JP5407893B2 - Secondary battery system and hybrid vehicle - Google Patents

Description

  The present invention relates to a secondary battery system and a hybrid vehicle having the secondary battery system.

  Secondary batteries, such as nickel metal hydride storage batteries and lithium ion secondary batteries, are in increasing demand as power sources for portable devices and as power sources for electric vehicles and hybrid vehicles. For this reason, in recent years, many secondary battery charge / discharge control devices and secondary battery systems equipped with charge / discharge control means have been proposed (for example, see Patent Document 1).

JP 7-255133 A

  In the charge / discharge control device of Patent Document 1, the ON / OFF switch is turned on at the time of charging the secondary battery, the voltage VE across the secondary battery is compared with the charge end voltage VMAX, and when VE ≧ VMAX, Turn off the OFF switch to finish charging. At the time of discharging, the control switch is turned on, the voltage VE between both ends is compared with the discharge end voltage VMIN, and when VE ≦ VMIN, the control switch is turned off to stop the discharge. Furthermore, the charging / discharging control device of Patent Document 1 has VMAX downward and VMIN upward in accordance with the number of times each switch is operated by the counter, the elapsed use time by the timer, and the travel distance by the odometer. to correct. Accordingly, it is described that even if the history of the secondary battery (history such as the number of charge / discharge cycles) progresses, the increasing state of the capacity deterioration rate is alleviated and the battery life can be extended.

  By the way, in secondary batteries, such as a lithium ion secondary battery, the salt concentration of electrolyte solution may become non-uniform | heterogenous in an electrode body by repeating charging / discharging (a salt concentration becomes uneven in an electrode body). Due to this salt concentration unevenness, the internal resistance of the secondary battery may increase, and the output characteristics of the secondary battery may deteriorate.

  In particular, the charging current average value A = ∫ (Ic) dt / t, which is the average value of the charging current value Ic, is 10% of the discharging current average value B = ∫ (Id) dt / t, which is the average value of the discharging current value Id. More than twice (A / B ≧ 10), and when charging / discharging of the secondary battery is performed with the charging current average value A being 10C or more (hereinafter, such charging / discharging is also referred to as high-rate overcharging / discharging). ), The salt concentration unevenness of the electrolytic solution increases in the electrode body. Due to this salt concentration unevenness, the internal resistance of the secondary battery greatly increases (for example, increases to 1.5 times or more of the initial value (internal resistance value of the secondary battery in the initial state without salt concentration unevenness)), and the secondary battery The output characteristics of the battery may be greatly degraded.

  On the other hand, the charging current average value A is 0.1 times or less (A / B ≦ 0.1) of the discharge current average value B, and the discharge current average value B is 10 C or more. Even when the battery is charged / discharged (hereinafter, such charge / discharge is also referred to as “high rate discharge excessive charge / discharge”), the salt concentration unevenness of the electrolytic solution increases in the electrode body. Even with this salt concentration unevenness, the internal resistance of the secondary battery is greatly increased (for example, increased to 1.5 times or more of the initial value), and the output characteristics of the secondary battery may be greatly deteriorated.

  In particular, when a secondary battery is mounted as a power source for driving a hybrid vehicle, the above-described high rate overcharge / discharge and high rate overcharge / discharge are performed, and the electrolyte concentration in the electrolyte is greatly uneven. It was easy. For this reason, in particular, the secondary battery mounted as a driving power source for a hybrid vehicle has a large increase in internal resistance (for example, more than 1.5 times the initial value) due to the above-described salt concentration unevenness, and a large output characteristic. There was a risk of lowering.

  However, in the control method using the charge / discharge control device of Patent Document 1, the internal resistance of the secondary battery increased due to the salt concentration unevenness of the electrolytic solution generated in the electrode body (for example, increased to 1.5 times or more of the initial value). Could not be lowered.

  The present invention has been made in view of the current situation, and a secondary battery system capable of appropriately reducing the internal resistance of a secondary battery that has been increased due to salt concentration unevenness of an electrolytic solution generated in an electrode body, And it aims at providing a hybrid vehicle.

  One aspect of the present invention is a secondary battery system comprising a secondary battery and charge / discharge control means for controlling charge / discharge of the secondary battery, wherein the charge / discharge control means includes the secondary battery. When the internal resistance value is 1.5 times or more of the initial value, the charging current average value A = ∫ (Ic) dt / t, which is the average value of the charging current value Ic of the secondary battery, and the two A value of A / B which is a ratio of discharge current average value B = ∫ (Id) dt / t which is an average value of discharge current value Id of the secondary battery is 10 or more, and the average charge current value A is 10C. When the above is satisfied, the secondary battery is subjected to a first pulse charge / discharge in which the discharge current value is made larger than the charge current value and charging and discharging are repeated, and the internal resistance value of the secondary battery is the initial value. In the case of 1.5 times or more, the A / B value is 0.1 or less, and the discharge current average value When B is 10 C or more, the secondary battery system performs second pulse charging / discharging for repeating the charging and discharging by making the charging current value larger than the discharging current value with respect to the secondary battery.

  In the above-described secondary battery system, when the internal resistance value of the secondary battery is 1.5 times or more of the initial value, the charging current average value A, which is the average value of the charging current value Ic of the secondary battery. The value of A / B, which is the ratio of discharge current average value B = ｄ (Id) dt / t, which is the average value of discharge current value Id of secondary battery = ∫ (Ic) dt / t, is 10 or more, In addition, when the charging current average value A is 10C or more, the charging / discharging control means performs the first pulse charging / discharging for the secondary battery to repeat the charging and discharging by making the discharging current value larger than the charging current value. Do.

  When the internal resistance value of the secondary battery is 1.5 times or more of the initial value, the A / B value is 10 or more, and the charging current average value A is 10 C or more. May cause non-aqueous electrolyte salt concentration unevenness in the electrode body of the secondary battery, and due to this influence, it may be determined that the internal resistance value of the secondary battery has increased to a value of 1.5 times or more of the initial value. it can. Therefore, the charge / discharge control means is used when the internal resistance of the secondary battery becomes 1.5 times or more of the initial value and the above-described high rate overcharge / discharge is performed. On the other hand, the first pulse charge / discharge is performed.

  In this way, by performing the first pulse charge / discharge in which the discharge current value is made larger than the charge current value and charging and discharging are repeated, the salt concentration unevenness caused by the above-mentioned high rate overcharge / discharge (which occurs in the electrode body). In addition, the internal resistance of the secondary battery can be reduced by reducing the salt concentration unevenness of the electrolytic solution.

  In the above secondary battery system, the internal resistance value of the secondary battery is 1.5 times or more of the initial value, and the A / B value is 0.1 or less, and the discharge current When the average value B is 10 C or more, the charge / discharge control means performs the second pulse charge / discharge for the secondary battery to repeat the charge and discharge by making the charge current value larger than the discharge current value.

  When the internal resistance value of the secondary battery is 1.5 or more times the initial value, the A / B value is 0.1 or less and the discharge current average value B is 10 C or more. In this case, non-aqueous electrolyte salt concentration unevenness occurs in the electrode body of the secondary battery, and it is determined that the internal resistance value of the secondary battery has increased to a value of 1.5 times or more of the initial value due to this influence. be able to. Therefore, the charge / discharge control means is used when the internal resistance of the secondary battery is 1.5 times or more of the initial value, and when the above-described high rate overcharge / discharge is performed, Second pulse charge / discharge is performed.

  In this way, by performing the second pulse charge / discharge in which the charge current value is made larger than the discharge current value and the charge and discharge are repeated, the salt concentration unevenness caused by the above-described high rate overcharge / discharge (which occurs in the electrode body). In addition, the internal resistance of the secondary battery can be reduced by reducing the salt concentration unevenness of the electrolytic solution.

  As described above, in the above-described secondary battery system, the internal resistance of the secondary battery that has been increased (increased to 1.5 times or more of the initial value) due to the salt concentration unevenness of the electrolyte generated in the electrode body can be appropriately reduced. Can do.

  For example, iR (internal resistance value) = ΔV / I can be used as the internal resistance value of the secondary battery. The iR (internal resistance value) can be calculated by the above formula based on the battery voltage change ΔV and the current value I during the predetermined time pulse discharge with respect to the secondary battery at a constant current value I, for example. it can.

