WO2011132300A1

WO2011132300A1 - Method for restoring secondary battery, system for restoring secondary battery and vehicle equipped with same

Info

Publication number: WO2011132300A1
Application number: PCT/JP2010/057205
Authority: WO
Inventors: 寿夫山重; 正規渡邊
Original assignee: トヨタ自動車株式会社
Priority date: 2010-04-23
Filing date: 2010-04-23
Publication date: 2011-10-27

Abstract

Disclosed is a method for restoring a secondary battery which can restore the charge/discharge capacity of a used secondary battery. The state of charge (SOC) of the battery to be restored is acquired; if the acquired SOC is within an already determined range, the acquired SOC is taken as the storage SOC; if the acquired SOC is outside of the already determined range, the secondary battery is charged and discharged until within range, and the SOC after charging and discharging is taken as the storage SOC; a restoration map with the relationship between storage SOC, storage temperature, storage period, and target restoration rate stored therein is used to determine a storage period which will allow restoration of the secondary battery charge/discharge capacity to the target restoration rate through storage at the storage temperature and storage SOC; and the secondary battery is stored for the determined storage period while the storage temperature and storage SOC are maintained.

Description

Secondary battery recovery method, secondary battery recovery system and vehicle equipped with the same

The present invention relates to a secondary battery recovery method and a recovery system for recovering a used secondary battery such as a lithium ion secondary battery. More specifically, a secondary battery recovery method and a secondary battery recovery system for recovering the battery capacity of a secondary battery in which SOC (state of charge) unevenness has occurred due to use, and a vehicle equipped with the secondary battery recovery system It is about.

Conventionally, it is known that secondary batteries such as lithium ion secondary batteries gradually deteriorate due to repeated charge and discharge, and the usable battery capacity decreases. There are various types of secondary battery deterioration, and the countermeasures are different. For example, Patent Document 1 proposes a technique for reusing a deteriorated electrolytic solution. According to the technique of this document, it is said that it can be returned to a usable state again by adding activated carbon to a deteriorated electrolyte and leaving it to stand.

Japanese Patent Application Laid-Open No. 09-232008

However, the above-described conventional technology corresponds to the deterioration of the electrolytic solution, and cannot cope with deterioration due to other causes. In addition, it is intended for batteries that are discarded after use, and is a process that is performed by disassembling and taking out the electrolyte. In other words, it is not a process used to improve the state of a battery in use and extend its life.

On the other hand, if SOC unevenness occurs inside the battery in use, there is a risk of shortening the life of the battery thereafter. Therefore, in order to extend the life of the battery, there has been a demand to reduce the generated SOC unevenness as much as possible. This is because the deterioration progresses further in the places where the charging efficiency is lowered due to the SOC unevenness than in other places, and the rate of decrease of the battery capacity as the whole battery increases. That is, the occurrence of SOC unevenness has a problem that the battery capacity as a whole is greatly reduced.

The present invention has been made in order to solve the problems of the conventional techniques described above. That is, the problem is that a secondary battery recovery method and a secondary battery recovery system that can alleviate the generated SOC unevenness and recover the battery capacity of the secondary battery without disassembling the battery, and the same It is in providing the vehicle which mounts.

A secondary battery recovery method according to an embodiment of the present invention for solving this problem is a secondary battery recovery method for recovering the charge / discharge capacity of a used secondary battery, the secondary battery being recovered When the SOC of the battery is acquired and the acquired SOC is within a predetermined allowable range, the acquired SOC is set as a storage SOC, and when the acquired SOC is out of the predetermined allowable range The secondary battery is charged / discharged until it falls within the allowable range, and the SOC after charging / discharging is used as the storage SOC, and a recovery map is used to store the relationship between the storage SOC, storage temperature, storage period, and target recovery rate. , Determine the storage period for recovering the charge / discharge capacity of the secondary battery to the target recovery rate by storage at storage temperature and storage SOC, and store the secondary battery at storage temperature and storage SOC for the determined storage period It is intended.

