Power storage cell

Abstract

To provide a power storage cell capable of stably fixing (holding) a wound electrode body to which an insulating tape is arranged on an outer peripheral surface at both ends of an axial direction by a case.SOLUTION: A power storage cell 100 comprises: a wound electrode body 10 around which a positive electrode sheet 1 (an electrode sheet), a negative electrode sheet 2 (an electrode sheet), and a separator 3 are wound; a cylindrical case 20 that houses the wound electrode body 10; an insulating tape 30 (a first insulating tape) that is arranged on an outer peripheral surface 11 of the wound electrode body 10; and an insulating tape 40 (a second insulating tape) that is arranged on an outer peripheral surface 12 of the wound electrode body 10. A case 20 includes: a cylindrical wide diameter part 21 (a first part) provided at a position in a Z-direction corresponding to the insulating tape 30; a cylindrical wide diameter part 22 (a second part) provided at the position in the Z-direction corresponding to the insulating tape 40; and a cylindrical compression diameter part 23 provided between the wide diameter part 21 and the wide diameter part 22. In the compression diameter part 23, an uneven part 23a is formed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a storage cell.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2007-200755 (Patent Document 1) discloses a secondary battery including a battery element and a hollow cylindrical battery container that houses the battery element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although not described in Patent Document 1 above, an insulating tape may be disposed on the outer peripheral surface of a battery element (wound electrode body). In this case, in order to reduce the load due to the insulating tape, it is conceivable that the insulating tape is disposed only on the outer peripheral surface of the axial end portion of the battery element. It is desired to stably fix (hold) such a battery element with a battery container (case).

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a storage cell capable of stably fixing (holding) a wound electrode body having insulating tapes disposed on the outer peripheral surfaces at both axial ends with a case.

Means for Solving the Problems

[0006] The power storage cell according to one aspect of the present disclosure includes a wound electrode body formed by winding an electrode sheet and a separator around a winding axis, a cylindrical case that houses the wound electrode body and is formed to extend in the axial direction of the wound electrode body, a first insulating tape disposed on the outer peripheral surface of one axial end of the wound electrode body, and a second insulating tape disposed on the outer peripheral surface of the other axial end of the wound electrode body. The case includes a cylindrical first portion provided at an axial position corresponding to the first insulating tape, a cylindrical second portion provided at an axial position corresponding to the second insulating tape, and a cylindrical reduced-diameter portion provided between the first portion and the second portion and having a diameter reduced in the radial direction of the wound electrode body compared to each of the first portion and the second portion. An uneven portion is formed in the reduced-diameter portion.

[0007] In the power storage cell according to one aspect of the present disclosure, as described above, a reduced-diameter portion having a diameter reduced in the radial direction of the wound electrode body compared to each of the first portion and the second portion is provided between the first portion and the second portion. Thereby, it is possible to suppress the formation of a space between the portion of the wound electrode body between the first insulating tape and the second insulating tape (the portion facing the reduced-diameter portion) and the case. As a result, the wound electrode body can be stably fixed (held) by the case.

[0008] Further, by forming the uneven portion in the reduced-diameter portion, it is possible to absorb the expansion and contraction of the wound electrode body. In addition, since the surface area of the reduced-diameter portion can be increased by forming the uneven portion, the amount of heat radiation from the reduced-diameter portion can be increased.

Advantages of the Invention

[0009] According to the present disclosure, the wound electrode body having insulating tapes disposed on the outer peripheral surfaces of both axial ends can be stably fixed (held) by the case.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

[0012] <Configuration of Power Storage Cell> FIG. 1 is a perspective view showing an overall configuration of a power storage cell 100 according to an embodiment of the present disclosure. The power storage cell 100 is used, for example, in a battery of an electric vehicle. Note that the use of the power storage cell 100 is not limited to electric vehicles.

[0013] As shown in FIG. 1, the power storage cell 100 includes a wound electrode body 10 (see FIG. 2), a case 20, an insulating tape 30 (see FIG. 3), and an insulating tape 40 (see FIG. 3). Note that the insulating tape 30 and the insulating tape 40 are examples of the "first insulating tape" and the "second insulating tape" of the present disclosure, respectively.