  In addition, the current value of “1C” is a current value that allows a constant current charge (pulse charge) of a SOC 0% battery to SOC 100% in 1 hour, or a constant current discharge of a SOC 100% battery to SOC 0% in 1 hour ( This refers to the current value that can be generated by pulse discharge. Therefore, the charging current value of “10C” corresponds to a current value of a magnitude that allows constant current charging (pulse charging) of the SOC 0% battery to SOC 100% in 0.1 hour. The discharge current value of “10C” corresponds to a current value of a magnitude that allows constant current discharge (pulse discharge) to a SOC of 0% in 0.1 hour.

The charging current average value A = ∫ (Ic) dt / t is an average value of the charging current value Ic of the secondary battery, and the charging current integrated value ∫ (Ic) obtained by integrating the charging current value Ic of the secondary battery. It is a value obtained by dividing (dividing) dt by the accumulated time t (charging time t).
Further, the average discharge current B = ∫ (Id) dt / t is an average value of the discharge current value Id of the secondary battery, and the discharge current integrated value ∫ (Id) obtained by integrating the discharge current value Id of the secondary battery. It is a value obtained by dividing (dividing) dt by the accumulated time t (discharge time t).

  Furthermore, in the above secondary battery system, an internal resistance value calculating means for calculating an internal resistance value of the secondary battery, a current value ratio calculating means for calculating the value of A / B, and the internal resistance value 1. Resistance value determining means for determining whether or not the internal resistance value calculated by the calculating means is a value equal to or greater than 1.5 times the initial value; First current value ratio determining means for determining whether or not the value of A / B calculated by the current value ratio calculating means is 10 or more when it is determined that the value is 5 times or more; When the charging current value determining means for determining whether or not the charging current average value A is 10 C or more and the resistance value determining means determine that the internal resistance value is 1.5 times or more of the initial value Further, the value of A / B calculated by the current value ratio calculating means is 0. A second current value ratio determining means for determining whether or not it is 1 or less, and a discharge current value determining means for determining whether or not the discharge current average value B is 10 C or more, the charge / discharge control The means is when the internal resistance value of the secondary battery is determined to be 1.5 times or more of the initial value by the resistance value determining means, and the A / B ratio is determined by the first current value ratio determining means. When it is determined that the value is 10 or more and the charging current value determination means determines that the charging current average value A is 10 C or more, the secondary battery is charged with the first pulse charge / discharge. And when the resistance value determining means determines that the internal resistance value of the secondary battery is 1.5 times or more of the initial value, the second current value ratio determining means determines the A / B value. Is determined to be 0.1 or less, and the discharge current value determination Above when the discharge current average value B is determined to be equal to or greater than 10C, it may be a secondary battery system for performing the second pulse charge and discharge with respect to the secondary battery by.

  In the above secondary battery system, the internal resistance value of the secondary battery is determined to be 1.5 times or more of the initial value by the resistance value determining means, and the A / B value is 10 by the first current value ratio determining means. When it is determined that the charging current value determining means determines that the charging current average value A is 10C or more, the charging / discharging control means discharges the secondary battery more than the charging current value. First pulse charging / discharging is performed by increasing the current value and repeating charging and discharging.

  When it is determined that the internal resistance value of the secondary battery is 1.5 or more times the initial value, the A / B value is 10 or more, and the charging current average value A is 10 C or more The salt concentration unevenness of the non-aqueous electrolyte occurs in the electrode body of the secondary battery, and it can be determined that the internal resistance value of the secondary battery has increased to a value of 1.5 times or more of the initial value due to this influence. . Therefore, the charge / discharge control means is a case where the internal resistance of the secondary battery is 1.5 times or more of the initial value, and when it is determined that the above-described high rate overcharge / discharge is performed, A first pulse charge / discharge is performed on the battery. Thereby, the salt concentration unevenness (salt concentration unevenness of the electrolytic solution generated in the electrode body) generated by the above-described high rate overcharge / discharge can be reduced, and the internal resistance of the secondary battery can be reduced.

  In the above secondary battery system, the internal resistance value of the secondary battery is determined to be 1.5 times or more of the initial value by the resistance value determining means, and the A / B value is determined by the second current value ratio determining means. Is determined to be 0.1 or less, and when it is determined that the discharge current average value B is 10C or more, the charge / discharge control means has a charge current value higher than the discharge current value for the secondary battery. The second pulse charge / discharge is repeated by repeating charging and discharging.

  When it is determined that the internal resistance value of the secondary battery is 1.5 or more times the initial value, the A / B value is 0.1 or less, and the discharge current average value B is 10 C or more The non-aqueous electrolyte has a non-uniform salt concentration in the electrode body of the secondary battery, and it is determined that the internal resistance value of the secondary battery has increased to 1.5 times or more of the initial value due to this effect. Can do. Therefore, the charging / discharging control means is a secondary battery when the internal resistance of the secondary battery is 1.5 times or more of the initial value and when it is determined that the above-described high rate overcharge / discharge is performed. A second pulse charge / discharge is performed on the battery. Thereby, the salt concentration unevenness (salt concentration unevenness of the electrolytic solution generated in the electrode body) caused by the above-described high-rate discharge overcharge / discharge can be reduced, and the internal resistance of the secondary battery can be lowered.

  As described above, in the above-described secondary battery system, the internal resistance of the secondary battery that has been increased (increased to 1.5 times or more of the initial value) due to the salt concentration unevenness of the electrolyte generated in the electrode body can be appropriately reduced. Can do.

  For example, the internal resistance value calculating means calculates iR (internal resistance value) = ΔV / I as the internal resistance value of the secondary battery. Specifically, for example, the secondary battery is subjected to pulse discharge at a constant current value I for a predetermined time, and the internal resistance value iR is calculated by the above formula based on the battery voltage change ΔV and the current value I during this time. .

  Furthermore, in any one of the above secondary battery systems, the charge / discharge control means sets the discharge current value to 10 times or more of the charge current value, and sets the discharge current value to 10C or more. It is preferable that the secondary battery system perform the second pulse charge / discharge by performing pulse charge / discharge, setting the charge current value to 10 times or more of the discharge current value, and setting the charge current value to 10C or more.

  In the above-described secondary battery system, the first pulse charge / discharge is performed by setting the discharge current value to 10 times or more of the charge current value and the discharge current value to 10 C or more. By performing the first pulse charging / discharging with such a current value, the salt concentration unevenness of the electrolytic solution generated in the electrode body can be surely reduced. As a result, the internal resistance of the secondary battery that has greatly increased (1.5 times or more of the initial value) can be reliably reduced.

  Further, in the above-described secondary battery system, the second pulse charge / discharge is performed by setting the charging current value to 10 times or more of the discharging current value and the charging current value to 10 C or more. By performing the second pulse charge / discharge at such a current value, the salt concentration unevenness of the electrolyte solution generated in the electrode body can be surely reduced. As a result, the internal resistance of the secondary battery that has greatly increased (1.5 times or more of the initial value) can be reliably reduced.

  Furthermore, in any one of the above secondary battery systems, the charge / discharge control means equalizes a charge electricity amount and a discharge electricity amount per charge / discharge cycle, and performs the first pulse charge / discharge and the second charge / discharge cycle. A secondary battery system that performs pulse charge and discharge is preferable.

  In the above secondary battery system, when performing the first pulse charge / discharge, the amount of charge per charge / discharge cycle (the amount of electricity charged to the secondary battery) and the amount of discharge (the amount of electricity discharged from the secondary battery) Are made equal to each other and the first pulse charge / discharge is performed. Moreover, also when performing 2nd pulse charging / discharging, the 2nd pulse charging / discharging is performed by making the charging electric quantity and charging electric quantity per charging / discharging cycle equal. Accordingly, the SOC (State Of Charge) of the secondary battery can be kept equal before and after the first pulse charge / discharge. Thereby, the secondary battery which made 1st pulse charging / discharging or 2nd pulse charging / discharging and made internal resistance small can be used appropriately as power supplies, such as a hybrid vehicle.

  Further, in any one of the above secondary battery systems, the secondary battery system further includes a leaving state determining unit that determines whether or not the secondary battery has been left in a neglected state, and the charge / discharge control unit is operated by the leaving state determining unit. It is preferable that the secondary battery system start the first pulse charge / discharge or the second pulse charge / discharge after it is determined that the secondary battery has been left unattended.

