JP2016126943A - Power storage device and power storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device and a power storage system excellent in the assembly work and maintainability.SOLUTION: A power storage device 30 includes a plurality of laminated lithium ion secondary battery cells 3, a lashing device 2 having a pair of lashing plates 20 for sandwiching the plurality of laminated lithium ion secondary battery cells 3 in the cell lamination direction, and lashing the plurality of laminated lithium ion secondary battery cells 3, and a displacement sensor 1 for detecting the expansion amount of the plurality of laminated lithium ion secondary battery cells 3 lashed by the pair of lashing plates 20, in the cell lamination direction. The displacement sensor 1 is arranged on the outside of the plurality of laminated lithium ion secondary battery cells 3 lashed by the pair of lashing plates 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage device and a power storage system.

  In order to widely spread power storage devices such as lithium ion batteries and capacitors for in-vehicle use and industrial use, it is essential to extend the life. When a lithium ion battery or capacitor is charged / discharged for a long time, the resistance increases due to deterioration of the battery material, and a predetermined output and capacity cannot be obtained, resulting in a battery life. In order to use the secondary battery beyond the target life, it is one effective measure to detect the deterioration state of the battery and adjust the charge / discharge conditions according to the deterioration state.

  In the technique described in Patent Document 1, in a power supply device composed of a plurality of cells (single cells) and a battery computer, when a pressure sensor is attached between the cells and the lashing plate and the cells expand due to deterioration, the pressure rises. The system which can detect as is proposed.

JP 2006-24445 A

  However, in the case where the pressure sensor is inserted between the cells or between the cells and the securing plate, the battery assembling work becomes complicated and the workability is inferior. Also, if there is a possibility that an error signal has been transmitted from the sensor, or if the sensor needs to be calibrated, the battery module must be disassembled each time, and there is a problem that the work takes time. .

The power storage device according to claim 1 includes a plurality of stacked power storage cells, and first and second securing members that sandwich the plurality of power storage cells in a cell stacking direction. And a displacement sensor for detecting an expansion amount in the cell stacking direction of the plurality of power storage cells secured by the first and second securing members, and The displacement sensor is disposed outside the plurality of power storage cells secured by the securing device.
A power storage system according to a sixth aspect of the present invention is the power storage device according to the first aspect, and a first estimation unit that estimates a deterioration state of the plurality of power storage cells based on a current value and a voltage value of the power storage cell. The second estimation unit that estimates the degradation state of the plurality of power storage cells based on the expansion amount, and the first estimation unit that is estimated based on the degradation state that is estimated by the second estimation unit. And a determination unit for determining reliability of the deteriorated state.
A power storage system according to an eighth aspect of the present invention is the power storage device according to claim 1 used for a vehicle driving power source of an electric vehicle, and deterioration of the plurality of power storage cells based on a current value and a voltage value of the power storage cell. A first estimation unit that estimates a state; a storage unit that stores reference expansion amounts of the plurality of storage cells measured by holding the plurality of storage cells at a predetermined temperature and a predetermined charge state; and the reference expansion Based on the second estimation unit that estimates the degradation state of the plurality of power storage cells based on the amount, the degradation state estimated by the first estimation unit, and the degradation state estimated by the second estimation unit And a charge / discharge control unit that changes the charge / discharge conditions of the power storage module.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage apparatus and electrical storage system excellent in assembly work and maintainability can be provided.

FIG. 1 is a diagram illustrating a first embodiment of a power storage system. FIG. 2 is a flowchart illustrating an example of the determination process for deterioration state estimation. FIG. 3 is a diagram for explaining expansion amount correction. FIG. 4 is a diagram showing the relationship between the charge / discharge time, battery resistance, and expansion amount. FIG. 5 is a diagram illustrating a second embodiment of the power storage system. FIG. 6 is a diagram for explaining the third embodiment. FIG. 7 is a diagram illustrating an example of the relationship between the load and the dimension in the stacking direction of the battery module. FIG. 8 is a diagram showing a first modification of the displacement sensor arrangement. FIG. 9 is a diagram illustrating a second modification of the displacement sensor arrangement. FIG. 10 is a schematic diagram when a linear encoder is used as the displacement sensor. FIG. 11 is a schematic diagram when a differential transformer type displacement sensor is used.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
-First embodiment-
FIG. 1 is a diagram for explaining a first embodiment of a power storage system according to the present invention. A power storage system 100 illustrated in FIG. 1 is an in-vehicle power storage system, and includes a power storage device 30, a cell controller 8, a storage circuit 9, and a battery controller 10.

