JP5444762B2 - Pressure measuring device and thickness measuring device - Google Patents

Description

  The present invention relates to a pressure measuring device. In particular, the present invention relates to a pressure measuring device used for measuring a volume change of a flat object to be measured. The present invention also relates to a thickness measuring device using the pressure measuring device.

  A technique for measuring the characteristics of a flat object to be measured is disclosed in Patent Document 1. Patent Document 1 discloses an apparatus for measuring electrochemical characteristics of a single cell (a laminate of a positive electrode plate, a separator, and a negative electrode plate) of a lithium ion secondary battery. The apparatus includes a pair of fixing members that clamp flat plate single cells from the front and back surfaces. A groove is formed in one of the pair of fixing members. After the single cell and the electrolytic solution are accommodated in the groove, the single cell and the electrolytic solution are sealed by a pair of fixing members. When measuring the volume change accompanying charging / discharging in order to know the electrochemical characteristics of the single cell, a hole penetrating the fixing member is formed, and the volume change of the single cell is measured using a piston or a displacement sensor. That is, the change in volume of the single cell is measured by utilizing the phenomenon that when the single cell expands, the pressure in the groove increases, and when the single cell contracts, the pressure in the groove decreases.

JP 2006-147513 A

For example, in a lithium ion secondary battery, the volume in a single cell changes with charge / discharge. At this time, if there is a variation in charge / discharge characteristics in the single cell, the volume change occurring in the single cell also varies. Therefore, in order to obtain a lithium ion secondary battery having uniform charge / discharge characteristics in a single cell, it is necessary to measure the distribution of volume changes occurring in the single cell.
The apparatus of Patent Document 1 can measure the volume change of the entire object to be measured (single cell). In other words, the average volume change of the object to be measured can be measured. However, it is impossible to measure the distribution of the volume change generated in the flat object to be measured. Therefore, even if the apparatus of Patent Document 1 is used, it can be said that it is impossible to confirm whether the charge / discharge characteristics in the single cell are uniform.
The present invention solves the above-described problems, and an object of the present invention is to provide an apparatus that can measure the distribution of volume change occurring in a flat plate-like object to be measured.

The pressure measuring device disclosed in the present specification is provided on at least one of a pair of fixing members for sandwiching a plate-like object to be measured from the front and back surfaces, and an inner surface of the pair of fixing members, A flat plate-shaped pressure sensor for detecting a pressure distribution generated between the fixed members is provided. Note that “the pair of fixing members sandwich the flat object to be measured from the front and back surfaces” means that the relative position between the pair of fixing members changes regardless of the pressure generated between the object to be measured and the fixing member. And a form in which the relative position between the pair of fixing members changes according to the pressure generated between the object to be measured and the fixing member. In the case where the relative position between the pair of fixing members is changed, the member to be measured may be clamped only by the weight of the fixing member, or a component that urges the fixing member against the object to be measured may be provided. May be used. Note that the pressure measurement device disclosed in the present specification further includes a charge / discharge device that charges and discharges the single cell, in which the object to be measured is a single cell of a power storage element.

  When a part of the flat object to be measured changes in volume, the pressure between the object to be measured at the corresponding position and the fixing member changes. In the pressure measuring device, since the pressure sensor for detecting the pressure distribution is provided on the inner surface of the fixed member, it is possible to measure the degree of volume change generated in the object to be measured for each position. That is, it is possible to measure the distribution of the volume change generated in the object to be measured on the flat plate. In the following description, the term “pressure distribution” refers to “pressure distribution generated between an object to be measured and a fixed member” measured by a pressure sensor.

As described above, the pressure measuring equipment disclosed herein, Ri single cell der of the object to be measured is the power storage device, that further comprise a rechargeable device for charging and discharging the unit cell.
When charging / discharging the single cell of an electrical storage element, a volume change will arise in the electrode plate which comprises the single cell. If there is a local abnormality (unevenness of mixing, mixing of foreign substances, etc.) in the electrode plate constituting the single cell, the volume change occurring in the single cell is also locally different. According to this pressure measuring device, it is possible to measure the distribution of volume changes that occur in the electrode plate due to charge / discharge, and it is possible to detect local abnormalities existing in the electrode plate. Note that the “single cell of a power storage element” refers to a pair of electrode plates facing each other with an electrolyte interposed therebetween.