According to the secondary battery recovery method in the above-described embodiment, the charge / discharge capacity is recovered to the target recovery rate by storing the secondary battery to be recovered at a storage SOC and storage temperature within an allowable range for a storage period. Can be made. The present inventors have found that by storing the secondary battery in a low SOC / high temperature environment without charging / discharging, the SOC unevenness inside the battery can be alleviated to some extent and the charge / discharge capacity can be recovered. In this aspect, since the recovery map that stores the relationship between the storage SOC, the storage temperature, the storage period, and the target recovery rate is used, an appropriate storage period can be easily determined. Therefore, the generated SOC unevenness can be alleviated and the battery capacity of the secondary battery can be recovered without disassembling the battery.

Furthermore, in one embodiment of the present invention, the allowable range of storage SOC is preferably in the range of 0% to 40%, and the storage temperature is preferably in the range of 45 ° C to 60 ° C.
By storing within this range, the secondary battery can be recovered efficiently.

Furthermore, in one aspect of the present invention, the temperature of the secondary battery is acquired before the start of the storage period, and if the acquired temperature is outside the storage temperature range, heating is performed until the temperature is within the storage temperature range. Or it is desirable to store after cooling.
In this way, the storage period can be started after the temperature of the secondary battery is set within the aforementioned temperature range.

Furthermore, in one embodiment of the present invention, when the acquired temperature is outside the storage temperature range and the secondary battery is discharged, the discharge power is used for heating or cooling the secondary battery. Is desirable.
In this way, it is possible to adjust both the storage temperature and the storage SOC without using extra energy.

According to another aspect of the present invention, there is provided a secondary battery recovery system for recovering the charge / discharge capacity of a used secondary battery, wherein the control unit controls the charge / discharge state of the secondary battery and acquires the SOC. , Storage SOC, storage temperature, storage period, and a recovery map that stores the relationship between the target recovery rate, the control unit acquires the SOC of the secondary battery to be recovered, and the acquired SOC is predetermined If it is within the allowable range, the acquired SOC is set as the storage SOC. If the acquired SOC is outside the predetermined allowable range, the secondary battery is charged / discharged until it is within the allowable range. At the same time, the SOC after charge / discharge is designated as the storage SOC, and the recovery map is used to determine the storage period for recovering the charge / discharge capacity of the secondary battery to the target recovery rate by storage at the storage temperature and storage SOC. Over the period Is for storage at the storage temperature and storage SOC of the secondary battery.

Furthermore, in another aspect of the present invention, it is desirable that the allowable range of storage SOC is 0% or more and 40% or less, and the storage temperature is 45 ° C or more and 60 ° C or less.

Further, in another aspect of the present invention, the control unit acquires the temperature of the secondary battery before the start of the storage period, and if the acquired temperature is out of the storage temperature range, the control temperature range. It is desirable to store after heating or cooling until it is inside.

Furthermore, in another aspect of the present invention, when the acquired temperature is outside the storage temperature range and the secondary battery is discharged, the discharge power is used for heating or cooling the secondary battery. It is desirable.

Still another aspect of the present invention is a vehicle equipped with the secondary battery recovery system described in the above aspect.

According to the secondary battery recovery method, the secondary battery recovery system and the vehicle equipped with the secondary battery recovery mode in the above aspect of the present invention, the generated SOC unevenness can be reduced without disassembling the battery, and the battery capacity of the secondary battery can be reduced. Can be recovered.

It is a block diagram which shows schematic structure of the recovery system which concerns on this form. It is explanatory drawing which shows the secondary battery in which SOC nonuniformity has not generate | occur | produced. It is explanatory drawing which shows the secondary battery in which SOC nonuniformity generate | occur | produced. It is a flowchart figure which shows the relaxation process of SOC nonuniformity. It is a map figure which shows the preservation | save conditions for relaxation of SOC nonuniformity. It is a graph which shows the temperature characteristic of the relaxation process of SOC nonuniformity. It is a graph which shows the SOC characteristic of the relaxation process of SOC nonuniformity. It is a graph which shows the storage period characteristic of the relaxation process of SOC nonuniformity. It is explanatory drawing which shows the vehicle carrying the recovery system of this form.

Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. The present embodiment relates to a recovery system that improves SOC unevenness of a secondary battery mounted on, for example, an automobile.

As shown in FIG. 1, the recovery system 1 according to the present embodiment includes a control unit 20 that is connected to the secondary battery 10 and controls charging and discharging thereof. The control unit 20 includes an SOC unevenness determination unit 21, an SOC acquisition unit 22, a temperature acquisition unit 23, and a storage period acquisition unit 24. The control unit 20 determines whether or not the SOC unevenness is generated in the secondary battery 10. When it is determined that the SOC is generated, the control unit 20 performs a process of reducing the SOC unevenness. The secondary battery 10 which is a target of this embodiment is a used battery. In other words, it is not a new or very new one, but is repeatedly charged and discharged to some extent, and the deterioration has progressed to some extent. However, it is intended for those that still have enough time to use up their lifetime.

As shown in FIG. 2, a part of the secondary battery 10 of the present embodiment has a positive electrode plate 31 and a negative electrode plate 32 wound with a separator 33 interposed therebetween. Further, the whole is enclosed in a case or the like, and the case is filled with an electrolytic solution. The positive electrode plate 31 of the secondary battery 10 includes a strip-shaped positive electrode current collector foil 35 and a positive electrode active material layer 36 formed on both surfaces thereof. The negative electrode plate 32 has a strip-shaped negative electrode current collector foil 38 and negative electrode active material layers 39 formed on both surfaces thereof. The positive electrode active material layer 36 and the negative electrode active material layer 39 are opposed to each other with the separator 33 interposed therebetween.

As shown in FIG. 2, the secondary battery 10 of the present embodiment is provided on the positive electrode plate 31 and the negative electrode plate 32 in the left-right direction in the drawing (that is, the width direction of the strip-like positive electrode plate 31 and negative electrode plate 32). , The active material layers 36 and 39 are not provided, and portions where the current collector foils 35 and 38 are exposed are provided. And in the secondary battery 10, this exposed part is arrange | positioned in the mutually opposite direction by the positive electrode plate 31 and the negative electrode plate 32, and an electrode terminal is connected here. In this figure, as the positive electrode active material layer 36 and the negative electrode active material layer 39, only those on one side of the current collector foils 35 and 38 are shown.

Among these, SOC unevenness is generated inside the positive electrode active material layer 36 and the negative electrode active material layer 39. In FIG. 2, a graph showing the degree of SOC at each location is shown superimposed on a schematic cross section of a very small portion of the positive electrode plate 31 and the negative electrode plate 32. As shown in FIG. 2,

uniform SOC graphs

41 and 42 are obtained in the secondary battery 10 in which the SOC unevenness does not occur. The

SOC graphs

41 and 42 virtually indicate the degree of SOC at the place, and do not mean that such a line appears inside the secondary battery 10. In this figure, the

SOC graphs

41 and 42 are horizontal, which indicates that the degree of SOC inside the positive electrode active material layer 36 and the negative electrode active material layer 39 is almost uniform regardless of location. ing.

However, the

SOC graphs

41 and 42 may be nonuniform as shown in FIG. This figure shows the SOC in the positive electrode active material layer 36 and the negative electrode active material layer 39 in the center portion in the horizontal direction (the width direction of the electrode plates 31 and 32) in the drawing compared to the end portions. Is in a lowered state. It is said that the SOC nonuniformity has occurred. It has been found that the SOC unevenness is likely to occur in the width direction of the

electrode plates

31 and 32 as shown in this figure. However, here, the SOC at both ends is increased, but in some cases, the SOC at the central portion may be high.

In the secondary battery 10 in which the SOC unevenness is generated, even when charging / discharging is not being performed, a distribution is made between a place where the secondary battery 10 is charged a lot and a place where it is not charged so much. This unevenness tendency is maintained even during charge / discharge. This uneven distribution state cannot be observed from the outside of the secondary battery 10, but can be grasped to some extent if the secondary battery 10 is disassembled and analyzed.