  The power storage device 30 includes a battery module MD, a base 7 on which the battery module MD is placed, and a reference plate 6 fixed to the base 7. The battery module MD includes a plurality of lithium ion secondary battery cells 3 stacked in the left-right direction in the figure, a lashing device 2 for securing the lithium ion secondary battery cells 3, and a pair of displacement sensors 1. ing. The lashing device 2 includes a pair of lashing plates 20 disposed at the left and right ends of the stacked lithium ion secondary battery cells 3 and side plates 21 that connect the lashing plates 20 to each other. The side plate 21 is provided on both sides. By attaching the side plate 21 to the lashing plate 20, the stacked body of the lithium ion secondary battery cells 3 is sandwiched between the pair of lashing plates 20 in the cell stacking direction.

The lithium ion secondary battery cell 3 is a rectangular battery cell. For example, the positive electrode and the negative electrode are stacked or wound through an electrical insulating separator and impregnated with a water-insoluble electrolyte solution. It is enclosed in. The positive electrode is obtained by mixing LiCoO ₂ particles on an aluminum foil with a conductive agent and a binder. As the positive electrode active material, lithium metal transition oxides such as LiNiO ₂ , LiMnO ₂ , and LiNiCoMnO ₂ can be used in addition to LiCoO ₂ . The negative electrode is obtained by mixing graphite particles with a binder on a copper foil. In addition to graphite, a mixed material of Si, SiO, and graphite can be used as the negative electrode active material. A microporous film in which PP and PE materials are laminated is used as a separator for electrical insulation, but non-woven fabric, cellulose and the like can be substituted. LiPF ₆ is used as the electrolyte of the water-insoluble electrolyte, but LiBF ₄ can be substituted. As a solvent for the electrolytic solution, a mixture of EC, DMC, and EMC was used.

  The battery capacity of the lithium ion secondary battery cell 3 decreases as the charge / discharge cycle increases. The decrease in the battery capacity is considered to be caused by expansion due to charging / discharging of the lithium ion secondary battery cell 3. The amount of expansion varies depending on the deterioration state of the lithium ion secondary battery cell 3, and also varies depending on the state of charge (SOC) of the lithium ion secondary battery cell 3. The battery module MD shown in FIG. 1 includes a lashing device 2 that ties the battery module MD in the stacking direction in order to suppress the expansion of the battery module MD and to suppress a decrease in battery capacity.

  The lashing device 2 is provided to suppress expansion of the lithium ion secondary battery cell 3. The lashing plates 20 are provided at both ends in the cell stacking direction of a plurality of lithium ion secondary battery cells 3 (hereinafter may be referred to as cell stacks), and sandwich them. The pair of lashing plates 20 are connected by side plates 21 so that the cell stack is sandwiched by a predetermined pressure. The battery module MD secured by the securing device 2 is fixed on the base 7. When the lithium ion secondary battery cell 3 expands due to charging / discharging and battery deterioration, the distance between the securing plates 20 changes even in a secured state.

  Each lashing plate 20 is provided with a displacement sensor 1 on a surface (hereinafter referred to as a non-clamping surface) 20a opposite to a surface that sandwiches the cell stack. A reference plate 6 is provided at a position facing the displacement sensor 1. The reference plate 6 is fixed to the base 7 on which the battery module MD is placed. The displacement sensor 1 is a sensor for measuring the distance between the reference plate 6 and the securing plate 20. As the displacement sensor 1, for example, a red light emitting diode (LED) displacement sensor is used. A laser displacement sensor may be used when more accurate measurement is required.

  Each lithium ion secondary battery cell 3 is charged and discharged under predetermined conditions by a battery controller 10 connected via a current line 4. The charge / discharge conditions of the lithium ion secondary battery cell 3 are adjusted by the battery controller 10 based on information from the cell controller 8 and the vehicle controller 11. A cell voltage of each lithium ion secondary battery cell 3 is input to the cell controller 8 via the voltage line 5. Further, distance information (detection signal) is input to the cell controller 8 from the displacement sensor 1 attached to each lashing plate 20. The cell controller 8 calculates the expansion amount of the battery module MD based on the input distance information (distance information of the lashing plate 20). The storage circuit 9 stores an input signal from the cell controller 8 as a log. The charge / discharge conditions of the battery module MD output from the battery controller 10 are input to the vehicle controller 11 that controls the entire vehicle.

