mechanically connects the three elements of the crankshaft of engine 940, the rotation shaft of motor generator 910, and the drive shaft.

  The engine 940 is an internal combustion engine such as a gasoline engine, and generates a driving force for the vehicle 9 to travel in response to a control signal from the ECU 100.

  The battery 10 is an assembled battery including a plurality of cells (unit cells). Each of the plurality of cells is a lithium ion secondary battery.

  The relay 20 is electrically connected between the battery 10 and the AC impedance measuring device 30. In response to a control command from the ECU 100, the relay 20 is closed when the AC impedance of the battery 10 is measured, and is opened when the battery 10 is charged and discharged.

  The AC impedance measuring device 30 is configured to be able to measure the AC impedance of the battery 10 (more specifically, each cell) in response to a control command from the ECU 100. The configuration of the AC impedance measuring device 30 will be described in more detail with reference to FIG. The AC impedance measuring device 30 corresponds to a “measuring device” according to the present disclosure.

  The SMR 40 is electrically connected to a power line that connects the battery 10 and the PCU 50. The SMR 40 is opened / closed in response to a control signal from the ECU 100. When SMR 40 is closed, power can be exchanged between battery 10 and PCU 50. The SMR 40 is not an essential component for the secondary battery system 1.

  Although not shown, the PCU 50 includes an inverter and a converter. The inverter is, for example, a general three-phase inverter. The converter boosts the voltage supplied from the battery 10 during the boosting operation and supplies the boosted voltage to the inverter. During the step-down operation, the converter steps down the voltage supplied from the inverter and charges the battery 10.

  The voltage sensor 61 detects the voltage VB of the battery 10. The current sensor 62 detects a current IB input / output to / from the battery 10. The temperature sensor 63 detects the temperature TB of the battery 10. Each sensor outputs the detection result to ECU 100. The ECU 100 estimates the SOC (State Of Charge) of the battery 10 or controls charging / discharging of the battery 10 based on the detection result by each sensor.

  Although not shown, ECU 100 includes a CPU (Central Processing Unit), a memory, and an input / output buffer. The ECU 100 determines each component (more specifically, the relay 20 and the AC impedance measuring device 30) so that the vehicle 9 is in a desired state based on a signal received from each sensor and a map and a program stored in the memory. , SMR 40 and PCU 50). The main control executed by the ECU 100 includes a process for estimating the degree of deterioration of the battery 10, and this process will be described in detail with reference to FIGS.

<AC impedance measurement>
FIG. 2 is a diagram showing the configuration of the AC impedance measuring apparatus 30 in more detail. Referring to FIG. 2, AC impedance measuring device 30 includes an oscillator 31, a potentiostat 32, and a lock-in amplifier 33.

  The oscillator 31 outputs a sine wave having the same phase to the potentiostat 32 and the lock-in amplifier 33.

  The potentiostat 32 superimposes an AC voltage in phase with the sine wave from the oscillator 31 (for example, a voltage having an amplitude of about 10 mV) on a predetermined DC voltage and applies it to the battery 10. The potentiostat 32 detects an AC component of the current flowing through the battery 10 and outputs the detection result to the lock-in amplifier 33. Further, the potentiostat 32 outputs the above-described AC voltage and the AC component of the current to the ECU 100 as measurement results.

  The lock-in amplifier 33 compares the phase of the sine wave received from the oscillator 31 with the phase of the AC component of the current detected by the potentiostat 32, and sends the phase difference between the sine wave and the AC component to the ECU 100 as a measurement result. Output.

  Generally, the impedance (internal resistance) of a lithium ion secondary battery can be roughly divided into a plurality of (for example, three) impedance components based on the lithium ion transfer reaction process in the charge / discharge reaction of the lithium ion secondary battery. . The plurality of impedance components include a direct current resistance (ohmic resistance) Rohm, a reaction resistance Rct, and a diffusion resistance Rd. The DC resistance Rohm includes the conduction resistance of lithium ions in the electrolytic solution and the electrical resistance at the electrodes (positive electrode and negative electrode). The reaction resistance Rct includes a charge transfer resistance at the electrode / electrolyte interface (resistance when lithium ions enter and exit the active material) and a film resistance. The diffusion resistance Rd includes a resistance associated with diffusion of lithium into the active material.

  The relaxation time (the time required for the current to flow) differs between the impedance components of the battery 10. Therefore, for example, when a high-frequency AC voltage is applied to the battery 10, an impedance component with a small relaxation time can follow a change in the AC voltage, while an impedance component with a large relaxation time is positive or negative before the current flows. Since the reverse voltage is applied, it is impossible to follow the change in the AC voltage. Therefore, the AC voltage applied to the battery 10 and the AC current flowing through the battery 10 are measured while gradually changing (sweeping) the frequency (or angular frequency ω) of the sine wave output from the oscillator 31. Thus, the dominant impedance component of the battery 10 at the angular frequency ω can be separated.