In the secondary battery system described above, the first pulse charge / discharge or the second pulse charge / discharge is started after it is determined that the secondary battery has been left in the left state by the left state determination unit. Thereby, 1 pulse charging / discharging or 2nd pulse charging / discharging can be performed appropriately.
Note that the neglected state determination means is configured such that, for example, when a power switch of a hybrid vehicle or the like equipped with the secondary battery as a power source is turned off and the current value flowing through the secondary battery becomes 0 mA, It can be determined that it has been left unattended.

  Furthermore, in the above secondary battery system, the charge / discharge control means may perform the first pulse charge / discharge or the second pulse after the leave state determination means determines that the secondary battery has been left in a leave state. The number of charge / discharge cycles of the first pulse charge / discharge or the second pulse charge / discharge is determined according to the standing time until charge / discharge is started, and the determined number of charge / discharge cycles is the same for the secondary battery. A secondary battery system that performs the first pulse charge / discharge or the second pulse charge / discharge may be used.

  The salt concentration unevenness of the electrolytic solution generated in the electrode body of the secondary battery is also reduced by leaving the secondary battery. Accordingly, in the case where the internal resistance of the secondary battery is lowered to an equivalent value by changing the leaving time, the first pulse becomes longer as the leaving time until the first pulse charging / discharging starts is increased. The number of charge / discharge cycles of charge / discharge or second pulse charge / discharge can be reduced.

  On the other hand, in the above-described secondary battery system, the charge / discharge control means starts the first pulse charge / discharge or the second pulse charge / discharge after it is determined that the secondary battery is left in the left state by the left state determination means. The number of charging / discharging cycles of the first pulse charging / discharging or the second pulse charging / discharging is determined according to the standing time until. Then, the first pulse charge / discharge or the second pulse charge / discharge is performed on the secondary battery for the determined number of cycles. Thereby, the internal resistance of a secondary battery can be reduced efficiently, without performing 1st pulse charging / discharging or 2nd pulse charging / discharging excessively.

  Another aspect of the present invention is a hybrid vehicle in which any one of the secondary battery systems is mounted as a drive power supply system for the hybrid vehicle.

  When a secondary battery is mounted as a driving power source for a hybrid vehicle, the above-described high rate overcharge / discharge and high rate overcharge / discharge are performed, and the salt concentration unevenness of the electrolytic solution tends to increase in the electrode body. . For this reason, in the secondary battery mounted as a driving power source for the hybrid vehicle, in particular, the internal resistance is greatly increased (increased to 1.5 times or more of the initial value) due to the above-described salt concentration unevenness, and the output characteristics are greatly decreased. There was a fear.

  On the other hand, in the above-described hybrid vehicle, the above-described secondary battery system is mounted as a drive power supply system for the hybrid vehicle. For this reason, in the above-described hybrid vehicle, the internal resistance of the secondary battery that has been greatly increased (increased to 1.5 times or more of the initial value) due to the salt concentration unevenness of the electrolyte generated in the electrode body can be appropriately reduced. it can. As a result, a decrease in output characteristics of the secondary battery can be suppressed, and a decrease in traveling performance of the hybrid vehicle can be suppressed.

1 is a schematic diagram of a hybrid vehicle according to an embodiment. It is the schematic of the secondary battery system concerning embodiment. It is sectional drawing of the lithium ion secondary battery concerning embodiment. It is sectional drawing of the electrode body of a lithium ion secondary battery. It is a partial expanded sectional view of an electrode body, and is equivalent to the B section enlarged view of FIG. It is a flowchart which shows the control method of the secondary battery concerning embodiment. It is a figure which shows the pattern of 1st pulse charging / discharging. It is a figure which shows the pattern of a 2nd pulse charging / discharging. It is a graph which shows the relationship between the cycle number of a 1st pulse charging / discharging (2nd pulse charging / discharging) and iR (internal resistance value) of a secondary battery.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the hybrid vehicle 1 of the present embodiment includes a vehicle body 2, an engine 3, a front motor 4, a rear motor 5, a secondary battery system 6, and a cable 7, and the engine 3, the front motor 4, This is a hybrid vehicle that is driven in combination with the rear motor 5. Specifically, the hybrid vehicle 1 is configured so that the secondary battery system 6 is mounted as a power supply system for driving the front motor 4 and the rear motor 5 and can be driven using the engine 3, the front motor 4, and the rear motor 5. Has been.

  Among these, the secondary battery system 6 is attached to the vehicle body 2 of the hybrid vehicle 1 and is connected to the front motor 4 and the rear motor 5 by a cable 7. As shown in FIG. 2, the secondary battery system 6 includes a battery pack 10 in which a plurality of lithium ion secondary batteries 100 are electrically connected in series to each other, a control device 30, a voltage detection device 40, and current detection. Device 50.

  As shown in FIG. 3, the lithium ion secondary battery 100 is a rectangular sealed lithium ion secondary battery including a rectangular parallelepiped battery case 110, a positive electrode terminal 120, and a negative electrode terminal 130. Among these, the battery case 110 is made of metal, and includes a rectangular housing portion 111 that forms a rectangular parallelepiped housing space, and a metal lid portion 112. An electrode body 150, a positive current collecting member 122, a negative current collecting member 132, and the like are accommodated in the battery case 110 (rectangular accommodation portion 111).

  The electrode body 150 is an oblong cross section, and is a flat wound body formed by winding a sheet-like positive electrode plate 155, a negative electrode plate 156, and a separator 157 (see FIGS. 4 and 5). The positive electrode plate 155 has a positive electrode current collecting member 151 made of an aluminum foil and a positive electrode mixture 152 coated on the surface thereof. The negative electrode plate 156 has a negative electrode current collector 158 made of copper foil and a negative electrode mixture 159 coated on the surface thereof.

  The electrode body 150 is positioned at one end portion (right end portion in FIG. 3) in the axial direction (left and right direction in FIG. 3), and a positive electrode winding portion 155b in which only a part of the positive electrode current collecting member 151 overlaps in a spiral shape. , Located at the other end (left end in FIG. 3), and only a part of the negative electrode current collecting member 158 spirally overlaps between the negative electrode winding part 156b and the positive electrode winding part 155b and the negative electrode winding part 156b. And a power generation unit 150b in which a positive electrode plate 155, a negative electrode plate 156, and a separator 157 are wound.

  The positive electrode plate 155 is coated with a positive electrode mixture 152 including a positive electrode active material 153 at a portion other than the positive electrode winding portion 155b (see FIG. 5). The negative electrode plate 156 is coated with a negative electrode mixture 159 including a negative electrode active material 154 at a portion excluding the negative electrode winding portion 156b (see FIG. 5). The positive electrode winding part 155 b is electrically connected to the positive electrode terminal 120 through the positive electrode current collecting member 122. The negative electrode winding part 156 b is electrically connected to the negative electrode terminal 130 through the negative electrode current collecting member 132.

In this embodiment, lithium nickelate is used as the positive electrode active material 153. Further, graphite is used as the negative electrode active material 154. Further, as the separator 157, a porous sheet made of polyethylene is used. Further, as the non-aqueous electrolyte, a solution obtained by dissolving lithium hexafluorophosphate as a lithium salt in a solution obtained by mixing EC (ethylene carbonate) and DEC (diethyl carbonate) is used.
The battery capacity of the lithium ion secondary battery 100 is 5.0 Ah.

The current detection device 50 (see FIG. 2) detects the value of current flowing through the lithium ion secondary battery 100 constituting the assembled battery 10. In the current detection device 50, the charging current value Ic when the lithium ion secondary battery 100 is charged and the discharging current value when the lithium ion secondary battery 100 is discharged. It is possible to detect it separately from Id.
Further, the voltage detection device 40 detects the battery voltage of the lithium ion secondary battery 100 constituting the assembled battery 10.

  The control device 30 includes a ROM, a CPU, a RAM, and the like (not shown), and controls charging / discharging of the lithium ion secondary battery 100 constituting the assembled battery 10. The control device 30 controls the exchange of electricity between the lithium ion secondary battery 100 constituting the assembled battery 10 and the inverter (motor) while the hybrid vehicle 1 is traveling.

  Further, the control device 30 calculates the internal resistance value of the lithium ion secondary battery 100 constituting the assembled battery 10. Specifically, iR = ΔV / I is calculated as the internal resistance value of the lithium ion secondary battery 100.

