JP2009199936A - Power supply system, vehicle mounted with the same, and control method for power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply system capable of preventing performance degradation of a lithium secondary battery caused by dendrite. <P>SOLUTION: A power supply system 100 comprises a precipitation amount calculating means 51 and dissolving/removing means 20 and 70. The precipitation amount calculating means 52 calculates a precipitation amount of dendrite of the lithium that is precipitated on the negative electrodes of lithium secondary batteries 10 and 11 when the lithium secondary batteries 10 and 11 are charged/discharged. The dissolving/removing means 20 and 70 dissolve/remove the dendrite according to the amount of precipitation dendrite, which is calculated by the precipitation amount calculating means 51. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply system using a lithium secondary battery as a power supply, a vehicle equipped with the same, and a control method for the power supply system.

  In recent years, lithium secondary batteries have been actively developed as power sources for driving motors of electric vehicles (EV) and hybrid electric vehicles (HEV).

As a technique related to a lithium secondary battery, a charging method for a lithium secondary battery as shown in Patent Document 1 described below has been proposed because of a demand for improving the durability of the secondary battery. The charging method disclosed in Patent Document 1 charges a lithium secondary battery by supplying a pulse current that alternately turns on and off. According to the charging method of such a structure, it can suppress that the dendritic of lithium which causes the performance fall of a lithium secondary battery to precipitate on the negative electrode of a lithium secondary battery at the time of charge.
Japanese Patent Laid-Open No. 7-263031

  However, although the above charging method can suppress the precipitation of dendrite, the dendrite precipitates with time, and there is a problem that any of them causes a decrease in performance of the lithium secondary battery.

  The present invention has been made to solve the above-described problems. Accordingly, an object of the present invention is to provide a power supply system and a control method for the power supply system that can prevent the performance degradation of the lithium secondary battery due to dendrites.

  Another object of the present invention is to provide a vehicle equipped with the power supply system.

  The above object of the present invention is achieved by the following means.

  The power supply system of the present invention has a precipitation amount calculating means and a dissolution removing means. The said precipitation amount calculation means calculates the precipitation amount of the lithium dendrite which deposits on the negative electrode of the said lithium secondary battery with charging / discharging of a lithium secondary battery. The dissolution removing means dissolves and removes the dendrite according to the amount of dendrant precipitated calculated by the precipitation amount calculating means.

  The power supply system control method of the present invention includes a calculation step and a dissolution removal step. The calculation step calculates the amount of lithium dendrite deposited on the negative electrode of the lithium secondary battery as the lithium secondary battery is charged and discharged. In the dissolution and removal step, the dendrite is dissolved and removed according to the amount of the dendrant deposited in the calculation step.

  The vehicle of the present invention is equipped with the power supply system as a drive power supply.

  According to the power supply system and the control method of the power supply system of the present invention, the dendrite is dissolved and removed while predicting the amount of lithium dendrite deposited on the negative electrode of the lithium secondary battery. Battery performance is effectively prevented from being degraded. Therefore, the durability of the lithium secondary battery can be improved.

  According to the vehicle of the present invention, the performance of the lithium secondary battery is maintained for a long time, so that the reliability of the vehicle is improved.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, a case where the present invention is applied to a power supply system for driving a motor of an electric vehicle will be described as an example. In the figure, the same symbols are used for the same members.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a power supply system according to the first embodiment of the present invention. The power supply system of the present embodiment dissolves the deposited dendrite by increasing the potential of the negative electrode of the lithium secondary battery when the amount of the dendrite deposited on the negative electrode of the lithium secondary battery exceeds an allowable amount. To be removed.

  As shown in FIG. 1, the power supply system 100 of the present embodiment includes an assembled battery 10, an external power supply 20, a voltage sensor 30, a temperature sensor 40, and a power supply control device 50. The assembled battery 10 is connected to the motor 70 via the inverter 60, and the power supply control device 50 is connected to the vehicle control device 80 through the in-vehicle network.

  The assembled battery 10 supplies power to the motor 70. The assembled battery 10 is a lithium secondary battery that can be repeatedly charged and discharged, and is configured by connecting a plurality of lithium single batteries (hereinafter referred to as battery cells) 11 having a positive electrode containing lithium in series. Detailed description of the battery cells 11 constituting the assembled battery 10 will be described later.

  The external power source 20 dissolves and removes lithium dendrite as a dissolution and removal means. The external power supply 20 dissolves and removes dendrite by applying a reverse voltage to the assembled battery 10 to raise the potential of the negative electrode of the assembled battery 10. The external power supply 20 has a negative terminal connected to the positive terminal of the battery pack 10 and a positive terminal connected to the negative terminal of the battery pack 10. The external power supply 20 of the present embodiment is a variable power supply including a DC power supply and a variable resistor, and is controlled by the power supply control device 50. Alternatively, unlike the present embodiment, the external power source 20 may include a pulse power source that applies a pulse voltage (pulse current) to the assembled battery 10.