  ECU 100 measures the impedance (amplitude ratio between AC voltage and current) for each of the swept angular frequencies ω. Then, the ECU 100 plots the impedance measurement result and the phase difference detected by the lock-in amplifier 33 on a complex plane (described later in FIG. 3).

  Note that the configuration of the AC impedance measuring apparatus 30 shown in FIG. 2 is merely an example, and the present invention is not limited to this. The AC impedance measurement device 30 may include a frequency response analyzer instead of the lock-in amplifier 33, for example. Further, the AC component of the current may be measured from the waveform of the current that varies when the vehicle 9 is traveling, for example, without providing the dedicated oscillator 31.

FIG. 3 is a diagram for explaining a complex impedance plot (also referred to as a Nyquist plot) of measurement results of AC impedance. In FIG. 3 and FIG. 4 to be described later, the horizontal axis represents the real component Z _Re of the complex impedance, and the vertical axis represents the imaginary component −Z _Im of the complex impedance. The angular frequency ω is swept in the range of ω1 to ω4 (ω4 <ω3 <ω2 <ω1). As an example, ω1 = 100 kHz, ω2 = 20 kHz, ω3 = 5 Hz, and ω4 = 100 mHz.

  As shown in FIG. 3, on the complex impedance plot, a semicircular locus, that is, “arc” in a high frequency region of angular frequency ω (region where angular frequency ω is ω2 to ω3 (ω3 and ω2 or less)). Appears. In this arc, the orthogonal component (see point P) with the frequency-dependent zero point represents the DC resistance Rohm. Hereinafter, the point P is also referred to as “arc start point”.

  In addition, a linear locus (straight line) appears in the low frequency region of the angular frequency ω (region where the angular frequency ω is ω3 to ω4 (ω4 to ω3). The distance (difference in real number component) on the horizontal axis between the connection point (see point Q) between the semicircular locus (arc) and the linear locus and the point P represents the reaction resistance Rct. Hereinafter, the distance between the point Q and the point P is also referred to as “arc size”.

  When the direct current resistance Rohm changes, that is, when the position of the starting point of the arc shifts on the complex impedance plot, the inventor makes a trigger (cause, incentive, or trigger) of the high rate deterioration, and causes the progress of the high rate deterioration. Focused on showing. Further, in the complex impedance plot, both the high rate deterioration and the aging deterioration can affect the size of the arc. However, the present inventor has found that the progress of the high rate deterioration is suppressed to some extent by the limitation of the current IB of the battery 10. We focused on the fact that changes in the size of the arc mainly indicate the progress of aging. Aged deterioration (or storage deterioration) means deterioration that can proceed even in a state where the battery 10 is stored without being charged or discharged. Hereinafter, the influence of high rate deterioration and aging deterioration on the arc will be described in more detail.

  FIG. 4 is a diagram for explaining the influence of high-rate deterioration and aging deterioration on the arc on the complex impedance plot. First, referring to FIG. 4A, in a state where battery 10 is not deteriorated (for example, an initial state immediately after battery 10 is manufactured), the starting point of the arc (indicated by X) is DC resistance Rohm. (Hereinafter, also referred to as initial DC resistance Rohm0). The difference in real number component between the connection point (indicated by Y) between the arc and the straight line and the start point (X) of the arc represents the initial value of the reaction resistance Rct (hereinafter also referred to as the initial reaction resistance Rct0).

  Next, referring to FIG. 4B, when high-rate deterioration of battery 10 proceeds, DC resistance Rohm increases. As a result, as indicated by an arrow in the figure, the starting point of the arc is shifted to the right in the figure (indicated by RohmB in FIG. 4B). On the other hand, when the aging of the battery 10 is not relatively advanced, the arc size (indicated by RctB) does not change much from the arc size (Rct0) in the initial state (that is, RohmB≈Rohm0). ).

  Thereafter, as the aging of the battery 10 progresses, as shown in FIG. 4C, the size of the arc increases as compared to before the aging deterioration (in FIG. 4C, RohmC> RohmB≈Rohm0). ). In the example shown in FIG. 4C, the current IB is limited from the state shown in FIG. 4B (charging / discharging at a large current is suppressed), so that the progress of high-rate deterioration is suppressed. . For this reason, there is almost no shift of the starting point of the arc (RohmC≈RohmB).

  In FIG. 4, for simplification of explanation, the difference in the real component between the starting point of the arc (indicated by X in FIG. 4A) and the connection point (indicated by Y) of the arc and the straight line (indicated by Y) The distance on the horizontal axis was defined as the size of the arc (Rct0). However, the intersection (indicated by Y ′ in FIG. 4A) of the extension of the arc (indicated by a dotted line) and the horizontal axis when the arc is virtually extended may be obtained by curve regression. The distance between the starting point (X) of the arc and the intersection (Y ′) can be the size of the arc.

