Battery cell control device and battery cell control method

Abstract

To provide a battery cell control device capable of suppressing high-rate deterioration when there is high-rate deterioration in a plurality of battery cells at the beginning of use.SOLUTION: A control device 110 of a battery cell 62 that controls the binding force of a plurality of battery cells 62 in a battery module 60 in which a plurality of battery cells 62, which are rechargeable secondary batteries, are arranged in a predetermined direction D, includes a detection unit 71 that detects high-rate deterioration of each of the plurality of battery cells 62, a determination unit 72 that determines whether the high-rate deterioration is due to insufficient aging at the beginning of use of the battery cell 62, a binding force applying unit 81 that exerts restraining force in a predetermined direction D on the plurality of battery cells 62, and a binding force control unit 82 that controls the binding force applying unit 81, and the binding force control unit 82 controls the binding force applying unit 81 to increase the binding force applied to the plurality of battery cells 62 when the determination unit 72 determines high-rate deterioration due to insufficient aging.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device and a control method for controlling the restraining force of a plurality of battery cells. [Background technology]

[0002] Conventionally, in battery cells, which are rechargeable secondary batteries used in electric vehicles and hybrid vehicles, a phenomenon known as high-rate degradation (or high-rate cycle degradation) can occur in which the internal resistance of the battery cell temporarily (i.e., reversibly) increases due to continuous charging and discharging (cycling) at a large current (high rate).When high-rate degradation occurs, it is not possible to increase the effective current at which the battery cell can be charged and discharged, making it difficult to improve the power consumption rate (electricity cost) of electric vehicles, etc.

[0003] In order to suppress high-rate degradation of battery cells, the battery cell control device described in Patent Document 1 includes a restraining load adjustment means for applying a restraining force in a predetermined direction to multiple battery cells arranged to overlap in the predetermined direction. In this control device, when high-rate degradation occurs in a battery cell, the restraining force applied by the restraining load adjustment means to the multiple battery cells is reduced. This eliminates the bias in the concentration distribution of lithium salt inside the battery cell and suppresses high-rate degradation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-129312 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the early stages of use, there may be variation in high-rate degradation among a plurality of battery cells. In such a state where there is variation in high-rate degradation, there is a problem in that the high-rate degradation cannot be eliminated even if the restraining force by the restraining load adjustment means is reduced.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a battery cell control device that can suppress high-rate degradation when high-rate degradation occurs in multiple battery cells in the early stages of use. [Means for solving the problem]

[0007] The inventors discovered that the variation in high-rate degradation of multiple battery cells in the early stages of use is due to insufficient aging of the battery cells (specifically, insufficient formation of an SEI film on the negative electrode due to insufficient aging), and discovered that in order to eliminate the high-rate degradation due to insufficient aging, the binding force of the battery cells can be increased to allow gas generated in the battery cells due to insufficient aging to be discharged to the outside of the battery cells. Based on these findings, the inventors have created the following control device.

[0008] In other words, the battery cell control device of the present invention is a control device that controls the constraint force of multiple battery cells in a battery module in which multiple battery cells, which are chargeable and dischargeable secondary batteries, are arranged overlapping in a predetermined direction, and is equipped with a detection unit that detects high-rate deterioration of each of the multiple battery cells, a judgment unit that determines whether the high-rate deterioration is high-rate deterioration due to insufficient aging in the early stage of use of the battery cells, a constraint force application unit that applies a constraint force in the predetermined direction to the multiple battery cells, and a constraint force control unit that controls the constraint force application unit, wherein the constraint force control unit controls the constraint force application unit to increase the constraint force applied to the multiple battery cells when the judgment unit determines high-rate deterioration due to insufficient aging.

[0009] In the battery cell control device of the present invention, when the determination unit determines that high-rate degradation due to insufficient aging has occurred in any of the multiple battery cells in the early stages of use, the constraint force control unit controls the constraint force application unit to increase the constraint force applied to the multiple battery cells. By applying a large constraint force to the insufficiently aged battery cell, it is possible to discharge gas generated inside the battery cell. This makes it possible to suppress a decrease in the reaction area of ​​the negative electrode caused by gas adhering to the negative electrode inside the battery cell. As a result, it is possible to suppress high-rate degradation due to insufficient aging in the battery cell in the early stages of use.

[0010] In the above-mentioned battery cell control device, when the determination unit determines that the high-rate degradation is not high-rate degradation due to insufficient aging, it is preferable that the constraint force control unit controls the constraint force application unit to reduce the constraint force applied to the multiple battery cells while charging and discharging of the multiple battery cells is suspended.

[0011] According to this configuration, high-rate degradation due to insufficient aging at the beginning of use of the battery cells is eliminated, and when high-rate degradation occurs after the beginning of use, the restraining force of the battery cells is reduced while the charging and discharging of the battery cells is suspended. This makes it possible to quickly eliminate the imbalance of ions in the electrolyte within the battery cells. As a result, it is possible to hasten the recovery of the battery cells from high-rate degradation.

[0012] In the above-mentioned battery cell control device, it is preferable that the judgment unit estimates an internal resistance from the charge / discharge history of the battery cell at the beginning of use, and compares the internal resistance with a predetermined reference internal resistance, thereby determining high-rate degradation due to insufficient aging.