  The voltage sensor 30 detects the voltage of the assembled battery 10 as charge amount detection means. The voltage sensor 30 is connected in parallel with the assembled battery 10 and detects the open voltage of the assembled battery 10 as the amount of charge (SOC) of the assembled battery 10. The voltage sensor 30 is electrically connected to the power supply control device 50, and the detected voltage signal is transmitted to the power supply control device 50.

  The temperature sensor 40 detects the temperature of the assembled battery 10. The temperature sensor 40 is provided inside the assembled battery 10 and detects the temperature inside the assembled battery 10 as the temperature of the environment where the assembled battery 10 is used. The temperature sensor 40 is electrically connected to the power supply control device 50, and the detected temperature signal is transmitted to the power supply control device 50.

  The power supply control device 50 processes signals detected by the voltage sensor 30 and the temperature sensor 40 and controls the external power supply 20 and the motor 70. The power supply control device 50 controls a high power switch provided in a high power harness that connects the inverter 60 and the assembled battery 10 and outputs a control signal to the inverter 60 connected to the motor 70 via the vehicle control device 80. can do.

  The power supply control device 50 is a general computer, for example, and includes a CPU 51 and a memory 52. The CPU 51 functions as a control unit that controls the operations of the external power source 20 and the motor 70 and a precipitation amount calculation unit (precipitation amount calculation means) that calculates the precipitation amount of lithium dendrite. The memory 52 stores charge / discharge history information of the assembled battery 10 and open-circuit voltage-charge amount data indicating a relationship between the open-circuit voltage and the charge amount of the assembled battery 10 as storage means.

  Next, the battery cell 11 which comprises the assembled battery 10 of this Embodiment is demonstrated in detail, referring FIG.

  FIG. 2 is a cross-sectional view for explaining the structure of the battery cell constituting the assembled battery in the power supply system shown in FIG.

  As shown in FIG. 2, the battery cell 11 of the present embodiment has a configuration in which a battery element (power generation element) and a reference electrode 13 are housed in an exterior material 12 made of a laminate film. In addition, a cell voltage sensor 31 that detects the potential of the negative electrode of the battery cell 11 is connected to the battery cell 11 of the present embodiment.

  The battery element includes a positive electrode active material and a negative electrode active material that occlude and release lithium ions, and is charged / discharged as lithium ions move through an electrolyte (nonaqueous electrolyte) between the positive electrode and the negative electrode. The battery element includes a positive electrode 14 having a positive electrode active material layer 14b formed on both surfaces of the positive electrode current collector 14a (one surface for the lowermost layer and the uppermost layer of the battery element), an electrolyte layer 15, and both surfaces of the negative electrode current collector 16a. And a plurality of negative electrodes 16 each having a negative electrode active material layer 16b formed thereon. The positive electrode current collector 14 a and the negative electrode current collector 16 a are extended and attached to the positive electrode tab 17 and the negative electrode tab 18 that are led out from the exterior material 12, respectively. Note that the positive electrode current collector 14a, the positive electrode active material layer 14b, the electrolyte layer 15, the negative electrode current collector 16a, and the negative electrode active material layer 16b themselves are composed of general materials used in lithium secondary batteries. Therefore, detailed description is omitted.

  The reference electrode 13 is for measuring the potential of the negative electrode of the battery cell 11. The reference electrode 13 is made of, for example, metallic lithium and is provided at the end of the separator that forms the electrolyte layer 15. A lead wire (not shown) led to the outside of the exterior material 12 is attached to the reference electrode 13, and the lead wire is connected to the cell voltage sensor 31. Note that unlike the present embodiment, only one reference electrode 13 may be provided inside the battery cell 11, and in this case, the reference electrode 13 is preferably provided in the vicinity of the negative electrode.

  In power supply system 100 of the present embodiment configured as described above, when the amount of lithium dendrite deposited on the negative electrode of battery cell 11 exceeds an allowable amount, the potential of negative electrode 16 of battery cell 11 is increased. The dissolved dendrite is dissolved and removed. Hereinafter, the control method of the power supply system of the present embodiment will be described in detail with reference to FIGS.

  FIG. 3 is a flowchart for explaining a control method of the power supply system shown in FIG. In the following flowchart, a case will be described as an example in which the lithium dendrite deposited on the negative electrode of the battery cell 11 is dissolved and removed before the battery pack 10 is charged.

  As shown in FIG. 3, in the control method of the power supply system in the present embodiment, first, the amount of dendrite deposited is calculated (step S101). In the present embodiment, based on charge / discharge history information indicating a history of charging / discharging of the assembled battery 10, the CPU 51 calculates an estimated value of the amount of dendrite deposited inside the assembled battery 10. Details of the dendrite precipitation amount calculation processing shown in step S101 will be described later.