  Next, a method for estimating the deterioration state of the lithium ion secondary battery cell 3 provided in the battery module MD will be described. The lithium ion secondary battery cell 3 is charged and discharged as lithium ions move between the positive electrode and the negative electrode and are repeatedly inserted and removed. When the lithium ion secondary battery cell 3 is charged and discharged for a long period of time, the amount of lithium ions that can move per unit time or the total amount of lithium ions that can move within a predetermined voltage range decreases due to deterioration of the electrode material, electrolyte, etc. The output and capacity will decrease. In order to use the lithium ion secondary battery cell 3 to the target life, it is necessary to grasp the deterioration state of such a battery and adjust the charge / discharge conditions according to the deterioration state.

  As described above, in the conventional estimation method for estimating the deterioration state from the battery resistance value calculated from the voltage value and the current value, if a measurement error occurs in the voltage value or the current value, the deterioration state is erroneously determined. There was a risk of it.

  One of the indexes indicating the deterioration of the lithium ion secondary battery cell 3 is expansion of the electrode due to cracking of the electrode active material, residual lithium ions in the active material, and the like. Therefore, in the present embodiment, the expansion amount of the battery module MD obtained based on the detection data of the displacement sensor 1 is used for the deterioration state determination, thereby improving the reliability of the deterioration state estimation.

  As described above, in the present embodiment, the distance information between the reference plate 6 and the securing plate 20 measured by the displacement sensor 1 is input to the cell controller 8 as a voltage value so as to grasp the expansion amount of the battery module MD. I have to. However, since the expansion amount also varies depending on the SOC of the battery module MD, it is desirable to measure the expansion amount with the displacement sensor 1 after adjusting the battery module MD to a predetermined SOC in order to accurately evaluate the expansion amount. Note that there is no particular value as the predetermined SOC, and for example, SOC = 50% may be set as the predetermined SOC.

  During vehicle operation, the charge / discharge state of the lithium ion secondary battery cell 3 often changes rapidly with respect to time, so it is difficult to adjust the expansion to a predetermined SOC. Further, the expansion amount of the battery module MD is affected by the ambient temperature, and in the case of in-vehicle use, the temperature change becomes large, so that the measurement accuracy may be lowered.

  Therefore, the battery module MD is removed from the vehicle at the time of vehicle inspection or periodic inspection, and the expansion amount is accurately measured by the following procedure. First, when the power storage device 30 is removed from the vehicle, the SOC of the battery module MD is adjusted to a predetermined SOC using the charge / discharge device. Next, the temperature of the battery module MD is held at a predetermined temperature, and the expansion amount of the battery module MD is measured. The expansion amount is measured using the displacement sensor 1 provided in the power storage device 30. The measured expansion amount E0 is stored in the storage circuit 9 as a reference expansion amount at a predetermined SOC and a predetermined temperature.

  FIG. 2 is a flowchart illustrating an example of the determination process for deterioration state estimation. The series of processing shown in FIG. 2 is executed by the battery controller 10 at a specific timing of the vehicle usage status (for example, immediately after vehicle inspection or timing of vehicle activation).

  In step S <b> 10, the current value, voltage value, and expansion amount E of the lithium ion secondary battery cell 3 are measured, and the measurement data is stored in the storage circuit 9. In step S20, the battery resistance R1 is calculated based on the current value and voltage value measurement data stored in the storage circuit 9. In step S30, an expansion amount E1 = E (SOC, T) × K (SOC, T) of a predetermined temperature and a predetermined SOC is calculated based on the measured expansion amount E, the battery temperature at the time of measurement, and the SOC. The battery module MD is provided with a temperature sensor, and a temperature detection signal is input to the battery controller 10. Since the expansion amount depends on the battery temperature and the SOC, the expansion coefficient E1 at a predetermined temperature and a predetermined SOC is converted using the conversion coefficient K (SOC, T) as described above. The conversion coefficient K (SOC, T) is stored in advance in the storage circuit 9 as map data.

