JP2020149879A - Secondary battery system - Google Patents

Abstract

To appropriately control high-rate deterioration of a lithium ion secondary battery.SOLUTION: A secondary battery system 2 comprises: a restraining member 23 which applies restraint pressure P to a battery 21 by restraining the battery 21; a damper actuator 24 which is configured to adjust the restraint pressure P; and an ECU 20 which controls the damper actuator 24. If a state of charge (SOC) is included in a resistance reduction region, then the battery 21 expands largely compared with the case where the SOC is not included in the resistance reduction region. If the SOC of the battery 21 is included in the resistance reduction region, then the ECU 20 controls the damper actuator 24 in such a way that the restraint pressure P becomes low compared with the case where the SOC of the battery 21 is not included in the resistance reduction region.SELECTED DRAWING: Figure 7

Description

The present disclosure relates to a secondary battery system, and more specifically, to a charging technique for suppressing deterioration of a lithium ion secondary battery.

In recent years, vehicles (hybrid vehicles, electric vehicles, etc.) equipped with assembled batteries made of lithium-ion secondary batteries have become widespread. For the purpose of fully exerting the performance of the lithium ion secondary battery, a technique for suppressing deterioration of the lithium ion secondary battery has been proposed.

For example, according to Japanese Patent Application Laid-Open No. 2016-123251 (Patent Document 1), the diffusion coefficient of lithium ions in the graphite negative electrode shows the maximum value in the SOC (State Of Charge) region of 0% or more and less than 40%, and is 40%. The minimum value is shown in the SOC region of 60% or more, and the intermediate value between the maximum value and the minimum value is shown in the SOC region of more than 60%. Therefore, in the method of charging the lithium ion secondary battery disclosed in Patent Document 1, the charging current is increased or decreased for each SOC region (see, for example, Tables 1 and 2 of Patent Document 1). As a result, heat generation of the lithium ion secondary battery due to charging can be minimized. As a result, deterioration of the lithium ion secondary battery (deterioration of battery characteristics such as charge / discharge cycle characteristics) can be suppressed.

JP-A-2016-123251 Japanese Unexamined Patent Publication No. 2015-09521 Japanese Unexamined Patent Publication No. 2012-12460

In general, it is known that when a lithium ion secondary battery is charged with a large current (so-called high-rate charging), the concentration of lithium salt in the electrolytic solution (hereinafter, also abbreviated as "salt concentration") may be biased. ing. If the salt concentration is biased, the internal resistance of the lithium ion secondary battery increases, which may reduce the battery characteristics. Generally, such deterioration is also referred to as "high rate deterioration".

The present inventor has found that, for example, in a lithium ion secondary battery using a negative electrode containing soft carbon, the susceptibility to high-rate deterioration depends on SOC. The method for charging a lithium ion secondary battery disclosed in Patent Document 1 has room for improvement in that the SOC dependence of the susceptibility to high-rate deterioration is not particularly considered.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to appropriately suppress high-rate deterioration of a lithium ion secondary battery.

The secondary battery system according to a certain aspect of the present disclosure is configured to adjust the restraint pressure with a battery pack containing a plurality of cells, a restraint member that applies a restraint pressure to the battery pack by restraining the battery pack. It includes a drive device and a control device that controls the drive device. The control device is a drive device so that when the SOC of the assembled battery is included in the predetermined region during charging of the assembled battery, the restraining pressure is lower than when the SOC of the assembled battery is not included in the predetermined region. To control.

When the assembled battery is charged at a high rate, the salt concentration distribution is biased in the electrolytic solution inside the electrode body, and the internal resistance of the assembled battery increases. On the other hand, as will be described in detail later, the lower the restraining pressure of the assembled battery, the easier it is for the electrode body to expand, so that the electrolytic solution easily flows inside the electrode body. When the diffusion of salt is promoted by the flow of the electrolytic solution, the bias of the salt concentration distribution in the electrolytic solution is easily alleviated. As a result, an increase in the internal resistance of the assembled battery is suppressed. Therefore, according to the above configuration, high-rate deterioration of the assembled battery made of a lithium ion secondary battery can be appropriately suppressed.