In the case where the storage element is a secondary battery, it is preferable that the pressure sensor is provided on a fixing member positioned at least on the negative electrode side of the single cell.
In the case of a secondary battery, a change in volume of the negative electrode plate often appears more significantly than a change in volume of the positive electrode plate with charge and discharge. If the pressure sensor is provided on the fixing member located on the negative electrode side of the single cell, the distribution of the volume change generated in the single cell can be measured with high sensitivity.

When the object to be measured is a single cell of a power storage element, it is preferable that the pressure measuring device further includes an electrolyte tank capable of storing a pair of fixing members and storing the electrolyte of the power storage element.
In a power storage element, ions move between a pair of electrodes through an electrolyte. Therefore, it is necessary to hold the electrolyte between the pair of electrodes. For example, a single cell must be covered with a film material or the like, and an electrolyte must be enclosed in the film material. If a film material or the like exists between the single cell and the pressure sensor, the sensitivity of detection of a pressure change generated between the single cell and the fixing member may be reduced due to the film material or the like. On the other hand, if the above-described electrolyte tank is provided, it is not necessary to cover the single cell with a film material or the like, and the pressure generated between the single cell of the power storage element and the fixing member can be detected more accurately.

When the object to be measured is a single cell of a storage element, the pressure measuring device is configured such that the pressure distribution measured by the pressure sensor before charging by the charging / discharging device and the pressure distribution measured by the pressure sensor after charging by the charging / discharging device. It is preferable to further include a pressure distribution calculation device that calculates the difference distribution.
If the single cell is uneven, a pressure distribution exists between the single cell and the fixing member, even though the single cell is not charged. Only by the pressure distribution between the single cell after charging and the fixing member, it cannot be determined whether the pressure distribution is caused by the volume change of the single cell due to charging or due to unevenness unique to the single cell. If the pressure distribution calculation device is provided, it is possible to accurately measure the volume change distribution of the single cell accompanying charging.

The present specification also discloses a thickness measuring device for measuring the thickness distribution of the object to be measured. The thickness measuring device includes the above-described pressure measuring device and a displacement sensor that detects a relative position between the pair of fixing members.
In the above thickness measuring apparatus, in addition to the pressure distribution between the fixing member and the object to be measured, the distance between the pair of fixing members sandwiching the object to be measured can be measured simultaneously. The pressure distribution between the fixing member and the object to be measured relatively indicates the thickness at each position of the object to be measured. The distance between the pair of fixing members absolutely indicates the average thickness of the object to be measured. Therefore, if these measured values are obtained, the thickness distribution of the object to be measured can be obtained quantitatively. Thereby, the local volume change which arose in the to-be-measured object can be grasped | ascertained quantitatively, for example.

It is preferable that the thickness measuring apparatus includes at least three or more displacement sensors, and at least one displacement sensor is disposed at a position offset from a straight line connecting the measurement positions of any two displacement sensors. That is, it is preferable that all the displacement sensors are not arranged on the same straight line.
In the thickness measuring apparatus, the relative inclination between the pair of fixing members can be measured. Accordingly, it is possible to calculate the thickness distribution of the object to be measured more accurately than when assuming that the distance between the pair of fixing members is constant over the entire surface.

The thickness measuring device calculates the thickness distribution of the object to be measured based on the data of the overall thickness of the object to be measured measured by the displacement sensor and the data of the pressure distribution measured by the pressure sensor. Is preferably further provided.
As described above, if the pressure distribution between the fixing member and the object to be measured and the distance between the pair of fixing members holding the object to be measured are found, the thickness distribution of the object to be measured can be obtained. . That is, if the measured pressure distribution is superimposed on the distance between the pair of fixing members, the thickness distribution of the object to be measured can be obtained. If the thickness distribution calculating device is provided, for example, a local volume change generated in the object to be measured can be easily detected.

  According to the present invention, it is possible to obtain an apparatus capable of measuring the distribution of volume change generated in a flat object to be measured. In addition, according to the present invention, it is possible to obtain an apparatus capable of quantitatively measuring the volume change distribution of a flat object to be measured.

