Electricity storage unit

Abstract

The utility model relates to an electric power storage unit which is provided with a winding electrode body, which is formed by winding an electrode plate and a partition plate by taking a winding axis as a center; a cylindrical case that accommodates the wound electrode body and extends 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; and a second insulating tape disposed on the outer peripheral surface of the other end of the wound electrode body in the axial direction. The housing 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; and a cylindrical reduced-diameter portion provided between the first portion and the second portion, the reduced-diameter portion having a smaller dimension in the radial direction of the wound electrode body than the first portion and the second portion. A concave-convex portion is formed in the reduced diameter portion. As a result, it is possible to more stably fix the wound electrode body, in which the insulating tape is disposed on the outer peripheral surfaces of both ends in the axial direction, to the case.

Description

Technical Field

[0001] The utility model relates to a power storage unit. Background Art

[0002] A secondary battery disclosed in Patent Document 1 has a battery unit and a hollow cylindrical battery container for housing the battery unit.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-200755

[0004] Although not described in the above Patent Document 1, an insulating tape is sometimes disposed on the outer peripheral surface of a battery element (wound electrode body). In this case, in order to reduce the load caused by the insulating tape, it is considered to dispose the insulating tape only on the outer peripheral surface of the axial end portion of the battery unit. It is desired to stably fix (hold) such a battery element by a battery container (case). Summary of the Utility Model

[0005] The technical problem to be solved by the utility model is how to provide a power storage unit that can more stably fix (hold) a wound electrode body having insulating tapes disposed on the outer peripheral surfaces at both axial ends to a case.

[0006] The power storage unit according to the utility model 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 has: 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; and a cylindrical reduced-diameter portion provided between the first portion and the second portion, and having a reduced size in the radial direction of the wound electrode body compared with the first portion and the second portion. An uneven portion is formed in the reduced-diameter portion.

[0007] As described above, in the power storage unit of the utility model, a reduced-diameter portion having a reduced size in the radial direction of the wound electrode body compared with 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 a portion (a portion opposite to the reduced-diameter portion) between the first insulating tape and the second insulating tape in the wound electrode body and the case. As a result, the wound electrode body can be more stably fixed (held) to the case.

[0008] In addition, by forming uneven portions in the reduced-diameter portion, the expansion and contraction of the wound electrode body can be absorbed. In addition, by forming the uneven portions, the surface area of the reduced-diameter portion can be increased, and thus the heat dissipation amount of the reduced-diameter portion can be increased.

[0009] According to the present utility model, the wound electrode body having insulating tapes disposed on the outer peripheral surfaces at both axial ends can be more stably fixed (held) to the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. is a perspective view showing the configuration of a power storage unit according to an embodiment.

[0011] Figure 2 FIG. is a perspective view schematically showing the configuration of a wound electrode body according to an embodiment.

[0012] Figure 3 is a sectional view taken along line III-III of Figure 1 .

[0013] Figure 4 FIG. is a view showing an example of a method for manufacturing a power storage unit according to an embodiment.

[0014] Figure 5 FIG. is a sectional view showing the configuration of a power storage unit according to a first modified example of an embodiment.

[0015] Figure 6 FIG. is a sectional view showing the configuration of a power storage unit according to a second modified example of an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] Hereinafter, embodiments of the present utility model will be described in detail with reference to the drawings. In addition, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

[0017] Figure 1 FIG. is a perspective view showing the overall configuration of a power storage unit 100 according to an embodiment of the present utility model. The power storage unit 100 is used, for example, in a battery of an electric vehicle. In addition, the use of the power storage unit 100 is not limited to electric vehicles.

[0018] As Figure 1 shown, the power storage unit 100 includes a wound electrode body 10 (see Figure 2 ), a housing 20, an insulating tape 30 (see Figure 3 ), and an insulating tape 40 (see Figure 3 ). In addition, the insulating tape 30 and the insulating tape 40 are examples of the "first insulating tape" and the "second insulating tape" of the present utility model, respectively.

[0019] Figure 2This 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. In addition, the positive electrode sheet 1 and the negative electrode sheet 2 are each an example of the "electrode sheet" of the present utility model.

[0020] The positive electrode sheet 1, the separator 3, and the negative electrode sheet 2 are stacked on top of each other. The separator 3 is disposed between the positive electrode sheet 1 and the negative electrode sheet 2. The separator 3 enables ions (such as lithium ions) to travel between the positive electrode sheet 1 (positive electrode active material) and the negative electrode sheet 2 (negative electrode active material), and separates the positive electrode sheet 1 from the negative electrode sheet 2.