According to the present disclosure, high-rate deterioration of a lithium ion secondary battery can be appropriately suppressed.

It is a figure which shows schematic the whole structure of the charging system which concerns on Embodiment 1 of this disclosure. It is a block diagram which shows schematic structure of a vehicle and a charger. It is a figure which shows the structure of a secondary battery system in more detail. It is a figure for demonstrating the structure of each cell in more detail. It is a figure which shows the SOC dependence of the surface pressure between cells. It is a figure for demonstrating the method of applying the confining pressure of a battery in this embodiment. It is a flowchart for demonstrating the restraint pressure control in this embodiment. It is a figure for demonstrating the method of applying a confining pressure of a battery in a modification. It is a flowchart for demonstrating the restraint pressure control in the modification.

Hereinafter, the present embodiment will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

[Embodiment]
<Overall configuration of charging system>
FIG. 1 is a diagram schematically showing an overall configuration of a charging system according to an embodiment of the present disclosure. With reference to FIG. 1, the charging system 100 includes a vehicle 1 and a charger 5. FIG. 1 shows a situation during external charge control in which the vehicle 1 and the charger 5 are electrically connected by a charging cable 6 and power is supplied from the charger 5 to the vehicle 1.

The vehicle 1 is, for example, an electric vehicle. However, the vehicle 1 may be, for example, a plug-in hybrid vehicle as long as it is a vehicle configured to enable external charging. The charger 5 may be a dedicated charger provided in the user's home or the like, or may be a charger provided in a public charging stand (also referred to as a charging station).

FIG. 2 is a block diagram schematically showing the configurations of the vehicle 1 and the charger 5. With reference to FIG. 2, the charger 5 is a direct current (DC) charger, and the power supplied from the system power source 7 (AC power) is used as the charging power (AC power) of the battery 21 mounted on the vehicle 1. Convert to DC power). The charger 5 includes a power line ACL, an AC / DC converter 51, a voltage sensor 52, feed lines PL0 and NL0, and a control circuit 50.

The power line ACL is electrically connected to the system power supply 7. The power line ACL transmits AC power from the system power source 7 to the AC / DC converter 51.

The AC / DC converter 51 converts the AC power on the power line ACL into DC power for charging the battery 21 mounted on the vehicle 1. The power conversion by the AC / DC converter 51 may be performed by a combination of AC / DC conversion for improving the power factor and DC / DC conversion for adjusting the voltage level. The DC power output from the AC / DC converter 51 is supplied by the feeder line PL0 on the positive electrode side and the feeder line NL0 on the negative electrode side.

The voltage sensor 52 is electrically connected between the feeder line PL0 and the feeder line NL0. The voltage sensor 52 detects the voltage between the feeder line PL0 and the feeder line NL0, and outputs the detection result to the control circuit 50.

The control circuit 50 includes a CPU, a memory, and input / output ports (none of which are shown). The control circuit 50 controls the power conversion operation by the AC / DC converter 51 based on the voltage detected by the voltage sensor 52, the signal from the vehicle 1, and the map and the program stored in the memory.

The vehicle 1 includes an inlet 11, a charging line PL1, NL1, a voltage sensor 121, a current sensor 122, a charging relay 131, 132, a system main relay (SMR) 141, 142, and a power line PL2. It includes an NL 2, a PCU (Power Control Unit) 16, a motor generator 17, a power transmission gear 18, a drive wheel 19, and a secondary battery system 2. The secondary battery system 2 includes a battery 21, a voltage sensor 221, a current sensor 222, a temperature sensor 223, a restraint member 23, a damper actuator 24, and an ECU (Electronic Control Unit) 20.

