All-solid-state battery system

Abstract

It properly protects the battery, which is an all-solid-state lithium-ion battery. [Solution] The vehicle 1 (all-solid-state battery system) comprises a battery 21 which is an all-solid-state lithium-ion battery, a voltage sensor 221, a current sensor 222, a temperature sensor 223, a PCU 31 configured to charge and discharge the battery 21, and an ECU 4 which controls the PCU 31. The ECU 4 calculates the internal resistance of the battery 21 based on first information including the temperature and state of charge of the battery 21, calculates the diffusion resistance of the battery based on second information including the integrated discharge current of the battery 21, corrects the internal resistance by adding the diffusion resistance to the internal resistance, estimates the voltage of the battery 21 from the present to a specified time later based on the corrected internal resistance, the current voltage of the battery 21, and the current current of the battery 21, and controls the PCU 31 so that the estimated voltage does not fall below the lower limit voltage.

Description

Technical Field

[0001] The present disclosure relates to an all-solid-state battery system.

Background Art

[0002] The battery system disclosed in Japanese Patent Application Laid-Open No. 2018-10722 (Patent Document 1) is configured to estimate the time during which a predetermined power can be continuously output until the voltage of a nickel-hydrogen battery reaches a lower limit voltage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to protect the battery, it is conceivable to estimate the voltage of the battery after a specified time from now and suppress (limit the output) the discharge of the battery so that the estimated voltage does not fall below a predetermined lower limit voltage. This control is referred to as "lower limit voltage protection control".

[0005] The present inventor has found that when the battery is an all-solid-state lithium-ion battery, due to the characteristics of the all-solid-state lithium-ion battery, the voltage of the battery is likely to fall below the lower limit voltage. Then, even if the lower limit voltage protection control is executed, there is a possibility that the battery cannot be appropriately protected.

[0006] The present disclosure has been made to solve the above problems, and one of the objects of the present disclosure is to appropriately protect a battery that is an all-solid-state lithium-ion battery.

Means for Solving the Problems

[0007] A solid-state battery system according to a certain aspect of the present disclosure comprises a battery which is a solid-state lithium-ion battery, a voltage sensor for detecting the battery voltage, a current sensor for detecting the battery current, a temperature sensor for detecting the battery temperature, a power converter configured to charge and discharge the battery, and a control device for controlling the power converter. The control device (1) calculates the internal resistance of the battery based on first information including the battery temperature and SOC, (2) calculates the diffusion resistance of the battery based on second information including the integrated discharge current of the battery, (3) corrects the internal resistance by adding the diffusion resistance to the internal resistance, (4) estimates the battery voltage from the present to a specified time later based on the corrected internal resistance, the current battery voltage, and the current battery current, and (5) controls the power converter so that the estimated voltage does not fall below a lower limit voltage. [Effects of the Invention]

[0008] According to this disclosure, all-solid-state lithium-ion batteries can be adequately protected. [Brief explanation of the drawing]

[0009] [Figure 1] A block diagram showing an example of the hardware configuration of a vehicle according to this embodiment. [Figure 2] This diagram shows the relationship between battery voltage and current. [Figure 3] This diagram provides a schematic explanation of lower voltage protection control. [Figure 4] This is a conceptual diagram to explain the diffusion resistance of a battery. [Figure 5] This is a functional block diagram showing an example of the functional configuration of the ECU in this embodiment. [Figure 6] This is a diagram to explain the diffusion resistance map. [Figure 7] This flowchart shows an example of the processing procedure for lower voltage protection control in this embodiment. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0011] In the following embodiments, the "all-solid-state battery system" described herein will be explained using a vehicle as an example. However, the "all-solid-state battery system" is not limited to a vehicle and may be various stationary systems (such as household or commercial energy storage systems).

[0012] [Embodiment] <Vehicle configuration> Figure 1 is a block diagram showing an example of the hardware configuration of a vehicle according to this embodiment. In this example, Vehicle 1 is an electric vehicle (BEV: Battery Electric Vehicle), but it may be a hybrid vehicle (HEV: Hybrid Electric Vehicle) or a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle). Vehicle 1 includes a battery pack 2, a drive system 3, and an ECU (Electronic Control Unit) 4.

[0013] Battery pack 2 includes a battery 21, a monitoring unit 22, and a system main relay (SMR) 23.