  In the present embodiment, the expansion amount E1 obtained during vehicle travel is corrected as shown in FIG. 3 using the expansion amount E0 measured during vehicle inspection. In FIG. 3, E (t) indicates a change in the expansion amount with respect to the charge / discharge time t when charge / discharge is performed under predetermined charge / discharge conditions. Since the expansion amount E0 obtained at the time of vehicle inspection is an accurate measured value, it is on the curve E (t). And the expansion amount E1 is acquired in the vehicle-mounted state immediately after vehicle inspection. The expansion amount E1 is converted into a value at a predetermined temperature and a predetermined SOC, but includes an error as compared with the expansion amount E0 obtained at the time of vehicle inspection. Therefore, the difference = E0−E1 is stored in the storage circuit 9 as a correction value (offset value), and for the expansion amount E1 (before correction) acquired thereafter, “expansion amount E1 (before correction) + correction value”. Is the corrected expansion amount E1. Therefore, the corrected expansion amount E1 is a value close to the curve E (t). The corrected expansion amount E1 is used as the expansion amount E1 in step S30. Of course, if a slight error is allowed, the expansion amount E1 (before correction) may be used.

  In step S40, charge / discharge times tr1 and te1 are calculated based on the battery resistance R1 and the expansion amount E1 acquired in steps S20 and S30, respectively. The storage circuit 9 stores in advance map data representing the correlation between the battery resistance R1 and the charge / discharge time tr1, and map data representing the correlation between the expansion amount E1 and the charge / discharge time te1 at a predetermined temperature and a predetermined SOC. ing. From these map data, the battery resistance R1, and the expansion amount E1, the charge / discharge times tr1, te1 are calculated.

  In step S50, it is determined whether or not the difference between charging and discharging times tr1 and te1 = | te1−tr1 | satisfies the difference ≦ Δt with respect to the allowable value Δt. FIG. 4 is a diagram showing the relationship between the charge / discharge time t, the battery resistance R, and the expansion amount E. The correlations R (t) and E (t) are stored in advance in the storage circuit 9 as map data or correlation functions. In the example shown in FIG. 4, the difference = | te 1 −tr 1 | satisfies the difference ≦ Δt. That is, it can be determined that the battery resistance R1 acquired in step S20 is reliable and the measurement system related to the current value and the voltage value is normal (step S60).

  On the other hand, when the battery resistance is a value like R2 in FIG. 4, since the difference between the charge / discharge time tr1 and the charge / discharge time te1 is large, it is determined that the acquired battery resistance R2 is not reliable (step) S70). That is, it can be determined that an abnormality has occurred in the measurement system related to the current value and the voltage value.

  If it is determined in step S60 that there is reliability, the deterioration state is estimated using the battery resistance R1 as usual. On the other hand, if it is determined that there is “no reliability” in step S70, the process proceeds to step S80, and an alarm notifying that there is an abnormality in the battery measurement system is transmitted from the battery controller 10 to the vehicle controller 11.

  Note that R (t) and E (t) shown in FIG. 4 indicate changes in battery resistance and expansion when the battery module MD is used in a predetermined charge / discharge pattern. Therefore, when charging / discharging is performed under charge / discharge conditions that are likely to deteriorate, the charging / discharging time tr1, te1 calculated in step S40 is longer than the charging / discharging time actually counted by the timer. That is, the remaining life of the battery module MD is shorter.

  In such a case, the remaining life is extended so that the battery module MD can be used up to the nominal battery guarantee time by changing the charge / discharge conditions. As such a countermeasure, for example, there is a method of setting the SOC upper limit value at the time of charging control lower than a preset SOC upper limit value. As a result, since the SOC usage range of the battery module MD is set to be lower, the degree of progress of deterioration of the battery module MD is reduced, and the remaining life can be improved.

  In the process shown in FIG. 2, the measurement system diagnosis in the in-vehicle state has been described. However, when the power storage device 30 is removed from the vehicle and the expansion amount E0 of the battery module MD is measured during vehicle inspection, the measurement system is calculated from the battery resistance R1 and the expansion amount E0 calculated from the voltage and current at the time of charging and discharging. You may diagnose the condition.

  Further, instead of the above-described deterioration diagnosis, the battery controller 10 may perform diagnosis of the measurement system and determination of the deterioration state by performing the following diagnosis. That is, the battery resistance R1 and the expansion amount E0 acquired at the time of vehicle inspection are larger than the battery resistance value and the expansion amount predicted from the actually counted charge / discharge time and the correlations R (t1) and E (t). In this case, it is determined that the deterioration of the battery module MD is proceeding from the prediction. In that case, since the target life cannot be achieved, the cell controller 10 is changed to a relaxed condition such as narrowing the operating range of current and voltage during charging / discharging or reducing the number of charge / discharge cycles per hour. Controls charging and discharging of

  On the other hand, the battery resistance is higher than the predicted value, but if the expansion amount is smaller than the predicted value, there is a possibility of deterioration of the electrolyte, poor contact between the member and the signal line, or a false signal. It is necessary to estimate and take measures.