The basic structure of a pressure measuring device is shown. The figure explaining the example (Example 1) which measures distribution of the volume change of a single cell is shown. 2 shows a flowchart of a method for measuring a distribution of volume change of a single cell. The pressure distribution before the first charge of a single cell is shown. The pressure distribution after the initial charge of a single cell is shown. The distribution of the volume change before and after the initial charge of a single cell is shown. The figure explaining the example (Example 2) which measures distribution of the volume change of a single cell is shown. The external appearance of the thickness measuring apparatus of Example 3 is shown. The external appearance of the thickness measuring apparatus of Example 4 is shown. The figure explaining the thickness distribution of a single cell is shown. The flowchart of the method of measuring the distribution of the entity value of the volume change of a single cell is shown.

FIG. 1 shows a basic structure of the pressure measuring device 10. FIG. 1 is a diagram for explaining the basic structure of the pressure measuring device 10, and does not illustrate the entire structure of the pressure measuring device 10.
As shown in FIG. 1, the pressure measuring device 10 includes a pair of fixing members 2 and 12. An object to be measured is sandwiched between the pair of fixing members 2 and 12. A pressure sensor 8 that can detect a pressure distribution generated between the object to be measured and the fixing member 12 is provided on the inner surface of the fixing member 12. As the pressure sensor 8, for example, a pressure-sensitive conductivity conversion type pressure sensor, a capacitance type pressure sensor, a piezoelectric pressure sensor, a strain type pressure sensor, or the like can be used.
If it has the above-mentioned structure, distribution of volume change which arises in a flat object to be measured can be measured. The features of the pressure measuring device 10 described below are not essential components, but are suitable for measuring the distribution of volume changes occurring in the object to be measured.

  The inner surfaces of the fixing members 2 and 12 are flat. Since the fixing member 12 can move along the guide 6, it is easy to pinch objects to be measured having various thicknesses. Note that the fixing members 2 and 12 can sandwich the object to be measured in a state where pressure is applied to the object to be measured. The guide 6 and the fixing member 12 may be fixed in a state where the fixing members 2 and 12 apply pressure to the object to be measured. Alternatively, the fixing member 2 and the fixing member 12 may be relatively movable while the fixing members 2 and 12 apply pressure to the object to be measured. If the fixing members 2 and 12 can be moved relative to each other, the pressure between the fixing members 2 and 12 and the object to be measured does not change even if a volume change occurs in the object to be measured. A pressure such as a spring may be employed to adjust the pressure applied to the object to be measured from the fixing members 2 and 12. The pressure applied to the object to be measured from the fixing members 2 and 12 may be adjusted by adjusting the weight of the fixing member 12. Further, the guide 6 can be omitted.

  When the fixing members 2 and 12 are metal, it is preferable that the pressure sensor 8 has insulation. Further, as shown in FIG. 1, an insulating film 4 is preferably provided on the surface side of the fixing member 2. Even if the object to be measured has conductivity, the object to be measured and the fixing members 2 and 12 can be insulated. The “insulating pressure sensor” includes not only a form in which the pressure sensor itself is manufactured from an insulating material, but also a form in which the pressure sensor having conductivity is covered with an insulating material.

  By using the pressure measuring device 10, it is possible to measure the distribution of volume changes of various objects to be measured. As shown in FIG. 2, when the object to be measured is a single cell 40 of a storage element, the pressure measuring device 10 preferably includes a charge / discharge device 20. The charge / discharge characteristics of the single cell 40 can be understood as a distribution of volume change of the single cell 40. Specific examples of the storage element include secondary batteries such as lithium ion secondary batteries, nickel hydride secondary batteries, and solid polymer secondary batteries, primary batteries, and capacitors.

  FIG. 2 shows a single cell 40 of a lithium ion secondary battery as an example of the object to be measured. In the single cell 40, a positive electrode 28, a separator 30 and a negative electrode 36 are laminated in this order. The pressure sensor 8 is provided on the fixing member 12 on the negative electrode 36 side. In the case of the single cell 40 of a lithium ion secondary battery, the negative electrode 36 often changes significantly in volume with charge / discharge. Therefore, if the pressure sensor 8 is provided only on the negative electrode 36 side, the volume change distribution of the single cell 40 can be sufficiently measured. However, the pressure sensor 8 may be provided on the fixing member 2 on the positive electrode 28 side, or the pressure sensor 8 may be provided on both the fixing members 2 and 12. In either case, the volume change distribution of the single cell 40 can be measured sufficiently.

  As shown in FIG. 2, the pressure measuring device 10 includes an electrolyte tank 14. As will be described later, the electrolyte tank 14 is not an essential component. However, when the electrolyte tank 14 is provided, the single cell 40 is placed in the electrolyte 16 after the single cell 40 is sandwiched between the fixing members 2 and 12. Can be dipped.