[0014] Battery 21 is an all-solid-state lithium-ion battery. Battery 21 is a battery pack containing multiple cells 211. Each cell 211 includes a positive electrode, a negative electrode, and a solid electrolyte layer as energy storage elements.

[0015] The positive electrode includes a positive electrode active material layer and a positive electrode current collector. The positive electrode active material layer contains a positive electrode active material. The positive electrode active material is, for example, Li2S. The positive electrode active material is, for example, LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3 Co=Mn 1 / 3 Rock salt layered active materials such as O, LiMn2O-, Li4Ti5O12 , Li(Ni 0.5 Mn 1.5 )O4 and other spinel-type active materials, or olivine-type active materials such as LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4 may be used.

[0016] The negative electrode includes a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer contains a negative electrode active material. In this embodiment, the negative electrode active material is lithium titanate (Li4Ti5O 12 ). However, the negative electrode active material may contain at least one selected from the group consisting of, for example, graphite, Si, SiO x (0 < x < 2).

[0017] The monitoring unit 22 includes a voltage sensor 221, a current sensor 222, and a temperature sensor 223. The voltage sensor 221 detects the voltage V of the battery 21 (which may be each cell). The current sensor 222 detects the current I flowing through the battery 21. The temperature sensor 223 detects the temperature T of the battery 21. Each sensor outputs its detection result to the ECU 4.

[0018] The drive system 3 includes a power control unit (PCU: Power Control Unit) 31, a motor generator 32 for running, and drive wheels 33. The PCU 31 corresponds to the "power conversion device" according to the present disclosure.

[0019] The ECU 4 includes a processor 41 such as a CPU (Central Processing Unit) and a memory 42 such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The processor 41 manages the battery 21 based on the signals received from each sensor and the programs stored in the memory 42. Further, the processor 41 controls the PCU 31 based on the signals received from each sensor and the programs and maps stored in the memory 42, thereby controlling the charge and discharge of the battery 21. As the main control executed by the ECU 4 in this embodiment, the "lower voltage protection control" described below is mentioned.

[0020] <Lower voltage protection control> Figure 2 shows the relationship between the voltage and current of battery 21. The horizontal axis represents the current flowing through battery 21. The vertical axis represents the voltage of battery 21. The rate of change (slope) in the voltage-current graph shown in Figure 3 corresponds to the internal resistance R of battery 21. The internal resistance R is calculated using a pre-prepared map (internal resistance map MP1, described later) in which the internal resistance R is a function of temperature T and SOC (State of Charge).

[0021] The ECU4 periodically calculates the internal resistance R of the battery 21 by referring to the map described above. Then, based on the current combination of the battery 21's voltage V and current I (V,I) (sensor detected value) and the internal resistance R, the ECU4 estimates the voltage of the battery 21 after a specified time (5 seconds in the example below). For example, by estimating the current after 5 seconds, assuming that the current I changes at the current rate, the voltage after 5 seconds can be estimated from the current voltage V and internal resistance R. The estimated voltage after 5 seconds will be referred to as "Estimated Voltage Vest" below.

[0022] ECU4 controls PCU31 to ensure that the estimated voltage Vest does not fall below the lower limit voltage LL. The lower limit voltage LL is the lower limit of the operating voltage range determined according to the characteristics and specifications of the battery 21 in order to protect the battery 21. As one specific example, the lower limit voltage LL is the voltage corresponding to the lower limit voltage of each cell 211 = 1.5V.

[0023] Figure 3 is a schematic diagram illustrating the lower voltage protection control. The horizontal axis represents elapsed time. The upper vertical axis represents the voltage of battery 21. The lower vertical axis represents the discharge power from battery 21.

[0024] If the estimated voltage Vest after 5 seconds reaches the lower limit voltage LL, the ECU4 suppresses the discharge power from the battery 21 so that the estimated voltage Vest does not decrease any further. For this suppression (output limiting), for example, equation (1) below is used. In equation (1), the estimated voltage Vest is equal to the lower limit voltage LL.

number

[0025] Here, the inventors focused on the fact that in the all-solid-state lithium-ion battery 21, an error may occur between the value calculated from the map of the internal resistance R and the precisely measured value. This means that the internal resistance R may not be calculated with sufficient accuracy from temperature T and SOC alone. If an error occurs in the internal resistance R, an error will occur in the discharge power tWout, and as a result, the battery 21 may not be properly protected even if lower limit voltage protection control is performed.