  In addition, when both the battery resistance and the expansion amount are equal to or less than the predicted values, the battery module MD is considered to be within the predicted range, and charging / discharging is performed without changing the conditions.

  In many cases, a life prediction formula is used for predicting the battery life, but the predicted value varies depending on the active material of the positive and negative electrodes, the electrolyte composition, charge / discharge conditions, temperature, and the like. Therefore, it is necessary to conduct a life evaluation test in advance under conditions as close as possible to the actual battery and use a prediction formula created based on the result.

  As described above, in the power storage device 30 of the present embodiment, by detecting the reference plate 6 by the displacement sensor 1, a change in the distance between each lashing plate 20 and the opposing reference plate 6 is detected. As a result, it is possible to detect the amount of expansion in the stacking direction of the cell stack that is secured by the securing plate 20.

  Since the displacement sensor 1 is disposed on the non-clamping surface 20a of the lashing plate 20, as shown in FIG. 1, that is, on the portion exposed to the outside of the lashing plate 20 (non-clamping surface 20a), the cell stack It is also possible to attach the displacement sensor 1 to the lashing plate 20 after the lashing is secured with the lashing plate 20, and the assembly workability is excellent. In addition, since the displacement sensor 1 can be attached to and detached from the non-clamping surface 20a even in a secured state, the displacement sensor 1 can be easily inspected and calibrated after being secured, and the displacement sensor 1 is broken. The replacement work can be easily performed.

  Further, in the battery controller 10, the deterioration state of the lithium ion secondary battery cell 3 is estimated based on the current value and voltage value of the lithium ion secondary battery cell 3, and the lithium ion secondary battery cell 3 is estimated based on the expansion amount of the battery module MD. The deterioration state of the secondary battery cell 3 is estimated, and the reliability of the deterioration state estimated based on the current value and the voltage value is determined based on the deterioration state estimated based on the expansion amount. As a result, it is possible to diagnose an abnormality in the current value and voltage value measurement system, and to prevent erroneous diagnosis of the deterioration state. That is, the reliability of the deterioration state diagnosis can be improved.

  Furthermore, the expansion amount E0 measured by holding the battery module MD at a predetermined temperature and a predetermined charged state is stored in the storage circuit 9, and the measured expansion amount is corrected by the battery controller 10 based on the reference expansion amount E0. By estimating the deterioration state based on the corrected expansion amount instead of the measured expansion amount, the above-described abnormality diagnosis of the measurement system can be performed more accurately.

-Second Embodiment-
FIG. 5 is a diagram for explaining the second embodiment. FIG. 5 is a schematic diagram illustrating a schematic configuration of an installation type power storage system 200. Compared with the in-vehicle power storage system 100 illustrated in FIG. 1, the power storage controller 12 is provided and the storage circuit 9 is not provided. Different. The power storage controller 12 controls the entire power storage system 200 and sends a control signal to the battery controller 10.

  The power storage system 200 is used for an emergency power supply in the event of a power failure, a backup power supply for leveling the power load, and the like. In the above-described in-vehicle power storage system 100, since the charging conditions, temperature, and the like change drastically, the power storage device 30 is removed from the vehicle, and the expansion amount E0 is measured at a predetermined temperature and a predetermined SOC state.

  On the other hand, in the case of the power storage system 200, the change in the charge / discharge state with respect to time is small and the change in the ambient temperature is small compared to the in-vehicle power storage system 100. Therefore, the current, voltage, and expansion amount during charging / discharging of the battery module MD are continuously measured on-time, and the battery resistance and the expansion amount are obtained from the current, voltage, and expansion amount when the predetermined SOC is reached. In addition, the process of grasping | ascertaining the deterioration state of a battery from battery resistance and an expansion amount is the same as the case of vehicle-mounted. However, since the storage device 30 is removed and the expansion amount E0 of the battery module MD is not measured, the expansion amount E1 in step S30 is the measured expansion amount itself.