The inlet (charging port) 11 is configured so that the connector 61 of the charging cable 6 can be inserted with mechanical connection such as fitting. With the insertion of the connector 61, an electrical connection between the feeder line PL0 and the contact on the positive electrode side of the inlet 11 is secured, and an electrical connection between the feeder line NL0 and the contact on the negative electrode side of the inlet 11 is secured. The connection is secured. Further, when the inlet 11 and the connector 61 are connected by the charging cable 6, the ECU 20 of the vehicle 1 and the control circuit 50 of the charger 5 communicate with each other according to a communication standard such as CAN (Controller Area Network) to obtain signals and commands. , Messages or data can be sent and received to and from each other.

The voltage sensor 121 is electrically connected between the charging line PL1 and the charging line NL1 on the inlet 11 side of the charging relays 131 and 132. The voltage sensor 121 detects the DC voltage between the charging line PL1 and the charging line NL1, and outputs the detection result to the ECU 20. The current sensor 122 is provided on the charging line PL1. The current sensor 122 detects the current flowing through the charging line PL1 and outputs the detection result to the ECU 20. The ECU 20 can also calculate the power supplied from the charger 5 (the amount of charge of the battery 21) based on the detection results of the voltage sensor 121 and the current sensor 122.

The charging relay 131 is connected to the charging line PL1, and the charging relay 132 is connected to the charging line NL1. The closing / opening of the charging relays 131 and 132 is controlled in response to a command from the ECU 20. When the charging relays 131 and 132 are closed and the SMRs 141 and 142 are closed, power can be transmitted between the inlet 11 and the battery 21.

The battery 21 is an assembled battery including a plurality of cells 3. The battery 21 supplies electric power for generating the driving force of the vehicle 1. Further, the battery 21 stores the electric power generated by the motor generator 17.

The positive electrode of the battery 21 is electrically connected to the node ND1 via the SMR 141. The node ND1 is electrically connected to the charging line PL1 and the power line PL2. Similarly, the negative electrode of the battery 21 is electrically connected to the node ND2 via the SMR 142. The node ND2 is electrically connected to the charging line NL1 and the power line NL2. The closing / opening of the SMRs 141 and 142 is controlled in response to a command from the ECU 20.

The voltage sensor 221 detects the voltage of the battery 21. The current sensor 222 detects the current input / output to / from the battery 21. The temperature sensor 223 detects the temperature of the battery 21. Each sensor outputs the detection result to the ECU 20. The ECU 20 can estimate the SOC of the battery 21 based on the detection results of the voltage sensor 221 and / or the current sensor 222.

The PCU 16 is electrically connected between the power lines PL2 and NL2 and the motor generator 17. The PCU 16 includes a converter and an inverter (neither of which is shown), and drives the motor generator 17 according to a command from the ECU 20.

The motor generator 17 is an AC rotating electric motor, for example, a permanent magnet type synchronous motor including a rotor in which a permanent magnet is embedded. The output torque of the motor generator 17 is transmitted to the drive wheels 19 through the power transmission gear 18 to drive the vehicle 1. Further, the motor generator 17 can generate electricity by the rotational force of the drive wheels 19 during the braking operation of the vehicle 1. The electric power generated by the motor generator 17 is converted into the charging electric power of the battery 21 by the PCU 16.

Like the control circuit 50, the ECU 20 includes a CPU 201, a memory 202 such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an input / output port 203. The ECU 20 controls the devices so that the vehicle 1 is in a desired state in response to signals from each sensor or the like. The ECU 20 may be divided into a plurality of ECUs for each function.

In the present embodiment, the main controls executed by the ECU 20 are "external charge control" in which the vehicle-mounted battery 21 is charged by the electric power supplied from the charger 5, and the restraint pressure applied to the battery 21 by the restraint member 23. "Constriction pressure control" that controls P can be mentioned. In this embodiment, the restraint pressure control is performed during the external charge control. The restraint pressure control will be described in detail later.

FIG. 3 is a diagram showing the configuration of the secondary battery system 2 in more detail. With reference to FIG. 3, the restraint member 23 includes a pair of end plates 231 and a restraint band 232, a plurality of bolts 233, a plurality of nuts (not shown), and a plurality of bus bars 234.