The pressure measuring device 10 includes a pressure distribution calculating device 22. Although the pressure distribution calculation device 22 is not essential, if the pressure distribution calculation device 22 is provided, the difference between the pressure distribution measured by the pressure sensor 8 before charging and the pressure distribution measured by the pressure sensor 8 after charging. Can be calculated. It is possible to accurately measure the distribution of volume change of the single cell 40 accompanying charging.
More precisely, the pressure distribution calculation device 22 can perform the following calculations: (1) Measured before the unit cell 40 is charged for the first time (when the unit cell 40 is installed on the fixed members 2 and 12). The difference between the measured pressure distribution and the pressure distribution measured after the unit cell 40 is charged for the first time is calculated.
(2) The difference between the pressure distribution measured before charging the single cell 40 for the first time and the pressure distribution after charging when the single cell 40 is charged and discharged a predetermined number of times is calculated.
(3) The difference in pressure distribution before and after charging when the single cell 40 is charged and discharged a predetermined number of times is calculated.

  When the single cell 40 is being charged / discharged, the pressure distribution may be continuously measured. In that case, instead of the pressure distribution calculation device 22, the difference between the pressure distribution measured by the pressure sensor 8 before charging and the pressure distribution continuously measured by the pressure sensor 8 during charging and discharging is calculated in real time. It is preferable to employ a pressure distribution calculation device.

With reference to FIG. 2, the example which measures distribution of the volume change of the single cell 40 is demonstrated in detail. 2, illustration of the guide 6 shown in FIG. 1 is omitted.
As shown in FIG. 2, the pressure measurement device 10 includes a charge / discharge device 20 that charges and discharges the single cell 40, a pressure distribution calculation device 22 that stores and processes the pressure distribution measured by the pressure sensor 8, and the fixing member 2. , 12 and an electrolyte tank 14 that can store an electrolyte. An electrolyte solution 16 is stored in the electrolyte tank 14. The fixing members 2 and 12 are disposed in the electrolytic solution 16 with the single cell 40 sandwiched therebetween.

Here, the single cell 40 will be described.
The single cell 40 is a laminate in which the positive electrode 28, the separator 30, and the negative electrode 36 are laminated. The positive electrode 28 includes a positive electrode current collector plate 26 and a positive electrode active material 24 formed on both surfaces of the positive electrode current collector plate 26. The negative electrode 36 includes a negative electrode current collector plate 34 and a negative electrode active material 32 formed on both surfaces of the negative electrode current collector plate 34. The separator 30 is porous and is impregnated with the electrolytic solution 16 inside. Therefore, it can be said that the positive electrode 28 and the negative electrode 36 are opposed to each other with the electrolytic solution 16 interposed therebetween. Ions can move between the positive electrode 28 and the negative electrode 36. The positive electrode active material 24 may be formed only on one side of the positive electrode current collector plate 26. Similarly, the negative electrode active material 32 may be formed only on one side of the negative electrode current collector plate 34. It is sufficient that the positive electrode active material 24 and the negative electrode active material 32 face each other with the separator 30 interposed therebetween.
The negative electrode active material 32 of the negative electrode 36 faces the fixing member 12 via the pressure sensor 8. As described above, since the pressure sensor 8 has an insulating property, the negative electrode 36 and the fixing member 12 are insulated. Further, the positive electrode active material 24 of the positive electrode 28 is in contact with the insulating film 4 and is not in direct contact with the fixing member 2. The positive electrode 28 and the fixing member 2 are insulated. As a result, the single cell 40 and the fixing members 2 and 12 are insulated.

As shown in FIG. 2, a reference electrode 18 made of lithium (Li) is disposed in the electrolyte tank 14. Since the reference electrode 18 is disposed, the characteristics of the negative electrode 36 and the characteristics of the positive electrode 28 can be measured separately. Since the reference electrode 18 is not in contact with the single cell 40, it does not short-circuit with the negative electrode 36 or the positive electrode 28. The reference electrode 18 can be disposed at any position as long as it is in contact with the electrolytic solution 16. Further, the number of reference electrodes 18 is also arbitrary.
The reference electrode 18 is connected to the charging / discharging device 20 via the wiring 20a. The positive electrode current collector plate 26 is connected to the charge / discharge device 20 via the wiring 20b. The negative electrode current collector plate 34 is connected to the charging / discharging device 20 through the wiring 20c. Moreover, the pressure sensor 8 is connected to the pressure distribution calculation device 22 via the wiring 22a. The pressure distribution detected by the pressure sensor 8 is input to the pressure distribution calculation device 22.