[0013] With this configuration, it is possible to easily determine high-rate deterioration due to insufficient aging by comparing the internal resistance of the battery cell with a reference internal resistance. Therefore, there is no need to directly detect the adhesion of gas inside the battery cell, and the configuration of the control device is simplified.

[0014] The battery cell control method of the present invention is a control method for controlling the constraint force of multiple battery cells in a battery module in which multiple battery cells, which are chargeable and dischargeable secondary batteries, are arranged overlapping in a predetermined direction, and includes a detection step for detecting high-rate deterioration of each of the multiple battery cells, a determination step for determining whether the high-rate deterioration is high-rate deterioration due to insufficient aging in the early stage of use of the battery cells, and a constraint force application step for applying a constraint force in the predetermined direction to the multiple battery cells, wherein the constraint force application step is characterized in that when high-rate deterioration due to insufficient aging is determined in the determination step, the constraint force applied to the multiple battery cells is increased.

[0015] According to this feature, when it is determined in the determination step that high-rate deterioration due to insufficient aging has occurred in any of the plurality of battery cells in the initial stage of use of the battery cells, the restraining force imparting step increases the restraining force applied to the plurality of battery cells. By subjecting the insufficiently aged battery cell to a large restraining force, it is possible to discharge gas generated inside the battery cell. This makes it possible to suppress a decrease in the reaction area of ​​the negative electrode caused by gas adhering to the negative electrode inside the battery cell. As a result, it is possible to suppress high-rate deterioration due to insufficient aging of the battery cell in the initial stage of use of the battery cell. Effect of the Invention

[0016] According to the battery cell control device and control method of the present invention, it is possible to suppress high-rate degradation due to insufficient aging that occurs in multiple battery cells in the early stages of use. It can be suppressed. [Brief description of the drawings]

[0017] [Figure 1] 1 is a perspective view showing the overall configuration of a hybrid vehicle equipped with a battery cell control device according to an embodiment of the present invention; [Diagram 2] 2A and 2B are cross-sectional explanatory views of the restraint mechanism and battery module of FIG. 1, in which (a) shows a state before the battery cell is restrained, and (b) shows a state after the battery cell is restrained. [Diagram 3] FIG. 2 is a perspective view of the battery module of FIG. [Figure 4] 10 is an explanatory diagram showing a state in which gas generated inside a battery cell due to insufficient aging adheres to the negative electrode. FIG. [Diagram 5] 11 is a graph showing the relationship between the integrated capacity and the resistance rise rate at the beginning of use for battery cells on the end plate side and the center side of a battery module, in order to explain the variation in high-rate deterioration due to insufficient aging. [Figure 6] 13 is a graph showing the relationship between the integrated capacity and the rate of increase in resistance at the beginning of use for the end plate side and the central side battery cells when the restraining force of multiple battery cells is increased to eliminate the variation in high-rate degradation due to insufficient aging. [Figure 7] 4 is a control flowchart when IG-ON occurs at the beginning of battery use according to one embodiment of the battery cell control method of the present invention. [Figure 8] 4 is a control flowchart when IG-OFF is performed at the beginning of battery use according to one embodiment of the battery cell control method of the present invention. [Figure 9] 4 is a control flowchart when IG-ON occurs after the middle stage of battery use according to one embodiment of the battery cell control method of the present invention. [Figure 10] 4 is a control flowchart during IG-OFF after a battery starting intermediate stage according to one embodiment of the battery cell control method of the present invention. [Figure 11] 8 is a map showing limit integrated current amount values ​​used in the control flowchart of FIG. 7. [Figure 12]9 is a map showing the relationship between an ion bias evaluation value, which is an evaluation value of high-rate deterioration used in the control flowchart of FIG. 8, and a pause time. [Figure 13] 10 is a map showing the relationship between an ion bias evaluation value, which is an evaluation value of high-rate deterioration used in the control flowchart of FIG. 9, and a pause time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a battery cell control device according to the present invention will be described with reference to the drawings.

[0020] FIG. 1 is a perspective view showing the overall configuration of a hybrid vehicle equipped with a battery cell control device according to an embodiment of the present invention.

[0021] The hybrid vehicle 100 shown in Figure 1 comprises wheels 10, 10, axles 12, an engine 20, a transmission 30, a motor 40, an inverter 50, a battery module (hereinafter referred to as battery) 60 having a plurality of battery cells 62 (see Figures 2 and 3), a control device 70 that detects and determines high-rate deterioration of the battery cells 62 and controls the current of the battery 60, a restraint mechanism 80 that adjusts the restraint force of the plurality of battery cells 62, and a temperature sensor 90 that detects the temperature of the battery cells 62.

[0022] The hybrid vehicle 100 is a so-called parallel hybrid vehicle. The engine 20 and the motor 40 function as a driving source that outputs driving force for the vehicle, and the hybrid vehicle 100 can run on the engine 20 alone, on both the engine 20 and the motor 40, or on the motor 40 alone, depending on the driving conditions.

[0023] The engine 20 is connected to the axle 12 via a transmission 30. The engine 20 is, for example, a gasoline engine.

[0024] The motor 40 is coupled to the axle 12 and is connected to a battery 60 via an inverter 50. The motor 40 receives power from the battery 60, which is converted to AC power by the inverter 50. The motor 40 receives the power supply and functions as an electric motor to rotate the axle 12. The motor 40 can also function as a generator by performing regenerative operation during deceleration. The electricity generated by the motor 40 is charged into the battery 60.