Therefore, if such SOC unevenness is generated, the range of SOC used depending on the location in the secondary battery 10 will be different when charging / discharging is performed. For example, in the example of FIG. 3, charging / discharging is performed within a relatively large SOC range near the ends of the positive electrode plate 31 and the negative electrode plate 32 in the width direction, and charging / discharging is performed within a relatively small SOC region near the center. Discharging is performed. If such a tendency continues, the degree of deterioration differs depending on the location in the

electrode plates

31 and 32. In addition, the effective charging capacity of the secondary battery 10 as a whole may be reduced, which is not preferable.

The present inventors can alleviate the SOC unevenness by storing the secondary battery 10 in such a state that the SOC is low and the cell temperature is high without charging / discharging for a certain period or longer. I found out that I can do it. For example, it has been confirmed that if the secondary battery 10 is stored in a constant temperature bath at about 45 to 60 ° C. for 7 days or more in a state where the SOC is 40% or less, the SOC unevenness can be considerably alleviated.

Therefore, in the present embodiment, when there is a possibility that such SOC unevenness has occurred, it is stored for a necessary period under low SOC and high temperature conditions, thereby reducing the SOC unevenness and restoring the charge capacity. Process. Therefore, as shown in the flowchart of FIG. 4, the control unit 20 of the present embodiment determines whether or not there is a high possibility that SOC unevenness has occurred in the secondary battery 10, and it is highly likely that it has occurred. If it is determined, recovery processing is performed to alleviate the SOC unevenness. This recovery process is performed at a timing when the secondary battery 10 is not used.

When the control unit 20 starts this process, the SOC unevenness determination unit 21 first acquires the capacity reduction rate of the secondary battery 10 (S101). The capacity reduction rate is an index indicating how much the battery capacity at the time of executing this process is reduced with respect to the capacity of the secondary battery 10 when it is new. For example, if the battery capacity is 80% of the new battery capacity, the capacity reduction rate is 20%. Actually, the battery capacity may be measured and acquired. However, for an in-vehicle battery or the like, the battery capacity may be acquired by referring to the battery usage history of the in-vehicle computer.

Further, in the case of the secondary battery 10 mounted on the vehicle, the elapsed time, travel time, and travel distance since the previous recovery process is acquired (S102). All of these may be acquired, or only one or two of them may be acquired. In addition to the on-vehicle device, the usage time of the secondary battery 10 and the number of times of charging / discharging may be acquired.

If any one of the capacity reduction rates acquired in S101 or each time and distance acquired in S102 exceeds a predetermined threshold value, the secondary battery 10 needs to alleviate unevenness. It is judged (S103: Yes). If none of these exceeds the threshold value, it is determined that the SOC unevenness that must be alleviated has not occurred (S103: No), and the recovery process is not performed. Just continue to use it. If it is determined No in S103, the process ends here.

If any of the values obtained in S101 and S102 exceeds the threshold value and it is determined in S103 that the unevenness needs to be alleviated (S103: Yes), the SOC acquisition unit 22 at that time The SOC of the secondary battery 10 is acquired (S104). Further, the cell temperature of the secondary battery 10 is acquired by the temperature acquisition unit 23 (S105). The order of S104 and S105 may be reversed or may be performed simultaneously.

Further, it is checked whether the SOC acquired in S104 is within an allowable range (predetermined value, 40% or less in this case) that is not too high for the recovery process. Further, it is checked whether or not the cell temperature acquired in S105 is within a temperature range suitable for the process of reducing unevenness (for example, 45 ° C. or more and 60 ° C. or less) (S106). If both of these are satisfied (S106; Yes), storage can be started as it is under these conditions.