  Next, it is determined whether or not the amount of dendrite deposited is greater than or equal to an allowable value (step S102). In the present embodiment, the CPU 51 compares the dendrite precipitation amount calculated in the process shown in step S101 with a preset allowable value, and determines whether or not the precipitation amount is greater than or equal to the allowable value. Here, the allowable value is, for example, 0.3 (mg), and it depends on the material used for the battery cell 11 and the dimensions of the battery cell 11 so that dendrites do not cause the performance of the battery cell 11 to deteriorate. Is set.

  If the amount of deposited dendrites is less than the allowable value (step S102: NO), the dendrite is unlikely to cause a decrease in the performance of the battery cell 11, and the process proceeds to the charging process shown in step S111 and below without dissolving the dendrite. To do.

  On the other hand, when the amount of dendrite deposited is greater than or equal to the allowable value (step S102: YES), the charge amount of the assembled battery 10 is detected (step S103). In the present embodiment, the CPU 51 calculates the charge amount of the assembled battery 10 from the open voltage of the assembled battery 10 detected by the voltage sensor 30. More specifically, the CPU 51 calculates the charge amount of the assembled battery 10 based on the open circuit voltage-charge amount data stored in the memory 52.

  Next, it is determined whether or not the detected charge amount of the assembled battery 10 is equal to or greater than a set value (step S104). In the present embodiment, the CPU 51 compares the charge amount calculated in the process shown in step S103 with the set value, and determines whether or not the charge amount is equal to or greater than the set value. Here, the set value is 60%, for example, and is set according to the substance used for the battery cell 11 so that the power consumed in the subsequent dendrite melting process does not become too large.

  When the charge amount of the assembled battery 10 is equal to or greater than the set value (step S104: YES), it is determined that the power consumed in the subsequent dendrite melting process is too large and not efficient, so that the dendrite is not dissolved and removed. The charging process shown in FIG. On the other hand, when the charge amount of the assembled battery 10 is less than the set value (step S104: NO), a reverse voltage is applied from the external power source 20 to the assembled battery 10 in order to dissolve and remove the dendrite (step S105). In the present embodiment, the power supply control device 50 outputs a command signal to the external power supply 20 and applies a reverse voltage from the external power supply 20 to the assembled battery 10. By applying a reverse voltage from the external power supply 20 as the potential adjusting means, the potential of the negative electrode 16 of the battery cell 11 is forcibly increased. When the potential of the negative electrode of the battery cell 11 is increased, the dendrite deposited on the negative electrode is dissolved.

  Next, the potential of the negative electrode of the battery cell 11 is detected (step S106). In the present embodiment, the cell voltage sensor 31 detects the potential difference between the reference electrode 13 and the negative electrode 16 provided inside one battery cell 11 as the negative electrode potential.

  Then, it is determined whether or not the detected potential of the negative electrode is equal to or higher than a preset dendrite dissolution potential (step S107). In the present embodiment, the CPU 51 compares the negative electrode potential detected in the process shown in step S106 with the dendrite dissolution potential to determine whether the negative electrode potential is equal to or higher than the dendrite dissolution potential. Here, the dendrite dissolution potential is, for example, 2 V, and is a potential that can effectively dissolve and remove the dendrite. The dendrite dissolution potential is set according to the substance used for the battery cell 11.

  When the negative electrode potential is lower than the dendrite dissolution potential (step S107: NO), the magnitude of the reverse voltage applied from the external power source 20 is increased until the negative electrode potential reaches the dendrite dissolution potential. On the other hand, when the potential of the negative electrode is equal to or higher than the dendrite dissolution potential (step S107: YES), the magnitude of the reverse voltage applied from the external power supply 20 is maintained (step S108).

  Next, it is determined whether or not a predetermined time has elapsed (step S109). When the predetermined time has not elapsed (step S109: NO), the magnitude of the reverse voltage applied from the external power supply 20 is maintained until the predetermined time has elapsed. On the other hand, when the predetermined time has elapsed (step S109: YES), the application of the reverse voltage from the external power source 20 is stopped (step S110), and the process is terminated.

  As described above, according to the processing shown in steps S <b> 105 to S <b> 110, the negative voltage of the battery cell 11 is forcibly increased by applying a reverse voltage from the external power supply 20 to the assembled battery 10. When the potential of the negative electrode 16 of the battery cell 11 is increased, the dendrite deposited on the negative electrode 16 of the battery cell 11 is dissolved and removed. Unlike the present embodiment, for example, the dendrite may be dissolved and removed by increasing the number of revolutions of the motor 70 and discharging the assembled battery 10 to increase the potential of the negative electrode of the battery cell 11.

  Next, charging of the assembled battery 10 is started (step S111). Then, the charging is continued until the charging of the assembled battery 10 is completed (steps S112 and S113), and the process ends. In addition, since the process shown to step S111-S113 is a charge process of a general lithium secondary battery, detailed description is abbreviate | omitted.