  In FIG. 2, the entire fixing members 2 and 12 are disposed in the electrolyte solution 16. It is sufficient that at least the single cell 40 is located in the electrolytic solution 16, and the entire fixing members 2 and 12 are not necessarily arranged in the electrolytic solution 16. Further, the single cell 40 does not necessarily have to be located in the electrolyte solution 16. It is only necessary that ions can move between the positive electrode 28 and the negative electrode 36. For example, the separator 30 may be previously impregnated with an electrolytic solution and then charged and discharged in the atmosphere.

A method for measuring the volume change distribution of the single cell 40 will be described with reference to FIG. FIG. 3 shows a flowchart for measuring the distribution of volume change.
First, the single cell 40 is installed in the pressure measuring device 10 (S1). At this time, the negative electrode current collector plate 34 and the positive electrode current collector plate 26 are connected to the charge / discharge device 20. The pressure sensor 8 is connected to the pressure distribution calculation device 22. Next, before charging the single cell 40, the pressure distribution generated between the single cell 40 and the fixing member 12 is measured (S2). In this measurement, the pressure distribution before the unit cell 40 is charged for the first time is measured. By this measurement, the pressure distribution due to the unevenness unique to the single cell 40 can be measured. The measurement result of the pressure distribution is input to the pressure distribution calculation device 22.

Next, the single cell 40 is charged (S3). After the completion of the charging, it is determined whether or not the number of times of charging / discharging has reached the predetermined number of times of measurement by the current charging (S4). If the number of times of charging / discharging has reached the number of times of measurement (S4: YES), the pressure distribution generated between the single cell 40 and the fixed member 12 is measured (S5). As the number of times of measurement, for example, a number of times such as 1 time, 100 times, 500 times, 1000 times, 2000 times,. Thereby, the pressure distribution after the first charge (first time), the pressure distribution after the 100th charge, the pressure distribution after the 500th charge, the pressure distribution after the 1000th charge, etc. are measured. It has become. The measurement result of the pressure distribution is input to the pressure distribution calculation device 22.
Next, the pressure distribution calculation device 22 calculates a difference distribution between the pre-charging pressure distribution measured in step S2 and the post-charging pressure distribution measured in step S5 (S6). For example, if the pressure distribution after the first charge is measured in the previous step S5, the difference in the pressure distribution measured before and after the first charge is calculated here. Thereby, the distribution of the volume change produced in the single cell 40 before and after the first charge can be measured. Thereafter, the single cell 40 is discharged (S7). After the discharge of the single cell 40 is completed, if the measurement has been completed for all the above-described measurement target times (S8: YES), the measurement is terminated. If the measurement has not been completed for all the measurement target times (S8: NO), the process returns to step S3 and the single cell 40 is charged again.

  After the single cell 40 is charged, if the number of charge / discharge of the single cell 40 has not reached the number of measurement objects (S4: NO), the single cell 40 is immediately discharged (S7). In this case, the pressure distribution after charging is not measured. After the unit cell 40 is discharged, the process returns to step S3 (S8: NO), and the unit cell 40 is charged again (S3). Thereby, charging / discharging of the single cell 40 is repeated until the number of times of charging / discharging reaches the number of times of measurement. That is, the steps (S3), (S4: NO), (S7), and (S8: NO) are repeated until the number of times of charge / discharge reaches the number of times of measurement.

  You may add the process of measuring the pressure distribution which arises between the single cell 40 and the fixing member 12 between S7 process and S8 process. It is possible to calculate the distribution of the difference in pressure distribution before and after the discharge when the single cell 40 is charged and discharged a predetermined number of times of measurement.

