JP7176499B2 - storage cell - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a power storage cell including an electrode winding body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween.

Japanese Patent Application Laid-Open No. 2013-235705 (Patent Document 1) discloses a technique of providing a gap between an electrode winding body and a winding core in a conventional storage cell.

JP 2013-235705 A

In the configuration disclosed in Patent Document 1, since the above-described gap exists, when the electrode winding body expands, the portion of the electrode winding body located near the above-mentioned gap will be the same as the electrode winding body. It expands not only toward the outside but also toward the inside of the electrode winding body where the gap exists.

Therefore, when charging and discharging are repeated and the wound electrode body expands, the wound electrode in the vicinity of the gap loosens. In such a case, the power storage capacity decreases.

The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a storage cell capable of suppressing loosening of the electrode winding body.

A storage cell of the present disclosure includes a winding core, and an electrode wound body in which a positive electrode and a negative electrode are wound around the winding core with a separator interposed therebetween. A cross section of the core perpendicular to the winding axis of the electrode winding body has a longitudinal shape whose longitudinal direction is the direction perpendicular to the winding axis. The winding core is provided at both ends of the main body portion in the longitudinal direction so as to be in close contact with the inner peripheral surface of the electrode winding body and the body portion extending in the longitudinal direction due to the pressing force received from the electrode winding body. and a pair of sealing portions. A spring constant of the body portion is smaller than a spring constant of the pair of contact portions.

In general, the wound electrode body expands more easily at the central portion in the longitudinal direction than at both ends in the longitudinal direction.

According to the above configuration, when the electrode winding body expands, the main body portion, which is arranged in the central portion of the winding core in the longitudinal direction and has a small spring constant, is pressed by the electrode winding body and deformed. At this time, the body portion deforms so as to extend in the longitudinal direction, and presses the pair of contact portions positioned at both ends of the winding core in the longitudinal direction toward the electrode winding body. The pair of contact portions pressed by the body portion deforms and presses the wound electrode body outward.

Here, since the spring constant of the pair of contact portions is large, the amount of deformation of the pair of contact portions is small. Therefore, the electrode winding body positioned near the pair of contact portions deforms following the pair of contact portions so that a gap is not formed between the electrode winding body and the pair of contact portions. As a result, the electrode winding body located near the pair of contact portions can be uniformly pressed outward. As a result, even if the electrode winding body expands due to repeated charging and discharging, loosening of the electrode winding body can be suppressed.

Advantageous Effects of Invention According to the present disclosure, it is possible to provide a storage cell capable of suppressing loosening of an electrode winding body.

1 is a schematic perspective view of a storage cell according to Embodiment 1; FIG. 1 is a schematic cross-sectional view of a storage cell according to Embodiment 1; FIG. 4 is a schematic cross-sectional view showing a state when the electrode winding body expands in the storage cell according to Embodiment 1. FIG. FIG. 5 is a schematic cross-sectional view of a storage cell according to Embodiment 2; FIG. 11 is a schematic perspective view of a body portion of a winding core according to Embodiment 2; FIG. 10 is a schematic cross-sectional view showing a state when the electrode winding body expands in the storage cell according to Embodiment 2; It is a figure which shows the result of the verification experiment performed in order to verify the effect of embodiment. 2 is a schematic cross-sectional view of a storage cell according to Comparative Example 1. FIG. 10 is a schematic cross-sectional view of a storage cell according to Comparative Example 2; FIG. 4 is a schematic cross-sectional view showing a state after repeated charging and discharging in a storage cell according to Comparative Example 1. FIG. FIG. 10 is a schematic cross-sectional view showing a state after repeated charging and discharging in a storage cell according to Comparative Example 2; 2 is a schematic cross-sectional view showing a state after repeated charging and discharging of the storage cell according to Example 1. FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments shown below, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic perspective view of a storage cell according to Embodiment 1. FIG. FIG. 2 is a schematic cross-sectional view of a storage cell according to Embodiment 1. FIG. A storage cell 100 according to Embodiment 1 will be described with reference to FIGS. 1 and 2. FIG.

A storage cell 100 according to Embodiment 1 is a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. The storage cell 100 may use a liquid electrolyte or a solid electrolyte.

A power storage module is configured by stacking a plurality of power storage cells 100 . The power storage module is used in a hybrid vehicle powered by an internal combustion engine such as a gasoline engine or a diesel engine and a motor supplied with power from a chargeable/dischargeable battery, a plug-in hybrid vehicle capable of external charging, an electric vehicle, or the like. installed in the

As shown in FIGS. 1 and 2 , the storage cell 100 includes a housing 10 , an electrode winding body 20 , a restraint portion 30 , a winding core 40 , a positive terminal 51 and a negative terminal 52 .