  As described above, according to the process shown in the flowchart of FIG. 3, first, based on the charge / discharge history information of the assembled battery 10, the amount of dendrite deposited on the negative electrode of the battery cell 11 constituting the assembled battery 10 is determined. Calculated. When the calculated amount of dendrites exceeds the allowable amount, the dendrites deposited on the negative electrode are dissolved and removed. As a result, the performance deterioration of the battery cell 11 due to the lithium dendrite deposited on the negative electrode of the battery cell 11 is prevented. Hereinafter, the dendrite precipitation amount calculation process for calculating the dendrite precipitation amount will be described in detail with reference to FIGS. 4 and 5.

  FIG. 4 is a flowchart for explaining the dendrite precipitation amount calculation processing shown in step S101 of FIG. In the dendrite deposition amount calculation process of the present embodiment, the dendrite deposition amount is calculated based on the charge count information, the fast charge count information, and the full charge count information of the assembled battery 10 which is the charge / discharge history information of the assembled battery 10. Is done.

  As shown in FIG. 4, in the dendrite deposition amount calculation process of the present embodiment, first, charging number information indicating the number of times the assembled battery 10 has been charged is read (step S201). In the present embodiment, the CPU 51 reads information on the number of times of charging the assembled battery 10 stored in advance in the memory 52.

Next, a dendrite deposition amount (hereinafter referred to as a first deposition amount) based on information on the number of times of charging the assembled battery 10 is calculated (step S202). In the present embodiment, the CPU 51 determines the first precipitation amount (k ₁ · a) of dendrites by the product of a preset first coefficient k ₁ (for example, 2 × 10 ⁻⁴ mg / time) and the number of times of charging a. ) Is calculated. The calculated first precipitation amount of dendrite is temporarily stored in the memory 52.

  Next, the temperature of the assembled battery 10 is detected (step S203). In the present embodiment, the temperature inside the assembled battery 10 is detected by the temperature sensor 40 so that the deposition amount of dendrite is corrected based on the temperature of the environment where the assembled battery 10 is used.

  Then, based on the detected temperature, first and second temperature correction values α and β of the dendrite precipitation amount are calculated (step S204). In the present embodiment, the CPU 51 uses the first temperature correction value α (for example, 7 mg) and the second temperature correction value β so that the amount of dendrite deposited increases as the temperature of the environment in which the assembled battery 10 is used increases. (For example, 5 mg) is calculated. The calculated first and second temperature correction values α and β are temporarily stored in the memory 52.

  Next, fast charge number information indicating the number of times the assembled battery 10 has been charged at high speed is read (step S205). In the present embodiment, the CPU 51 reads information on the number of times of fast charging of the assembled battery 10 stored in advance in the memory 52.

Next, a dendrite deposition amount (hereinafter referred to as a second deposition amount) based on the information on the number of times of fast charging of the battery pack 10 is calculated (step S206). In the present embodiment, the CPU 51 adds the first temperature correction value α to the product of a preset second coefficient k ₂ (for example, 6 × 10 ⁻² mg / time) and the fast charge count b. Is calculated as the second precipitation amount of dendrite (k ₂ · b + α). The calculated second precipitation amount of dendrite is temporarily stored in the memory 52.

  Next, full charge number information indicating the number of times the assembled battery 10 is fully charged is read (step S207). In the present embodiment, the CPU 51 reads information on the number of full charges of the assembled battery 10 stored in advance in the memory 52.

Next, a dendrite deposition amount (hereinafter referred to as a third deposition amount) based on the full charge count information of the battery pack 10 is calculated (step S208). In the present embodiment, the CPU 51 adds the second temperature correction value β to the product of a preset third coefficient k ₃ (for example, 7.5 × 10 ⁻³ mg / time) and the full charge count c. This value is calculated as the third precipitation amount of dendrite (k ₃ · c + β). The calculated third precipitation amount of dendrite is temporarily stored in the memory 52.

  Then, the total amount of dendrite deposited is calculated (step S209). In the present embodiment, the CPU 51 calculates the sum of the first to third precipitation amounts calculated in steps S202, S206, and S208 as the total precipitation amount of dendrites.

  As described above, according to the process shown in the flowchart of FIG. 4, the amount of the dendrite deposited on the negative electrode of the battery cell 11 is determined based on the charging number information, the fast charging number information, and the full charging number information of the assembled battery 10. A predicted value is calculated.

  In the dendrite deposition amount calculation process described above, the dendrite deposition amount was corrected based on the temperature inside the assembled battery 10 detected by the temperature sensor 40. However, the amount of dendrite deposited may be corrected based on the outside air temperature of the electric vehicle detected by a temperature sensor provided in the electric vehicle. Alternatively, as shown in step S <b> 203 ′ in FIG. 5, the amount of dendrite deposition may be corrected based on the climate data of the region where the electric vehicle is traveling.

  In addition, among the charging / discharging history information of the assembled battery 10, the fast charge count information and the full charge count information of the assembled battery 10 may be omitted, and the deposition amount of dendrites is based only on the charge count information of the assembled battery 10. It may be calculated.

  Next, the effect in the power supply system 100 of this Embodiment is demonstrated.