[0021] The wound electrode body 10 is composed of a plate group formed by winding the positive electrode sheet 1 and the negative electrode sheet 2 with the separator 3 therebetween. The positive electrode sheet 1, the separator 3, and the negative electrode sheet 2 are wound around the winding axis α. In addition, in this specification, the direction in which the winding axis α extends is defined as the Z direction. In addition, the Z direction is an example of the "axial direction" of the present utility model.

[0022] Refer again to Figure 1 , the housing 20 houses the wound electrode body 10 (refer to Figure 2 ). The housing 20 is formed to extend in the Z direction. The housing 20 has a cylindrical shape (hollow shape) that extends in the Z direction. The housing 20 has a circular cylindrical shape.

[0023] The housing 20 includes a diameter-expanded portion 21, a diameter-expanded portion 22, a diameter-reduced portion 23, an upper cover 24, and a lower cover 25 (refer to Figure 3 ). In addition, the diameter-expanded portion 21 and the diameter-expanded portion 22 are each an example of the "first part" and the "second part" of the present utility model.

[0024] The diameter-expanded portion 21 is provided at the end portion on the Z1 side of the housing 20. The diameter-expanded portion 22 is provided at the end portion on the Z2 side of the housing 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. The diameter-expanded portion 21, the diameter-expanded portion 22, and the diameter-reduced portion 23 are each formed in a cylindrical shape (circular cylindrical shape).

[0025] An uneven portion 23a is formed in the diameter-reduced portion 23. The uneven portion 23a is formed by alternately arranging and disposing convex portions 23b and concave portions 23c in the Z direction. The convex portion 23b is a circular ring-shaped portion that protrudes outward from the concave portion 23c. The concave portion 23c is a circular ring-shaped portion that is recessed inward from the convex portion 23b. That is, the concave portion 23c is composed of a groove portion provided between the convex portions 23b arranged in the Z direction.

[0026] The upper cover 24 is connected to the end portion on the Z1 side of the diameter-expanded portion 21. The upper cover 24 is arranged so as to cover the wound electrode body 10 (the internal space of the housing 20) from the Z1 side. The lower cover 25 is connected to the end portion on the Z2 side of the diameter-expanded portion 22. The lower cover 25 is arranged so as to cover the wound electrode body 10 (the internal space of the housing 20) from the Z2 side.

[0027] Figure 3 Indicates a sectional view along Figure 1 the axial direction of the power storage unit 100. The insulating tape 30 is disposed on the outer peripheral surface 11 of the end portion on the Z1 side in 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.

[0028] The insulating tape 40 is disposed on the outer peripheral surface 12 of the end portion on the Z2 side in 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.

[0029] In addition, the insulating tape 30 and the insulating tape 40 are each formed of an insulating resin or the like.

[0030] The diameter-expanded 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 clamped between the diameter-expanded portion 21 and the outer peripheral surface 11 of the wound electrode body 10.

[0031] 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 clamped between the diameter-expanded portion 22 and the outer peripheral surface 12 of the wound electrode body 10.

[0032] 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 located between the insulating tape 30 (outer peripheral surface 11) and the insulating tape 40 (outer peripheral surface 12). In addition, the diameter-reduced portion 23 may be in contact with the outer peripheral surface 13.

[0033] Here, as described above, in the conventional power storage unit in which the insulating tape is only disposed at the end portion in the Z direction 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 the insulating tape is not disposed and the housing. It is desired to stably fix (hold) the power storage unit in which the insulating tape is disposed at the above position by the housing.

[0034] Therefore, in the present embodiment, compared with the diameter-expanded portion 21 and the diameter-expanded portion 22, the diameter-reduced portion 23 is reduced in size (diameter reduction) in the radial direction ( Figure 3 the R direction) of the wound electrode body 10. In other words, the diameter-expanded portion 21 and the diameter-expanded portion 22 are each enlarged in diameter in the radial direction compared with the diameter-reduced portion 23.

[0035] Specifically, the diameter (outer diameter) of the enlarged diameter portion 21 is R1. The diameter (outer diameter) of the enlarged diameter portion 22 is R2. The diameter of the reduced diameter portion 23 is R3, which is smaller than both the diameter R1 and the diameter R2. Additionally, the diameter R3 of the reduced diameter portion 23 refers to the distance between the outer peripheral ends 23d (vertices) of the convex portions 23b that are arranged on opposite sides of each other with the winding axis α as the center. Additionally, the diameter R1 may be equal to the diameter R2.

[0036] One 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. Additionally, the thickness t1 may be equal to the thickness t2.

[0037] Additionally, the diameter R3 is constant regardless of the position in the Z direction of the convex portion 23b. Additionally, both the diameter R1 and the diameter R2 are constant regardless of the position in the Z direction.