[0014] FIG. 2 is a schematic perspective view showing the configuration of the wound electrode body 10. The wound electrode body 10 includes a positive electrode sheet 1, a negative electrode sheet 2, and a separator 3. Note that each of the positive electrode sheet 1 and the negative electrode sheet 2 is an example of the "electrode sheet" of the present disclosure.

[0015] The positive electrode sheet 1, the separator 3, and the negative electrode sheet 2 are laminated on one another. The separator 3 is provided between the positive electrode sheet 1 and the negative electrode sheet 2. The separator 3 separates the positive electrode sheet 1 and the negative electrode sheet 2 while enabling the passage of ions (such as lithium ions) between the positive electrode sheet 1 (positive electrode active material) and the negative electrode sheet 2 (negative electrode active material).

[0016] The wound electrode body 10 is composed of a group of electrode plates in which the positive electrode sheet 1 and the negative electrode sheet 2 are wound via the separator 3. The positive electrode sheet 1, the separator 3, and the negative electrode sheet 2 are wound around the winding axis α. In this specification, the direction in which the winding axis α extends is defined as the Z direction. Also, the Z direction is an example of the "axial direction" of the present disclosure.

[0017] Referring to FIG. 1 again, the case 20 houses the wound electrode body 10 (see FIG. 2). The case 20 is formed to extend in the Z direction. The case 20 has a cylindrical shape (hollow shape) extending in the Z direction. Note that the case 20 has a circular cylindrical shape.

[0018] The case 20 includes a diameter-expanded portion 21, a diameter-expanded portion 22, a diameter-reduced portion 23, an upper lid 24, and a lower lid 25 (see FIG. 3). Note that the diameter-expanded portion 21 and the diameter-expanded portion 22 are examples of the "first portion" and the "second portion" of the present disclosure, respectively.

[0019] The diameter-expanded portion 21 is provided at the end on the Z1 side of the case 20. The diameter-expanded portion 22 is provided at the end on the Z2 side of the case 20. The diameter-reduced portion 23 is provided between the diameter-expanded portion 21 and the diameter-expanded portion 22. The diameter-reduced portion 23 connects the diameter-expanded portion 21 and the diameter-expanded portion 22. Each of the diameter-expanded portion 21, the diameter-expanded portion 22, and the diameter-reduced portion 23 is formed in a cylindrical shape (circular cylindrical shape).

[0020] The reduced-diameter portion 23 is formed with uneven portions 23a. The uneven portions 23a are formed by alternately arranging convex portions 23b and concave portions 23c in the Z direction. The convex portion 23b is an annular portion provided so as to protrude to the outer peripheral side from the concave portion 23c. The concave portion 23c is an annular portion provided so as to be recessed to the inner peripheral side from the convex portion 23b. That is, the concave portion 23c is constituted by a groove portion provided between the convex portions 23b arranged in the Z direction.

[0021] The upper lid 24 is connected to the end portion on the Z1 side of the enlarged-diameter portion 21. The upper lid 24 is arranged so as to cover the wound electrode body 10 (the internal space of the case 20) from the Z1 side. The lower lid 25 is connected to the end portion on the Z2 side of the enlarged-diameter portion 22. The lower lid 25 is arranged so as to cover the wound electrode body 10 (the internal space of the case 20) from the Z2 side.

[0022] FIG. 3 shows a cross-sectional view along the axial direction of the power storage cell 100 of FIG. 1. The insulating tape 30 is disposed on the outer peripheral surface 11 of the end portion on the Z1 side of the wound electrode body 10. The insulating tape 30 is provided so as to cover (surround) the outer peripheral surface 11 from the outer peripheral side. That is, the insulating tape 30 is wound around the winding axis α.

[0023] The insulating tape 40 is disposed on the outer peripheral surface 12 of the end portion on the Z2 side of the wound electrode body 10. The insulating tape 40 is provided so as to cover (surround) the outer peripheral surface 12 from the outer peripheral side. That is, the insulating tape 40 is wound around the winding axis α.

[0024] Note that each of the insulating tape 30 and the insulating tape 40 is formed of an insulating resin or the like.