  FIG. 6 is a diagram for explaining the effect of improving the durability of the lithium secondary battery by the power supply system of the present embodiment. Specifically, FIG. 6 schematically shows the amount of dendrite deposited over time on the negative electrode of a lithium secondary battery. In FIG. 6, a case where a general power supply system is used is shown as a comparative example. The broken line in FIG. 6 represents the change with time of the dendrite precipitation amount in the comparative example, and the solid line represents the change with time of the dendrite precipitation amount in the present embodiment.

  In the comparative example, charging and discharging of the lithium secondary battery are repeated without dissolving and removing the lithium dendrite. With the charging / discharging of the lithium secondary battery, dendrites, which are dendritic precipitates, are deposited and grown on the concavo-convex portion of the negative electrode surface or the end portion of the negative electrode of the lithium secondary battery. Such a dendrite may cause an internal short circuit between the positive electrode and the negative electrode of the lithium secondary battery by penetrating the separator forming the electrolyte layer. Therefore, in a general power supply system, dendrites are deposited on the negative electrode due to repeated charging and discharging of the lithium secondary battery, which may cause a decrease in performance of the lithium secondary battery.

  On the other hand, in the present embodiment, when more than an allowable amount of dendrite is deposited, the deposited dendrite is dissolved and removed. Therefore, even if charging / discharging is repeated, the amount of dendrite deposited is maintained below an allowable amount, and performance deterioration of the lithium secondary battery is prevented. As a result, the durability of the lithium secondary battery is improved.

  Next, a vehicle equipped with the power supply system of the present embodiment will be described with reference to FIG.

  FIG. 7 is a diagram showing an electric vehicle on which the power supply system of the present embodiment is mounted as a driving power supply. Power supply system 100 of the present embodiment is mounted on vehicles such as automobiles and trains, and can be used as a power source for driving electric devices such as motors.

  As shown in FIG. 7, in the electric vehicle 200 equipped with the power supply system 100 of the present embodiment, the driving wheels are rotated by the motor 70 supplied with power from the assembled battery 10, and the electric vehicle 200 travels. In the electric vehicle 200 of the present embodiment, the performance of the assembled battery 10 is maintained for a long period of time, so the reliability of the electric vehicle 200 is improved.

  As described above, the described embodiment has the following effects.

  (A) The power supply system of the present embodiment includes a deposition amount calculation unit, an external power supply, and a motor. The precipitation amount calculation unit calculates the amount of lithium dendrite deposited on the negative electrode of the battery cell as the battery cell is charged and discharged. The external power source and the motor dissolve and remove the dendrite in accordance with the amount of the dendrant deposited calculated by the deposition amount calculating unit. Therefore, since the dendrite is dissolved and removed while the amount of lithium dendrite deposited on the negative electrode of the battery cell is predicted, the performance degradation of the battery cell due to the deposition of dendrite is efficiently prevented. As a result, the durability of the battery cell can be improved.

  (B) The power supply system of the present embodiment further includes a memory that stores charge / discharge history information indicating a history of charging / discharging of the battery cell, and the deposition amount calculation unit is based on the charge / discharge history information of the assembled battery. Thus, the amount of Dendland deposited is calculated. Therefore, the amount of dendrite deposited can be calculated.

  (C) The charge / discharge history information includes charge count information indicating the number of times the assembled battery has been charged. Accordingly, the amount of dendrite deposited can be calculated based on the number of times the assembled battery is charged.

  (D) The deposition amount calculation unit includes the number of times of charging the battery pack and the number of times of fast charging so that the deposition amount of dendrite increases as the number of times that the battery cell is charged at high speed and the number of times that the battery cell is fully charged increases. Based on the information on the number of full charges, the amount of dendland deposition is calculated. Therefore, the effects of high-speed charging and full charging that accelerate the precipitation of dendrite are added to the calculation of the amount of dendrite deposited in terms of acceleration coefficient, so that the amount of dendrite deposited can be accurately calculated.

  (E) The external power supply and the motor dissolve and remove the dendrite by increasing the potential of the negative electrode of the battery cell. Therefore, the dendrite deposited on the negative electrode of the battery cell can be electrically dissolved and removed.

  (F) The amount of dendrite deposited is corrected based on temperature information of the environment in which the battery cell is used so that the amount of dendrite deposited increases as the temperature of the environment in which the battery cell is used increases. Therefore, the amount of dendrite deposited can be calculated more accurately.

  (G) The temperature information includes temperature information of the battery cell, outside air temperature information of an electric vehicle equipped with the battery cell as a driving power source, or climate information of a region where the electric vehicle is used. Therefore, the amount of dendrite deposited can be corrected based on the temperature information of the environment in which the battery cell is used.

  (H) The power supply system of the present embodiment further includes a voltage sensor that detects the charge amount of the battery cell, and the external power supply and the motor dissolve and remove the dendrite when the charge amount of the battery cell is less than the set value. . Therefore, for example, when the charge amount of the assembled battery is high to some extent after low-rate discharge or the like, it is possible to prevent the power stored in the assembled battery from being discarded inefficiently outside the battery. As a result, efficient control is realized.

