Electrode structure observation cell assembly

Abstract

To provide an electrode structure observation cell assembly in which, when relatively rotating a cell targeted for observation around a rotation axis orthogonal to an optical axis of an X-ray, incidence of the X-ray upon the cell is not obstructed even if an incidence angle of the X-ray gets close to 90 degrees.SOLUTION: A structure observation cell assembly 1 for observing an internal structure of a cell 3 by an X-ray CT comprises a restraint member 4 that restrains the cell 3 serving as an observation object from both surfaces in a thickness direction of the cell. The restraint member 4 includes: a tabular resin member 10 that is disposed so as to cover an area a of an electrode facing part 9 according to observation of the cell 3 on one surface side of both surfaces of the cell; and two metal leaf springs 11 and 12 that extend toward a center part of the tabular resin member 10 respectively, facing each other in a direction along a principal surface of the tabular resin member 10, are disposed so as to create a prescribed gap g between mutual extension ends, and pressurize to urge a non-contact surface side with the cell 3 with respect to the tabular resin member 10. In the structure observation cell assembly 1, the gap g is formed so as to match an irradiation position of an X-ray by the X-ray CT.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a cell assembly for observing an electrode structure.

Background Art

[0002] A cell, which is a component of a secondary battery module, expands and contracts during charging and discharging. Therefore, the electrode is often used in a state of being restrained from the thickness direction. A method of observing the electrode structure in a form simulating such a use state has been proposed. For example, it is a method of observing an electrode cross section by SEM (scanning microscope) or a confocal optical system with the electrode restrained by a restraining member from the thickness direction. In these methods, in the case of an electrode with a large expansion and contraction amount, it is difficult to completely suppress the expansion of the electrode in the protruding direction from the cross section processed for observation. For this reason, there is a possibility that the observation result may be different from the behavior of the structure during actual use. On the other hand, although the above-mentioned possibility can be eliminated in the case of observation by X-ray CT which does not require processing of the observation cross section, the image quality of the X-ray CT image deteriorates due to X-ray absorption by the restraining member that restrains the electrode from the thickness direction. The deterioration of the image quality becomes an obstacle when making a detailed observation.

[0003] As a cell assembly for observing an electrode structure for performing observation by X-ray CT on a cell of a secondary battery in a state where the cell is restrained from the thickness direction by a restraining member, it has been proposed to apply a disk-shaped restraining member provided with a hole for passing X-rays in the center (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the cell assembly for observing the electrode structure of Patent Document 1, regarding the hole for passing X-rays provided in the center of the disk-shaped member which is a restraining member, a mode is disclosed in which a tapered surface that expands outward is provided on the inner peripheral edge thereof. It is said that X-rays can be incident on the cell to be observed from a wide angle range. However, when the cell is relatively rotated to bring the incident angle of the X-rays close to 90 degrees, it is inevitable that the incidence of the X-rays on the cell is inhibited by the inner peripheral edge of the hole for passing the X-rays. On the other hand, in recent years, efforts to realize a low-carbon society or a decarbonized society have become active, and research and development from the viewpoints of reducing CO2 emissions and improving energy efficiency have been carried out also in devices related to the development and testing of vehicle electronic components.

[0006] The present invention has been made in view of the above circumstances, and when the cell to be observed is relatively rotated around a rotation axis orthogonal to the optical axis of the X-rays, even if the incident angle of the X-rays is brought close to 90 degrees, the incidence of the X-rays on this cell is not inhibited. An object is to provide a cell assembly for observing an electrode structure. Further, it improves the efficiency of X-ray irradiation on the cell, and thus contributes to the improvement of energy efficiency.