Each cell 3 has a positive electrode terminal 43 and a negative electrode terminal 44 (see FIG. 3). The positive electrode terminal 43 of a certain cell and the negative electrode terminal 44 of an adjacent cell are fastened by a bus bar 234 and electrically connected. As a result, a plurality of cells 3 are connected in series. However, a configuration in which a plurality of cells 3 are connected in series is not essential. For example, a plurality of cells 3 may be connected in parallel to form a block, and the blocks may be connected in series to form a battery 21.

In FIG. 3, one end of the stacking direction (x-axis direction) of the laminated body formed by stacking the plurality of cells 3 is partially shown. A pair of end plates 231 are arranged so as to face one end of the laminated body and the other end in the stacking direction. The pair of end plates 231 are restrained by the restraint band 232 with all the cells 3 sandwiched therein.

Further, the pair of end plates 231 are fastened to each other by bolts 233 and nuts (not shown). A restraint pressure P [unit: Pa] is applied to each cell 3 by the end plate 231 and the restraint band 232, the bolt 233, and the nut.

The damper actuator 24 is configured to be able to adjust the restraint pressure P by controlling the distance between the pair of end plates 231 according to the control signal from the ECU 20. More specifically, the restraint pressure P can be measured by installing a pressure sensor (not shown) between the cells 3. Therefore, by obtaining the correlation between the interval between the end plates 231 and the restraint pressure P in advance, the interval for generating the desired restraint pressure P can be calculated. Alternatively, the damper actuator 24 may be configured so that the restraint pressure P can be adjusted by controlling the tightening amount of the bolt 233 according to the control signal from the ECU 20. Also in this case, the tightening amount of the bolt 233 for generating the desired restraining pressure P can be calculated based on the result of the previous experiment. The damper actuator 24 corresponds to the "driving device" according to the present disclosure.

However, the configuration shown in FIG. 3 is only an example of a configuration for applying the restraint pressure P to the battery 21. The mechanical configuration of the "constraining member" and the "driving device" according to the present disclosure is not particularly limited as long as the restraining pressure P on the battery 21 is adjustable.

<Cell configuration>
FIG. 4 is a diagram for explaining the configuration of each cell 3 in more detail. In FIG. 4, the cell 3 is shown through the inside thereof. The cell 3 has a battery case 41 having a substantially rectangular parallelepiped shape. The upper surface of the battery case 41 is sealed by the lid 42. One end of each of the positive electrode terminal 43 and the negative electrode terminal 44 projects outward from the lid body 42. The other ends of the positive electrode terminal 43 and the negative electrode terminal 44 are connected to the internal positive electrode terminal and the internal negative electrode terminal (neither of them is shown) inside the battery case 41, respectively.

The electrode body 45 is housed inside the battery case 41. The electrode body 45 is formed by laminating a positive electrode 46 and a negative electrode 47 via a separator 48 and winding the laminated body. The electrolytic solution (not shown) is held in the positive electrode 46, the negative electrode 47, the separator 48, and the like.

Soft carbon (easily graphitized carbon) is used for the negative electrode 47. As the material of the positive electrode 46, the separator 48, and the electrolytic solution, various conventionally known materials can be used. As an example, lithium cobalt oxide or lithium manganate is used for the positive electrode 46. Polyolefin is used for the separator 48. The electrolytic solution contains an organic solvent, lithium ions, and an additive. It is not essential that the electrode body 45 is a wound body, and the electrode body 45 may be a laminated body that is not wound.

<SOC dependency of high rate deterioration>
The present inventor carried out the following measurements in order to investigate the SOC dependence of the likelihood of high rates occurring in the battery 21. A battery of the same type as the battery 21 was prepared, and a surface pressure sensor (not shown) was installed between two adjacent cells. Then, the SOCs of these cells were adjusted to various values, and the surface pressure between the cells was measured after the steady state was reached.