The housing 10 accommodates the electrode winding body 20, the winding core 40, and the electrolytic solution. The housing 10 includes a case body 11 and a sealing body 12 . The case body 11 has a bottomed prismatic shape that opens upward. The sealing body 12 seals the opening provided in the case body 11 . The case body 11 and the sealing body 12 are made of metal such as aluminum.

A positive terminal 51 and a negative terminal 52 are attached to the sealing member 12 . The positive electrode terminal 51 is electrically connected to the positive electrode of the electrode winding body 20 by a positive electrode current collector (not shown). The negative electrode terminal 52 is electrically connected to the negative electrode of the electrode winding body 20 by a negative electrode current collector (not shown).

The restraining portion 30 suppresses deformation of the housing 10 when the electrode winding body 20 expands. The restraint part 30 includes a pair of restraint members 31 and 32 . A pair of restraining members 31 and 32 are provided so as to extend along a direction parallel to the winding axis C of the electrode winding body 20 . A pair of restraining members 31 and 32 are arranged outside the housing 10 . A pair of binding members 31 and 32 are arranged so as to sandwich the central portion of storage cell 100 in the height direction of storage cell 100 . Accordingly, when the electrode winding body 20 expands, the deformation of the housing 10 is suppressed by the pair of restraining members 31 and 32 . The pair of restraining members 31 and 32 are made of a resin member such as polypropylene.

The electrode wound body 20 has a positive electrode and a negative electrode wound around a winding core 40 with a separator interposed therebetween. The electrode wound body 20 is formed by sequentially laminating a positive electrode, a separator, a negative electrode, and a separator and winding them around a winding axis C around a winding core 40 . In addition, the winding axis C extends in the direction perpendicular to the paper surface in FIG.

The positive electrode is composed of, for example, a positive electrode sheet in which a positive electrode active material is applied to a metal foil such as aluminum foil. The negative electrode is composed of, for example, a negative electrode sheet in which a negative electrode active material is applied to a metal foil such as copper foil.

On one side of the positive electrode, an uncoated portion where the aluminum foil is exposed without being coated with the positive electrode active material is formed. The uncoated portion is exposed from one end of the separator in the direction parallel to the winding axis C. As shown in FIG. The positive electrode current collector described above is connected to the uncoated portion exposed from one end of the separator.

On one side of the negative electrode sheet, an uncoated portion where the copper foil is exposed without being coated with the negative electrode active material is formed. The uncoated portion is exposed from the other end of the separator in the direction parallel to the winding axis C. As shown in FIG. The negative electrode current collector described above is connected to the uncoated portion exposed from the other end of the separator.

The electrode winding body 20 has a flat shape. The electrode winding body 20 has two flat portions 21 and two curved portions 22 as its constituent parts.

The two flat portions 21 have a thin plate shape parallel to the height direction of the storage cell 100 . The two flat portions 21 are perpendicular to the direction parallel to the winding axis C. As shown in FIG. The two flat portions 21 are arranged to face each other.

The two curved portions 22 are connected to both ends of the flat portion 21 in a direction perpendicular to both the thickness direction of the flat portion 21 and the winding axis C (height direction of the storage cell 100). The two curved portions 22 form both ends of the electrode winding body 20 in the height direction of the storage cell 100 . Of the two curved portions 22, the upper curved portion 22 curves upwardly. Of the two curved portions 22, the lower curved portion 22 is curved so as to be convex downward.

The winding core 40 is arranged between the two curved portions and the two flat portions 21 . The winding core 40 has a flat shape. The cross section of the winding core 40 perpendicular to the winding axis C has a longitudinal shape whose longitudinal direction is the direction perpendicular to the winding axis C (the height direction of the storage cell 100).

The winding core 40 has a body portion 41 and a pair of contact portions 42 . The body portion 41 constitutes the central portion of the winding core 40 in the longitudinal direction. The body portion 41 is sandwiched between the two flat portions 21 . The body portion 41 is provided so as to be able to expand and contract in the longitudinal direction. The body portion 41 extends in the longitudinal direction due to the pressing force received from the electrode winding body 20 .

The pair of contact portions 42 are provided at both ends of the body portion 41 in the longitudinal direction so as to be in contact with the inner peripheral surface of the electrode winding body 20 . The pair of contact portions 42 are in contact with the inner peripheral surfaces of the two curved portions 22 . The pair of contact portions 42 are sandwiched between the two curved portions 22 , the body portion 41 , and the two flat portions 21 exposed from the body portion 41 .