  Thus, by calculating the shift amount of the starting point of the arc, that is, the shift amount ΔRohm (= Rohm−Rohm0) of the DC resistance Rohm from the initial DC resistance Rohm0, the high-rate deterioration trigger can be estimated. Further, by calculating the increase amount of the arc, that is, the increase amount ΔRct (= Rct−Rct0) of the reaction resistance Rct from the initial reaction resistance Rct0, it is possible to estimate the degree of progress of aging degradation. That is, according to the present embodiment, it is possible to directly specify the deterioration mode (whether it is high-rate deterioration or aging deterioration) of battery 10 by using the measurement result of the AC impedance of battery 10. Become.

<Initial state map>
The initial DC resistance Rohm0 is known for calculating the DC resistance shift amount ΔRohm, and the initial reaction resistance Rct0 is required to be known for calculating the reaction resistance increase amount ΔRct. The resistance Rct0 has temperature dependency. Therefore, in the present embodiment, at each temperature TB of battery 10, initial DC resistance Rohm0 and initial reaction resistance Rct0 are measured in advance, and the measurement results are prepared as a map. This map (hereinafter referred to as “initial state map MP”) is stored in a memory (not shown) of ECU 100.

  FIG. 5 is a diagram showing an example of the initial state map MP in the present embodiment. As shown in FIG. 5, the initial state map MP defines a correspondence relationship between the temperature TB of the battery 10, the initial DC resistance Rohm0, and the initial reaction resistance Rct0.

  In the present embodiment, in the initial state map MP, the SOC range of the battery 10 that ensures that the change in the DC resistance Rohm is caused by the high rate deterioration is defined as the “effective SOC range”. When the SOC of the battery 10 is within the effective SOC range, it is ensured that the DC resistance Rohm is due to high rate deterioration. Although the detailed description will not be repeated, the reaction resistance Rct is similarly guaranteed to be caused by aging deterioration when the SOC of the battery 10 is within the effective SOC range. The effective SOC range can be determined based on preliminary experiments.

  FIG. 5 shows an example in which both the initial DC resistance Rohm0 and the initial reaction resistance Rct0 are defined in one map, but the initial DC resistance Rohm0 and the initial reaction resistance Rct0 may be prepared as separate maps. Good. Moreover, the setting of the effective SOC range is not essential.

<Deterioration estimation flow>
FIG. 6 is a flowchart showing the deterioration estimation process of battery 10 in the present embodiment. The process of this flowchart is called from a main routine (not shown) and executed when a predetermined condition is satisfied or every time a predetermined calculation cycle elapses. Note that each step (hereinafter abbreviated as “S”) included in this flowchart is basically realized by software processing by the ECU 100, but part or all of the hardware (electrical circuit) created in the ECU 100 is used. ).

  Referring to FIGS. 1 and 6, in S <b> 1, ECU 100 obtains voltage VB of battery 10 using voltage sensor 61. Furthermore, ECU 100 acquires current IB of battery 10 using current sensor 62 and acquires temperature TB of battery 10 using temperature sensor 63.

  In S2, ECU 100 estimates the SOC of battery 10 based on each information acquired in S1. A known method can be used as the SOC estimation method.

  In S3, the ECU 100 refers to the initial state map MP (see FIG. 5) to determine whether the SOC of the battery 10 estimated in S2 is within the effective SOC range or not. The determination is based on the temperature TB of 10. If the SOC of battery 10 is outside the effective SOC range (NO in S3), the subsequent process is skipped and the process returns to the main routine.

  If the SOC of battery 10 is within the effective SOC range (YES in S3), ECU 100 advances the process to S4 and controls AC impedance measuring device 30 to measure the AC impedance of battery 10. Then, ECU 100 acquires DC resistance Rohm of battery 10 from the measurement result of AC impedance. Since the method of obtaining DC resistance Rohm has been described in detail with reference to FIGS. 3 and 4, the description thereof will not be repeated here.

  In S5, the ECU 100 acquires the initial DC resistance Rohm0 corresponding to the temperature TB of the battery 10 by referring to the initial state map MP. Then, the ECU 100 calculates a shift amount ΔRohm (= Rohm−Rohm0) indicating a difference between the DC resistance Rohm acquired in S4 and the initial DC resistance Rohm0 (S6).