[0025] 2 and 3, the battery 60 has a configuration in which a plurality of battery cells 62, which are chargeable and dischargeable secondary batteries, are arranged overlapping in a predetermined arrangement direction D (horizontal direction in this embodiment). Specifically, the battery 60 includes a casing 61 which is a rectangular parallelepiped box extending in the arrangement direction D, a plurality of battery cells 62 housed in the casing 61 and arranged overlapping in the arrangement direction D, a bus bar 64 connecting electrode terminals 63 of two adjacent battery cells 62, a spring 65 interposed between the two adjacent battery cells 62, and a pair of end plates 66 arranged between both ends of the plurality of battery cells 62 in the arrangement direction D and a vertical wall of the casing 61.

[0026] The bus bar 64 has a pair of connection portions 64a electrically connected to the electrode terminals 63 of each battery cell 62, and a wiring portion 64b that connects between the pair of connection portions 64a and bends when the multiple battery cells 62 are subjected to a restraining force from a predetermined arrangement direction D.

[0027] The temperature of each of the multiple battery cells 62 inside the casing 61 is detected by a temperature sensor 90.

[0028] As shown in FIG. 1, the control device 70 includes a detection unit 71 that detects high-rate deterioration of the multiple battery cells 62, and a determination unit 72 that determines whether the high-rate deterioration is due to insufficient aging.

[0029] The detection unit 71 is configured to detect high-rate deterioration of the battery cell 62. Here, high-rate deterioration is a phenomenon in which the internal resistance of the battery cell temporarily (i.e., reversibly) increases due to continued charging and discharging (cycles) with an excessive current (high rate). In order to detect such high-rate deterioration, the detection unit 71 of this embodiment calculates a high-rate deterioration evaluation value N from the temperature of the battery cell 62 (for example, the average temperature of the temperatures of the multiple battery cells 62) detected by the temperature sensor 90 and the effective current of the battery cell 62, as shown in steps S1 to S9 of the flowchart in Fig. 7 described later, and detects high-rate deterioration by determining whether the evaluation value N is greater than a target value.

[0030] The determination unit 72 determines whether the high-rate deterioration detected by the detection unit 71 is high-rate deterioration due to insufficient aging at the beginning of use of the battery cell 62. As shown in steps S12 to S14 of Fig. 7, the determination unit 72 of this embodiment calculates a resistance value (internal resistance) of the battery cell 62 estimated from the charge / discharge history while the hybrid vehicle 100 is in IG-ON (i.e., while the battery 60 is being charged / discharged while the hybrid vehicle 100 is being operated), determines whether the resistance value estimated during IG-ON is smaller by a predetermined percentage X% than a resistance value previously stored in the control device 70, and if it is not smaller by the predetermined percentage X% (if it is X% or more), determines that there is high-rate deterioration due to insufficient aging.

[0031] Here, high-rate degradation due to insufficient aging is a phenomenon that occurs at the beginning of use of a battery cell 62, and is caused by gas generation in the electrolyte inside the battery cell 62 due to insufficient aging even after assembling a battery module 60 having a plurality of battery cells 62, as shown in FIG. 4. That is, when gas generated in the electrolyte containing lithium salt adheres to the surface of the negative electrode mixture layer that constitutes the negative electrode, lithium (Li) is precipitated at the adhered portion and the reaction area of ​​the negative electrode is reduced. As a result, it becomes difficult for current to flow inside the electrolyte, and the internal resistance of the battery cell 62 increases. This is high-rate degradation due to insufficient aging.

[0032] Among the multiple battery cells 62, the high-rate deterioration due to aging tends to be larger in the battery cells 62B on the side of the end plates 66 (see FIG. 2) located at both ends of the multiple battery cells 62 than in the central battery cell 62A shown in FIG. 3 (this is thought to be because the gas expansion is less in the battery cell 62B on the side of the end plates 66 than in the central battery cell 62A, and the internal resistance is more likely to increase). For example, when comparing using the graph shown in FIG. 5 showing the relationship between the cumulative capacity C (kAh) of the battery cells and the resistance increase rate Rr (%), it can be seen that the resistance increase rate Rr is suddenly larger in the battery cell 62B on the side of the end plates 66 (curve II) than in the central battery cell 62A (curve I) in the range where the cumulative capacity C is greater than 5 kAh (i.e., after the time when the cumulative capacity C becomes 5 kAh or more). From this point, it can be understood that the high-rate deterioration due to aging causes variations in the high-rate deterioration among the multiple battery cells 62.

[0033] Furthermore, as shown in FIG. 1, the control device 70 includes a current setting unit 73 and a current control unit 74 as components for controlling the current of the multiple battery cells 62 in the battery 60 via the inverter 50.

[0034] The current setting unit 73 sets an upper limit current value based on high-rate deterioration of the battery cells 62. The current control unit 74 limits the effective current value of the entire battery cells 62 (battery 60) to be equal to or lower than the upstream current value. The above "upper limit current value" is the upper limit current value at which high-rate deterioration does not occur, and is defined as the allowable value for a high-rate cycle (i.e., a cycle of charging and discharging with a large current).

[0035] 2(a)-(b), the restraint mechanism 80 has a configuration capable of adjusting the restraint force of the multiple battery cells 62. Specifically, the restraint mechanism 80 includes a restraint force application unit 81 and a restraint force control unit 82.