[0038] The reduced diameter portion 23 is formed integrally with the enlarged diameter portion 21 and the enlarged diameter portion 22 respectively. That is, the housing 20 is formed of a single cylindrical member.

[0039] The outer peripheral ends 23d of the convex portions 23b arranged in the Z direction are separated by a distance D. The distance D is smaller than, 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. Additionally, the distance D may be equal to or greater than the width W1 and the width W2 respectively.

[0040] Figure 4 This is a diagram showing an example of the manufacturing method of the power storage unit 100 (housing 20). In the housing 20 that houses the wound electrode body 10, the portion 123 (the subsequent 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 above-mentioned portion 123 is recessed inward to form the reduced diameter portion 23. Additionally, in Figure 4 for simplicity, the illustration of the concavo-convex portion 23a is omitted.

[0041] As described above, in the present embodiment, the housing 20 includes: a cylindrical enlarged diameter portion 21 provided at a position in the Z direction corresponding to the insulating tape 30; a cylindrical enlarged diameter portion 22 provided at a position in the Z direction corresponding to the insulating tape 40; and a cylindrical reduced diameter portion 23 provided between the enlarged diameter portion 21 and the enlarged diameter portion 22. A concavo-convex portion 23a is formed in the reduced diameter portion 23. Thus, the reduced diameter portion 23 can hold the portion with a relatively small diameter between the insulating tape 30 and the insulating tape 40 in the wound electrode body 10. 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. Thus, the wound electrode body 10 can be stably fixed (held) by the housing 20.

[0042] In addition, compared with the case where the reduced-diameter portion 23 is not formed (where the diameter of the housing is equal regardless of the position in the Z direction), the mechanical strength (rigidity) of the housing 20 can be improved. Thereby, even if the thickness of the metal plate constituting the housing 20 is reduced, a certain level of mechanical strength (rigidity) can be ensured.

[0043] In addition, by forming the concavo-convex portion 23a in the reduced-diameter portion 23, the surface area of the reduced-diameter portion 23 becomes larger, and the heat exchange efficiency of the reduced-diameter portion 23 can be improved.

[0044] In addition, since the insulating tape is not 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 caused by the insulating tape can be suppressed) compared with the case where the insulating tape is disposed in the above portion.

[0045] In the above embodiment, an example is shown 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, but the present invention is not limited thereto. The diameter R3 may also vary according to the position of the convex portion 23b in the Z direction. For example, as Figure 5 shown, the diameter of the reduced-diameter portion 223 of the housing 220 may also vary according to the position in the Z direction due to the bending of the reduced-diameter portion 223 of the housing 220 (formed convexly toward the wound electrode body 10). In addition, in Figure 5 for simplicity, the illustration of the concavo-convex portion in the reduced-diameter portion 223 is omitted.

[0046] In the above embodiment, an example is shown in which the overall reduction in diameter is approximately between the enlarged-diameter portion 21 and the enlarged-diameter portion 22, but the present invention is not limited thereto. As Figure 6 shown, the reduced-diameter portion 323 of the housing 320 may also be formed, for example, at a position adjacent to the enlarged-diameter portion 21 in the Z direction. In addition, the position of the reduced-diameter portion 323 in the Z direction is not limited to the above example. In addition, in Figure 6 for simplicity, the illustration of the concavo-convex portion in the reduced-diameter portion 323 is omitted.

[0047] In the above embodiment, an example is shown in which the reduced-diameter portion 23 is formed by pressing the housing 20 from the outside, but the present invention is not limited thereto. The portion of the housing 20 corresponding to the reduced-diameter portion 23 and the portions of the housing 20 corresponding to the enlarged-diameter portion 21 and the enlarged-diameter portion 22 may also be joined by welding (for example, laser welding). In addition, the power storage unit 100 may also be formed by inserting the wound electrode body 10 into the housing 20 that has undergone thermal expansion (thermal fitting).

[0048] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the present invention is shown not by the description of the above embodiments but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A power storage unit, characterized in that: have: A wound electrode body formed by winding an electrode sheet and a separator around a winding axis; a cylindrical case that accommodates the wound electrode body and is formed to extend in the axial direction of the wound electrode body; a first insulating tape disposed on an outer peripheral surface of one end of the wound electrode body in the axial direction; and a second insulating tape disposed on the outer peripheral surface of the other end of the wound electrode body in the axial direction, The housing has: A first cylindrical portion disposed at a position in the axial direction corresponding to the first insulating band; a second cylindrical portion disposed at a position in the axial direction corresponding to the second insulating band; and The cylindrical reduced diameter portion is provided between the first portion and the second portion, and has a smaller dimension in the radial direction of the wound electrode body than the first portion and the second portion. The reduced diameter portion has a concavo-convex portion formed therein.

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