However, if neither the SOC nor the cell temperature is within the appropriate range (S106; No), these need to be adjusted (S107). That is, when the SOC is higher than the appropriate range for the recovery process, the discharge is forcibly performed until the SOC is within the appropriate range. The SOC is not too low. In this embodiment, the SOC is set to 40% or less, but it is preferable if it can be lowered.

If the cell temperature is not within the appropriate temperature range, heating or cooling is performed until the cell temperature is within the appropriate temperature range. There is an appropriate range (upper and lower limits) for cell temperature. In the experiments by the inventors, it was found that 45 ° C. or higher and 60 ° C. or lower is appropriate. In addition, when the cell temperature is forcibly adjusted after the start of storage by storing it in a thermostatic chamber or the like, it is not always necessary to acquire or adjust the cell temperature before the start of storage. However, the storage period should be the period after the cell temperature is adjusted.

The SOC and the cell temperature can be adjusted more efficiently if they are adjusted at the same time. For example, when the SOC is high and the cell temperature is low, forcible discharge and heating by Joule heat generated thereby may be performed. Further, when the SOC is high and the cell temperature is high, a cooling device such as a fan may be driven by forced discharge and the electric power generated thereby. Alternatively, when the SOC is high and the cell temperature is within an appropriate range, forced discharge may be performed and the generated heat may be released to the outside. In addition, when the SOC is not high and the cell temperature is not appropriate, it is preferable that heating or cooling be performed by obtaining electric power from the outside rather than by discharging the secondary battery 10.

When the SOC and the cell temperature are within appropriate ranges, the storage period acquisition unit 24 acquires the necessary storage period based on the SOC value and the cell temperature at that time (S108). Therefore, in this embodiment, the necessary storage period corresponding to the storage conditions is stored for each target recovery rate as a map as shown in FIG. 5, for example. This figure shows an example in which the target recovery rate is 50%, and there are other target recovery rate maps. The numbers in the circles indicate the number of storage days corresponding to the storage conditions. Using this map, the required storage days can be read out by giving the storage SOC, storage temperature, and target recovery rate as storage conditions.

Here, the target recovery rate is an index indicating the degree of battery capacity recovery. In this embodiment, the battery capacity can be recovered by reducing the SOC unevenness and bringing the SOC closer to a uniform state. A recovery rate of 100% means recovery to an ideal state with no SOC unevenness, but is impossible in practice. The target recovery rate of 50% means that the recovery to the extent that the capacity reduction rate acquired in S101 is halved is targeted. For example, when the capacity reduction rate before recovery is 20%, the recovery is performed until the capacity reduction rate after recovery is about 10%, that is, the battery capacity is about 90% of the new capacity.

In this embodiment, a plurality of maps are stored within a target recovery rate of 10 to 80%. From these maps, the one with an appropriate target recovery rate is selected and used according to the elapsed time from the previous processing, the travel distance, and the like. From the example of the map shown in FIG. 5, it is shown that a storage period of 4 days is required for a target recovery rate of 50% under the condition that the SOC is 20% and the cell temperature is 50 ° C. ing. Note that storage at a cell temperature of less than 40 ° C. cannot be said to be a very appropriate treatment because it takes too much time to recover, but it is not impossible. Therefore, in this figure, the number of storage days in the case of such low temperature storage is indicated by being surrounded by a broken-line circle.

As can be seen from the example of FIG. 5, at the same storage temperature and the same target recovery rate, the lower the storage SOC, the shorter the storage period. Although only one example is shown here, for example, when compared at the same storage temperature and the same storage SOC, the higher the target recovery rate, the longer the storage period. However, there is a saturation point that is not recovered indefinitely and does not exceed a certain recovery rate.

In this recovery process, a map corresponding to the target recovery rate that meets the purpose is selected from a plurality of maps, and a storage period that meets the conditions is acquired from the map (S108). Further, during the selected storage period, the state is maintained without charging / discharging and without actively changing the temperature (S109). Even if the SOC changes due to natural discharge during the storage period, or the cell temperature changes due to the environment, etc., unless the SOC and the cell temperature are actively changed, these are the storage SOC and storage temperature. Included in storage. Then, when the storage period ends (S110; Yes), this recovery process ends. Further, for the next time, the date and time when the process is completed are stored, and then the present process is terminated.