Means for Solving the Problems

[0007] (1) A cell structure observation cell assembly (for example, the cell structure observation cell assembly 1 described later) for observing the internal structure of a cell (for example, the cell 3 described later) by X-ray CT, comprising a restraining member (for example, the restraining member 4 described later) that restrains the cell to be observed from both sides in its thickness direction, the restraining member being a plate-shaped resin member (for example, the plate-shaped resin member 10 described later) arranged to cover a region (for example, the region a described later) of the electrode facing portion (for example, the electrode facing portion 9 described later) related to the observation on one side of the two sides of the cell, and two metal plate springs (for example, the two metal plate springs 11 and 12 described later) that face each other in a direction along the main surface of the plate-shaped resin member, extend toward the center portion of the plate-shaped resin member respectively, and are arranged to create a predetermined gap (for example, the gap g described later) between their extending ends, and press and bias the non-contact surface side of the cell with respect to the plate-shaped resin member, the gap being formed to match the X-ray irradiation position by the X-ray CT.

[0008] (2) The restraining member is supported by a rotation support member (for example, the rotation support member 2 described later) that rotates the cell around a predetermined rotation axis (for example, the virtual rotation axis Va described later) during observation by the X-ray CT, and the gap portion of the two metal plate springs spaced apart in the direction of the rotation axis is formed in the region of the electrode facing portion. The cell structure observation cell assembly according to (1).

[0009] (3) Each of the two metal plate springs is supported by a support member (for example, the support member 15 described later) on the base portion (for example, the base portions 13 and 14 described later) side opposite to the extending end side, and the extending end side is located in the region of the electrode facing portion. The cell structure observation cell assembly according to (1).

[0010] (4) The region of the electrode facing portion is located between the positive electrode terminal (for example, the positive electrode terminal 20 described later) and the negative electrode terminal (for example, the negative electrode terminal 19 described later) led out from the cell. The cell structure observation cell assembly according to (1).

[0011] (5) The structure observation cell assembly of (1), wherein the region of the electrode facing portion is located between a positive electrode bus bar (for example, the positive electrode bus bar 22 described later) connected to the positive electrode terminal derived from the cell and a negative electrode bus bar (for example, the negative electrode bus bar 21 described later) connected to the negative electrode terminal.

[0012] (6) The structure observation cell assembly of (5), wherein a housing (for example, the housing 23 described later) for housing the positive electrode terminal, the negative electrode terminal, the positive electrode bus bar, and the negative electrode bus bar is provided, and the housing is formed with a positive electrode side opening (for example, the positive electrode side opening 27 described later) and a negative electrode side opening (for example, the negative electrode side opening 26 described later) that can be energized from the outside to the positive electrode bus bar and the negative electrode bus bar during observation by the X-ray CT.

Advantages of the Invention

[0013] (1) In the structure observation cell assembly of (1), X-rays by X-ray CT can be irradiated to the cell to be observed from the gap between the extended ends of the two metal plate springs. Therefore, even if the incident angle of the X-rays to the cell is made close to 90 degrees, the incidence of the X-rays is not inhibited, and the efficiency of X-ray irradiation to the cell can be improved.

[0014] (2) In the structure observation cell assembly of (2), when irradiating the cell to be observed with X-rays by X-ray CT while rotating the cell around a predetermined rotation axis, it is possible to avoid the absorption of X-rays by the metal plate spring.

[0015] (3) In the structure observation cell assembly of (3), when irradiating the cell to be observed with X-rays by X-ray CT while rotating the cell around a predetermined rotation axis, it is possible to avoid the absorption of X-rays by the support member that supports the metal plate spring on the base side.

[0016] (4) In the structure observation cell assembly of (4), when irradiating the cell to be observed with X-rays by X-ray CT while rotating the cell around a predetermined rotation axis, it is possible to avoid the absorption of X-rays by the positive electrode terminal and the negative electrode terminal derived from the cell.

[0017] In the cell assembly for structural observation of (5), when irradiating the cell to be observed with X-rays by X-ray CT while rotating the cell around a predetermined rotation axis, it is possible to avoid the absorption of X-rays by the positive electrode bus bar and the negative electrode bus bar led out from the cell.