[0026] Therefore, in this embodiment, the ECU4 calculates the diffusion resistance Rdyn of the battery 21 and corrects the internal resistance R using the diffusion resistance Rdyn. This improves the accuracy of the discharge power tWout calculation (the error in the discharge power tWout is reduced). Thus, it becomes possible to properly protect the battery 21 with lower voltage protection control.

[0027] <Diffusion Resistance> Figure 4 is a conceptual diagram illustrating the diffusion resistance of battery 21. In all-solid-state lithium-ion batteries, electrode reactions are more non-uniform compared to liquid-based lithium-ion batteries, and lithium reaction unevenness is more likely to occur. More specifically, in the negative electrode, lithium ion desorption reactions occur preferentially in the region close to the non-fluid solid electrolyte layer compared to the region farther away from the solid electrolyte layer, resulting in reaction unevenness. Since all-solid-state lithium-ion batteries do not contain a fluid electrolyte, the diffusion of lithium ions within the negative electrode (intra-solid phase diffusion) is slow. Therefore, reaction unevenness that occurs within the negative electrode is difficult to mitigate, and lithium may be depleted on the negative electrode surface. Lithium depletion on the negative electrode surface can cause an increase in internal resistance (diffusion resistance). This can be particularly pronounced when battery 21 contains lithium titanate as the negative electrode active material. Therefore, it is preferable to calculate the internal resistance R considering the diffusion resistance Rdyn of battery 21.

[0028] Figure 5 is a functional block diagram showing an example of the functional configuration of the ECU4 in this embodiment. Referring to Figures 1 and 5, the ECU4 includes an internal resistance calculation unit 5, a diffusion resistance calculation unit 6, a relaxation amount calculation unit 7, a subtraction unit 8, and an addition unit 9. The functions of each block are realized by the processor 41 and / or memory 42.

[0029] The internal resistance calculation unit 5 calculates the internal resistance R of the battery 21 (mainly contact resistance and resistive overvoltage). The internal resistance calculation unit 5 includes a temperature acquisition unit 51, a SOC estimation unit 52, and a first map storage unit 53.

[0030] The temperature acquisition unit 51 acquires the temperature T from the temperature sensor 223 and outputs the acquired temperature T to the first map storage unit 53.

[0031] The SOC estimation unit 52 acquires at least one of the voltage V from the voltage sensor 221 and the current I from the current sensor 222. The SOC estimation unit 52 estimates the State of Charge (SOC) of the battery 21 using known methods such as referring to the SOC-OCV (Open Circuit Voltage) curve or integrating the current I. The SOC estimation unit 52 outputs the estimated SOC to the first map storage unit 53.

[0032] The first map storage unit 53 stores an internal resistance map MP1 in which the internal resistance R is defined for each combination of temperature T and state of temperature (T, SOC). The first map storage unit 53 calculates the internal resistance R from (T, SOC) by referring to the internal resistance map MP1. The first map storage unit 53 outputs the calculated internal resistance R to the adder 9. The internal resistance map MP1 corresponds to the "first information" relating to this disclosure.

[0033] The diffusion resistance calculation unit 6 calculates the diffusion resistance Rdyn of the battery 21. The diffusion resistance calculation unit 6 includes a current integration unit 61, a temperature acquisition unit 62, a SOC estimation unit 63, and a second map storage unit 64.

[0034] The current integration unit 61 calculates the discharge current integrated value ΣI by integrating the current I (discharge current) obtained from the current sensor 222. The current integration unit 61 may increase the discharge current integrated value ΣI when the battery 21 is discharging, while decreasing the discharge current integrated value ΣI when the battery 21 is charging. The current integration unit 61 outputs the calculated discharge current integrated value ΣI to the second map storage unit 64.

[0035] The temperature acquisition unit 62 acquires the temperature T from the temperature sensor 223, similar to the temperature acquisition unit 51. The temperature acquisition unit 62 outputs the acquired temperature T to the second map storage unit 64.

[0036] The SOC estimation unit 63 estimates the State of Charge (SOC) of the battery 21, similar to the SOC estimation unit 52. The SOC estimation unit 63 outputs the estimated SOC to the second map storage unit 64.