With reference to FIGS. 4-6, the measurement example which measured distribution of the volume change of the single cell 40 is demonstrated. Here, an example in which the volume change distribution of the single cell 40 is measured from the pressure distribution before the initial charging of the single cell 40 (step S2) and the pressure distribution after the initial charging of the single cell 40 (step S5) will be described. . FIG. 4 shows the pressure distribution when the single cell 40 is installed on the fixing members 2 and 12 (before the first charge), and FIG. 5 shows the pressure distribution after the first charge of the single cell 40. FIG. 6 shows the volume change distribution before and after the initial charging of the single cell 40. Reference numeral 8a indicates a measurement range of the pressure distribution, and reference numeral 50 indicates an isobaric line indicating the pressure distribution generated between the single cell 40 and the fixing member 12.
As shown in FIG. 4, even if the single cell 40 is not charged / discharged, a pressure distribution is generated between the single cell 40 and the fixing member 12. That is, FIG. 4 shows unevenness unique to the single cell 40.
As shown in FIG. 5, the pressure distribution after the initial charging of the single cell 40 is more complicated than the pressure distribution of FIG. The pressure distribution in FIG. 5 is a distribution in which unevenness unique to the single cell 40 and a distribution of volume change due to charging of the single cell 40 are superimposed. Therefore, FIG. 5 does not accurately show the distribution of volume change due to charging of the single cell 40.
Therefore, the difference distribution between the pressure distribution of FIG. 4 and the pressure distribution of FIG. 5 is calculated using the pressure distribution calculation device 22. FIG. 6 shows a difference distribution between the pressure distribution of FIG. 4 and the pressure distribution of FIG. The pressure distribution due to the unevenness unique to the single cell 40 is removed from the pressure distribution of FIG. Therefore, it can be said that FIG. 6 shows the distribution of the volume change after the initial charging of the single cell 40.

  In the above description, the method for measuring the volume change distribution before and after the initial charging of the single cell 40 has been described. When the single cell 40 is charged / discharged the number of times of measurement using the pressure distribution before the first charge of the single cell 40 and the pressure distribution after charging when the charge / discharge of the single cell 40 is repeated the number of times of measurement. It is also possible to measure the distribution of volume change before the first charge. In addition, by using the pressure distribution before and after charging when the charge / discharge of the single cell 40 is repeated for the number of times of measurement, the distribution of the volume change before and after charging when the charge / discharge of the single cell 40 is repeated for the number of times of measurement. It can also be measured. Alternatively, the distribution of the volume change during charging / discharging of the single cell 40 is made in real time using the pressure distribution before the initial charging of the single cell 40 and the continuous change of the pressure distribution during charging / discharging of the single cell 40. It can also be measured.

With reference to FIG. 7, another example of measuring the volume change distribution of the single cell 40 will be described.
As shown in FIG. 7, the single cell 40 is sealed in the film 60. The film 60 is sealed with an electrolytic solution 62 together with the single cell 40. In the single cell 40, a part of the negative electrode current collector plate 34 and a part of the positive electrode current collector plate 26 protrude from the film 60. The negative electrode current collector plate 34 and the charge / discharge device 20 are connected outside the film 60. The positive electrode current collector plate 26 and the charge / discharge device 20 are also connected outside the film 60.
In this embodiment, the single cell 40 and the electrolytic solution 62 are sealed in the film 60 in advance. Therefore, the electrolyte tank 14 is not required as shown in FIG.

Further, since the single cell 40 is covered with the film 60, the insulating film 4 provided on the fixing member 2 can be omitted. Similarly, the pressure sensor 8 may not have insulation. That is, a member for insulating the single cell 40 and the fixing members 2 and 12 from the pressure measuring device 10 can be omitted.
A reference electrode may be disposed inside the film 60. Similar to the first embodiment, the characteristics of the negative electrode 36 and the characteristics of the positive electrode 28 can be measured separately.

FIG. 8 shows the appearance of the thickness measuring apparatus 100 using the pressure measuring apparatus 10. In addition, about the detail of the pressure measuring apparatus 10, description is abbreviate | omitted.
In the thickness measuring apparatus 100, the pressure measuring apparatus 10 is not provided with the guide 6 (see FIG. 1). The single cell 40 is sandwiched between the fixing members 2 and 12 by the weight of the fixing member 12. In other words, a pressure corresponding to the weight of the fixing member 12 is applied to the single cell 40. In addition to the pressure measurement device 10, the thickness measurement device 100 includes a displacement sensor 74 (74 a to 74 c), a displacement amount calculation device 70, and a thickness amount calculation device 80. Each displacement sensor 74 is connected to a displacement amount calculation device 70 via a wiring 72. The displacement amount calculation device 70 is connected to the thickness amount calculation device 80 by a wiring 82. The pressure distribution calculation device 22 is also connected to the thickness amount calculation device 80 by a wiring 78. In addition, although illustration is abbreviate | omitted, in the thickness measuring apparatus 100, the pressure sensor 8 (refer FIG. 1) is attached to the fixing member 2. FIG.