[0036] The restraining force application unit 81 has a configuration that applies a restraining force in a compressive direction to the multiple battery cells 62. In the configuration shown in Figures 2(a) and (b) where the multiple battery cells 62 are linearly arranged along a predetermined arrangement direction D, the restraining force application unit 81 can have various configurations as long as it is configured to simultaneously apply a restraining force to each of the battery cells 62 from the predetermined arrangement direction D.

[0037] 2(a) and (b), for example, the binding force applying unit 81 includes a pressing gear 84 that presses one end plate 66 of the battery 60, a drive gear 86 that rotates in a manner that meshes with the pressing gear 84 and pushes the pressing gear 84 into the casing 61, and a motor 85 that rotates the drive gear 86. As shown in FIGS. 2(a) and (b), the binding force applying unit 81 applies a horizontal binding force to the multiple battery cells 62 arranged horizontally inside the casing 61 via the end plate 66 and compresses the springs 65 between the battery cells 62 by rotating the drive gear 86 in the forward direction upon receiving a driving force from the motor 85, thereby pushing the pressing gear 84 into the casing 61. In addition, the binding force applied to the multiple battery cells 62 can be reduced by rotating the drive gear 86 in the reverse direction.

[0038] The restraining force control unit 82 controls the motor 85 of the restraining force application unit 81 so as to adjust the restraining force.

[0039] When the determination unit 72 determines that the high-rate deterioration detected by the detection unit 71 at the beginning of battery use is high-rate deterioration due to insufficient aging, the constraint force control unit 82 controls the constraint force application unit 81 to increase the constraint force on the battery cells 62 when the multiple battery cells 62 are not charging or discharging (IG-OFF) (i.e., to transition from the state of FIG. 2(a) to the state of FIG. 2(b)) (see steps S21-23 of the flowchart in FIG. 8). For example, in an initial state other than when the multiple battery cells 62 are not charging or discharging (IG-OFF), the battery cells 62 are constrained with an initial constraint force of a predetermined magnitude, and when the multiple battery cells 62 are not charging or discharging (IG-OFF) and high-rate deterioration due to insufficient aging is determined, the constraint force on the battery cells 62 may be increased beyond the initial constraint force.

[0040] On the other hand, when the detection unit 71 detects high-rate deterioration at the beginning of battery use but the determination unit 72 does not determine that the high-rate deterioration is high-rate deterioration due to insufficient aging, the constraint force control unit 82 controls the constraint force application unit 81 to reduce the constraint force on the battery cells 62 (i.e., to return from the state of FIG. 2(b) to the state of FIG. 2(a)) when the charging and discharging of the multiple battery cells 62 is suspended (IG-OFF) (see steps S22 and S24 in FIG. 8). Also, even after the middle stage of battery use, if the deterioration evaluation value of the battery cell 62 with the highest degree of transition to high-rate deterioration is smaller than a predetermined value (for example, N<1), when the charging and discharging of the multiple battery cells 62 is suspended (IG-OFF), the constraint force control unit 82 controls the constraint force application unit 81 to reduce the constraint force on the battery cells 62 (see steps S61 to S62 in FIG. 10). When the constraint force on the battery cells 62 is reduced, it may be reduced to, for example, less than the initial constraint force.

[0041] The control device 110 for the battery cell 62 according to the embodiment of the present invention configured as shown in FIGS. 1 to 2 above only needs to include a detection unit 71, a determination unit 72, a restraint force application unit 81, and a restraint force control unit 82 as essential components. Note that the control device 110 for the battery cell 62 of the present invention is applicable not only to the hybrid vehicle 100 as described above but also to an electric vehicle (EV).

[0042] (Control Method for Battery Cell 62) Next, regarding the control method for the battery cell 62 of the present invention, the control in four cases, namely, I. When the ignition is ON at the initial stage of battery use, II. When the ignition is OFF at the initial stage of battery use, III. When the ignition is ON after the mid - stage of battery use starts, IV. When the ignition is OFF after the mid - stage of battery use starts will be described in order.

[0043] <I. When the ignition is ON at the initial stage of battery use> Regarding the control method for the battery cell 62 when the ignition is ON at the initial stage of battery use (when the battery cell 62 is being charged or discharged), it will be described using the flowchart shown in FIG. 7.

[0044] In the flowchart shown in FIG. 7, it starts by turning on the ignition (IG - ON) of the hybrid vehicle 100.

[0045] In step S1, at the start of running, the high - rate degradation evaluation value N = 1 is obtained, and then the battery temperature (the average temperature of a plurality of battery cells 62 or the temperature of the battery cell 62 with the lowest temperature among a plurality of battery cells 62) is detected (step S2).

[0046] Next, in step S3, it is determined whether the battery temperature detected by the temperature sensor 90 (for example, the average temperature of the temperatures of a plurality of battery cells 62) has reached the target value. The target temperature is a relatively high temperature at which high - rate degradation is difficult to occur and is set to a temperature suitable for the driver's operation.

[0047] If the battery temperature has reached the target temperature, the process proceeds to step S4, where the effective current of the battery 60 (i.e., all of the multiple battery cells 62) is detected. If the battery temperature has not reached the target temperature, the process proceeds to step S5, where battery temperature control is turned ON, and then the process proceeds to step S4. Specifically, in battery temperature control, the multiple battery cells 62 are temperature-adjusted (heated or cooled) by a temperature control device (not shown) to approach the target temperature (note that it is not necessary to reach the target temperature).