[0025] The enlarged-diameter portion 21 is provided at a position in the Z direction corresponding to the insulating tape 30. The insulating tape 30 is provided so as to be sandwiched between the enlarged-diameter portion 21 and the outer peripheral surface 11 of the wound electrode body 10.

[0026] The diameter-expanded portion 22 is provided at a position in the Z direction corresponding to the insulating tape 40. The insulating tape 40 is provided so as to be sandwiched between the diameter-expanded portion 22 and the outer peripheral surface 12 of the wound electrode body 10.

[0027] The diameter-reduced portion 23 is provided at a position in the Z direction corresponding to the outer peripheral surface 13 of the portion of the wound electrode body 10 between the insulating tape 30 (outer peripheral surface 11) and the insulating tape 40 (outer peripheral surface 12). Note that the diameter-reduced portion 23 may be in contact with the outer peripheral surface 13.

[0028] Here, as described above, in a conventional power storage cell in which insulating tapes are arranged only at the Z-direction ends of the wound electrode body, a gap (space) corresponding to the thickness of the insulating tape is formed between the portion of the wound electrode body where no insulating tape is arranged and the case. It is desired to stably fix (hold) the power storage cell with the insulating tape arranged at the above position by the case.

[0029] Therefore, in the present embodiment, the diameter-reduced portion 23 is reduced in diameter in the radial direction (R direction in FIG. 3) of the wound electrode body 10 compared to each of the diameter-expanded portions 21 and 22. In other words, each of the diameter-expanded portions 21 and 22 is expanded in diameter in the radial direction compared to the diameter-reduced portion 23.

[0030] Specifically, the diameter-expanded portion 21 has a diameter (outer diameter) R1. The diameter-expanded portion 22 has a diameter (outer diameter) R2. The diameter-reduced portion 23 has a diameter R3 that is smaller than each of the diameter R1 and the diameter R2. Note that the diameter R3 of the diameter-reduced portion 23 means the distance between the outer peripheral ends 23d (apexes) of the convex portions 23b arranged on opposite sides with the central axis α as the center. Also, the diameter R1 may be equal to the diameter R2.

[0031] Half of the difference between the diameter R1 (R2) and the diameter R3 is smaller than, for example, the thickness t1 in the radial direction (R direction) of the insulating tape 30 and the thickness t2 in the radial direction of the insulating tape 40. Note that the thickness t1 may be equal to the thickness t2.

[0032] Note that the diameter R3 is constant regardless of the position of the convex portion 23b in the Z direction. Also, each of the diameter R1 and the diameter R2 is constant regardless of the position in the Z direction.

[0033] The reduced-diameter portion 23 is integrally formed with each of the enlarged-diameter portions 21 and 22. That is, the case 20 is formed of a single cylindrical member.

[0034] The outer peripheral ends 23d of the convex portions 23b arranged side by side in the Z direction are separated from each other by a distance D. The distance D is smaller than each of, for example, the width W1 in the Z direction of the insulating tape 30 and the width W2 in the Z direction of the insulating tape 40. Note that the distance D may be equal to or greater than each of the width W1 and the width W2.

[0035] <Method for manufacturing a power storage cell> FIG. 4 is a diagram showing an example of a method for manufacturing the power storage cell 100 (case 20). Among the cases 20 in which the wound electrode body 10 is housed, a portion 123 (the later reduced-diameter portion 23) corresponding to the outer peripheral surface 13 of the wound electrode body 10 is pressed from the outer peripheral side. As a result, the reduced-diameter portion 23 is formed by the portion 123 being recessed toward the inner peripheral side. Note that in FIG. 4, for simplicity, the illustration of the uneven portion 23a is omitted.

[0036] As described above, in the present embodiment, the case 20 includes the cylindrical enlarged-diameter portion 21 provided at the position in the Z direction corresponding to the insulating tape 30, the cylindrical enlarged-diameter portion 22 provided at the position in the Z direction corresponding to the insulating tape 40, and the cylindrical reduced-diameter portion 23 provided between the enlarged-diameter portion 21 and the enlarged-diameter portion 22. The reduced-diameter portion 23 is formed with the uneven portion 23a. Thereby, among the wound electrode bodies 10, a portion having a relatively small diameter between the insulating tapes (30, 40) can be held by the reduced-diameter portion 23. As a result, it is possible to suppress the formation of a gap (space) between the wound electrode body 10 and the reduced-diameter portion 23. Thereby, the wound electrode body 10 can be stably fixed (held) by the case 20.