The spring constant of the body portion 41 is smaller than the spring constant of the pair of contact portions 42 . Main body portion 41 is made of, for example, a rubber material such as styrene-butadiene rubber. The pair of contact portions 42 are made of, for example, a resin member such as polypropylene.

FIG. 3 is a schematic cross-sectional view showing a state when the electrode winding body expands in the storage cell according to Embodiment 1. FIG. With reference to FIG. 3, a state in which electrode winding body 20 expands in storage cell 100 according to Embodiment 1 will be described.

When the electrode winding body 20 expands due to repeated charging and discharging, the central portion of the electrode winding body 20 in the height direction (the longitudinal direction) of the storage cell 100 is shifted from the electrode winding body 20 in the longitudinal direction. bulge out beyond the ends of the . The central portion of the electrode winding body 20 is located in the central portion of the housing 10 in the height direction.

When the central portion of the electrode winding body 20 swells, the central portion of the housing 10 is pressed by the electrode winding body 20. Outside the central portion of the housing 10, a pair of restraining members 31, 32 are arranged. Therefore, when the electrode-wound body 20 expands, a reaction force acts toward the inside of the electrode-wound body 20 by the housing 10 and the pair of restraining members 31 and 32 . As a result, when the electrode winding body 20 expands, the electrode winding body 20 presses the body portion 41 arranged in the central portion in the longitudinal direction.

The body portion 41 is easily deformed due to its small spring constant, and is deformed so as to extend in the longitudinal direction by being pressed by the wound electrode body 20 . As a result, the pair of contact portions 42 are pressed by the body portion 41 toward the electrode winding body 20 (more specifically, the curved portion 22). The pair of contact portions 42 pressed by the body portion 41 deforms and presses the wound electrode body 20 (the curved portion 22) outward.

Here, since the spring constant of the pair of contact portions 42 is large, the amount of deformation of the pair of contact portions 42 is small. For this reason, the electrode winding body 20 (more specifically, the curved portion 22) positioned near the pair of contact portions 42 is arranged so as not to form a gap with the pair of contact portions 42. 42 is followed and deformed.

As a result, the electrode winding body 20 (curved portion 22) positioned near the pair of contact portions 42 can be uniformly pressed outward. As a result, even if the electrode-wound body 20 expands due to repeated charging and discharging, loosening of the electrode-wound body 20 can be suppressed.

(Embodiment 2)
FIG. 4 is a schematic cross-sectional view of a storage cell according to Embodiment 2. FIG. FIG. 5 is a schematic perspective view of the main body of the winding core according to Embodiment 2. FIG. A storage cell 100A according to Embodiment 2 will be described with reference to FIGS. 4 and 5. FIG.

As shown in FIG. 4, in the storage cell 100A according to Embodiment 2, when compared with the storage cell 100 according to Embodiment 1, the configuration of the core 40A (more specifically, the main body portion of the core 40A 41) is different. Other configurations are almost the same.

The body portion 41 functions as a pressing direction changing portion that changes the direction of the pressing force pressed by the central portion of the electrode wound body 20 to the direction orthogonal to the winding axis C (height direction of the storage cell 100A).

As shown in FIGS. 4 and 5, the body portion 41 includes a plurality of block bodies 411, 412, 413, 414. As shown in FIG. In the cross section of the body portion 41 perpendicular to the winding axis C, the length between the upper surface 411a of the block body 411 and the lower surface 412a of the block body 412, which will be described later, is It is longer than the length of the pressed surface 414a. That is, the cross section of the winding core 40A perpendicular to the winding axis C has a longitudinal shape with the direction perpendicular to the winding axis C as the longitudinal direction.

The block bodies 413 and 414 are arranged so as to face each other in the thickness direction of the flat portion 21 . The block bodies 413 and 414 have a triangular tubular shape with a triangular cross section perpendicular to the tubular axis. The cylinder axis direction of the block bodies 413 and 414 is parallel to the winding axis C. As shown in FIG.

The block body 413 has a pressed surface 413a and inclined surfaces 413b and 413c. The pressed surface 413 a is pressed from the flat portion 21 of the wound electrode body 20 . The pressed surface 413a is parallel to the height direction of the storage cell 100A. The inclined surfaces 413b and 413c are provided on both end sides of the pressed surface 413a in the height direction of the storage cell 100A. The inclined surfaces 413 b and 413 c are inclined so that the distances in the height direction become closer to each other toward the block body 414 .