[0048] Next, the control device 70 (specifically, the detection unit 71) determines whether the effective current is greater than a threshold value (step S6).

[0049] If the effective current is greater than the threshold value, the process proceeds to step S7, where the limit integrated current value is obtained from the map, and then the effective current value is used to calculate the evaluation value N (step S7). On the other hand, if the effective current is smaller than the predetermined value, step S7 is skipped and the process proceeds to step S8.

[0050] The limit integrated current value in step S7 is calculated based on a map showing a curve indicated by three parameters, rms current, battery temperature, and limit integrated amount, in Fig. 11. Specifically, first, the effective current value (e.g., 80 A) and battery temperature are inputted into the map in Fig. 11, and the integrated current value on the curve corresponding to the effective current value (40 to 95 A) and battery temperature T (°C) is calculated as the limit integrated current value IS (Ah).

[0051] In step S8, the evaluation value N is calculated by substituting the effective current value Ie (A), the elapsed time t (seconds), and the limit integrated current value IS (Ah) calculated in step S7 into the following (Equation 1). N=1-(Ie×t / 3600) / IS (Equation 1) For example, if the effective current value Ie is 80A, the elapsed time t is 10 seconds, and the limit integrated current value IS is 239Ah, input these values ​​into the above (Equation 1), the high-rate degradation evaluation value N will be: N=1-(80×10 / 3600) / 239=0.999073 It can be obtained as follows.

[0052] Next, it is determined whether the evaluation value N is greater than the target value (step S9). The target value is an arbitrary numerical value, and for example, it is arbitrarily set within the range from 0 to 1.

[0053] If the evaluation value N is greater than the target value, the process proceeds to step S10, and the evaluation value N is recorded in the control device 70. On the other hand, if the evaluation value N is smaller than the target value, the process proceeds to step S11. After the current control unit 74 limits the effective current to a predetermined value or less (specifically, less than or equal to the upper limit current value determined by the current setting unit 73), the process proceeds to the above step S10.

[0054] Next, in step S12, the control device 70 (specifically, the determination unit 72) calculates the resistance value (internal resistance) of the battery cell 62 estimated from the charge / discharge history during IG-ON of the hybrid vehicle 100 (that is, while the battery 60 is being charged and discharged during the operation of the hybrid vehicle 100).

[0055] Next, in step S13, the control device 70 (determination unit 72) determines whether the resistance value estimated during IG-ON is smaller than a reference resistance value previously stored in the control device 70 by a predetermined ratio X%. If it is smaller by the predetermined ratio X%, the series of controls for the battery cell 62 is terminated. On the other hand, if it is not smaller by the predetermined ratio X% (when it is X% or more), the process proceeds to step S14. After determining that there is high-rate degradation due to insufficient aging in step S14, the control is terminated.

[0056] <II. Case at the time of IG-OFF at the initial stage of battery use> A control method for the battery cell 62 in the case of IG-OFF at the initial stage of battery use (when the charge / discharge of the battery cell 62 is suspended) will be described using the flowchart shown in FIG. 8.

[0057] In the flowchart shown in FIG. 8, it starts by turning off the ignition (IG-OFF) of the hybrid vehicle 100.

[0058] In step S21, the control device 70 (specifically, the determination unit 72) determines whether there is high-rate degradation in the multiple battery cells 62. If there is high-rate degradation, the process proceeds to step S22, and if there is no high-rate degradation, the series of controls shown in FIG. 8 is terminated.

[0059] Next, in step S22, if there is high-rate deterioration of the battery cell 62, the control device 70 (determination unit 72) determines whether there is high-rate deterioration due to insufficient aging.

[0060] If there is high-rate deterioration due to insufficient aging, the process proceeds to step S23, where the restraining force control unit 82 of the restraining mechanism 80 controls the restraining force application unit 81 to increase the restraining force of the multiple battery cells 62. This makes it possible to discharge gas (see FIG. 4) generated inside the insufficiently aged battery cell 62 to the outside of the battery cell 62. This makes it possible to suppress a decrease in the reaction area of ​​the negative electrode caused by gas adhering to the negative electrode inside the battery cell 62. As a result, it is possible to suppress high-rate deterioration due to insufficient aging of the battery cell 62 in the early stages of use of the battery cell 62.

[0061] In this way, by increasing the constraint force of multiple battery cells 62 when there is high-rate degradation due to insufficient aging, as shown in the graph in FIG. 6, in the range where the integrated capacity C is greater than 23 kAh (i.e., after the constraint force is increased when the integrated capacity C becomes 23 kAh or greater), the resistance rise rate Rr of the battery cell 62B (curve II) on the end plate 66 side falls to the same level as that of the central battery cell 62A (curve I) when compared with the graph in FIG. 5 where the constraint force is not increased, eliminating variation in high-rate degradation and suppressing high-rate degradation due to aging.

[0062] On the other hand, if there is no high-rate deterioration due to insufficient aging, the process proceeds to step S24, where the binding force control unit 82 of the binding mechanism 80 controls the binding force application unit 81 to reduce the binding force of the multiple battery cells 62.

[0063] After the step of increasing the binding force of the battery cells 62 in step S23 or after the step of decreasing the binding force of the battery cells 62 in step S24, the process proceeds to step S25, where the control device 70 reads out a map of high-rate degradation evaluation value and downtime. Specifically, as shown in Fig. 12, a graph of the ion bias evaluation value N as the high-rate degradation evaluation value and the downtime tr(h) is read out, which shows a curve L1 in which the binding force during downtime is small and a curve L2 in which the binding force during downtime is large.