  By having the plurality of displacement sensors 74, the gaps between the fixing members 2 and 12 can be measured at a plurality of locations. As shown in FIG. 8, the displacement sensor 74b is provided at a position offset from a straight line 76 connecting the measurement position of the displacement sensor 74a and the measurement position of the displacement sensor 74c. Therefore, the inclination of the fixing member 12 with respect to the fixing member 2 can be grasped in a plane. As displacement sensors, laser triangulation displacement sensors, laser top displacement displacement sensors, laser confocal displacement sensors, eddy current displacement sensors, ultrasonic displacement sensors, differential transformer displacements A sensor, a capacitance type displacement sensor, or the like can be used.

Here, the inclination between the fixing member 12 and the fixing member 2 will be described. FIG. 9 shows a state in which a part of the unit cell 40 is expanded in the cross section taken along the line IX-IX in FIG. The single cell 40 and the fixing member 12 indicated by a two-dot chain line indicate a state where the single cell 40 is not expanded. A single cell 40a and a fixing member 12a indicated by solid lines indicate a state in which the single cell 40 is expanded.
As shown in FIG. 9, when the single cell 40 expands, the relative position between the fixing member 12 and the fixing member 2 changes. A change in the relative position between the two is detected by the displacement sensor 74 as a displacement amount of the fixed member 12. At that time, if the relative inclination between the fixing member 12 and the fixing member 2 changes, the displacement amounts of the displacement sensors 74a and 74c differ. By calculating the displacement amount of the displacement sensors 74a and 74c by the displacement amount calculation device 70, the relative inclination between the fixed member 12 and the fixed member 2 can be detected. The overall pressure applied to the single cell 40 from the fixing member 12 is the same as before the single cell 40 expands. Therefore, the entire pressure between the fixing members 2 and 12 and the single cell 40 can always be kept constant while charging and discharging are repeated.

Another advantage of the thickness measuring apparatus 100 will be described.
As described above, in the thickness measuring apparatus 100, the fixing member 2 and the fixing member 12 are not restrained. Therefore, for example, even if the environmental temperature changes and the volumes of the fixing members 2 and 12 change, the pressure between the fixing members 2 and 12 and the single cell 40 is not affected. That is, it can suppress that the volume change of the fixing members 2 and 12 is detected as the volume change of the single cell 40. The volume change distribution of the single cell 40 can be detected more accurately.
The thickness measuring apparatus 100 can measure the thickness change of the single cell 40 by measuring the thickness change between the fixing members 2 and 12. That is, the actual thickness change of the single cell 40 can be measured for each position.

  As described above, when the volume of the single cell 40 changes, the relative position between the fixing member 12 and the fixing member 2 changes. For this reason, it is difficult for the pressure sensor 8 to distinguish the pressure at a portion where the volume change of the single cell 40 is large and the pressure at a small portion. Therefore, the detection value of the pressure sensor 8 is corrected by the inclination of the fixing member 12 and the fixing member 2. That is, the value of the pressure sensor 8 at the site where the volume change is large is corrected to be large, and the value of the pressure sensor 8 at the site where the volume change is small is corrected to be small. As a result, the volume change of the single cell 40 can be detected more accurately for each position.

With reference to FIG. 10, how to measure the distribution of volume change (thickness change) of the single cell 40 will be described. FIG. 10 shows a flowchart for measuring the distribution of volume change.
First, the single cell 40 is installed in the thickness measuring apparatus 100 (S11). Next, the pressure distribution generated between the single cell 40 and the fixing member 12 is measured (S12). The steps S11 and S12 are substantially the same as the steps S1 and S2 described in the first embodiment. In the thickness measuring apparatus 100, the value of each displacement sensor 74a-74c is input into the displacement amount calculation apparatus 70 after process S11 (S13). By step S13, the inclination of the fixing member 12 and the initial state of the fixing member 2 can be measured. Note that the values of the displacement sensors 74a to 74c may be initialized to “zero” after the displacement amount calculation device 70 has input the values.