[0018] In the cell assembly for structural observation of (6), since it is possible to energize externally the positive electrode bus bar and the negative electrode bus bar led out from the cell during observation by X-ray CT, it is possible to observe the cell under the same conditions as during charging. That is, it is possible to change the SOC of cell 3 and perform observation.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0020] FIG. 1 is a perspective view of the cell assembly 1 for structural observation of the present disclosure. FIG. 2 is a cross-sectional view taken along line A-A of the cell assembly 1 for structural observation. FIG. 1 shows a state in which the cell assembly 1 for structural observation is attached to a rotation support member 2 to be described later, and the rotation axis (virtual rotation axis Va) of the cell assembly 1 for structural observation and the rotation support member 2 is drawn in a direction inclined with respect to the vertical direction. However, the direction of the rotation axis Va is set to an appropriate direction according to the form and operating conditions of the X-ray CT (not shown) to be applied.

[0021] The cell assembly 1 for structure observation is an assembly for observing the internal structure of a cell, which is a component of a secondary battery module, by X-ray CT (not shown). The cell assembly 1 for structure observation includes a restraining member 4 that sandwiches a flat cell 3 to be observed from both sides and restrains it from both sides in the thickness direction. The restraining member 4 includes a base member 5 that is a plate-like member whose longitudinal direction is along the direction of the rotation axis Va. The base member 5 is fastened by a screw 8 to an attachment portion 7, which is, for example, in the shape of a rectangular parallelepiped, provided so as to protrude from the tip surface of the rotation support member 2 at the base portion 6 on one end side in the longitudinal direction. The rotation support member 2 rotates by itself by a rotation drive mechanism (not shown), and thereby, the cell assembly 1 for structure observation rotates.

[0022] The restraining member 4 includes a plate-like resin member 10 disposed on one main surface side of the base member 5 so as to cover a region a of an electrode facing portion 9 related to observation on one side of the two sides of the cell 3, and two metal plate springs 11 and 12 that press and bias the non-contact surface side with the cell 3 against the plate-like resin member 10. The two metal plate springs 11 and 12 face each other in a direction along the main surface of the plate-like resin member 10 and extend toward the center portion of the plate-like resin member 10, and are arranged so as to create a predetermined gap g between their extending ends. This gap g is formed so as to match the X-ray irradiation position by X-ray CT (the position indicated by the thick downward arrow in FIG. 2). That is, the gap g is formed in the region a of the electrode facing portion 9. In other words, the extending end sides of the two metal plate springs 11 and 12 are located in the region a of the electrode facing portion 9.

[0023] The two metal plate springs 11 and 12 are supported by the support members 15 on the base sides opposite to the extended end sides facing the gap g, that is, on the base 13 side of the metal plate spring 11 and the base 14 side of the metal plate spring 12, respectively. The support member 15 includes mounting plates 16 interposed between each of the two metal plate springs 11 and 12 and the base member 5, leaf spring fastening screws 17 for fastening each of the two metal plate springs 11 and 12 to the corresponding mounting plate 16, and mounting plate fastening screws 18 for fastening the mounting plate 16 to the base member 5. In this example, the above-described screw 8, the leaf spring fastening screw 17, and the mounting plate fastening screw 18 are all male screws and are screwed into screw holes formed with corresponding female screws. As shown in FIG. 1, there are three leaf spring fastening screws 17 and three mounting plate fastening screws 18 each.

[0024] With the cell 3 being pressed and constrained to the normal position during observation by X-ray CT via the plate-shaped resin member 10 by the two metal plate springs 11 and 12, the negative electrode terminal 19 of the cell 3 is located at substantially the same position as the extended end of the metal plate spring 11 in a front view. Further, the positive electrode terminal 20 of the cell 3 is located at substantially the same position as the extended end of the metal plate spring 12 in a front view. The negative electrode bus bar 21 is led out from the negative electrode terminal 19 and extends to a position near the base 13 of the metal plate spring 11 in a front view. Also, the positive electrode bus bar 22 is led out from the positive electrode terminal 20 and extends to a position near the base 14 of the metal plate spring 12 in a front view. The negative electrode bus bar 21 and the positive electrode bus bar 22 are arranged as described above. For this reason, the region a of the electrode facing portion 9 is located between the negative electrode bus bar 21 and the positive electrode bus bar 22.