[0064] Next, in step S26, a high-rate degradation evaluation value is calculated from the pause time. Specifically, after the process of increasing the binding force of the battery cell 62 in step S23, an ion bias evaluation value N is calculated as a high-rate degradation evaluation value corresponding to the pause time from the curve L2 where the binding force during pause is large. On the other hand, after the process of decreasing the binding force of the battery cell 62 in step S24, an ion bias evaluation value N is calculated as a high-rate degradation evaluation value corresponding to the pause time from the curve L1 where the binding force during pause is small in the graph of FIG.

[0065] Next, in step S27, the control device determines whether or not to turn on the ignition (IG-ON). If the IG-ON is not to be turned on, the process proceeds to step S28, and if the IG-ON is to be turned on, the process proceeds to step S29.

[0066] In step S28, it is determined whether or not the high-rate degradation evaluation value N has reached 1 (N≧1). If the evaluation value N has reached 1, the process proceeds to step S29, and if not, the process returns to step S26 to recalculate the evaluation value N.

[0067] In step S29, the binding force control unit 82 controls the binding force application unit 81 to return the binding force of the battery cell 62 to the initial state before the process of increasing or decreasing the binding force in steps S23 to S24.

[0068] Next, in step S30, the evaluation value N is recorded in the control device 70, and the series of control steps is terminated.

[0069] <III. Case when the ignition is turned on (IG-ON) after the mid-term of battery use starts> Regarding the control method of the battery cell 62 when the ignition is turned on (IG-ON) after the mid-term of battery use starts (when the battery cell 62 is being charged and discharged), it will be described using the flowchart shown in FIG. 9.

[0070] In the flowchart shown in FIG. 9, it starts by turning on the ignition (IG-ON) of the hybrid vehicle 100.

[0071] In step S41, the control device 70 (see FIG. 1) detects the worst high-rate degradation evaluation value N during the previous driving (that is, between the previous IG-ON and IG-OFF). Specifically, as the degradation evaluation value indicating the transition state to high-rate degradation for the battery cell 62 that is most likely to experience high-rate degradation, the high-rate degradation evaluation value N during the previous driving is called from the memory of the control device 70. The method for identifying the battery cell 62 that is most likely to experience high-rate degradation is not particularly limited in the present invention. For example, it may be identified by a method such as finding the battery cell 62 with the lowest temperature among the temperatures of the plurality of battery cells 62.

[0072] Next, in step S42, the control device 70 determines whether a predetermined time has elapsed since the previous driving. The predetermined time is a time sufficient for the evaluation value N to return to 1. If the predetermined time has elapsed, it proceeds to step S43 to obtain the evaluation value N = 1 at the start of driving, and then detects the battery temperature (the average temperature of the plurality of battery cells 62 or the temperature of the battery cell 62 that is most likely to experience high-rate degradation (for example, the temperature of the battery cell 62 with the lowest temperature among the plurality of battery cells 62)) (step S44).

[0073] On the other hand, if the predetermined time has not elapsed, the process proceeds to step S45, where a current evaluation value N is obtained from the map of evaluation value N and downtime shown in Fig. 13, and then the process proceeds to step S44. The map shown in Fig. 13 shows the relationship between the ion bias evaluation value N as a high-rate degradation evaluation value and the downtime tr. For example, when the downtime tr is 1.2 hours, the ion bias evaluation value N is 0.7, and when the downtime is 8 hours, the evaluation value N is 0.97. According to Fig. 13, the "predetermined time" in step S42 corresponds to 11 hours, which is the downtime at which the evaluation value N returns to 1.

[0074] Incidentally, the following steps S46 to S54 are basically the same as the steps S3 to S11 in the control flow chart of FIG.

[0075] First, in step S46, it is determined whether the detected battery temperature has reached a target value. The target temperature is set to, for example, a relatively high temperature that is unlikely to cause high-rate degradation and is suitable for driving by the driver.

[0076] If the battery temperature has reached the target temperature, the process proceeds to step S47, where the effective current of the battery 60 (i.e., all of the multiple battery cells 62) is detected. If the battery temperature has not reached the target temperature, the process proceeds to step S48, where battery temperature control is turned ON, and then the process proceeds to step S47. Specifically, in battery temperature control, the multiple battery cells 62 are temperature-adjusted (heated or cooled) by a temperature adjustment device to approach the target temperature (note that it is not necessary to reach the target temperature).

[0077] Next, the control device 70 (detection unit 71) determines whether the effective current is greater than a threshold value (step S49).

[0078] If the effective current is greater than the threshold value, the process proceeds to step S50, similar to step S7 in Fig. 7, where the limit integrated current value is obtained from the map in Fig. 11 (step S50), and the evaluation value N is calculated using the effective current value (step S51). On the other hand, if the effective current is smaller than the predetermined value, step S50 is skipped and the process proceeds to step S51.

[0079] In step S51, in the same manner as step S8 in FIG. 7 above, the evaluation value N is obtained from the effective current value Ie (A), the elapsed time t (seconds), and the limit integrated current value IS (Ah) obtained in step S50 according to the above (Equation 1).