  Thus, in the present embodiment, the deterioration state of the battery module MD is estimated based on the current value and voltage value of the lithium ion secondary battery cell 3. Then, the reliability of the estimated deterioration state is determined based on the expansion amount obtained from the detection value of the displacement sensor 1. The power storage system 200 generally has a larger capacity than that for in-vehicle use, and the number of battery modules MD increases. For this reason, in the same method as that for in-vehicle use described above, it takes a lot of time to grasp the deterioration state of the battery and to adjust the charge / discharge state, leading to an increase in running cost and a decrease in system operation rate. Therefore, by measuring the expansion amount of the battery module MD on-time as described above, it is possible to shorten the time for deterioration state diagnosis.

-Third embodiment-
FIG. 6 is a diagram for explaining the third embodiment. FIG. 6 is a diagram illustrating the power storage device 30. In FIG. 6, the illustration of the side plate 21 is omitted. This power storage device 30 can be applied to the in-vehicle power storage system 100 shown in the first embodiment and the installed power storage system 200 shown in the second embodiment.

  In the present embodiment, the displacement sensor 1 is provided on the upper end surface (that is, the non-clamping surface) 20b of one lashing plate 20, and the reference plate 6 as a sensor target is disposed on the upper end surface 20b of the other lashing plate 20. I tried to do it. In the example shown in FIG. 6, the displacement sensor 1 is provided on the right lashing plate 20 and the reference plate 6 is provided on the left lashing plate 20 in the drawing. However, the arrangement may be reversed.

  In the present embodiment, since the displacement sensor 1 is disposed on the upper end surface 20b exposed to the outside of one of the lashing plates 20, the assembly workability of the power storage device 30 is the same as in the case of the first embodiment. Is excellent. Further, since the displacement sensor 1 can be attached to and detached from the upper end surface 20b even in a lashed state, the displacement sensor 1 after the lashing can be easily inspected and calibrated, and the displacement sensor 1 is broken. The replacement work can be easily performed.

  When a plurality of lithium ion secondary battery cells 3 are secured, the securing plates 20 are attached to both sides of the laminated body of the lithium ion secondary battery cells 3, and the battery module MD to which the securing plates 20 are attached is pressed against the holding plate 22 a. And the load plate 22b. Then, the load plate 22b is pressed in the direction of the lashing plate 20 to apply a predetermined load, and a side plate 21 (not shown) (see FIG. 1) is attached to the lashing plate 20 with the load applied. Thereby, battery module MD will be in a locked state.

  FIG. 7 is a diagram illustrating an example of a relationship between a load and a dimension in the stacking direction of the battery module MD (here, referred to as a width dimension) when a load is applied to the battery module MD. The width dimension of the battery module MD decreases as the load increases. Moreover, even if it is the same load, a width dimension changes with the height of SOC of battery module MD. In FIG. 7, the relationship is SOC1> SOC2> SOC3. For the same load F, the width dimensions W1, W2, and W3 in the case of SOC1, SOC2, and SOC3 are W1> W2> W3.

  Therefore, when mass-producing the battery module MD having the same configuration, the following assembly operation can be performed using the detection result of the displacement sensor 1. First, the correlation between the load and the width dimension as shown in FIG. 7 is obtained in advance for the battery module MD to be used. Then, when a load is applied to the load plate 22b as shown in FIG. 6 and the distance between the lashing plates 20 detected by the displacement sensor 1 (that is, the width dimension) reaches a predetermined size, The side plate 21 is fixed.

  As a result, the battery module MD is secured with a predetermined securing load without measuring the securing load at the time of securing. In such a lashing operation, management by the width dimension detected by the displacement sensor 1 is superior to management by a lashing load, and workability can be shortened. Further, the displacement sensor 1 can be used for both the width dimension management at the time of lashing operation and the detection of the expansion amount associated with charging / discharging.

  The embodiment described above has the following operational effects. As shown in FIG. 1, the power storage device 30 includes a plurality of stacked lithium ion secondary battery cells 3 (power storage cells) and a pair of lashes that sandwich the plurality of lithium ion secondary battery cells 3 in the cell stacking direction. A lashing device 2 having a plate 20 and a displacement sensor 1 for detecting an expansion amount in a cell stacking direction of a plurality of lithium ion secondary battery cells 3 lashed by a pair of lashing plates 20 are provided. The displacement sensor 1 is disposed outside the plurality of lithium ion secondary battery cells 3 that are secured by the securing device 2.