[0037] In addition, compared with the case where the reduced-diameter portion 23 is not formed (when the diameter of the case is equal regardless of the position in the Z direction), the mechanical strength (rigidity) of the case 20 can be improved. As a result, even if the thickness of the metal plate constituting the case 20 is reduced, a certain level of mechanical strength (rigidity) can be ensured.

[0038] In addition, since the uneven portion 23a is formed in the reduced-diameter portion 23, the surface area of the reduced-diameter portion 23 is increased, so that the heat exchange efficiency in the reduced-diameter portion 23 can be improved.

[0039] In addition, since no insulating tape is disposed in the portion of the wound electrode body 10 corresponding to the reduced-diameter portion 23, the load (stress) applied to the above portion can be reduced (interference by the insulating tape can be suppressed) compared with the case where the insulating tape is disposed in the above portion.

[0040] In the above embodiment, an example in which the diameter R3 of the reduced-diameter portion 23 is constant regardless of the position of the convex portion 23b in the Z direction is shown, but the present disclosure is not limited thereto. The diameter R3 may vary depending on the position of the convex portion 23b in the Z direction. For example, as shown in FIG. 5, due to the fact that the reduced-diameter portion 223 of the case 220 is curved (formed convex toward the wound electrode body 10), the diameter of the reduced-diameter portion 223 may vary depending on the position in the Z direction. In FIG. 5, for simplicity, the illustration of the uneven portion in the reduced-diameter portion 223 is omitted.

[0041] In the above embodiment, an example in which substantially the entire portion between the enlarged-diameter portion 21 and the enlarged-diameter portion 22 is reduced in diameter is shown, but the present disclosure is not limited thereto. As shown in FIG. 6, the reduced-diameter portion 323 of the case 320 may be formed, for example, at a position adjacent to the enlarged-diameter portion 21 in the Z direction. The position of the reduced-diameter portion 323 in the Z direction is not limited to the above example. In FIG. 6, for simplicity, the illustration of the uneven portion in the reduced-diameter portion 323 is omitted.

[0042] In the above embodiment, an example in which the diameter-reduced portion 23 is formed by pressing the case 20 from the outside has been shown, but the present disclosure is not limited thereto. The portion of the case 20 corresponding to the diameter-reduced portion 23 and the portions of the case 20 corresponding to the diameter-expanded portions 21 and 22 may be joined by welding (for example, laser welding). Further, the power storage cell 100 may be formed by fitting the wound electrode body 10 into the thermally expanded case 20 (performing shrink fitting).

[0043] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is shown not by the description of the above embodiments but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0044] 1 Positive electrode sheet (electrode sheet), 2 Negative electrode sheet (electrode sheet), 10 Wound electrode body, 11 Outer peripheral surface (outer peripheral surface of one end), 12 Outer peripheral surface (outer peripheral surface of the other end), 20, 220, 320 Case, 21 Diameter-expanded portion (first portion), 22 Diameter-expanded portion (second portion), 23, 223, 323 Diameter-reduced portion, 23a Concave-convex portion, 30 Insulating tape (first insulating tape), 40 Insulating tape (second insulating tape), 100 Power storage cell, Z direction (axial direction), α Winding axis.

Claims

【Claim 1】 A wound electrode body formed by winding an electrode sheet and a separator around a winding axis; A cylindrical case that houses the wound electrode body and is formed to extend in the axial direction of the wound electrode body; A first insulating tape disposed on the outer peripheral surface of one end of the wound electrode body in the axial direction; A second insulating tape disposed on the outer peripheral surface of the other end of the wound electrode body in the axial direction, and comprising: The case includes: A cylindrical first portion provided at a position in the axial direction corresponding to the first insulating tape; A cylindrical second portion provided at a position in the axial direction corresponding to the second insulating tape; A cylindrical reduced-diameter portion provided between the first portion and the second portion and having a diameter reduced in the radial direction of the wound electrode body compared to each of the first portion and the second portion; A power storage cell in which uneven portions are formed in the reduced-diameter portion.

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