Specifically, the control device 30 applies a predetermined current value I (for example, a constant current value of 10C) to the lithium ion secondary battery 100 at a predetermined time (for example, every hour) for a predetermined time (for example, Perform pulse discharge for 10 seconds. At this time, the control device 30 uses the voltage detection device 40 to detect the battery voltage of the lithium ion secondary battery 100 before and after pulse discharge. Then, based on the constant current value I and the battery voltage change amount ΔV of the lithium ion secondary battery 100 before and after the pulse discharge, the internal resistance value iR is calculated by the arithmetic expression (iR = ΔV / I).
In addition, since the battery capacity of the lithium ion secondary battery 100 of this embodiment is 5.0 Ah, the current value of “10 C” corresponds to “50 A”.

  Further, the control device 30 determines that the internal resistance value (iR) of the lithium ion secondary battery 100 calculated as described above is 1.5 times or more of the initial value every predetermined time (for example, every hour). Determine whether it is a value. Here, the initial value is an internal resistance value (iR) of the lithium ion secondary battery 100 in the initial state. This initial value is stored in advance in a ROM (not shown) of the control device 30.

  The initial value (iR) was 3.0 mΩ when calculated based on iR = ΔV / I as described above. Therefore, in the present embodiment, the control device 30 determines whether or not the internal resistance value (iR) of the lithium ion secondary battery 100 is 4.5 mΩ or more every predetermined time (for example, every hour). Will do.

  In addition, the control device 30 integrates the charging current value Ic of the lithium ion secondary battery 100 detected by the current detection device 50 during charging of the lithium ion secondary battery 100. Furthermore, the control device 30 integrates the discharge current value Id of the lithium ion secondary battery 100 detected by the current detection device 50 during the discharge of the lithium ion secondary battery 100. In this way, the control device 30 integrates the charging current value Ic and the discharging current value Id during charging / discharging of the lithium ion secondary battery 100, respectively.

  Further, the control device 30 determines the charging current value from the time when the calculation (measurement) of the internal resistance value is started to the time when the calculation (measurement) of the internal resistance value is started from a predetermined time (for example, one hour before). Based on the charging current integrated value ∫ (Ic) dt obtained by integrating Ic, the charging current average value A = ∫ (Ic) dt / t, which is the average value of the charging current value Ic within the period, is determined every predetermined time (for example, Every 1 hour). That is, the charging current average value A = ∫ (Ic) dt / t obtained by dividing (dividing) the charging current integrated value ∫ (Ic) dt by the integration time t (charging time t) is set at predetermined intervals (for example, 1 hour). Every).

Furthermore, based on the discharge current integrated value ∫ (Id) dt obtained by integrating the discharge current value Id within the same period (within a predetermined time), the discharge current average value B = the average value of the discharge current value Id within that period. ∫ (Id) dt / t is calculated every predetermined time (for example, every hour). That is, a discharge current average value B = ∫ (Id) dt / t obtained by dividing (dividing) the discharge current integrated value ∫ (Id) dt by the integration time t (discharge time t) is set at predetermined intervals (for example, 1 hour). Every).
Then, a value of A / B, which is a ratio between the charging current average value A and the discharging current average value B, is calculated every predetermined time (for example, every hour).

  That is, the control device 30 charges the charging current from a predetermined time (for example, one hour before) to the start of calculation (measurement) of the internal resistance value before the start of (measurement) calculation of the internal resistance value. Charge current average value A = ∫ (Ic) dt / t, which is an average value of values Ic, and discharge current average value B = ∫ (Id) dt / t, which is an average value of discharge current values Id during the same period The ratio A / B is calculated every predetermined time (for example, every hour).

  Here, the charging current integrated value ∫ (Ic) dt is a value obtained by integrating the charging current value Ic during a predetermined time (for example, 1 hour), and the lithium ion secondary battery 100 is charged during the predetermined time. This corresponds to the amount of electricity (charged electricity) (Ah). Further, the integrated discharge current value Ｉ (Id) dt is a value obtained by integrating the charge current value Ic during the predetermined time (for example, 1 hour), and is discharged from the lithium ion secondary battery 100 during the predetermined time. This corresponds to the amount of electricity (discharged electricity) (Ah).

Further, the control device 30 determines whether or not the calculated A / B value is 10 or more every predetermined time (for example, every hour).
Furthermore, when it is determined that the calculated A / B value is 10 or more, the control device 30 determines whether or not the charging current average value A is 10 C or more.

  The internal resistance value (iR) of the lithium ion secondary battery 100 is determined to be 1.5 times or more of the initial value (specifically, 4.5 mΩ or more). When it is determined that the value of B is 10 or more and the charging current average value A is 10 C or more, the salt concentration unevenness (non-aqueous electrolyte) in the electrode body 150 of the lithium ion secondary battery 100 ( Lithium hexafluorophosphate concentration unevenness) occurs, and as a result, the internal resistance value (iR) of the lithium ion secondary battery 100 is 1.5 times or more of the initial value (specifically, 4.5 mΩ or more) ).

Specifically, when the electrode body 150 is viewed in the axial direction (left-right direction in FIG. 3), the Li salt concentration of the non-aqueous electrolyte contained in the central portion of the power generation unit 150b increases, while both ends of the power generation unit 150b. Part (left and right ends in FIG. 3), the Li salt concentration of the nonaqueous electrolytic solution is reduced, and non-aqueous electrolyte salt concentration unevenness (Li salt bias) occurs in the electrode body 150. It can be determined that the internal resistance value (iR) of the lithium ion secondary battery 100 has increased to a value that is 1.5 times or more of the initial value (specifically, 4.5 mΩ or more).
The internal resistance value of the lithium ion secondary battery 100 that has increased due to such salt concentration unevenness can be reduced by performing a first pulse charge / discharge, which will be described later, on the lithium ion secondary battery 100.

  Furthermore, when it is determined that the charging current average value A is 10 C or more, the control device 30 determines whether or not the lithium ion secondary battery 100 constituting the assembled battery 10 has been left unattended. Specifically, when the vehicle power switch of the hybrid vehicle 1 is turned off and the current value flowing through the lithium ion secondary battery 100 becomes 0 mA, it is determined that the lithium ion secondary battery 100 has been left unattended. .

  Note that the control device 30 is electrically connected to a vehicle power switch (not shown), and the vehicle power switch of the hybrid vehicle 1 is turned OFF by receiving a signal that the vehicle power switch is turned OFF. Judgment can be made. In addition, the control device 30 can determine that the current value flowing through the lithium ion secondary battery 100 has become 0 mA when the current value detected by the current detection device 50 has become 0 mA.

  Furthermore, after determining that the lithium ion secondary battery 100 has been left as it is, the control device 30 measures the time during which the lithium ion secondary battery 100 is left until the first pulse charge / discharge described below is started. In addition, the leaving time of the lithium ion secondary battery 100 until the first pulse charge / discharge is started is determined by the control device 30 based on, for example, the leaving history (leaving time) of the lithium ion secondary battery 100, for example. Can do.

  Further, the control device 30 determines the first pulse charge according to the leaving time of the lithium ion secondary battery 100 from when it is determined that the lithium ion secondary battery 100 is left to stand until the first pulse charge / discharge is started. Determine the number of charge / discharge cycles for discharge. Specifically, it is determined as follows.

  The salt concentration unevenness of the non-aqueous electrolyte (concentration unevenness of lithium hexafluorophosphate) generated in the electrode body 150 of the lithium ion secondary battery 100 is also reduced by leaving the lithium ion secondary battery 100 to stand. Therefore, in the case where the internal resistance of the lithium ion secondary battery 100 is lowered to an equivalent value by changing the leaving time, the longer the leaving time until the first pulse charging / discharging starts, the more the first pulse charging / discharging takes place. The number of charge / discharge cycles can be reduced.

Here, the experiment which investigated the relationship between the leaving time of the lithium ion secondary battery 100, the number of charge / discharge cycles of the first pulse charge / discharge, and the internal resistance value (iR) will be described.
First, high-rate overcharge / discharge is performed on the lithium ion secondary battery 100 in the initial state, and the internal resistance value (iR) of the lithium ion secondary battery 100 is reduced to 4.5 mΩ (1.5 times the initial value). Raised. Specifically, as a high rate charge overcharge / discharge, the charge current value Ic is set to a high rate of 10C, the discharge current value Id is set to 1C, the charge time and the discharge time are equalized, and overcharge pulse discharge is performed. went. In this high rate overcharge / discharge, the charging current average value A is 10C, and the charging current average value A is 10 times the discharge current average value B (A / B = 10).