  (I) The voltage sensor detects the open voltage of the assembled battery. Therefore, the charge amount of the assembled battery can be detected.

  (J) The vehicle according to the present embodiment is equipped with the power supply system as a drive power supply. Therefore, since the performance of the assembled battery comprised of a plurality of battery cells is maintained for a long time, the reliability of the vehicle is improved.

  (K) The control method of the power supply system in the present embodiment includes a calculation stage and a dissolution removal stage. In the calculation step, the amount of lithium dendrite deposited on the negative electrode of the battery cell as the battery cell is charged and discharged is calculated. In the dissolution and removal step, the dendrite is dissolved and removed according to the amount of the dendrant deposited in the calculation step. Therefore, since the dendrite is dissolved and removed while the amount of lithium dendrite deposited on the negative electrode of the battery cell is predicted, the performance degradation of the battery cell due to the deposition of dendrite is efficiently prevented. As a result, the durability of the battery cell can be improved.

(Second Embodiment)
In the first embodiment, the amount of dendrite deposited is calculated based on the charging number information, the fast charging number information, and the full charging number information of the assembled battery. In the present embodiment, the amount of dendrite deposited is calculated based on the operating time of the assembled battery.

  FIG. 8 is a flowchart for explaining a control method of the power supply system according to the second embodiment of the present invention. In the following flowchart, a case will be described as an example in which the lithium dendrite deposited on the negative electrode of the battery cell 11 is dissolved and removed before the battery pack 10 is charged.

  As shown in FIG. 8, in the method of controlling the power supply system in the present embodiment, first, the operating time of the assembled battery 10 is read (step S301). In the present embodiment, the CPU 51 reads the operating time of the assembled battery 10 stored in advance in the memory 52.

  Next, the amount of dendrite deposited based on the operating time of the battery pack 10 is calculated (step S302). In the present embodiment, the CPU 51 calculates the precipitation amount of dendrite by the product of a preset coefficient and the operating time.

  Next, it is determined whether or not the amount of dendrite deposited is greater than or equal to an allowable value (step S303). If the amount of deposited dendrites is less than the allowable value (step S303: NO), the dendrite is unlikely to cause a decrease in the performance of the battery cell 11, and the process proceeds to the charging process shown in step S312 and subsequent steps without dissolving and removing the dendrite. To do. On the other hand, if the dendrite deposition amount is greater than or equal to the allowable value (step S303: YES), the charge amount of the assembled battery 10 is detected, and it is determined whether or not the detected charge amount of the assembled battery 10 is greater than or equal to the set value ( Steps S304 and S305).

  When the charge amount of the assembled battery 10 is equal to or greater than the set value (step S305: YES), the process proceeds to the charging process shown in step S312 and subsequent steps without dissolving and removing the dendrite. On the other hand, when the charge amount of the assembled battery 10 is less than the set value (step S305: NO), a reverse voltage is applied from the external power source 20 to the assembled battery 10 in order to dissolve and remove the dendrite (step S306).

  Next, the potential of the negative electrode of the battery cell 11 is detected, and it is determined whether or not the detected potential of the negative electrode is equal to or higher than a preset dendrite dissolution potential (steps S307 and S308). When the negative electrode potential is less than the dendrite dissolution potential (step S308: NO), the magnitude of the reverse voltage applied from the external power source 20 is increased until the negative electrode potential reaches the dendrite dissolution potential. On the other hand, when the potential of the negative electrode is equal to or higher than the dendrite dissolution potential (step S308: YES), the magnitude of the reverse voltage applied from the external power supply 20 is maintained (step S309).

  Next, it is determined whether or not a predetermined time has elapsed (step S310). When the predetermined time has not elapsed (step S310: NO), the magnitude of the reverse voltage applied from the external power supply 20 is maintained until the predetermined time has elapsed. On the other hand, when the predetermined time has elapsed (step S310: YES), the application of the reverse voltage from the external power source 20 is stopped (step S311), and the process ends.

  Next, charging of the assembled battery 10 is started (step S312). Then, the charging is continued until the charging of the assembled battery 10 is completed (steps S313 and S314), and the process is ended.

  As described above, according to the process shown in the flowchart of FIG. 8, first, the amount of dendrite deposited on the negative electrode of the battery cell 11 constituting the assembled battery 10 is calculated based on the operating time information of the assembled battery 10. Is done. When the calculated amount of dendrites exceeds the allowable amount, the dendrites deposited on the negative electrode are dissolved and removed. As a result, the performance deterioration of the battery cell 11 due to the lithium dendrite deposited on the negative electrode of the battery cell 11 is prevented.

  As described above, the described embodiment has the following effects in addition to the effects of the first embodiment.

  (L) The charge / discharge history information includes inter-operation information indicating the operation time of the assembled battery. Accordingly, the amount of dendrite deposited can be calculated based on the operating time of the assembled battery.