[0080] Next, it is determined whether the evaluation value N is greater than the target value (step S52). The target value is an arbitrary numerical value, for example, arbitrarily set within the range from 0 to 1.

[0081] When the evaluation value N is greater than the target value, the process proceeds to step S53, the evaluation value N is recorded in the control device 70, and a series of current control is terminated.

[0082] On the other hand, when the evaluation value N is smaller than the target value, the process proceeds to step S54. In the same manner as step S11 in FIG. 7 above, the current control unit 74 restricts the effective current to a value equal to or less than a predetermined value (for example, equal to or less than the upper limit current value). Then, the process proceeds to step S53 and ends.

[0083] By executing the above series of control flowcharts, it becomes possible to limit the effective current of the battery cell 62 that is likely to deteriorate at a high rate and suppress the high-rate deterioration.

[0084] <IV. Case when IG-OFF occurs after the mid-term of battery use start> A control method for the battery cell 62 in the case when IG-OFF occurs after the mid-term of battery use start (when the charge and discharge of the battery cell 62 are paused) will be described using the flowchart shown in FIG. 10.

[0085] The flowchart shown in FIG. 10 starts by turning off the ignition (IG-OFF) of the hybrid vehicle 100.

[0086] In step S61, the control device 70 (see FIG. 1) determines whether the worst high-rate degradation evaluation value N immediately before IG-OFF is smaller than 1 (N<1). Here, the worst high-rate degradation evaluation value N refers to the high-rate degradation evaluation value N during driving immediately before IG-OFF for the battery cell 62 most susceptible to high-rate degradation (for example, the battery cell 62 with the lowest temperature).

[0087] If the high-rate degradation evaluation value N is smaller than 1, the process proceeds to step S62, where the binding force control unit 82 controls the binding force application unit 81 to reduce the binding force of the battery cell 62. If the evaluation value N is 1 or greater, the process proceeds to step S68, which will be described later, and then ends.

[0088] After the process of reducing the restraining force on the battery cell 62 in step S62, the process proceeds to step S63.

[0089] Incidentally, the following steps S63 to S68 are basically the same as the steps S25 to S30 in the control flow chart of FIG.

[0090] In step S63, similarly to step S25 in FIG. 8, the control device 70 reads out the map of high-rate degradation evaluation value and pause time shown in FIG.

[0091] Next, in step S64, a high-rate degradation evaluation value is calculated from the pause time, similarly to step S26 in Fig. 8. Specifically, an ion bias evaluation value N is calculated as a high-rate degradation evaluation value corresponding to the pause time from curve L1 where the binding force during pause is small in the graph in Fig. 12. Here, by looking at the graph in Fig. 12, it can be seen that, in curve L1 where the binding force during pause is small, the ion bias evaluation value N returns to 1 when the pause time t1 is 7 hours, whereas, in curve L2 where the binding force during pause is large, the ion bias evaluation value N does not return to 1 until the pause time t2 reaches 11 hours.

[0092] Next, in step S65, the control device determines whether or not to turn on the ignition (IG-ON). If the IG-ON is not to be turned on, the process proceeds to step S66, and if the IG-ON is to be turned on, the process proceeds to step S67.

[0093] In step S66, it is determined whether or not the high-rate degradation evaluation value N has reached 1 (N≧1). If the evaluation value N has reached 1, the process proceeds to step S67, and if not, the process returns to step S64 to recalculate the evaluation value N.

[0094] In step S67, the binding force control unit 82 controls the binding force application unit 81 to return the binding force of the battery cell 62 to the initial state before the process of reducing the binding force in step S62.

[0095] Next, in step S68, the evaluation value N is recorded in the control device 70, and the series of control steps is terminated.

[0096] This reduces the restraining force on the battery cells 62 during the rest period, making it possible to quickly recover from high-rate degradation.

[0097] (Features of this embodiment) (1) 1, the control device 110 for the battery cells 62 of this embodiment is a control device that controls the restraining force of a plurality of battery cells 62 in a battery module (battery 60) in which a plurality of battery cells 62, which are chargeable and dischargeable secondary batteries, are arranged overlapping in a predetermined direction D. The control device 110 includes a detection unit 71 that detects high-rate deterioration of each of the plurality of battery cells 62, a determination unit 72 that determines whether the high-rate deterioration is due to insufficient aging at the beginning of use of the battery cells 62, a restraining force application unit 81 that applies a restraining force to the plurality of battery cells 62 in the predetermined direction D, and a restraining force control unit 82 that controls the restraining force application unit 81.

[0098] When the determination unit 72 determines that high-rate deterioration has occurred due to insufficient aging, the constraint force control unit 82 controls the constraint force application unit 81 to increase the constraint force applied to the multiple battery cells 62 (see Figures 2(a) and (b) and steps S21 to 23 in Figure 8).

[0099] In the control device 110 for the battery cell 62 of this embodiment, when the determination unit 72 determines that high-rate deterioration due to insufficient aging has occurred in any of the multiple battery cells 62 at the beginning of use of the battery cell 62, the binding force control unit 82 controls the binding force application unit 81 so as to increase the binding force applied to the multiple battery cells 62. By applying a large binding force to the insufficiently aged battery cell 62, it is possible to discharge gas generated inside the battery cell 62. Therefore, it is possible to suppress a decrease in the reaction area of ​​the negative electrode caused by gas adhering to the negative electrode inside the battery cell 62. As a result, it is possible to suppress high-rate deterioration due to insufficient aging of the battery cell 62 at the beginning of use of the battery cell 62.