[0037] The second map storage unit 64 stores a diffusion resistance map MP2 in which the diffusion resistance Rdyn is defined for each combination of discharge current integrated value ΣI, temperature T, and SOC (ΣI, T, SOC).

[0038] Figure 6 is a diagram illustrating the diffusion resistance map MP2. As shown in Figure 6, the diffusion resistance map MP2 is a map in which, for example, the correspondence between the integrated discharge current value ΣI (horizontal axis) and the diffusion resistance Rdyn (vertical axis) is defined for each combination of temperature T and state of charge (T, SOC). Under the same conditions for battery temperature T and SOC, the diffusion resistance Rdyn increases as the integrated discharge current value ΣI increases. The diffusion resistance map MP2 corresponds to "Second Information" in this disclosure.

[0039] Returning to Figure 5, the second map storage unit 64 calculates the diffusion resistance Rdyn from (ΣI,T,SOC) by referring to the diffusion resistance map MP2. The second map storage unit 64 outputs the calculated diffusion resistance Rdyn to the subtraction unit 8.

[0040] The relaxation amount calculation unit 7 calculates the relaxation amount ΔRdyn of the diffusion resistance Rdyn of the battery 21. Hereafter, the current values ​​of the diffusion resistance Rdyn and relaxation amount ΔRdyn are denoted with (n), and the previous values ​​are denoted with (n-1) to distinguish between the previous values ​​and the current values ​​(n is a natural number). The relaxation amount calculation unit 7 includes a temperature acquisition unit 71, a SOC estimation unit 72, a previous value acquisition unit 73, and a third map storage unit 74.

[0041] The temperature acquisition unit 71 acquires the temperature T from the temperature sensor 223, similar to the temperature acquisition units 51 and 62. The temperature acquisition unit 71 outputs the acquired temperature T to the third map storage unit 74.

[0042] The SOC estimation unit 72 estimates the State of Charge (SOC) of the battery 21, similar to the SOC estimation units 52 and 63. The SOC estimation unit 72 outputs the estimated SOC to the third map storage unit 74.

[0043] The previous value acquisition unit 73 acquires the value obtained by subtracting the previous relaxation amount ΔRdyn(n-1) from the previous diffusion resistance Rdyn(n-1) from the subtraction unit 8 (i.e., the previous corrected diffusion resistance Rdyn(n-1)). The previous value acquisition unit 73 outputs the acquired value (Rdyn(n-1)-ΔRdyn(n-1)) to the third map storage unit 74 for the calculation of the current relaxation amount ΔRdyn(n).

[0044] The third map storage unit 74 stores a relaxation amount map MP3 in which the relaxation amount ΔRdyn is defined for each combination of temperature T, SOC, and diffusion resistance Rdyn (T, SOC, Rdyn). The relaxation amount map MP3 is created taking into account the relaxation of lithium reaction unevenness (decrease in diffusion resistance) over time. The third map storage unit 74 calculates the current value of the relaxation amount ΔRdyn(n) from (T, SOC, Rdyn) by referring to the relaxation amount map MP3. The third map storage unit 74 outputs the current value of the relaxation amount ΔRdyn(n) to the subtraction unit 8. The relaxation amount map MP3 corresponds to the "third information" relating to this disclosure.

[0045] The subtraction unit 8 corrects the diffusion resistance Rdyn by subtracting the current relaxation amount ΔRdyn(n) from the current diffusion resistance Rdyn(n). The subtraction unit 8 outputs the subtraction result (Rdyn(n)-ΔRdyn(n)) to the addition unit 9. The subtraction unit 8 also outputs the subtraction result to the previous value acquisition unit 73 in preparation for the next calculation.

[0046] The addition unit 9 corrects the internal resistance R by adding the subtraction result (Rdyn(n)-ΔRdyn(n)) from the subtraction unit 8 to the internal resistance R. The addition unit 9 outputs the summation result (R+Rdyn(n)-ΔRdyn(n)) to the control unit (not shown) of the PCU 31. As a result, the internal resistance R corrected by the diffusion resistance Rdyn is reflected in the discharge power tWout, and the output limit of the battery 21 by the discharge power tWout is realized.