  By repeatedly performing such high-rate overcharge / discharge (pulse charging with a large current), salt concentration unevenness of the non-aqueous electrolyte occurs in the electrode body 150 of the lithium ion secondary battery 100. Specifically, when the electrode body 150 is viewed in the axial direction (left-right direction in FIG. 3), the Li salt concentration of the non-aqueous electrolyte contained in the central portion of the power generation unit 150b increases, while both ends of the power generation unit 150b. Li salt concentration of the non-aqueous electrolyte contained in the portion (left and right end portions in FIG. 3) decreases, and non-aqueous electrolyte salt concentration unevenness (Li salt bias) occurs in the electrode body 150. Due to such salt concentration unevenness, the internal resistance value (iR) of the lithium ion secondary battery 100 increases.

  In addition, since the battery capacity of the lithium ion secondary battery 100 of this embodiment is 5.0 Ah, the current value of “10C” corresponds to “50 A”, and the current value of “1C” corresponds to “5 A”. .

  Next, the first pulse charge / discharge was performed on the lithium ion secondary battery 100 whose internal resistance (iR) was increased to 4.5 mΩ without leaving the lithium ion secondary battery 100. The first pulse charge / discharge was performed in the pattern shown in FIG. Specifically, the first pulse charge / discharge was performed with a discharge current value of 20 C, a charge current value of 2 C, a discharge time in a charge / discharge cycle of 10 seconds, and a charge time in a charge / discharge cycle of 100 seconds. By repeatedly performing such first pulse charge / discharge, high-rate pulse discharge (pulse discharge with a large current of 20 C) is repeatedly performed on the lithium ion secondary battery 100.

  As described above, high-rate pulse discharge (pulse discharge with a large current of 20 C) is repeatedly performed, so that salt concentration unevenness caused by the above-described high-rate charge overcharge / discharge can be reduced. Specifically, when the electrode body 150 is viewed in the axial direction (left-right direction in FIG. 3), the Li salt concentration of the non-aqueous electrolyte contained in the central portion of the power generation unit 150b is reduced, while the power generation unit 150b The Li salt concentration of the non-aqueous electrolyte contained in both end portions (left and right end portions in FIG. 3) is increased, and the non-aqueous electrolyte solution salt concentration unevenness (Li salt bias) in the electrode body 150 is reduced. Thereby, the internal resistance value (iR) of the raised lithium ion secondary battery 100 can be reduced.

  As described above, the first pulse charge / discharge of the pattern shown in FIG. 7 was performed for 500 charge / discharge cycles. At this time, the internal resistance value (iR) of the lithium ion secondary battery 100 was measured after 300 charge / discharge cycles and after 500 charge / discharge cycles. The results are shown in Table 1.

  Further, after the plurality of lithium ion secondary batteries 100 whose internal resistance value (iR) has been increased to 4.5 mΩ as described above are left for different periods of time, the first pulse having the pattern shown in FIG. Charging / discharging was performed 500 cycles. The standing time was varied from 6 hours, 12 hours, and 24 hours. For these lithium ion secondary batteries 100, the internal resistance values (iR) were measured after 300 charge / discharge cycles and 500 charge / discharge cycles, respectively. These results are also shown in Table 1.

  As shown in Table 1, when the first pulse charge / discharge is performed without leaving the lithium ion secondary battery 100 (standby time is 0 hour), the internal resistance value (iR) is set after 300 charge / discharge cycles. It could be reduced to 4.0 mΩ. Furthermore, after 500 charge / discharge cycles, the internal resistance value (iR) could be reduced to 3.8 mΩ.

  In addition, when the lithium ion secondary battery 100 was allowed to stand for 6 hours (leaving time was 6 hours), the internal resistance value (iR) could be reduced to 4.2 mΩ. Thereafter, the internal resistance value (iR) could be reduced to 3.7 mΩ by performing the first pulse charge / discharge cycle for 300 charge / discharge cycles. Furthermore, after 500 charge / discharge cycles, the internal resistance value (iR) could be reduced to 3.5 mΩ.

  Further, when the lithium ion secondary battery 100 was left for 12 hours (leaving time was 12 hours), the internal resistance value (iR) could be reduced to 4.0 mΩ by being left. Thereafter, the internal resistance value (iR) could be reduced to 3.5 mΩ by performing the first pulse charge / discharge cycle for 300 charge / discharge cycles. Furthermore, after 500 charge / discharge cycles, the internal resistance value (iR) could be reduced to 3.3 mΩ.

  Further, when the lithium ion secondary battery 100 was left for 24 hours (left time was 24 hours), the internal resistance value (iR) could be reduced to 3.8 mΩ. Then, the internal resistance value (iR) could be reduced to 3.3 mΩ by performing the first pulse charge / discharge cycle for 300 charge / discharge cycles. Furthermore, after 500 charge / discharge cycles, the internal resistance value (iR) could be reduced to 3.1 mΩ.

Furthermore, the relationship between the standing time of the lithium ion secondary battery 100 and the number of charge / discharge cycles of the second pulse charge / discharge and the internal resistance (iR) was also investigated.
First, high-rate discharge overcharge / discharge is performed on the lithium ion secondary battery 100 in the initial state, and the internal resistance value (iR) of the lithium ion secondary battery 100 is reduced to 4.5 mΩ (1.5 times the initial value). Raised. Specifically, as a high-rate discharge overcharge / discharge, charge current value Ic is set to 1C, discharge current value Id is set to a high rate of 10C, charge time and discharge time are equalized, and overcharge pulse discharge is performed. went. In this high rate overcharge / discharge, the discharge current average value B is 10 C, and the charge current average value A is 0.1 times the discharge current average value B (A / B = 0.1).

  By repeatedly performing such high-rate discharge overcharge / discharge (pulse discharge due to a large current), unevenness in the salt concentration of the non-aqueous electrolyte occurs in the electrode body 150 of the lithium ion secondary battery 100. Specifically, when the electrode body 150 is viewed in the axial direction (left-right direction in FIG. 3), the Li salt concentration of the non-aqueous electrolyte contained in the central portion of the power generation unit 150b decreases, while both ends of the power generation unit 150b The Li salt concentration of the non-aqueous electrolyte contained in the portion (left and right end portions in FIG. 3) increases, and the salt concentration unevenness (Li salt bias) of the non-aqueous electrolyte occurs in the electrode body 150. Due to such salt concentration unevenness, the internal resistance value (iR) of the lithium ion secondary battery 100 increases.

  Next, as in the case where the internal resistance value (iR) of the lithium ion secondary battery 100 is reduced by the first pulse charge / discharge, the standing time is changed to 0 hours, 6 hours, 12 hours, and 24 hours. Then, the second pulse charge / discharge was performed on the lithium ion secondary battery 100. The second pulse charge / discharge was performed for 500 cycles in the pattern shown in FIG. Specifically, the second pulse charge / discharge was performed with a charge current value of 20 C, a discharge current value of 2 C, a charge time in a charge / discharge cycle of 10 seconds, and a discharge time in a charge / discharge cycle of 100 seconds. By repeatedly performing such second pulse charge / discharge, high-rate pulse charge (pulse charge with a large current of 20 C) is repeatedly performed on the lithium ion secondary battery 100.

  As described above, high-rate pulse charging (pulse charging with a large current of 20 C) is repeatedly performed, so that salt concentration unevenness caused by the above-described high-rate discharge overcharge / discharge can be reduced. Specifically, when the electrode body 150 is viewed in the axial direction (left-right direction in FIG. 3), the Li salt concentration of the non-aqueous electrolyte contained in the central portion of the power generation unit 150b is increased, while the power generation unit 150b The Li salt concentration of the non-aqueous electrolyte contained in both ends (left and right ends in FIG. 3) is reduced to reduce the non-aqueous electrolyte salt concentration unevenness (Li salt bias) in the electrode body 150. Thereby, the internal resistance value (iR) of the raised lithium ion secondary battery 100 can be reduced.

  As in the case of performing the first pulse charge / discharge, the internal resistance value (iR) of the lithium ion secondary battery 100 was measured after standing, after 300 charge / discharge cycles, and after 500 charge / discharge cycles. The same result as that obtained when the first pulse charge / discharge was performed was obtained. The results are shown in Table 2.