[0025] A flat housing 23 made of an insulating material that houses the cell 3, the negative electrode terminal 19, the negative electrode bus bar 21, the positive electrode terminal 20, and the positive electrode bus bar 22 is provided. The housing 23 has its outer surface side in close contact with the base member 5 and its housing space side is open. The housing 23 is composed of a first housing half 24 and a second housing half 25. The first housing half 24 houses the cell 3, the negative electrode terminal 19, the negative electrode bus bar 21, the positive electrode terminal 20, and the positive electrode bus bar 22 in the housing space. The second housing half 25 seals the open side of the first housing half 24. A negative electrode side opening 26 is provided on the end side surface of the housing 23 on the base 13 side of the metal plate spring 11. The negative electrode side opening 26 is a window portion formed so as to be electrically conductive to the negative electrode bus bar 21 from the outside. Also, a positive electrode side opening 27 is provided on the end side surface of the housing 23 on the base 14 side of the metal plate spring 12. The positive electrode side opening 27 is a window portion formed so as to be electrically conductive to the positive electrode bus bar 22 from the outside.

[0026] A window portion 28 penetrating the second housing half 25 in the thickness direction is formed at a corresponding position in the region a of the electrode facing portion 9 in the second housing half 25 so that the non-contact surface with respect to the cell 3, which is the other surface side of the plate-shaped resin member 10 whose one surface side is the contact surface with the cell 3, is exposed. Thereby, the biasing forces of the two metal plate springs 11 and 12 that press the non-contact surface side with respect to the cell 3, which is the other surface side of the plate-shaped resin member 10, effectively act on the cell 3 via the plate-shaped resin member 10. That is, a structure is adopted in which the cell 3 is pressed via the plate-shaped resin member 10 from the opposing extended ends of the two metal plate springs 11 and 12 respectively.

[0027] Therefore, the pressurization of the region a of the electrode facing portion 9 in the cell 3 is directly performed in the region where the plate-shaped resin member 10 has a planar spread. For this reason, the two metal plate springs 11 and 12 can effectively pressurize the entire region a of the electrode facing portion 9 while making the moment length from their respective bases 13 and 14 to the extended ends, which are the acting ends of the biasing force, relatively short. For this reason, the strength required for the support member 15 including the two metal plate springs 11 and 12, the plate spring fastening screw 17, the mounting plate 16, and the mounting plate fastening screw 18 can be reduced.

[0028] Here, a plurality of types of two metal plate springs 11 and 12 are prepared, which have the same planar projection shape on the main surface side of the base member 5 and different spring constants. These plurality of types of two metal plate springs 11 and 12 are typically made of the same metal but have different thickness dimensions. Since the planar projection shapes of the plurality of types of two metal plate springs 11 and 12 on the main surface side of the base member 5 are the same, they can be easily attached to and detached from the mounting plate 16 by the leaf spring fastening screw 17.

[0029] Thereby, while replacing the two metal plate springs 11 and 12 with those having various spring constants, different pressing forces can be applied to the cell 3 through the plate-shaped resin member 10, and the properties of the cell 3 at that time can be observed by X-ray CT. As a form of exchanging the two metal plate springs 11 and 12, as described above, in addition to the form of attaching to and detaching from the mounting plate 16 by the leaf spring fastening screw 17, a form can be adopted in which blocks in a state where the two metal plate springs 11 and 12 are each fixed to the mounting plate 16 by the leaf spring fastening screw 17 are detachably attached to the base member 5 by the mounting plate fastening screw 18.

[0030] The plurality of types of two metal plate springs 11 and 12 with different spring constants are prepared, for example, as the following two types. The first type covers the range where the biasing force is 0.1 MPa - 1.0 MPa, and the second type covers the range where the biasing force is 2.0 MPa - 4.0 MPa.