[0047] <Processing Flow> Figure 7 is a flowchart showing an example of the lower voltage protection control process in this embodiment. The process shown in this flowchart is executed when predetermined conditions are met (for example, at predetermined intervals). Each step is implemented by software processing by the ECU4, but may also be implemented by hardware (electrical circuits) located within the ECU4. Hereinafter, each step will be abbreviated as S.

[0048] Referring to Figures 1, 5, and 7, in S1, the ECU4 obtains the current voltage V from the voltage sensor 221, the current current I from the current sensor 222, and the temperature T from the temperature sensor 223.

[0049] In S2, the ECU4 calculates the integrated discharge current value ΣI by integrating the currents I.

[0050] In S3, ECU4 estimates SOC from voltage V by referring to an SOC-OCV curve (not shown). ECU4 may also estimate SOC from the integrated discharge current value ΣI.

[0051] In S4, ECU4 calculates the internal resistance R from the temperature T and SOC. The internal resistance map MP1 is used to calculate the internal resistance R.

[0052] In S5, ECU4 calculates the diffusion resistance Rdyn from the integrated discharge current ΣI, temperature T, and state of emergency (SOC). The diffusion resistance map MP2 (see Figure 6) is used to calculate the diffusion resistance Rdyn. Alternatively, ECU4 may calculate the diffusion resistance Rdyn from only the integrated discharge current ΣI. That is, ECU4 may calculate the diffusion resistance Rdyn without using temperature T and SOC. However, using temperature T and SOC can improve the accuracy of the diffusion resistance Rdyn calculation.

[0053] In S6, ECU4 calculates the current relaxation value ΔRdyn(n) from the temperature T, SOC, and the previous diffusion resistance value Rdyn(n-1). The relaxation map MP3 is used to calculate the current relaxation value ΔRdyn(n).

[0054] In S7, ECU4 corrects the diffusion resistance Rdyn calculated in S5 using the current value of relaxation amount ΔRdyn(n) calculated in S6. That is, ECU4 calculates the corrected diffusion resistance Rdyn by subtracting the current value of relaxation amount ΔRdyn(n) from the current value of diffusion resistance Rdyn(n).

[0055] In S8, ECU4 corrects the internal resistance R calculated in S4 using the corrected diffusion resistance Rdyn calculated in S7. That is, ECU4 calculates the corrected internal resistance R by adding the corrected diffusion resistance Rdyn to the internal resistance R.

[0056] In S9, ECU4 calculates the estimated voltage Vest after 5 seconds. ECU4 calculates the estimated current Iest after 5 seconds, for example, assuming that the current rate of change of current I is maintained. Then, the voltage change ΔV due to the current change from I to Iest is expressed as ΔV = (I - Iest) / R. ECU4 can then calculate the estimated current Iest after 5 seconds using Vest = V + ΔV.

[0057] In S10, the ECU4 determines whether the estimated voltage Vest after 5 seconds is less than or equal to the lower limit voltage LL. The lower limit voltage LL is predetermined according to the characteristics (materials) and specifications (application) of the battery 21. If the estimated voltage Vest after 5 seconds is less than or equal to the lower limit voltage LL (YES in S10), the ECU4 proceeds to S11. On the other hand, if the estimated voltage Vest after 5 seconds is higher than the lower limit voltage LL (NO in S10), the ECU4 skips the process in S11 and terminates the series of processes.

[0058] In S11, ECU4 calculates the discharge power tWout by substituting the voltage V and current I obtained in S1 and the corrected internal resistance R calculated in S8 into equation (1). Then, ECU4 controls PCU31 so that the discharge power of battery 21 becomes tWout.

[0059] As described above, in this embodiment, the ECU4 calculates the diffusion resistance Rdyn using the integrated discharge current value ΣI of the battery 21, and corrects the internal resistance R using the calculated diffusion resistance Rdyn. As a result, the increase in resistance caused by the slow diffusion of lithium ions at the negative electrode (and the resulting reaction unevenness) is reflected in the internal resistance R, improving the accuracy of the calculation of the internal resistance R. Consequently, output limiting by discharge power tWout in the lower limit voltage protection control can be appropriately performed. Therefore, according to this embodiment, the battery 21, which is an all-solid-state lithium-ion battery, can be appropriately protected.