  In S7, the ECU 100 determines whether or not the shift amount ΔRohm is greater than or equal to a predetermined reference value (corresponding to “a predetermined value” according to the present disclosure). When shift amount ΔRohm is greater than or equal to the reference value (YES in S7), ECU 100 suppresses the charge / discharge current of battery 10 in order to suppress (prevent) further high rate deterioration (S8). For example, ECU 100 determines maximum current IBmax indicating the maximum value of current IB (the maximum absolute value of current IB) in accordance with shift amount ΔRohm. More specifically, ECU 100 suppresses the charging / discharging current of battery 10 so that maximum current IBmax (absolute value) decreases as shift amount ΔRohm increases in accordance with a predetermined map or relational expression. Thereafter, the ECU 100 advances the process to S9.

  If the shift amount ΔRohm is less than the reference value in S7 (NO in S7), the ECU 100 determines that the high rate deterioration has not progressed so much (the high rate deterioration trigger has hardly occurred) and performs the process of S8. The process can be skipped and the process can proceed to S9.

  In S9, the ECU 100 acquires the reaction resistance Rct of the battery 10 from the measurement result of the AC impedance in S4. Since the method for obtaining reaction resistance Rct has also been described in detail with reference to FIGS. 3 and 4, description thereof will not be repeated.

  In S10, the ECU 100 acquires the initial reaction resistance Rct0 corresponding to the temperature TB of the battery 10 by referring to the initial state map MP. Then, the ECU 100 calculates an increase amount ΔRct (= Rct−Rct0) indicating a difference between the direct current resistance Rohm acquired in S9 and the initial reaction resistance Rct0 (S11).

  In S12, ECU 100 determines whether increase amount ΔRct is equal to or greater than a predetermined determination value. When increase amount ΔRct is equal to or larger than the determination value (YES in S12), ECU 100 executes charge / discharge control of battery 10 for suppressing further deterioration over time (S13). For example, in general, when a lithium ion secondary battery is left in a high SOC region, it is likely to deteriorate over time as compared with a case where it is left in a middle SOC region or a low SOC region. Therefore, when the SOC of battery 10 is higher than a predetermined value, ECU 100 discharges battery 10 such that the SOC of battery 10 decreases to the middle SOC region. Thereafter, the process is returned to the main routine.

  When the increase amount ΔRct is less than the determination value in S12 (NO in S12), the ECU 100 determines that the progress of the aging deterioration is relatively slow (the aging deterioration has not progressed so much), and in S13. Processing can be skipped and processing can be returned to the main routine.

  As described above, according to the present embodiment, the DC resistance Rohm (see point P in FIG. 3) of the battery 10 is acquired from the measurement result of the AC impedance of the battery 10. Further, the initial DC resistance Rohm0 corresponding to the temperature TB detected by the temperature sensor 63 is obtained by referring to the initial state map MP (see FIG. 5). Then, a shift amount ΔRohm between the DC resistance Rohm and the initial DC resistance Rohm0 is calculated, and charge / discharge current control (S8) for suppressing high-rate deterioration is executed based on the shift amount ΔRohm. By using the shift amount ΔRohm, it is possible to identify the deterioration mode and appropriately take into account the high-rate deterioration trigger. Therefore, the high rate deterioration of the battery 10 can be suppressed more appropriately.

  In the present embodiment, an example has been described in which charge / discharge current control for suppressing high-rate deterioration is executed based on the shift amount ΔRohm. That is, an example in which “shift amount ΔRohm = high rate deterioration trigger” has been described. However, another index value may be calculated using the shift amount ΔRohm and the index value may be used as a high rate deterioration trigger.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present disclosure is shown not by the above description of the embodiments but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  DESCRIPTION OF SYMBOLS 1 Secondary battery system 10 Battery 20 Relay 30 AC impedance measuring device 31 Oscillator 32 Potentiostat 33 Lock-in amplifier 40 SMR 50 PCU 61 Voltage sensor 62 Current sensor 63 Temperature sensor 100 ECU , 9 Vehicle, 910, 920 Motor generator, 930 Power split device, 940 Engine, 950 Drive wheel.

Claims (1)

A secondary battery having an electrode body impregnated with an electrolyte containing lithium ions;
A temperature sensor for detecting a temperature of the secondary battery;
A measuring device configured to be able to measure the AC impedance of the secondary battery;
When the high rate deterioration trigger indicating a factor causing the deterioration of the secondary battery caused by the uneven distribution of the lithium ion concentration in the electrode body is larger than a predetermined value, the high rate deterioration trigger is smaller than the predetermined value. And a control device that suppresses the charge / discharge current of the secondary battery as compared with the case,
The control device includes:
Storing the correspondence between the initial DC resistance indicating the DC resistance of the secondary battery in the initial state of the secondary battery and the temperature of the secondary battery;
Obtaining the DC resistance of the secondary battery from the measurement result of the AC impedance of the secondary battery measured by the measuring device,
A secondary battery system that estimates the high-rate degradation trigger using a difference between the acquired DC resistance and the initial DC resistance corresponding to the temperature detected by the temperature sensor.