  As described above, since the displacement sensor 1 is arranged outside the plurality of lithium ion secondary battery cells 3 secured by the securing device 2, the assembly workability is excellent. Furthermore, even in the locked state, the displacement sensor 1 can be easily calibrated, repaired, exchanged, and the like.

  In addition, as a method of arrange | positioning on the outer side of the some lithium ion secondary battery cell 3 tied with the securing device 2, for example, like the structure shown in FIG. The displacement sensor 1 is provided on the clamping surface 20a, and the reference plate 6 disposed opposite to each displacement sensor 1 is used as the detected part.

  Further, as in the configuration shown in FIG. 6, the displacement sensor 1 is provided on the upper end surface 20 b of one of the lashing plates 20, and the reference plate 6 as a detected portion is provided on the upper end surface 20 b of the other tying plate 20. Anyway. By setting it as such a structure, the number of the displacement sensors 1 can be reduced. Instead of providing the upper end surface 20b of the lashing plate 20, the tying plate 20 may be extended above the lithium ion secondary battery cell 3, and the non-clamping surface of the tying plate 20 may be used as the detected portion.

  In addition, as shown in FIG. 8, the displacement sensor 1 may be provided on a reference plate 6 that is disposed so as to face the non-clamping surface 20 a of the tying plate 20. In this case, the non-clamping surface 20 a of the lashing plate 20 functions as a detected portion of the displacement sensor 1. By setting it as such a structure, it becomes possible to measure expansion | swelling amount also about battery module MD (for example, existing battery module MD for vehicle installation or electrical storage) to which the displacement sensor 1 is not attached.

  Moreover, as shown in FIG. 9, it is good also as a structure which attaches the displacement sensor 1 to the part exposed to the outer side of the metal plate 31 inserted between the lithium ion secondary battery cells 3. FIG. When the displacement sensor 1 cannot be attached to the lashing plate 20 or the reference plate 6, it is possible to measure the expansion amount of the battery module MD by adopting such a configuration. In the example shown in FIG. 9, since five lithium ion secondary battery cells 3 are provided between the pair of metal plates 31, the detected expansion amount E is the expansion amount for five pieces. Therefore, the expansion amount of the battery module MD is estimated to be (E / 5) × 7.

  In the above-described embodiment, an example in which an optical displacement sensor (a red light emitting diode (LED) displacement sensor or a laser displacement sensor) is used as the displacement sensor 1 has been described. However, another type of displacement sensor may be used. Absent. For example, as a non-contact type displacement sensor, for example, there is a linear encoder or the like, and if it is a contact type, a differential transformer type displacement sensor or the like can be raised.

  FIG. 10 is a schematic diagram in the case of using a linear encoder, FIG. 10 (a) is a plan view, and FIG. 10 (b) is a side view. In the example shown in FIG. 10, linear encoders 40 are provided for both of the lashing plates 20, and the position (displacement) of each lashing plate 20 in the cell stacking direction is determined by the linear encoder 40 provided for each. Detected. In FIG. 10A, the lower side plate 21 is indicated by a two-dot chain line.

  The linear encoder 40 is provided with a detection unit 40a and a main scale 40b. The main scale 40 b is provided on the side surface 20 c that is an exposed portion of the lashing plate 20. The detection head 40a is provided with a light source 402 and a light receiving unit 401 with a main scale 40b interposed therebetween. Although not shown, the light receiving unit 401 is provided with an index scale and a light receiving element. When the battery module MD expands and the lashing plate 20 moves in the cell stacking direction (the left-right direction in the figure), the main scale 40b moves relative to the detection head 40a, and the amount of movement is detected by the linear encoder 40. The expansion amount of the battery module MD can be calculated from the movement amount of each linear encoder 40.

  FIG. 11 is a schematic diagram when a differential transformer type displacement sensor is used. The displacement sensor 50 is provided with a movable iron core 51. The movable iron core 51 is configured to move in the horizontal direction in the figure, and the amount of movement is detected by a differential transformer. The displacement sensor 50 is provided such that the tip of the movable iron core 51 is in contact with the non-clamping surface 20a of the securing plate 20. Therefore, when the battery module MD expands and the lashing plate 20 moves in the cell stacking direction (the left-right direction in the drawing), the movable iron core 51 moves in the left-right direction, and the movement amount of each lashing plate 20 is detected. The expansion amount of the battery module MD can be calculated from the movement amount detected by each displacement sensor 50.