[0031] The cell assembly 1 for structure observation as described above is attached to the rotary support member 2 and rotates around the virtual rotation axis Va. During this time, X-rays by an X-ray CT (not shown) are irradiated as shown by the thick solid arrows in FIG. 2, and a CT image as an observation result regarding the cell 3 is obtained. At an appropriate timing, energization to the negative electrode bus bar 21 and the positive electrode bus bar 22 is adjusted using the negative electrode opening 26 and the positive electrode opening 27, and the SOC of the cell 3 is changed for observation.

[0032] According to the cell assembly 1 for structure observation of the present disclosure, the following effects are achieved.

[0033] In the cell assembly 1 for structural observation of (1), a restraint member 4 is provided for restraining the cell 3 to be observed from both sides in its thickness direction. The restraint member 4 includes a plate-shaped resin member 10 arranged to cover the region a of the electrode facing portion 9 related to observation on one side of the two sides of the cell 3, and two metal plate springs 11, 12 that face each other in the direction along the main surface of the plate-shaped resin member 10 and extend toward the center of the plate-shaped resin member 10 respectively, and are arranged so that a predetermined gap g is formed between their extending ends, and press and bias the non-contact surface side with the cell 3 with respect to the plate-shaped resin member 10. The gap g is formed to match the X-ray irradiation position by X-ray CT. Thereby, while rotating the cell assembly 1 for structural observation around the virtual rotation axis Va, X-rays by X-ray CT can be irradiated to the cell to be observed from the gap g between the extending ends of the two metal plate springs 11, 12. For this reason, even if the incident angle of the X-rays to the cell 3 approaches 90 degrees, the incidence of the X-rays is not inhibited, and the efficiency of X-ray irradiation to the cell can be improved.

[0034] In the cell assembly 1 for structural observation of (2), the restraint member 4 is supported by a rotation support member 2 that rotates the cell 3 around a virtual rotation axis Va which is a predetermined rotation axis during observation by X-ray CT. The site of the gap g where the two metal plate springs 11, 12 are separated in the direction of the virtual rotation axis Va is formed in the region a of the electrode facing portion 9. For this reason, when irradiating the cell 3 with X-rays by X-ray CT while rotating the cell 3 to be observed around the virtual rotation axis Va, it is possible to avoid the absorption of X-rays by the two metal plate springs 11, 12.

[0035] In the cell assembly 1 for structural observation of (3), each of the two metal plate springs 11, 12 is supported by a support member 15 on the base portions 13, 14 sides respectively, which are opposite to their extending end sides, and their extending end sides are located in the region a of the electrode facing portion 9. For this reason, when irradiating the cell 3 with X-rays by X-ray CT while rotating the cell 3 to be observed around the virtual rotation axis Va, it is possible to avoid the absorption of X-rays by the support member 15 that supports the two metal plate springs 11, 12 on their base portions 13, 14 sides.

[0036] In the cell assembly 1 for structure observation of (4), the region a of the electrode facing portion 9 is located between the positive electrode terminal 20 and the negative electrode terminal 19 led out from the cell 3. Therefore, when irradiating the cell 3 with X-rays by X-ray CT while rotating the cell 3 to be observed around the virtual rotation axis Va, it is possible to avoid the absorption of X-rays by the positive electrode terminal 20 and the negative electrode terminal 19 led out from the cell 3.

[0037] In the cell assembly 1 for structure observation of (5), the region a of the electrode facing portion 9 is located between the positive electrode bus bar 22 connected to the positive electrode terminal 20 led out from the cell 3 and the negative electrode bus bar 21 connected to the negative electrode terminal 19. Therefore, when irradiating the cell 3 with X-rays by X-ray CT while rotating the cell 3 to be observed around the virtual rotation axis Va, it is possible to avoid the absorption of X-rays by the positive electrode bus bar 22 and the negative electrode bus bar 21 led out from the cell 3.