  Based on the experimental results shown in Tables 1 and 2, a graph showing the relationship between the number of cycles of the first pulse charge / discharge or the second pulse charge / discharge and the iR (internal resistance value) of the secondary battery was prepared. This graph is shown in FIG. In FIG. 9, the case where the first pulse charge / discharge (or second pulse charge / discharge) is performed with the leave time set to 0 hours is indicated by a solid line, and the first pulse charge / discharge (or the second pulse charge / discharge set with the leave time set to 6 hours). The case where the first pulse charging / discharging (or the second pulse charging / discharging) is performed with the standing time being 12 hours is indicated by a two-dot chain line.

Here, a case where the internal resistance value (iR) of the lithium ion secondary battery 100 whose internal resistance value (iR) has increased to 4.5 mΩ is decreased to, for example, 3.8 mΩ will be considered with reference to FIG. .
The internal resistance value of the lithium ion secondary battery 100 can be obtained by the first pulse charge / discharge (or second pulse charge / discharge) without leaving the lithium ion secondary battery 100 whose internal resistance value (iR) has increased to 4.5 mΩ. In order to reduce (iR) to 3.8 mΩ, the first pulse charge / discharge (or second pulse charge / discharge) needs to be performed 500 cycles.

Further, after the lithium ion secondary battery 100 whose internal resistance value (iR) has increased to 4.5 mΩ is left for 6 hours, the internal resistance value (iR) is set to 3 by the first pulse charge / discharge (or second pulse charge / discharge). It is considered that the first pulse charge / discharge (or second pulse charge / discharge) may be performed for 230 cycles in order to reduce the voltage to 0.8 mΩ (see FIG. 9).
Further, after the lithium ion secondary battery 100 whose internal resistance value (iR) has increased to 4.5 mΩ is left for 12 hours, the internal resistance value (iR) is set to 3 by the first pulse charge / discharge (or second pulse charge / discharge). It is considered that the first pulse charge / discharge (or second pulse charge / discharge) may be performed 100 cycles in order to reduce the voltage to 0.8 mΩ (see FIG. 9).

  Therefore, in the secondary battery system 6 of this embodiment, the lithium ion secondary battery 100 whose internal resistance value (iR) has increased to 4.5 mΩ can be reduced to 3.8 mΩ so that the internal resistance value (iR) of the lithium ion secondary battery 100 can be decreased to 3.8 mΩ. The number of charge / discharge cycles of the first pulse charge / discharge is determined according to the standing time of the ion secondary battery 100. For example, when the leaving time is 6 hours, the control device 30 determines the number of charge / discharge cycles of the first pulse charge / discharge to be 230 cycles. When the standing time is 12 hours, the control device 30 determines the number of charge / discharge cycles of the first pulse charge / discharge as 100 cycles. When the leaving time is set to 0 hour, the control device 30 determines the number of charge / discharge cycles of the first pulse charge / discharge as 500 cycles.

  Furthermore, the control device 30 performs the first pulse charge / discharge with respect to the lithium ion secondary battery 100 by the determined number of charge / discharge cycles. The first pulse charge / discharge is performed in the pattern shown in FIG. Specifically, the first pulse charge / discharge is performed with a discharge current value of 20 C, a charge current value of 2 C, a discharge time in a charge / discharge cycle of 10 seconds, and a charge time in a charge / discharge cycle of 100 seconds. Thereby, high-rate pulse discharge (pulse discharge due to a large current of 20 C) is repeatedly performed, so that the salt concentration unevenness of the non-aqueous electrolyte in the electrode body 150 is reduced, and the internal resistance value of the lithium ion secondary battery 100 is reduced. (IR) can be reliably reduced.

  The assembled battery 10 (lithium ion secondary battery 100) is connected to another secondary battery (assembled battery) (not shown) via the control device 30. For this reason, the control device 30 exchanges electricity between the lithium ion secondary battery 100 constituting the assembled battery 10 and another secondary battery (assembled battery), so that the lithium ion secondary battery 100 On the other hand, the first pulse charge / discharge is performed. Specifically, the lithium ion secondary battery 100 constituting the assembled battery 10 is charged by supplying power to the assembled battery 10 from another secondary battery (assembled battery). On the other hand, when the lithium ion secondary battery 100 constituting the assembled battery 10 is discharged, the assembled battery 10 is discharged by supplying power discharged from the assembled battery 10 to another secondary battery (assembled battery). Let The same applies to the case of performing the second pulse charge / discharge described later.

  In addition, when it is determined that the calculated A / B value is not 10 or more, the control device 30 determines whether the calculated A / B value is 0.1 or less. When it is determined that the A / B value is 0.1 or less, it is determined whether or not the discharge current average value B is 10 C or more.

  The internal resistance value (iR) of the lithium ion secondary battery 100 is determined to be 1.5 times or more of the initial value (specifically, 4.5 mΩ or more). When it is determined that the value of B is 0.1 or less and the discharge current average value B is 10 C or more, the salt concentration of the non-aqueous electrolyte in the electrode body 150 of the lithium ion secondary battery 100 Unevenness (unevenness of concentration of lithium hexafluorophosphate) occurs, and due to this influence, the internal resistance value (iR) of the lithium ion secondary battery 100 is 1.5 times or more of the initial value (specifically, 4. It can be determined that it has increased to 5 mΩ or more.

Specifically, when the electrode body 150 is viewed in the axial direction (left-right direction in FIG. 3), the Li salt concentration of the non-aqueous electrolyte contained in the central portion of the power generation unit 150b decreases, while both ends of the power generation unit 150b Li salt concentration of the non-aqueous electrolyte contained in the portion (left and right ends in FIG. 3) is increased, and non-aqueous electrolyte salt concentration unevenness (Li salt bias) occurs in the electrode body 150. It can be determined that the internal resistance value (iR) of the lithium ion secondary battery 100 has increased to a value that is 1.5 times or more of the initial value (specifically, 4.5 mΩ or more).
The internal resistance value of the lithium ion secondary battery 100 that has increased due to such uneven salt concentration can be reduced by performing second pulse charge / discharge on the lithium ion secondary battery 100.

  Furthermore, when it is determined that the discharge current average value B is 10 C or more, the control device 30 determines whether or not the lithium ion secondary battery 100 constituting the assembled battery 10 has been left unattended. Furthermore, after determining that the lithium ion secondary battery 100 has been left as it is, the control device 30 measures the time during which the lithium ion secondary battery 100 is left until the second pulse charge / discharge is started. In addition, the leaving time of the lithium ion secondary battery 100 until the second pulse charge / discharge is started is determined by the control device 30 based on, for example, the leaving history (leaving time) of the lithium ion secondary battery 100, for example. Can do.

  Furthermore, the control device 30 determines the second pulse charge according to the leaving time of the lithium ion secondary battery 100 from when it is determined that the lithium ion secondary battery 100 is left to stand until the second pulse charge / discharge is started. Determine the number of charge / discharge cycles for discharge. Specifically, the control device 30 can reduce the internal resistance value (iR) of the lithium ion secondary battery 100 whose internal resistance value (iR) has increased to 4.5 mΩ to 3.8 mΩ so as to reduce the internal resistance value (iR) to 3.8 mΩ. The number of charge / discharge cycles of the second pulse charge / discharge is determined according to the time for which the battery 100 is left. For example, when the standing time is 6 hours, the number of charge / discharge cycles of the second pulse charge / discharge is determined to be 230 cycles. When the standing time is 12 hours, the number of charge / discharge cycles of the second pulse charge / discharge is determined to be 100 cycles (see FIG. 9). When the standing time is 0 hour, the number of charge / discharge cycles of the second pulse charge / discharge is determined to be 500 cycles.

  Furthermore, the control device 30 performs the second pulse charge / discharge with respect to the lithium ion secondary battery 100 by the determined number of charge / discharge cycles. The second pulse charge / discharge is performed in the pattern shown in FIG. Specifically, the second pulse charge / discharge is performed with a charge current value of 20 C, a discharge current value of 2 C, a charge time in a charge / discharge cycle of 10 seconds, and a discharge time in a charge / discharge cycle of 100 seconds. Thereby, high-rate pulse charging (pulse discharge with a large current of 20 C) is repeatedly performed, so that the salt concentration unevenness of the non-aqueous electrolyte in the electrode body 150 is reduced, and the internal resistance value of the lithium ion secondary battery 100 is reduced. (IR) can be reliably reduced.

