Energy 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 an electricity storage cell.

Background Art

[0002] Japanese Patent 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 Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Although not described in the above Patent Document 1, 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 applied by the insulating tape, it is conceivable to dispose the insulating tape only on the outer peripheral surface of the axial end portion of the battery element. It is desired to more stably fix (hold) such a battery element in a battery container (case).

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

Means for Solving the Problem

[0006] A storage cell according to one aspect of the present disclosure comprises 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 circumferential surface of one axial end of the wound electrode body; and a second insulating tape disposed on the outer circumferential 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 and second portions and having a reduced diameter in the radial direction of the wound electrode body compared to each of the first and second portions. The reduced-diameter portion has an uneven surface.

[0007] In a storage cell according to one aspect of this disclosure, as described above, a reduced-diameter portion is provided between the first and second portions, which is radially smaller than the first and second portions, respectively. This prevents the formation of a space between the portion of the wound electrode between the first and second insulating tapes (the portion facing the reduced-diameter portion) and the case. As a result, the wound electrode can be stably fixed (held) by the case.

[0008] Furthermore, the formation of irregularities in the reduced-diameter section allows for the absorption of expansion and contraction of the wound electrode body. Additionally, the formation of irregularities increases the surface area of ​​the reduced-diameter section, thereby increasing the amount of heat dissipated from the reduced-diameter section. [Effects of the Invention]

[0009] According to this disclosure, a wound electrode body, on which insulating tape is placed on the outer circumferential surfaces of both ends in the axial direction, can be stably fixed (held) by a case. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing the configuration of a storage cell according to one embodiment. [Figure 2]This is a perspective view showing a schematic configuration of a wound electrode body according to one embodiment. [Figure 3] This is a cross-sectional view along line III-III in Figure 1. [Figure 4] This figure shows an example of a method for manufacturing an energy storage cell according to one embodiment. [Figure 5] This is a cross-sectional view showing the configuration of a storage cell according to a first modified example of one embodiment. [Figure 6] This is a cross-sectional view showing the configuration of a storage cell according to a second modification of one embodiment. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0012] <Configuration of energy storage cells> Figure 1 is a perspective view showing the overall configuration of a storage cell 100 according to an embodiment of this disclosure. The storage cell 100 is used, for example, in the battery of an electric vehicle. However, the application of the storage cell 100 is not limited to electric vehicles.

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

[0014] Figure 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 the positive electrode sheet 1 and the negative electrode sheet 2 are examples of the "electrode sheets" of this disclosure.

[0015] The positive electrode sheet 1, the separator 3, and the negative electrode sheet 2 are stacked on each other. 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 allowing ions (for example, lithium ions) to travel 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 constituted by an electrode plate group in which the positive electrode sheet 1 and the negative electrode sheet 2 are wound with the separator 3 interposed therebetween. The positive electrode sheet 1, the separator 3, and the negative electrode sheet 2 are wound around a winding axis α. In the present specification, the direction in which the winding axis α extends is defined as the Z direction. The Z direction is also an example of the "axial direction" in the present disclosure.

[0017] Referring again to FIG. 1, the case 20 accommodates 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. Further, the case 20 has a cylindrical shape.

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

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

[0020] An uneven portion 23a is formed in the diameter-reduced portion 23. The uneven portion 23a is 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 more to the outer peripheral side than the concave portion 23c. The concave portion 23c is an annular portion provided so as to be recessed more to the inner peripheral side than the convex portion 23b. That is, the concave portion 23c is constituted by a groove portion provided between the convex portions 23b aligned in the Z direction.

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

[0022] FIG. 3 is a cross-sectional view taken along the axial direction of the electricity storage cell 100 of FIG. 1. The insulating tape 30 is arranged on the outer peripheral surface 11 of the end portion on the Z1 side of the wound electrode assembly 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 arranged on the outer peripheral surface 12 of the end portion on the Z2 side of the wound electrode assembly 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 diameter-enlarged 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 diameter-enlarged portion 21 and the outer peripheral surface 11 of the wound electrode assembly 10.

[0026] The enlarged diameter portion 22 is positioned in the Z direction corresponding to the insulating tape 40. The insulating tape 40 is positioned so as to be sandwiched between the enlarged diameter portion 22 and the outer circumferential surface 12 of the wound electrode body 10.