[0060] As explained in Figure 5, in calculating the integrated discharge current value ΣI of the battery 21, the ECU 4 may increase the integrated discharge current value ΣI when the battery 21 is discharging, while decreasing the integrated discharge current value ΣI when the battery 21 is charging. By decreasing the integrated discharge current value ΣI when the battery 21 is charging, the amount of active mitigation of reaction unevenness due to charging is reflected in the diffusion resistance Rdyn. Therefore, the calculation accuracy of the diffusion resistance Rdyn is improved, and consequently, the calculation accuracy of the internal resistance R is further improved. However, it is not necessary to reduce the integrated discharge current value ΣI during charging.

[0061] Figures 5 and 7 illustrate the correction of the diffusion resistance Rdyn by the relaxation amount ΔRdyn. By correcting with the relaxation amount ΔRdyn, the amount of relaxation due to reaction unevenness over time is reflected in the diffusion resistance Rdyn. Therefore, the accuracy of calculating the diffusion resistance Rdyn is improved, and consequently, the accuracy of calculating the internal resistance R is further improved. However, it is not necessary to perform the correction with the relaxation amount ΔRdyn.

[0062] When using the internal resistance map MP1, diffusion resistance map MP2, and relaxation map MP3, it is preferable to use the lowest temperature Tmin and lowest SOCmin among the temperatures T and SOC of the multiple cells 211 contained in the battery 21 as the temperature T and SOC. Generally, the lower the temperature and the lower the SOC, the higher the resistance (internal resistance and diffusion resistance). Therefore, by using the lowest temperature Tmin and lowest SOCmin, the maximum values ​​of internal resistance R and diffusion resistance Rdyn can be calculated. As a result, R in the denominator of equation (1) above is maximized, and the discharge power tWout is minimized. In other words, the output limit of the battery 21 becomes the strictest. This allows for more appropriate protection of the battery 21.

[0063] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0064] 1 Vehicle, 2 Battery pack, 21 Battery, 22 Monitoring unit, 221 Voltage sensor, 222 Current sensor, 223 Temperature sensor, 3 Drive system, 31 PCU, 32 Motor generator, 33 Drive wheels, 4 ECU, 41 Processor, 42 Memory.

Claims

1. A battery that is an all-solid-state lithium-ion battery, A voltage sensor for detecting the voltage of the aforementioned battery, A current sensor for detecting the current of the aforementioned battery, A temperature sensor for detecting the temperature of the aforementioned battery, A power conversion device configured to charge and discharge the aforementioned battery, The power converter is equipped with a control device for controlling the power converter, The control device is Based on the first information including the temperature and SOC of the battery, the internal resistance of the battery is calculated. Based on the second information, which includes the integrated discharge current of the battery, the diffusion resistance of the battery is calculated. By adding the aforementioned diffusion resistance to the aforementioned internal resistance, the aforementioned internal resistance is corrected. Based on the corrected internal resistance, the current battery voltage, and the current battery current, the battery voltage at a specified time from the present is estimated. A solid-state battery system that controls the power converter so that the estimated voltage does not fall below a lower limit voltage.

2. The second information further includes the temperature and SOC of the battery, The control device is During the discharge of the battery, the integrated discharge current value is increased, while during the charging of the battery, the integrated discharge current value is decreased. The all-solid-state battery system according to claim 1, wherein, under the same conditions for the temperature and SOC of the battery, the diffusion resistance is calculated such that the diffusion resistance increases as the integrated discharge current increases.

3. The control device is configured to repeatedly calculate the diffusion resistance, The control device is Based on the first information, the internal resistance is calculated, Based on the second piece of information, the current value of the diffusion resistance is calculated. Based on the temperature and SOC of the battery, and third information including the previous value of the diffusion resistance, the relaxation amount of the diffusion resistance is calculated. By subtracting the relaxation amount from the current value of the diffusion resistance, the current value of the diffusion resistance is corrected. The all-solid-state battery system according to claim 2, wherein the internal resistance is corrected by adding the corrected current value to the internal resistance.

4. The aforementioned battery is a battery pack containing multiple cells, The all-solid-state battery system according to claim 3, wherein the control device uses the lowest temperature and lowest SOC among the temperatures and SOC of the plurality of cells as the first to third information.

5. The all-solid-state battery system according to any one of claims 1 to 4, wherein the battery contains lithium titanate as the negative electrode active material.

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