In the case of the in-vehicle secondary battery 10, the storage period is a period when the car is not used, and it cannot be freely set at any time. In other words, the storage period may be restricted depending on the usage status of the user's vehicle. Due to the limited storage period, the target recovery rate may not be reached, but better than not. In the case of reuse, that is, when the secondary battery 10 is recovered as a single unit rather than being installed in an automobile or the like, the temperature can be controlled and stored in a thermostatic chamber or the like. , Can be recovered more reliably.

The inventors conducted storage at various storage temperatures, storage SOCs, and storage periods using the secondary battery 10 that artificially generated SOC unevenness, and examined how much the recovery rates differ from each other. It was. Examples of the results are shown in FIG. 6, FIG. 7, and FIG.

Fig. 6 shows the relationship between storage temperature and recovery rate when stored for 14 days at storage SOC of 30%. As can be seen from this figure, at a low temperature of less than 45 ° C. or a high temperature of more than 60 ° C., the recovery was insufficient during this storage period. That is, it was found that it is desirable to store at 45 ° C. or higher and 60 ° C. or lower in order to recover efficiently in a shorter period of time.

FIG. 7 shows the relationship between the storage SOC and the recovery rate, which was stored for 14 days at a storage temperature of 45 ° C. As can be seen from this figure, the smaller the stored SOC, the higher the recovery rate. Since no current flows during storage, there is no particular problem even if the storage SOC is very small.

FIG. 8 shows the relationship between the storage period and the recovery rate when stored at a storage SOC of 30% and a storage temperature of 45 ° C. As can be seen from this figure, the longer the storage period, the better the recovery, but the degree of recovery gradually saturates. In this example, the recovery rate did not increase much over 20 days even if the storage period was extended.

Note that the recovery system 1 of this embodiment can be mounted on a hybrid vehicle or other vehicle. FIG. 9 shows a hybrid vehicle 100 equipped with the recovery system 1 of the present embodiment. In this hybrid vehicle 100, an engine 3, a motor 4, a battery pack 5, and a controller 6 are mounted on a vehicle body 2. The battery pack 5, the motor 4 and the controller 6 are connected by a cable 7. A plurality of secondary batteries 10 are built in the battery pack 5. The controller 6 includes a control unit 20 of this embodiment.

The hybrid vehicle 100 is configured to drive the wheels by using the engine 3 and the motor 4 together. In the hybrid vehicle 100 of the present embodiment, a battery discharge current is supplied from the battery pack 5 to the motor 4 so that the motor 4 generates power. Depending on the traveling state of the hybrid vehicle 100, regenerative electric power may be generated by the motor 4. Thereby, a charging current is supplied to the battery of the battery pack 5, and the battery is charged. Here, the controller 6 controls the exchange of current between the battery pack 5 and the motor 4. That is, the controller 6 has not only the function of the control unit 20 but also an inverter.

It should be noted that the vehicle of this embodiment is not limited to a hybrid vehicle as long as the vehicle uses electric energy from a battery for all or part of its power source. For example, an electric vehicle, a plug-in hybrid vehicle, a hybrid railway vehicle, a forklift, an electric wheelchair, an electric assist bicycle, an electric scooter, etc. may be used.

As described above in detail, according to the recovery system 1 of the present embodiment, the occurrence of SOC unevenness is determined, and the recovery process is performed accordingly, so the SOC unevenness of the secondary battery 10 is alleviated. Therefore, it is possible to recover the battery capacity of the secondary battery whose charge state is not uniform without disassembling.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, the criteria for determination in S103 of the flowchart of FIG. 4 may be changed as follows. In the above embodiment, the recovery process is executed when any one of the conditions such as the battery capacity reduction rate exceeds the threshold, but it is executed only when two or more or all of the conditions are satisfied. You may do it.