Next, a method for controlling the lithium ion secondary battery 100 according to the present embodiment will be described with reference to FIG.
In step S <b> 1, the control device 30 calculates the internal resistance value of the lithium ion secondary battery 100 constituting the assembled battery 10. Specifically, iR = ΔV / I is calculated as the internal resistance value of the lithium ion secondary battery 100. Specifically, the control device 30 performs pulse discharge on the lithium ion secondary battery 100 at a constant current value I (for example, a constant current value of 10 C) for a predetermined time (for example, 10 seconds), and a voltage detection device. 40 is used to detect the battery voltage of the lithium ion secondary battery 100 before and after pulse discharge. Then, based on the constant current value I and the battery voltage change amount ΔV of the lithium ion secondary battery 100 before and after the pulse discharge, the internal resistance value iR is calculated by the arithmetic expression (iR = ΔV / I).

  Next, it progresses to step S2, and the control apparatus 30 judges whether the internal resistance value (iR) of the lithium ion secondary battery 100 calculated in step S1 is a value 1.5 times or more of the initial value. To do. Since the initial value (iR) is 3.0 mΩ, in step S2, it is determined whether or not the internal resistance value (iR) calculated in step S1 is 4.5 mΩ or more.

  If it is determined in step S2 that the internal resistance value (iR) is not 1.5 times the initial value (4.5 mΩ or more) (No), the routine processing shown in FIG. After the elapse of time (for example, 1 hour), the process of step S1 is performed again.

  On the other hand, if it is determined in step S2 that the internal resistance value (iR) is 1.5 times or more of the initial value (4.5 mΩ or more) (Yes), the process proceeds to step S3, and the control device 30 Charge current average value A = ∫ (Ic) dt / t, which is an average value of charge current value Ic of lithium ion secondary battery 100, and discharge current average, which is an average value of discharge current value Id of lithium ion secondary battery 100 A value of A / B which is a ratio of value B = ∫ (Id) dt / t is calculated. Specifically, the control device 30 performs charging from a predetermined time (for example, one hour before) to the time when the process of Step S1 is started (for a predetermined time) before the process of Step S1 is started. A value of A / B, which is a ratio between the current average value A and the discharge current average value B within the same period, is calculated.

Next, in step S4, the control device 30 determines whether the calculated A / B value is 10 or more.
In step S4, when it is determined that the value of A / B is 10 or more (Yes), the process proceeds to step S5, and it is determined whether or not the charging current average value A is 10C or more.

  In step S5, when it is determined that the charging current average value A is not 10C or more (No), the routine processing shown in FIG. 6 is once ended, and after a predetermined time (for example, 1 hour) has elapsed, the processing of step S1 is performed again. Process.

  On the other hand, when it is determined in step S5 that the charging current average value A is 10 C or more (Yes), the process proceeds to step S6, and the control device 30 leaves the lithium ion secondary battery 100 constituting the assembled battery 10 in an untreated state. It is determined whether or not. Specifically, when the vehicle power switch of the hybrid vehicle 1 is turned off and the current value flowing through the lithium ion secondary battery 100 becomes 0 mA, it is determined that the lithium ion secondary battery 100 has been left unattended. .

  In step S6, when it is determined that the lithium ion secondary battery 100 constituting the assembled battery 10 has been left as it is (Yes), the process proceeds to step S7, and the control device 30 determines that the lithium ion secondary battery 100 is left as it is. Start measuring. Specifically, for example, when the leaving time is set to 6 hours, the control device 30 determines that the lithium ion secondary battery 100 has been left in step S6 (Yes) until 6 hours have passed. , Measure the standing time.

  Subsequently, it progresses to step S8 and the control apparatus 30 determines the charging / discharging cycle number of a 1st pulse charging / discharging. Specifically, for example, the control device 30 may reduce the internal resistance value (iR) of the lithium ion secondary battery 100 whose internal resistance value (iR) has increased to 4.5 mΩ to 3.8 mΩ. The number of charge / discharge cycles of the first pulse charge / discharge is determined according to the standing time of the secondary battery 100. For example, when the standing time is 6 hours, the number of charge / discharge cycles of the first pulse charge / discharge is determined to be 230 cycles (see FIG. 9). Thus, in the secondary battery system 6 of the present embodiment, the number of charge / discharge cycles of the first pulse charge / discharge is determined according to the leaving time of the lithium ion secondary battery 100.

  Thereafter, when the leaving time at which the measurement is started in step S7 reaches a planned leaving time (for example, 6 hours), the measurement of the standing time is finished and the process proceeds to step S9, and the lithium ion secondary battery constituting the assembled battery 10 The first pulse charge / discharge is performed on 100. The first pulse charge / discharge is performed in the pattern shown in FIG. Specifically, the first pulse charge / discharge is performed with a discharge current value of 20 C, a charge current value of 2 C, a discharge time in a charge / discharge cycle of 10 seconds, and a charge time in a charge / discharge cycle of 100 seconds.

  Thus, the measurement of the standing time started in step S7 is performed until the first pulse charge / discharge is started. That is, the control device 30 measures the leaving time from when it is determined in step S6 that the lithium ion secondary battery 100 has been left to stand (Yes) until the processing of step S9 is performed.

  Next, the process proceeds to step SA, and the control device 30 determines whether or not the first pulse charge / discharge has been performed for the number of cycles determined in step S8 (for example, 230 cycles). That is, it is determined whether or not the number of cycles of the first pulse charge / discharge has reached the number of cycles determined in step S8 (for example, 230 cycles).

  In step SA, when it is determined that the first pulse charge / discharge has been performed for the determined number of cycles (for example, 230 cycles) (Yes), the process proceeds to step SB, and the control device 30 ends the first pulse charge / discharge. As described above, the lithium ion secondary battery 100 constituting the assembled battery 10 is subjected to the first pulse charge / discharge for the determined number of cycles, so that the high rate pulse discharge (pulse discharge due to a large current of 20C) is determined. (E.g., 230 cycles). Thereby, the salt concentration nonuniformity of the non-aqueous electrolyte in the electrode body 150 can be reduced, and the internal resistance value (iR) of the lithium ion secondary battery 100 can be reliably reduced. For example, when the first pulse charge / discharge is performed for 230 cycles after being allowed to stand for 6 hours, the internal resistance value (iR) of the lithium ion secondary battery 100 increased to 4.5 mΩ is decreased to 3.8 mΩ. (See FIG. 9).

  In the present embodiment, as described above, the discharge current value is 20 C, the charge current value is 2 C, the discharge time in the charge / discharge cycle is 10 seconds, and the charge time in the charge / discharge cycle is 100 seconds. Charging / discharging is performed. Therefore, the first pulse charge / discharge is performed with the discharge electricity amount per charge / discharge cycle (20C × 10 seconds) equal to the charge electricity amount (2C × 100 seconds). Thereby, before and after the first pulse charge / discharge, the SOC (State Of Charge) of the lithium ion secondary battery 100 can be kept equal. Therefore, after the first pulse charge / discharge, the lithium ion secondary battery 100 whose internal resistance has been reduced by the first pulse charge / discharge can be appropriately used as a driving power source for the hybrid vehicle 1.

  If it is determined in step S4 that the A / B value is not 10 or more (No), the process proceeds to step SC, and the control device 30 determines whether the A / B value is 0.1 or less. to decide. If it is determined in step SC that the value of A / B is 0.1 or less (Yes), the process proceeds to step SD to determine whether or not the discharge current average value B is 10 C or more.

  In step SC, when it is determined that the value of A / B is not 0.1 or less (No), the routine processing shown in FIG. 6 is once ended, and after a predetermined time (for example, 1 hour) has elapsed, the step is again performed. The process of S1 is performed. The same applies when it is determined in step SD that the discharge current average value B is not 10 C or more (No).

  On the other hand, when it is determined in step SD that the discharge current average value B is 10 C or more (Yes), the process proceeds to step SE, and the control device 30 determines the lithium ion secondary battery constituting the assembled battery 10 as in step S6. It is determined whether or not the next battery 100 is left unattended. In step SE, when it is determined that the lithium ion secondary battery 100 constituting the assembled battery 10 has been left as it is (Yes), the process proceeds to step SF, and the control device 30 performs the lithium ion secondary battery similarly to step S7. The measurement of the leaving time of the secondary battery 100 is started.