(Third embodiment)
In the present embodiment, lithium dendrite is dissolved and removed by applying ultrasonic vibration to the battery cell.

  FIG. 9 is a block diagram showing a schematic configuration of the power supply system according to the third embodiment of the present invention.

  As shown in FIG. 9, the power supply system 100 of the present embodiment includes an assembled battery 10, a voltage sensor 30, a temperature sensor 40, a power supply control device 50, and an ultrasonic oscillator 25. The assembled battery 10 is connected to the motor 70 via the inverter 60, and the power supply control device 50 is connected to the vehicle control device 80 through the in-vehicle network. Since the configuration of the power supply system in the present embodiment is the same as that in the first embodiment except that the ultrasonic oscillator dissolves and removes the dendrites instead of the external power supply, a detailed description will be given. Is omitted.

  The ultrasonic oscillator 25 dissolves and removes lithium dendrite as a dissolution and removal means. The ultrasonic oscillator 25 dissolves and removes dendrite by applying ultrasonic vibration to the assembled battery 10. The ultrasonic oscillator 25 is connected to the assembled battery 10 and is controlled by the power supply control device 50.

  FIG. 10 is a flowchart for explaining a control method of the power supply system shown in FIG. In the following flowchart, a case will be described as an example in which the lithium dendrite deposited on the negative electrode of the battery cell 11 is dissolved and removed before the battery pack 10 is charged.

  As shown in FIG. 10, in the control method of the power supply system in the present embodiment, first, the amount of dendrite deposited is calculated (step S401). The dendrite precipitation amount calculation process shown in step S401 is the same as that in the first embodiment, and a detailed description thereof will be omitted.

  Next, it is determined whether or not the amount of dendrite deposited is greater than or equal to an allowable value (step S402). If the amount of deposited dendrites is less than the allowable value (step S402: NO), the dendrite is unlikely to cause a decrease in the performance of the battery cell 11, and the process proceeds to the charging process shown in step S408 and below without dissolving the dendrite. To do. On the other hand, if the dendrite deposition amount is greater than or equal to the allowable value (step S402: YES), the charge amount of the assembled battery 10 is detected, and it is determined whether or not the detected charge amount of the assembled battery 10 is greater than or equal to the set value ( Steps S403 and S404).

  When the charge amount of the assembled battery 10 is equal to or greater than the set value (step S404: YES), the process proceeds to the charging process shown in step S408 and subsequent steps without dissolving and removing the dendrite. On the other hand, when the charge amount of the assembled battery 10 is less than the set value (step S404: NO), ultrasonic vibration is applied to the assembled battery 10 in order to dissolve and remove the dendrite (step S405). In the present embodiment, the power supply control device 50 outputs a command signal to the ultrasonic oscillator 25 and applies ultrasonic vibrations from the ultrasonic oscillator 25 to the assembled battery 10. By applying ultrasonic vibration from the ultrasonic oscillator 25, the dendrites deposited on the negative electrode of the battery cell 11 are dissolved.

  Next, it is determined whether or not a predetermined time has passed (step S406). If the predetermined time has not elapsed (step S406: NO), the ultrasonic vibration applied from the ultrasonic oscillator 25 is maintained until the predetermined time has elapsed. On the other hand, when the predetermined time has elapsed (step S406: YES), application of ultrasonic vibration from the ultrasonic oscillator 25 is stopped (step S407).

  Next, charging of the assembled battery 10 is started (step S408). Then, the charging is continued until the charging of the assembled battery 10 is completed (steps S409 and S410), and the process is ended.

  As described above, according to the process shown in the flowchart of FIG. 10, first, based on the charge / discharge history information of the assembled battery 10, the amount of dendrite deposited on the negative electrode of the battery cell 11 constituting the assembled battery 10 is determined. Calculated. When the calculated amount of dendrite deposited exceeds the allowable amount, ultrasonic vibration is applied to the assembled battery 10 to dissolve and remove the dendrite deposited on the negative electrode of the battery cell. As a result, the performance deterioration of the battery cell 11 due to the lithium dendrite deposited on the negative electrode of the battery cell 11 is prevented.

  As described above, the described embodiment has the following effects in addition to the effects of the first and second embodiments.

  (M) The power supply system according to the present embodiment includes an ultrasonic oscillator that dissolves and removes dendrites according to the amount of dendrant deposited calculated by the amount-of-deposition calculating unit. Therefore, the performance degradation of the battery cell due to dendrite deposited on the negative electrode of the battery cell is prevented. As a result, the durability of the battery cell can be improved.

  As described above, in the first to third embodiments, the power supply system, the control method for the power supply system, and the vehicle of the present invention have been described. However, it goes without saying that the present invention can be appropriately added, modified, and omitted by those skilled in the art within the scope of the technical idea.

  For example, in the above-described embodiment, when the amount of deposited dendrites exceeds the allowable amount, the dendrites are dissolved and removed. However, regardless of the allowable amount, the dendrite may be dissolved and removed while changing conditions such as the application time of the reverse voltage from the external power source according to the amount of deposited dendrites.