[0100] (2) In the control device 110 of the battery cells 62 of this embodiment, when the determination unit 72 determines that the high-rate degradation is not high-rate degradation due to insufficient aging, the constraint force control unit 82 controls the constraint force application unit 81 to reduce the constraint force applied to the multiple battery cells 62 while charging and discharging of the multiple battery cells 62 is suspended (see steps S22 and S24 in Figure 8).

[0101] According to this configuration, high-rate degradation due to insufficient aging at the beginning of use of the battery cells 62 is eliminated, and when high-rate degradation occurs after the beginning of use, the restraining force of the battery cells 62 is reduced while charging and discharging of the multiple battery cells 62 is suspended. This makes it possible to quickly eliminate the bias of ions in the electrolyte within the battery cells 62. As a result, it becomes possible to hasten the recovery of the battery cells 62 from high-rate degradation.

[0102] (3) In the control device for the battery cell 62 of this embodiment, the judgment unit 72 estimates the internal resistance from the charge / discharge history of the battery cell 62 at the beginning of use, and compares the internal resistance with a predetermined reference internal resistance to judge high-rate deterioration due to insufficient aging (steps S12 to S14 in FIG. 7).

[0103] With this configuration, it is possible to easily determine high-rate deterioration due to insufficient aging by comparing the internal resistance of the battery cell 62 with a reference internal resistance. Therefore, there is no need to directly detect the adhesion of gas inside the battery cell 62, and the configuration of the control device is simplified.

[0104] (4) The control method for battery cells 62 in this embodiment is a control method for controlling a restraining force of a plurality of battery cells 62 in a battery module in which a plurality of battery cells 62, which are chargeable and dischargeable secondary batteries, are arranged overlapping in a predetermined direction D. This control method includes a detection step (see steps S1 to S9 in FIG. 7) for detecting high-rate deterioration of each of the plurality of battery cells 62, a determination step (steps S12 to S14 in FIG. 7) for determining whether the high-rate deterioration is high-rate deterioration due to insufficient aging in the early stage of starting to use the battery cells 62, and a restraining force applying step (see steps S21 to S23 in FIG. 8) for applying a restraining force to the plurality of battery cells 62 in the predetermined direction D.

[0105] In the restraining force applying step, when high-rate deterioration due to insufficient aging is determined in the determining step, the restraining force applied to the plurality of battery cells 62 is increased.

[0106] According to this feature, when it is determined in the determination step that high-rate deterioration due to insufficient aging has occurred in any of the plurality of battery cells 62 in the initial stage of use of the battery cell 62, the restraining force imparted to the plurality of battery cells 62 is increased in the restraining force imparting step. By subjecting the insufficiently aged battery cell 62 to a large restraining force, it is possible to discharge gas generated inside the battery cell 62. For this reason, it is possible to suppress a decrease in the reaction area of ​​the negative electrode caused by gas adhering to the negative electrode inside the battery cell 62. As a result, it is possible to suppress high-rate deterioration due to insufficient aging of the battery cell 62 in the initial stage of use of the battery cell 62. [Explanation of symbols]

[0107] 60 Battery module 62 Battery Cell 80 Restraint mechanism 81 Binding force application section 82 Restraint force control unit 70 Control device 71 Detection unit 72 Judgment section 100 Hybrid cars 110 Control device D Array direction

Claims

1. A control device for controlling a restraining force of a plurality of battery cells in a battery module in which a plurality of battery cells, which are chargeable and dischargeable secondary batteries, are arranged in a stacked manner in a predetermined direction, comprising: A detection unit that detects high-rate deterioration of each of the plurality of battery cells; a determination unit that determines whether the high-rate deterioration is due to insufficient aging at an early stage of use of the battery cell; a restraining force applying unit that applies a restraining force to the plurality of battery cells in the predetermined direction; A binding force control unit that controls the binding force application unit; Equipped with the constraint force control unit controls the constraint force application unit to increase the constraint force applied to the plurality of battery cells when the determination unit determines that high-rate deterioration is caused by insufficient aging. Battery cell control device.

2. 2. The battery cell control device according to claim 1, the constraint force control unit controls the constraint force application unit to reduce the constraint force applied to the plurality of battery cells while charging / discharging of the plurality of battery cells is suspended when the determination unit determines that the high-rate deterioration is not high-rate deterioration due to insufficient aging. Battery cell control device.

3. The battery cell control device according to claim 1 or 2, the determination unit estimates an internal resistance from a charge / discharge history of the battery cell at an early stage of use, and determines high-rate deterioration due to insufficient aging by comparing the internal resistance with a predetermined reference internal resistance; Battery cell control device.

4. A control method for controlling a binding force of a plurality of battery cells in a battery module in which a plurality of battery cells, which are chargeable and dischargeable secondary batteries, are arranged in a stacked manner in a predetermined direction, comprising: a detection step of detecting high-rate deterioration of each of the plurality of battery cells; a determination step of determining whether the high-rate deterioration is due to insufficient aging at an early stage of use of the battery cell; a restraining force applying step of applying a restraining force to the plurality of battery cells in the predetermined direction; having In the restraining force applying step, when high-rate deterioration due to insufficient aging is determined in the determining step, the restraining force applied to the plurality of battery cells is increased. A method for controlling battery cells.

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