  Subsequently, it progresses to step SG and the control apparatus 30 determines the charging / discharging cycle number of a 2nd pulse charging / discharging. Specifically, for example, the control device 30 may reduce the internal resistance value (iR) of the lithium ion secondary battery 100 whose internal resistance value (iR) has increased to 4.5 mΩ to 3.8 mΩ. The number of charge / discharge cycles of the second pulse charge / discharge is determined according to the standing time of the secondary battery 100. For example, when the standing time is 6 hours, the number of charge / discharge cycles of the second pulse charge / discharge is determined to be 230 cycles (see FIG. 9). As described above, in the secondary battery system 6 of the present embodiment, the number of charge / discharge cycles of the second pulse charge / discharge is determined according to the leaving time of the lithium ion secondary battery 100.

  Thereafter, when the leaving time at which the measurement is started in step SF reaches a predetermined leaving time (for example, 6 hours), the measurement of the standing time is finished and the process proceeds to step SH, and the lithium ion secondary battery constituting the assembled battery 10 The second pulse charge / discharge is performed on 100. The second pulse charge / discharge is performed in the pattern shown in FIG. Specifically, the second pulse charge / discharge is performed with a charge current value of 20 C, a discharge current value of 2 C, a charge time in a charge / discharge cycle of 10 seconds, and a discharge time in a charge / discharge cycle of 100 seconds.

  As described above, the measurement of the standing time started in step SF is performed until the second pulse charge / discharge is started. That is, the control device 30 measures the leaving time from when it is determined in step SE that the lithium ion secondary battery 100 has been left (Yes) until the processing of step SH is performed.

  Next, the process proceeds to step SI, and the control device 30 determines whether or not the second pulse charge / discharge has been performed for the number of cycles determined in step SG (for example, 230 cycles). That is, it is determined whether or not the number of cycles of the second pulse charge / discharge has reached the number of cycles determined in step SG (for example, 230 cycles).

  In step SI, when it is determined that the second pulse charge / discharge has been performed (Yes) for the determined number of cycles (for example, 230 cycles), the process proceeds to step SJ, and the control device 30 ends the second pulse charge / discharge. As described above, the lithium ion secondary battery 100 constituting the assembled battery 10 is subjected to the second pulse charge / discharge for the determined number of cycles, so that the high rate pulse charge (pulse charge with a large current of 20C) is determined. (E.g., 230 cycles). Thereby, the salt concentration nonuniformity of the non-aqueous electrolyte in the electrode body 150 can be reduced, and the internal resistance value (iR) of the lithium ion secondary battery 100 can be reliably reduced. For example, when the second pulse charge / discharge is performed for 230 cycles after being allowed to stand for 6 hours, the internal resistance value (iR) of the lithium ion secondary battery 100 that has increased to 4.5 mΩ is decreased to 3.8 mΩ. (See FIG. 9).

  In the present embodiment, as described above, the charge current value is 20 C, the discharge current value is 2 C, the charge time in the charge / discharge cycle is 10 seconds, the discharge time in the charge / discharge cycle is 100 seconds, and the second pulse Charging / discharging is performed. Therefore, the second pulse charge / discharge is performed with the charge electricity amount per charge / discharge cycle (20C × 10 seconds) equal to the discharge electricity amount (2C × 100 seconds). Thereby, the SOC (State Of Charge) of the lithium ion secondary battery 100 can be kept equal before and after the second pulse charge / discharge. Therefore, after the second pulse charging / discharging, the lithium ion secondary battery 100 having a reduced internal resistance can be appropriately used as a driving power source for the hybrid vehicle 1.

  Moreover, in this embodiment, the control apparatus 30 which performs the process of step S1 is equivalent to an internal resistance value calculation means. Furthermore, the control device 30 that performs the process of step S2 corresponds to a resistance value determination unit. Furthermore, the control device 30 that performs the process of step S3 corresponds to a current value ratio calculation unit. Furthermore, the control device 30 that performs the process of step S4 corresponds to the first current value ratio determination unit, and the control device 30 that performs the process of step S5 corresponds to the charging current value determination unit. Furthermore, the control device 30 that performs the process of step SC corresponds to the second current value ratio determination unit, and the control device 30 that performs the process of step SD corresponds to the discharge current value determination unit. Furthermore, the control device 30 that performs the processes of steps S8 to SB and SG to SJ corresponds to charge / discharge control means. Furthermore, the control device 30 that performs the processing of steps S6 and SE corresponds to the neglected state determination means.

  In the above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 6 Secondary battery system 10 Assembly battery 30 Control apparatus (Charge / discharge control means, internal resistance value calculation means, resistance value judgment means, current value ratio calculation means, leaving state judgment means)
40 Voltage detector 50 Current detector 100 Lithium ion secondary battery 150 Electrode body

Claims (7)

A secondary battery,
Charge / discharge control means for controlling charge / discharge of the secondary battery, and a secondary battery system comprising:
The charge / discharge control means includes
When the internal resistance value of the secondary battery is 1.5 times or more of the initial value, the charging current average value A = ∫ (Ic) dt, which is the average value of the charging current value Ic of the secondary battery. The value of A / B, which is the ratio of the discharge current average value B =) (Id) dt / t, which is the average value of the discharge current value Id of the secondary battery is 10 or more, and the charging current When the average value A is 10C or more, the secondary battery is subjected to a first pulse charge / discharge that repeats charging and discharging with a discharge current value larger than the charge current value,
When the internal resistance value of the secondary battery is 1.5 times or more of the initial value, the A / B value is 0.1 or less, and the discharge current average value B is 10 C or more. In some cases, a secondary battery system that performs second pulse charging / discharging on the secondary battery by repeating charging and discharging with a charging current value larger than the discharging current value. The secondary battery system according to claim 1,
An internal resistance value calculating means for calculating an internal resistance value of the secondary battery;
Current value ratio calculating means for calculating the value of A / B;
Resistance value determining means for determining whether or not the internal resistance value calculated by the internal resistance value calculating means is a value equal to or greater than 1.5 times the initial value;
Whether the A / B value calculated by the current value ratio calculating means is 10 or more when the resistance value determining means determines that the internal resistance value is 1.5 times or more of the initial value First current value ratio determining means for determining whether or not,
Charging current value determining means for determining whether or not the charging current average value A is 10C or more;
When the internal resistance value is determined to be 1.5 times or more of the initial value by the resistance value determining means, the A / B value calculated by the current value ratio calculating means is 0.1 or less. Second current value ratio determining means for determining whether or not there is;
Discharge current value determining means for determining whether or not the discharge current average value B is 10 C or more,
The charge / discharge control means includes
When the resistance value determining means determines that the internal resistance value of the secondary battery is 1.5 times or more of the initial value, the A / B value is 10 by the first current value ratio determining means. When it is determined that the charge current average value A is determined to be 10 C or more by the charge current value determination means, the first pulse charge / discharge is performed on the secondary battery.
When the resistance value determining means determines that the internal resistance value of the secondary battery is 1.5 times or more of the initial value, the A / B value is 0 by the second current value ratio determining means. When the discharge current value determination means determines that the discharge current average value B is 10 C or more, the second pulse charge / discharge is performed on the secondary battery. Secondary battery system. The secondary battery system according to claim 1 or 2,
The charge / discharge control means includes
The discharge current value is 10 times or more of the charge current value, and the discharge current value is 10 C or more, and the first pulse charge / discharge is performed.
A secondary battery system that performs the second pulse charge / discharge by setting the charging current value to 10 times or more of the discharging current value and setting the charging current value to 10C or more. The secondary battery system according to any one of claims 1 to 3,
The charge / discharge control means includes
The secondary battery system which performs the said 1st pulse charge / discharge and the said 2nd pulse charge / discharge by making the charge electric quantity per 1 charge / discharge cycle equal. The secondary battery system according to any one of claims 1 to 4,
A neglected state judging means for judging whether or not the secondary battery is left neglected;
The charge / discharge control means includes
A secondary battery system which starts the first pulse charge / discharge or the second pulse charge / discharge after the left battery is determined to be left by the left state determination means. The secondary battery system according to claim 5,
The charge / discharge control means includes
The first pulse charging / discharging according to the leaving time from the time when the secondary battery is determined to be left to stand until the start of the first pulse charging / discharging or the second pulse charging / discharging by the leaving state determining means. Or the secondary battery system which determines the charging / discharging cycle number of the said 2nd pulse charging / discharging, and performs the said 1st pulse charging / discharging with respect to the said secondary battery only for the determined charging / discharging cycle number. A hybrid vehicle,
A hybrid vehicle comprising the secondary battery system according to any one of claims 1 to 6 mounted as a power supply system for driving the hybrid vehicle.

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