For example, it may be considered that it is not necessary to perform this recovery process on the secondary battery 10 that has a small capacity reduction rate, that is, a capacity that has not decreased so much from the new state. Alternatively, even if the capacity decrease rate is large to some extent and the recovery process is in a better range, if the time from the previous process is short (the results of S102 are both smaller than the threshold value), the process is not performed this time. It is also good. This is because the effect is small even if the treatment is performed continuously. Alternatively, even when the capacity decrease rate is small, it may be determined that the recovery process is performed depending on various types of information acquired in S102.

In the storage period acquisition unit 24, the storage period is obtained using the map from the SOC and the cell temperature. However, when the storage period is limited, the reverse procedure may be used. That is, the storage SOC or the storage temperature may be adjusted until the storage period is within a possible range.

DESCRIPTION OF SYMBOLS 1 Recovery system 10 Secondary battery 20 Control part 100 Hybrid vehicle

Claims

In a secondary battery recovery method for recovering the charge / discharge capacity of a used secondary battery,
Obtain the SOC (State Of Charge) of the secondary battery to be recovered,
If the acquired SOC is within a predetermined allowable range, the acquired SOC is set as a storage SOC,
When the obtained SOC is outside the predetermined allowable range, the secondary battery is charged and discharged until it is within the allowable range, and the SOC after the charge and discharge is used as the storage SOC.
A storage period in which the charge / discharge capacity of the secondary battery is recovered to the target recovery rate by storage at the storage temperature and storage SOC using a recovery map that stores the relationship between the storage SOC, storage temperature, storage period, and target recovery rate. Determine
A secondary battery recovery method, wherein the secondary battery is stored at a storage temperature and a storage SOC over a determined storage period.
In the recovery method of the secondary battery of Claim 1,
The allowable range of the storage SOC is in the range of 0% to 40%,
The method for recovering a secondary battery, wherein the storage temperature is in a range of 45 ° C to 60 ° C.
In the recovery method of the secondary battery of Claim 2,
Obtaining the temperature of the secondary battery before the start of the storage period;
When the acquired temperature is outside the storage temperature range, the secondary battery is recovered after being heated or cooled until it falls within the storage temperature range.
In the recovery method of the secondary battery according to claim 3,
When the acquired temperature is outside the storage temperature range and the secondary battery is discharged, the secondary battery is used for heating or cooling the secondary battery. Battery recovery method.
In a secondary battery recovery system that recovers the charge / discharge capacity of a used secondary battery,
A control unit for controlling a charge / discharge state of the secondary battery and acquiring an SOC (State Of Charge);
A recovery map that stores the relationship between the storage SOC, storage temperature, storage period, and target recovery rate;
The controller is
Obtain the SOC of the secondary battery to be recovered,
If the acquired SOC is within a predetermined allowable range, the acquired SOC is set as a storage SOC,
When the obtained SOC is outside the predetermined allowable range, the secondary battery is charged and discharged until it is within the allowable range, and the SOC after the charge and discharge is used as the storage SOC.
Using the recovery map, determine a storage period for recovering the charge / discharge capacity of the secondary battery to a target recovery rate by storage at storage temperature and storage SOC,
A secondary battery recovery system, wherein the secondary battery is stored at a storage temperature and a storage SOC over a determined storage period.
The secondary battery recovery system according to claim 5,
The allowable range of the storage SOC is in the range of 0% to 40%,
The storage temperature of the secondary battery is in a range of 45 ° C or higher and 60 ° C or lower.
The secondary battery recovery system according to claim 6,
The controller is
Obtaining the temperature of the secondary battery before the start of the storage period;
When the acquired temperature is outside the range of the storage temperature, the secondary battery recovery system is stored after being heated or cooled until it falls within the range of the storage temperature.
The secondary battery recovery system according to claim 7,
When the acquired temperature is outside the storage temperature range and the secondary battery is discharged, the secondary battery is used for heating or cooling the secondary battery. Battery recovery system.
A vehicle equipped with the secondary battery recovery system according to any one of claims 5 to 8.