  In the above-described embodiment, the lithium dendrite is dissolved and removed by raising the potential of the negative electrode of the battery cell or by applying ultrasonic vibration to the battery cell. However, the lithium dendrite may be dissolved and removed by irradiating the battery cell with pulsed laser light.

  In the above-described embodiment, the amount of dendrite deposited calculated based on the charge / discharge history information is compared with an allowable value. However, the charge / discharge history information itself may be directly compared with a predetermined threshold value.

  In the above-described embodiment, the charge amount of the assembled battery is calculated from the open voltage of the assembled battery detected by the voltage sensor. However, the charge amount of the battery pack may be calculated based on the charge / discharge history of the battery pack obtained from the current value detected by the current sensor.

It is a block diagram which shows schematic structure of the power supply system in the 1st Embodiment of this invention. It is sectional drawing for demonstrating the structure of the battery cell which comprises the assembled battery in the power supply system shown in FIG. It is a flowchart for demonstrating the control method of the power supply system shown in FIG. It is a flowchart for demonstrating the dendrite precipitation amount calculation process shown to step S101 of FIG. 6 is a flowchart for explaining a modification of the dendrite precipitation amount calculation process shown in FIG. 4. It is a figure for demonstrating the effect by the power supply system shown in FIG. It is a figure for demonstrating the electric vehicle carrying the power supply system shown in FIG. It is a flowchart for demonstrating the control method of the power supply system in the 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the power supply system in the 3rd Embodiment of this invention. 10 is a flowchart for explaining a control method of the power supply system shown in FIG. 9.

Explanation of symbols

10 battery pack (lithium secondary battery),
11 battery cell (lithium secondary battery),
14 positive electrode,
16 negative electrode,
20 External power supply (dissolution removal means, potential adjustment means),
25 Ultrasonic oscillator (dissolution removal means),
30 voltage sensor (charge amount detection means),
31 cell voltage sensor,
40 temperature sensor,
50 power supply control device,
51 CPU (precipitation amount calculation means),
52 memory (storage means),
70 motor (dissolution removal means, potential adjustment means),
100 power supply system,
200 Electric car (vehicle).

Claims (12)

A deposition amount calculating means for calculating a deposition amount of lithium dendrite deposited on the negative electrode of the lithium secondary battery in accordance with charge and discharge of the lithium secondary battery;
A power supply system comprising: a dissolution removal unit that dissolves and removes the dendrite in accordance with a precipitation amount of the dendrant calculated by the precipitation amount calculation unit. A storage means for storing charge / discharge history information indicating a history of charging and discharging of the lithium secondary battery;
2. The power supply system according to claim 1, wherein the deposition amount calculation unit calculates the deposition amount of the dendland based on charge / discharge history information of the lithium secondary battery.   The power supply system according to claim 2, wherein the charge / discharge history information includes charge count information indicating the number of times the lithium secondary battery has been charged.   The power supply system according to claim 2, wherein the charge / discharge history information includes operating time information indicating an operating time of the lithium secondary battery. The charge / discharge history information further includes fast charge number information indicating the number of times the lithium secondary battery is fast charged, and full charge number information indicating the number of times the lithium secondary battery is fully charged,
The precipitation amount calculating means is configured to reduce the dendrite precipitation amount as the number of times the lithium secondary battery is charged at high speed and the number of times the lithium secondary battery is fully charged increases. 4. The power supply system according to claim 3, wherein the deposition amount of the dendland is calculated based on the charge count information, the fast charge count information, and the full charge count information.   2. The power supply system according to claim 1, wherein the dissolution removing unit includes a potential adjusting unit configured to dissolve and remove the dendrite by increasing a potential of a negative electrode of the lithium secondary battery.   The dendrite deposition amount is corrected based on temperature information of the environment in which the lithium secondary battery is used so that the dendrite deposition amount increases as the temperature of the environment in which the lithium secondary battery is used increases. The power supply system according to claim 1, wherein:   The temperature information includes temperature information of the lithium secondary battery, outside air temperature information of a device equipped with the lithium secondary battery as a driving power source, or climate information of a region where the device is used. The power supply system according to claim 7. A charge amount detecting means for detecting a charge amount of the lithium secondary battery;
2. The power supply system according to claim 1, wherein the dissolution removal unit dissolves and removes the dendrite when the charge amount of the lithium secondary battery is less than a set value.   The power supply system according to claim 9, wherein the charge amount detection unit includes a voltage sensor that detects an open voltage of the lithium secondary battery.   A vehicle comprising the power supply system according to claim 1 as a drive power supply. A calculation step of calculating the amount of lithium dendrite deposited on the negative electrode of the lithium secondary battery in accordance with the charge and discharge of the lithium secondary battery;
A power supply system control method comprising: a dissolution removal step of dissolving and removing the dendrite in accordance with the amount of dendrant deposited calculated in the calculation step.

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