The block body 414 has a pressed surface 414a and inclined surfaces 414b and 414c. The pressed surface 414 a is pressed from the flat portion 21 of the wound electrode body 20 . The pressed surface 414a is parallel to the height direction of the storage cell 100A. The inclined surfaces 414b and 414c are provided on both end sides of the pressed surface 414a in the height direction of the storage cell 100A. The inclined surfaces 414b and 414c are inclined so that the distances in the height direction become closer to each other toward the block body 414. As shown in FIG.

The block bodies 411 and 412 are arranged so as to face each other in the height direction of the storage cell 100A. The block bodies 411 and 412 have a rectangular tubular shape with a trapezoidal cross section orthogonal to the tubular axis. The block bodies 411 and 412 have a width parallel to the thickness direction of the flat portion 21 that narrows toward the central portion of the storage cell 100A. The cylinder axis direction of the block bodies 411 and 412 is parallel to the winding axis C. As shown in FIG.

The block body 411 is arranged above the block body 412 . The block 411 is arranged between the inclined surface 413 b of the block 413 and the inclined surface 414 b of the block 414 . The height position of the block 411 is changed by changing the distance between the inclined surface 413b and the inclined surface 414b.

The block body 412 is arranged below the block body 411 . The block 412 is arranged between the inclined surface 413 c of the block 413 and the inclined surface 414 c of the block 414 . The height position of the block 412 is changed by changing the distance between the inclined surface 413c and the inclined surface 414c.

The block body 411 moves upward as the surfaces to be pressed 413a and the surfaces to be pressed 414a are pressed and the inclined surfaces 413b and 414b approach each other. The block body 412 moves downward as the pressed surface 413a and the pressed surface 414a are pressed and the inclined surfaces 413c and 414c approach each other. As a result, the direction of the pressing force from the flat portion 21 of the electrode wound body 20 is changed to the direction orthogonal to the winding axis C (height direction of the storage cell 100A).

Even in such a configuration, the body portion 41 is more easily deformed than the pair of contact portions 42, and the spring constant of the body portion 41 is smaller than the spring constant of the pair of contact portions 42. It's becoming

FIG. 6 is a schematic cross-sectional view showing a state when the electrode winding body expands in the storage cell according to Embodiment 2. FIG. With reference to FIG. 6, a state when electrode winding body 20 expands in storage cell 100A according to Embodiment 2 will be described.

As described above, when charging and discharging are repeated and the electrode winding body 20 expands, the central portion of the electrode winding body 20 in the height direction (the longitudinal direction) of the storage cell 100 is It expands more than both ends of the electrode winding body 20 .

When the central portion of the electrode winding body 20 swells, the pressed surfaces 413a and 414a of the block bodies 413 and 414 are pressed. As a result, the block bodies 413 and 414 move closer to each other. As the blocks 413 and 414 approach each other, the slopes 413b and 414b approach each other, and the slopes 413c and 414c approach each other. As a result, the block body 411 moves upward, and the block body 411 presses the contact portion 42 positioned between the block body 411 and the curved portion 22 . Further, the block body 412 moves downward, and the contact portion 42 positioned between the block body 412 and the curved portion 22 is pressed by the block body 412 .

The pair of contact portions 42 pressed by the body portion 41 deforms and presses the wound electrode body 20 (the curved portion 22) outward.

Here, since the spring constant of the pair of contact portions 42 is large, the amount of deformation of the pair of contact portions 42 is small. For this reason, the electrode winding body 20 (more specifically, the curved portion 22) positioned near the pair of contact portions 42 is arranged so as not to form a gap with the pair of contact portions 42. 42 is followed and deformed.

As a result, the electrode winding body 20 (curved portion 22) positioned near the pair of contact portions 42 can be uniformly pressed outward. As a result, in the second embodiment, as in the first embodiment, loosening of the electrode-wound body 20 can be suppressed even when the electrode-wound body 20 expands due to repeated charging and discharging. .

(Verification experiment)
FIG. 7 is a diagram showing the results of verification experiments conducted to verify the effects of the embodiment. A verification experiment conducted to verify the effects of the embodiment will be described with reference to FIG.

As shown in FIG. 7, in the verification experiment, a storage cell 100S according to Example 1 (see FIG. 12), a storage cell 100X1 according to Comparative Example 1 (see FIG. 8), and a storage cell 100X2 according to Comparative Example 2 ( 9) was prepared. In these electric storage cells, charging and discharging were repeated 1000 times in an environment of 50°C. After repeating charging and discharging, the strain of the electrode winding body 20 in each storage cell was observed, and the capacity of each storage cell was confirmed. In charging and discharging, the amount of stored electricity was changed between 0% and 100%.

The storage cell 100S according to Example 1 has the same configuration as the storage cell 100 according to Embodiment 1. As shown in FIG.