  Following the steps S12 and S13, the single cell 40 is charged and discharged a predetermined number of times (S14). Next, the distribution of the difference between the pressure distribution before charging the single cell 40 and the pressure distribution after charging is calculated (S15). Steps S14 and S15 are substantially equal to steps S3 to S8 described in the first embodiment. In the thickness measuring apparatus 100, in addition to the pressure distribution before and after charging, a difference value between the values of the displacement sensors 74 before and after charging is calculated (S16). Next, the displacement amount calculation device 70 uses the value of each displacement sensor 74 to calculate the change in the inclination of the fixed member 12 after charging (S17). If there is a partial difference in the volume change of the single cell 40, the inclination of the fixing member 12 after charging changes. Next, a position coefficient is determined using the inclination obtained in step S17 (S18). The position coefficient is determined for each position of the single cell 40 in accordance with the change in inclination. That is, a large position coefficient is given to a portion where the volume change of the single cell 40 is large, and a small position coefficient is given to a portion where the volume change of the single cell 40 is small.

  Next, the pressure distribution result of the single cell 40 obtained in step S15 is corrected with the position coefficient. As a result, the thickness change rate for each position of the single cell 40 is calculated (S19). That is, the relative volume change for each position of the single cell 40 is calculated. In the thickness measuring apparatus 100, the average value of the values of the displacement sensors 74 is calculated using the result of step S16. That is, the total thickness change amount of the single cell 40 is calculated (S20). Next, using the thickness change rate for each position of the single cell 40 obtained in step S19 and the total thickness change amount of the single cell 40 obtained in step S20, the thickness change for each position of the single cell 40 is obtained. The amount is calculated (S21). Through the above steps, the thickness change amount for each position of the unit cell 40 can be quantitatively measured.

  FIG. 11 shows the appearance of the thickness measuring apparatus 100a. In the thickness measuring apparatus 100a, the main body of the displacement sensor 74 is fixed to the fixing member 2. The sensor part of the displacement sensor 74 does not contact the fixed member 2 but contacts only the fixed member 12. A restraint arm or the like for positioning the displacement sensor 74 can be omitted.

  In the said Example 3, 4, the illustration for the structure for storing electrolyte solution is abbreviate | omitted. As described in the first embodiment, the electrolyte tank 14 (see FIG. 1) that accommodates the fixing members 2 and 12 may be used. As described in the second embodiment, the film that seals the single cell 40 is used. 60 (see FIG. 7) may be used.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in the present specification or the drawings can achieve a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2: Fixed member 8: Pressure sensor 10: Pressure measuring device 12: Fixed member 14: Electrolyte tank 20: Charge / discharge device 22: Pressure distribution calculating device 40: Single cell (measurement object)
70: Displacement amount calculation device 74: Displacement sensor 80: Thickness amount calculation device 100: Thickness measurement device

Claims (7)

A pair of fixing members for sandwiching the single cell of the plate-shaped power storage element from the front and back surfaces;
A pressure sensor that is provided on at least one of the inner surfaces of the pair of fixing members and detects a pressure distribution generated between the single cell and the fixing member;
A charge / discharge device for charging / discharging a single cell;
A pressure measuring device comprising: The power storage element is a secondary battery;
2. The pressure measuring device according to claim 1 , wherein the pressure sensor is provided at least on a fixing member positioned on the negative electrode side of the single cell. Wherein accommodates a pair of fixing members, a pressure measuring device according to claim 1 or 2, characterized in that it comprises an electrolyte bath capable of storing an electrolyte. A pressure distribution calculation device that calculates a difference distribution between the pressure distribution measured by the pressure sensor before charging by the charge / discharge device and the pressure distribution measured by the pressure sensor after charging by the charge / discharge device; The pressure measuring device according to any one of claims 1 to 3 , wherein the pressure measuring device is provided. A thickness measuring device for measuring a thickness distribution of a single cell of a storage element ,
A pressure measuring device according to any one of claims 1 to 4 ;
A displacement sensor for detecting a relative position between the pair of fixing members;
A thickness measuring device comprising: Comprising at least three displacement sensors;
6. The thickness measuring apparatus according to claim 5 , wherein at least one displacement sensor is arranged at a position offset from a straight line connecting the measurement positions of any two displacement sensors. The apparatus further comprises a thickness distribution calculating device for calculating the thickness distribution of the single cell based on the data of the overall thickness of the single cell measured by the displacement sensor and the data of the pressure distribution measured by the pressure sensor. The thickness measuring device according to claim 5 or 6 .

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