FIG. 5 is a diagram showing the SOC dependence of the surface pressure between cells. In FIG. 5, the horizontal axis represents the SOC of the battery 21. The vertical axis represents the surface pressure between cells [unit: Pa (= N / m ² )].

In the example shown in FIG. 5, in the low SOC region of 20% or less or the high SOC region of 60% or more, the surface pressure between cells is larger than that in the intermediate SOC region of more than 20% and less than 60%. A large surface pressure between cells means that the volume of each cell is large. That is, in the low SOC region or the high SOC region, each cell expands even when it is not being charged, as compared with the intermediate SOC region.

When the battery 21 is charged at a high rate, the electrode body 45 expands. However, in the low SOC region or high SOC region of the battery 21, since each cell 3 is expanded before the start of high-rate charging as compared with the intermediate SOC region, there is room for the electrode body 45 to expand with high-rate charging. small. When the expansion of the electrode body 45 is hindered, the salt concentration distribution tends to be biased in the electrolytic solution inside the electrode body 45 with high-rate charging, which tends to increase the internal resistance R of the battery 21. That is, high-rate deterioration of the battery 21 is likely to occur. Therefore, the measurement result shown in FIG. 5 means that the resistance of the battery 21 to high rate deterioration is lower in the low SOC region or the high SOC region than in the intermediate SOC region. Therefore, in the following, a low SOC region having an SOC of 20% or less and a high SOC region having an SOC of 60% or more will also be referred to as a “resistance reduction region”. The area of reduced resistance corresponds to the "predetermined area" according to the present disclosure.

In the present embodiment, in view of the fact that the ease of progress of high-rate deterioration shows SOC dependence as shown in FIG. 5, the SOC of the battery 21 is included in the resistance reduction region and the SOC of the battery 21 is The mode in which the restraint pressure P of the battery 21 is applied by the restraint member 23 is different from that in the case where it is not included in the resistance reduction region. More specifically, in the present embodiment, as described below, the restraint pressure P of the battery 21 is changed so as to be inversely correlated with the surface pressure between the adjacent cells 3.

FIG. 6 is a diagram for explaining a method of applying the restraint pressure P of the battery 21 in the present embodiment. In FIG. 6, the horizontal axis represents the SOC of the battery. The vertical axis represents the surface pressure [unit: Pa] between cells and the confining pressure P [unit: Pa] of the battery 21 in order from the top. Since the surface area of the battery case 41 of each cell 3 (the area of the side surface to which the restraint pressure P is applied) is known, the load [unit] to which the restraint pressure P is applied to the cell 3 using the surface area of the battery case 41. : N] may be converted and the load may be represented on the vertical axis.

With reference to FIG. 6, in the present embodiment, when the SOC of the battery 21 is included in the resistance reduction region, the damper actuator 24 is controlled as compared with the case where the SOC of the battery 21 is not included in the resistance reduction region. By doing so, the restraining pressure P of the battery 21 is lowered.

By lowering the restraining pressure P of the battery 21 in the resistance lowering region, the expansion of the electrode body 45 due to high-rate charging is less likely to be hindered. When the electrode body 45 easily expands, the electrolytic solution easily flows inside the electrode body 45. Then, the salt in the electrolytic solution is easily diffused, and the bias of the salt concentration distribution in the electrolytic solution is alleviated (eventually eliminated). As a result, an increase in the internal resistance R of the battery 21 is suppressed. That is, it becomes possible to suppress the high rate deterioration of the battery 21.

<Constriction pressure control flow>
FIG. 7 is a flowchart for explaining the restraint pressure control in the present embodiment. The processes included in the flowcharts shown in FIGS. 7 and 9 described later are called and executed from the main routine (not shown) every time a predetermined control cycle elapses during the external charge control of the vehicle 1. Further, each step (hereinafter, abbreviated as "S") included in this flowchart is basically realized by software processing by the ECU 20, but is realized by dedicated hardware (electric circuit) manufactured in the ECU 20. May be done.