  In addition, the content regarding the diagnosis of the measurement system mentioned above and the change of charging / discharging conditions is not the structure which provides the displacement sensor 1 mentioned above, but the conventional which provides a pressure sensor between the battery cells or between the battery cells and the lashing plate 20. The present invention can also be applied in the configuration.

  In the above-described embodiment, the lithium ion secondary battery cell 3 is described as an example of a power storage cell. However, the present invention can also be applied to a power storage device including a power storage module using a lithium ion capacitor or the like as a power storage cell. Further, the present invention can be applied not only to the rectangular lithium ion secondary battery cell 3 but also to a laminate type battery cell.

  As described above, various embodiments and modifications have been described, but the present invention is not limited to these contents. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1,50 ... Displacement sensor, 2 ... Lashing device, 3 ... Lithium ion secondary battery cell, 6 ... Reference | standard board, 7 ... Base, 8 ... Cell controller, 9 ... Memory circuit, 10 ... Battery controller, 11 ... Vehicle controller , 12 ... Storage controller, 20 ... Secure plate, 20a ... Non-clamping surface, 20b ... Upper end surface, 20c ... Side surface, 21 ... Side plate, 30 ... Power storage device, 31 ... Metal plate, 40 ... Linear encoder, 100, 200 ... electric storage system, MD ... battery module

Claims (8)

A plurality of stacked storage cells;
A lashing device for lashing the plurality of cells, the first and second lashing members sandwiching the plurality of power storage cells in the cell stacking direction;
A displacement sensor for detecting the amount of expansion in the cell stacking direction of the plurality of power storage cells secured by the first and second securing members,
The power storage device, wherein the displacement sensor is disposed outside the plurality of power storage cells secured by the securing device. The power storage device according to claim 1,
The displacement sensor is disposed on at least one non-clamping surface of the first and second tying members, or separated from at least one non-clamping surface of the first and second tying members. Placed opposite,
A power storage device including a detected portion that is disposed to face the displacement sensor and is detected by the displacement sensor. The power storage device according to claim 2,
A first displacement sensor provided on a non-clamping surface of the first securing member;
A second displacement sensor provided on a non-clamping surface of the second securing member;
A first detected portion that is disposed opposite to the first displacement sensor and is detected by the first displacement sensor;
A power storage device comprising: a second detected portion that is disposed to face the second displacement sensor and is detected by the second displacement sensor. The power storage device according to claim 2,
The displacement sensor is provided on a non-clamping surface of the first securing member;
The power storage device, wherein the detected part is provided on a non-clamping surface of the second securing member. The power storage device according to claim 2,
A first displacement sensor disposed opposite to the non-clamping surface of the first securing member;
A second displacement sensor disposed opposite to the non-clamping surface of the second securing member,
The non-clamping surface of the first securing member is used as the detected portion detected by the first displacement sensor,
A power storage device in which a non-clamping surface of the second securing member is used as the detected portion detected by the second displacement sensor. The power storage device according to claim 1;
A first estimation unit that estimates a deterioration state of the plurality of power storage cells based on a current value and a voltage value of the power storage cells;
A second estimation unit for estimating a deterioration state of the plurality of power storage cells based on the expansion amount;
An electrical storage system comprising: a determination unit that determines reliability of the degradation state estimated by the first estimation unit based on the degradation state estimated by the second estimation unit. The power storage system according to claim 6,
A storage unit for storing reference expansion amounts of the plurality of storage cells measured by holding the plurality of storage cells at a predetermined temperature and a predetermined charge state;
A correction unit that corrects the expansion amount based on the reference expansion amount,
The second estimation unit estimates a deterioration state of the plurality of power storage cells based on an expansion amount corrected by the correction unit instead of the expansion amount. The power storage device according to claim 1, wherein the power storage device is used as a vehicle driving power source for an electric vehicle.
A first estimation unit that estimates a deterioration state of the plurality of power storage cells based on a current value and a voltage value of the power storage cells;
A storage unit for storing reference expansion amounts of the plurality of storage cells measured by holding the plurality of storage cells at a predetermined temperature and a predetermined charge state;
A second estimation unit that estimates a deterioration state of the plurality of power storage cells based on the reference expansion amount;
And a charge / discharge control unit that changes a charge / discharge condition of the power storage module based on the deterioration state estimated by the first estimation unit and the deterioration state estimated by the second estimation unit. .

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