[0038] In the cell assembly 1 for structure observation of (6), a housing 23 for housing the positive electrode terminal 20, the negative electrode terminal 19, the positive electrode bus bar 22, and the negative electrode bus bar 21 is provided. The housing 23 has a positive electrode side opening 27 and a negative electrode side opening 26 formed so as to be externally energizable with respect to the positive electrode bus bar 22 and the negative electrode bus bar 21 during observation by X-ray CT. Therefore, since the positive electrode bus bar 22 and the negative electrode bus bar 21 led out from the cell 3 can be externally energized during observation by X-ray CT, it is possible to observe under the same conditions as when the cell is charged. That is, it is possible to perform observation while changing the SOC of the cell 3.

[0039] In addition to the aspects described above with reference to FIGS. 1 and 2, the cell assembly 1 for structure observation of the present disclosure can be configured with various modifications. For example, regarding the preparation of a plurality of types of metal plate springs 11 and 12 having different spring constants, the planar projection shape of the base member 5 on the main surface side was made the same, and those made of the same metal with different thickness dimensions were prepared. Instead of this, those having different planar projection shapes (width dimensions) of the base member 5 on the main surface side and the same metal with the same thickness dimensions may be prepared. In any case, it is preferable that the positions and dimensions of the leaf spring fastening screws 17 to be applied are common.

Explanation of Symbols

[0040] a…Region g…Gap Va…Virtual Rotation Axis 1…Cell Assembly for Structure Observation 2…Rotation Support Member 3…Cell 4…Restraint Member 5…Base Member 6…Base 7…Attachment Port 8…Screw 9…Electrode Opposing Port 10…Plate - shaped Resin Member 11, 12…Metal Plate Springs 13, 14…Bases 15…Support Member 16…Attachment Plate 17…Plate Spring Fastening Screw 18…Attachment Plate Fastening Screw 19…Negative Terminal 20…Positive Terminal 21…Negative Busbar 22…Positive Busbar 23…Container 24…First Half Container 25…Second Half Container 26…Negative - side Opening 27…Positive - side Opening 28…Window Port

Claims

1. A cell assembly for observing the internal structure of a cell by X-ray CT, comprising: a restraining member for restraining the cell to be observed from both sides in the thickness direction thereof; The restraining member includes: a plate-shaped resin member arranged to cover a region of an electrode facing portion related to the observation on one side of the two sides of the cell; two metal plate springs that face each other in a direction along the main surface of the plate-shaped resin member, extend toward the center portion of the plate-shaped resin member respectively, and are arranged so as to create a predetermined gap between their extending ends, and press and bias the non-contact surface side of the cell with respect to the plate-shaped resin member; The gap is formed to match the X-ray irradiation position by the X-ray CT. The cell assembly for structure observation.

2. The restraining member is supported by a rotation support member that rotates the cell around a predetermined rotation axis during observation by the X-ray CT, and a region of the gap spaced in the direction of the rotation axis of the two metal plate springs is formed in the region of the electrode facing portion. The cell assembly for structure observation according to claim 1.

3. Each of the two metal plate springs is supported by a support member on the base side opposite to the extending end side, and the extending end side is located in the region of the electrode facing portion. The cell assembly for structure observation according to claim 1.

4. The region of the electrode facing portion is located between a positive electrode terminal and a negative electrode terminal led out from the cell. The cell assembly for structure observation according to claim 1.

5. The region of the electrode facing portion is located between a positive electrode bus bar connected to the positive electrode terminal led out from the cell and a negative electrode bus bar connected to the negative electrode terminal. The cell assembly for structure observation according to claim 1.

6. There is provided a container that houses the positive electrode terminal, the negative electrode terminal, the positive electrode bus bar, and the negative electrode bus bar, and the container has a positive electrode side opening and a negative electrode side opening that are formed so as to be externally energizable to the positive electrode bus bar and the negative electrode bus bar during observation by the X-ray CT. The cell assembly for structure observation according to claim 5.

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