With reference to FIG. 7, in S11, the ECU 20 estimates the SOC of the battery 21. For SOC estimation, various known methods such as a method of referring to an OCV-SOC curve or a current integration method can be used.

In S12, the ECU 20 determines whether the SOC of the battery 21 estimated in S11 is within the resistance reduction region. When the SOC of the battery 21 is within the resistance reduction region, that is, when the SOC of the battery 21 is 20% or less or 60% or more (YES in S12), the ECU 20 advances the process to S13. On the other hand, when the SOC of the battery 21 is outside the resistance reduction region, that is, when the SOC of the battery 21 is more than 20% and less than 60% (NO in S12), the ECU 20 advances the process to S14. ..

In S13, the ECU 20 controls the damper actuator 24 so that the restraint pressure P of the battery 21 decreases with reference to the restraint pressure P (described as the reference restraint pressure P0) when the SOC of the battery 21 is 60%. .. On the other hand, in S14, the ECU 20 controls the damper actuator 24 so that the restraint pressure P of the battery 21 rises with respect to the reference restraint pressure P0. When the processing of S13 and S14 is completed, the processing is returned to the main routine, and when the next control cycle comes, a series of processing is executed again.

In the example shown in FIG. 7, the restraint pressure P when the SOC of the battery 21 is 60% is set to the reference restraint pressure P0, but this is only an example of the reference setting method of the restraint pressure P. When the SOC of the battery 21 is outside the resistance reduction region (for example, when SOC = 40%), the restraint pressure P may be set to the reference restraint pressure P0. In this case, the ECU 20 controls the damper actuator 24 so that the restraint pressure P of the battery 21 becomes lower than the reference restraint pressure P0 when the SOC of the battery 21 is within the resistance reduction region (S13), while the battery When the SOC of 21 is outside the resistance reduction region, the restraint pressure P is not particularly reduced (S14).

As described above, in the present embodiment, considering that the ease of progress of high-rate deterioration indexed by the surface pressure between the cells 3 has SOC dependence, the SOC of the battery 21 is within the resistance reduction region. The confining pressure P of the battery 21 in the case of is lower than the confining pressure P of the battery 21 in the case where the SOC of the battery 21 is outside the resistance reduction region. By lowering the restraining pressure P of the battery 21, expansion of the electrode body 45 is allowed, and the flow of the electrolytic solution inside the electrode body 45 is promoted. As a result, the diffusion of the salt in the electrolytic solution is accelerated, so that the bias of the salt concentration distribution can be easily eliminated. As a result, according to the present embodiment, it is possible to suppress an increase in the internal resistance R of the battery 21. In other words, the high rate deterioration of the battery 21 can be appropriately suppressed.

[Modification example]
Even if the progress of the high rate deterioration of the battery 21 is suppressed by the restraint pressure control, the aged deterioration of the battery 21 progresses, so that the capacity of the battery 21 can be reduced. In this modification, a configuration will be described in which the SOC region defined as the resistance reduction region is appropriately changed as the battery capacity decreases.

FIG. 8 is a diagram for explaining a method of applying the restraint pressure P of the battery 21 in the modified example. In FIG. 8, the horizontal axis represents the SOC of the battery 21. The vertical axis represents the confining pressure P of the battery 21. In FIG. 8, the restraint pressure P applied to the battery 21 in the initial state is shown by a alternate long and short dash line for comparison, and after the capacity is reduced (in this example, after the capacity is reduced by 10% as compared with the initial state). The restraint pressure P applied to the battery 21 is shown by a solid line.

Referring to FIG. 8, in the initial state, the SOC region having an SOC of 20% or less and the SOC region having an SOC of 60% or more are resistance-decreasing regions, whereas the resistance-decreasing region after volume reduction has an SOC of 30. The SOC region is 70% or less and the SOC region is 70% or more. From this, it is understood that the restraint pressure P applied to the battery 21 after the capacity is reduced shifts to a higher SOC side than the restraint pressure P applied to the battery 21 in the initial state. As the capacity reduction amount of the battery 21 increases, the shift amount of the restraint pressure P toward the high SOC side also increases. A correspondence relationship between the capacity reduction amount of the battery 21 and the shift amount of the confining pressure P is obtained by a preliminary experiment, and is stored in advance in the memory (not shown) of the ECU 20 as, for example, a map.