8 is a schematic cross-sectional view of a storage cell according to Comparative Example 1. FIG. As shown in FIG. 8, as a storage cell 100X1 according to Comparative Example 1, a storage cell that does not have a winding core as compared with the storage cell 100 according to Embodiment 1 was prepared. That is, in the storage cell 100X1 according to Comparative Example 1, a gap is formed inside the electrode wound body 20. As shown in FIG.

9 is a schematic cross-sectional view of a storage cell according to Comparative Example 2. FIG. As shown in FIG. 9, as a storage cell 100X2 according to Comparative Example 2, a core 40 composed only of the main body portion 41 in the first embodiment was prepared. That is, in the storage cell 100X2 according to Comparative Example 2, the pair of contact portions 42 are not formed, and a gap is formed between the main body portion 41 and the curved portion 22 .

10 is a schematic cross-sectional view showing a state after repeated charging and discharging in the storage cell according to Comparative Example 1. FIG. As shown in FIG. 10, in the storage cell 100X1 according to Comparative Example 1, a gap is formed inside the electrode-wound body 20, and the electrode-wound body 20 expands not only to the outside but also to the inside. A plurality of slacks 90 were observed in both the flat portion 21 and the curved portion 22 of the electrode wound body 20 . In addition, as shown in FIG. 7 again, due to the plurality of slacks 90, the capacity of the storage cell 100X1 was greatly reduced.

FIG. 11 is a schematic cross-sectional view showing a state after repeated charging and discharging in a storage cell according to Comparative Example 2. FIG. As shown in FIG. 11, in the storage cell 100X2 according to Comparative Example 2, a gap is formed between the main body portion 41 and the curved portion 22, and the curved portion 22 expands not only outward but also inward. , a plurality of slacks 90 were observed in the curved portion 22 . In addition, as shown in FIG. 7 again, the capacity of the storage cell 100X2 decreased due to the plurality of slacks 90 .

12 is a schematic cross-sectional view showing a state after repeated charging and discharging of the storage cell according to Example 1. FIG. As shown in FIG. 12 , in the storage cell 100S according to Example 1, looseness was not observed in the electrode wound body 20 due to the configuration similar to that of the storage cell 100 according to Embodiment 1. Moreover, as shown in FIG. 7 again, the capacity of the storage cell 100S did not decrease.

From the above results, it can be seen that the main body portion 41 that extends in the longitudinal direction due to the pressing force received from the electrode wound body 20 and the main body portion 41 that extends in the longitudinal direction so as to be in close contact with the inner peripheral surface of the electrode wound body 20 . By making the spring constant of the body portion 41 smaller than the spring constant of the pair of contact portions 42 including the pair of contact portions 42 provided at both ends, loosening of the electrode winding body 20 can be suppressed. confirmed.

As described above, the embodiments disclosed this time are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the scope of claims, and includes all modifications within the meaning and scope of equivalence to the scope of claims.

10 Housing 11 Case Body 12 Sealing Body 20 Electrode Winding Body 21 Flat Part 22 Curved Part 30 Restraint Part 31 Restraint Member 40, 40A Winding Core 41 Body Part 42 Close Contact Part 51 Positive Electrode Terminal 52 Negative electrode terminal 90 Looseness 100, 100A, 100S, 100X1, 100X2 Storage cell 411, 412, 413, 414 Block body 411a Upper surface 412a Lower surface 413a, 414a Pressed surface 413b, 413c, 414b, 414c Inclined plane, C winding axis.

Claims (1)

a winding core;
an electrode wound body in which a positive electrode and a negative electrode are wound around the winding core with a separator interposed therebetween;
a cross section of the core perpendicular to the winding axis of the electrode winding body has a longitudinal shape whose longitudinal direction is a direction perpendicular to the winding axis;
In the cross section perpendicular to the winding axis, the electrode winding body connects a pair of flat portions facing each other in a direction perpendicular to the longitudinal direction and end portions of the pair of flat portions in the longitudinal direction, a pair of longitudinally opposed curved portions;
The winding core is provided at both ends of the main body portion in the longitudinal direction so as to be in close contact with the inner peripheral surface of the electrode winding body and the main body portion extending in the longitudinal direction due to the pressing force received from the electrode winding body. and a pair of contacting portions,
Each of the two ends of the main body in the longitudinal direction has an end surface extending from the inner surface of one of the pair of flat portions to the inner surface of the other of the pair of flat portions. death,
The pair of tight contact portions are provided so as to fill a gap between the inner peripheral surfaces of the pair of curved portions and the end surfaces of the both ends of the body portion,
The energy storage cell, wherein the spring constant of the body portion is smaller than the spring constant of the pair of contact portions.

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