FIG. 9 is a flowchart for explaining the restraint pressure control in the modified example. With reference to FIG. 9, first, in S21, the ECU 20 determines whether or not the capacity (full charge capacity) of the battery 21 has been calculated with the start of execution of the external charge control.

When the capacity of the battery 21 is not calculated at the start of execution of the external charge control (NO in S21). The ECU 20 calculates the capacity (fully charged capacity) of the battery 21 (S22). Specifically, the ECU 20 estimates the SOC of the battery 21 twice during the external charge control of the vehicle 1, and the current sensor 122 estimates the electric energy ΔAh charged in the battery 21 during the two SOC estimations. It is measured by current integration using. The ECU 20 calculates the capacity C of the battery 21 according to the following equation (1) by using S1 and S2, which are the estimation results of the two SOC estimation processes, and the charging electric energy ΔAh.
C = ΔAh / (S1-S2) × 100 ... (1)

After that, the ECU 20 determines the resistance reduction region based on the capacity C calculated in S22 (S23). More specifically, the ECU 20 calculates the amount of decrease in the capacity C of the battery 21 from the capacity C0 of the battery 21 in the initial state (10% in the above example). Then, the ECU 20 determines the resistance reduction region from the capacity reduction amount of the battery 21 by referring to the map as described with reference to FIG. If the capacity of the battery 21 has already been calculated at the start of execution of the external charge control (YES in S21), the ECU 20 skips the processes of S22 and S23 and proceeds to the process of S24.

Since the processes of S24 to S28 are the same as the processes of S11 to S14 (see FIG. 7) in the present embodiment, detailed description will not be repeated.

As described above, according to the present modification, the high rate deterioration of the battery 21 can be appropriately suppressed as in the above-described embodiment. Further, according to this modification, the influence of the aged deterioration of the battery 21 is reflected in determining the resistance reduction region. In other words, the resistance reduction region is corrected based on the capacity reduction amount due to the aging deterioration of the battery 21. This makes it possible to more appropriately suppress the high rate deterioration of the battery 21.

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

100 charging system, 1 vehicle, 11 inlets, 12 AC / DC converters, 121 voltage sensors, 122 current sensors, 131, 132 SMRs, 141,142 charging relays, 15 PCUs, 16 motor generators, 17 power transmission gears, 18 drives Wheel, 2 Secondary battery system, 20 ECU, 201 CPU, 202 memory, 203 input / output port, 21 battery, 221 voltage sensor, 222 current sensor, 223 temperature sensor, 23 restraint member, 231 end plate, 232 restraint band, 233 Bolt, 234 bus bar, 24 damper actuator, 3 cells, 41 battery case, 42 lid, 43 positive electrode terminal, 44 negative electrode terminal, 45 electrode body, 46 positive electrode, 47 negative electrode, 48 separator, 5 charger, 50 control circuit, 51 AC / DC converter, 52 voltage sensor, 6 charging cable, 61 connector, 7 system power supply, ACL, NL2, PL2 power line, ND1, ND2 node, NL0, PL0 power supply line, NL1, PL1 charging line.

Claims (1)

An assembled battery containing multiple cells and
A restraining member that applies a restraining pressure to the assembled battery by restraining the assembled battery,
A drive device configured to adjust the restraint pressure and
A control device for controlling the drive device is provided.
When each SOC of the plurality of cells is within a predetermined region, the assembled battery expands as compared with a case where each SOC of the plurality of cells is outside the predetermined region.
In the control device, when the SOC of the assembled battery is within the predetermined region during charging of the assembled battery, the restraining pressure is increased as compared with the case where the SOC of the assembled battery is outside the predetermined region. A secondary battery system that controls the drive so that it is low.

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