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

[0028] In conventional energy storage cells, as described above, where insulating tape is placed only at the Z-direction end of the wound electrode body, a gap (space) equivalent to the thickness of the insulating tape is formed between the portion of the wound electrode body without insulating tape and the case. It is desirable to stably fix (hold) the energy storage cell with insulating tape in the above position using the case.

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

[0030] Specifically, the enlarged diameter portion 21 has a diameter (outer diameter) R1. The enlarged diameter portion 22 has a diameter (outer diameter) R2. The reduced diameter portion 23 has a diameter R3 that is smaller than both diameters R1 and R2. Note that 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, which are arranged on opposite sides of the central axis α. Also, diameter R1 may be equal to diameter R2.

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

[0032] Furthermore, the diameter R3 is constant regardless of the position of the protrusion 23b in the Z direction. Also, the diameters R1 and R2 are each constant regardless of their position in the Z direction.

[0033] The reduced-diameter portion 23 is integrally formed with the enlarged-diameter portion 21 and the enlarged-diameter portion 22, respectively. In other words, the case 20 is formed from a single cylindrical member.

[0034] The outer edges 23d of the convex portions 23b, which are arranged in a line in the Z direction, are spaced apart by a distance D. This distance D is smaller than, for example, the width W1 of the insulating tape 30 in the Z direction and the width W2 of the insulating tape 40 in the Z direction. However, the distance D may be greater than or equal to the widths W1 and W2, respectively.

[0035] <Manufacturing method for energy storage cells> Figure 4 shows an example of a manufacturing method for the energy storage cell 100 (case 20). In the case 20 containing the wound electrode body 10, a portion 123 (later the 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 portion 123 is recessed toward the inner peripheral side, forming the reduced diameter portion 23. Note that in Figure 4, for simplification, the illustration of the uneven portion 23a is omitted.

[0036] As described above, in this embodiment, the case 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. The reduced diameter portion 23 has an uneven surface 23a formed thereon. This allows the reduced diameter portion 23 to hold the portion of the wound electrode body 10 that has a relatively small diameter between the insulating tapes (30, 40). 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. This allows the wound electrode body 10 to be stably fixed (held) by the case 20.

[0037] Furthermore, the mechanical strength (rigidity) of the case 20 can be improved compared to the case where the reduced diameter portion 23 is not formed (where the diameter of the case is the same regardless of its position in the Z direction). As a result, even if the thickness of the metal plates constituting the case 20 is reduced, a certain level of mechanical strength (rigidity) can be ensured.

[0038] Furthermore, because the reduced diameter portion 23a is formed on the reduced diameter portion 23, the surface area of ​​the reduced diameter portion 23 is increased, which improves the heat exchange efficiency in the reduced diameter portion 23.

[0039] Furthermore, since insulating tape is not placed on the portion of the wound electrode body 10 corresponding to the reduced diameter portion 23, the load (stress) on the above portion can be reduced (interference due to insulating tape is suppressed) compared to the case where insulating tape is placed on the above portion.

[0040] In the above embodiment, an example was 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 disclosure is not limited thereto. The diameter R3 may differ depending on the position of the convex portion 23b in the Z direction. For example, as shown in Figure 5, the diameter of the reduced-diameter portion 223 may differ depending on the position in the Z direction due to the curvature of the reduced-diameter portion 223 of the case 220 (formed convex toward the wound electrode body 10). Note that in Figure 5, for simplification, the illustration of the unevenness of the reduced-diameter portion 223 is omitted.

[0041] In the above embodiment, an example was shown in which substantially the entire area between the enlarged diameter portion 21 and the enlarged diameter portion 22 is reduced in diameter, but the disclosure is not limited thereto. As shown in Figure 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. Note that the position of the reduced diameter portion 323 in the Z direction is not limited to the above example. Also, in Figure 6, for simplification, the illustration of the unevenness of the reduced diameter portion 323 is omitted.

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

[0043] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0044] 1 Positive electrode sheet (electrode sheet), 2 Negative electrode sheet (electrode sheet), 10 Winding electrode body, 11 Outer surface (outer surface of one end), 12 Outer surface (outer surface of the other end), 20, 220, 320 Case, 21 Enlarged diameter section (first part), 22 Enlarged diameter section (second part), 23, 223, 323 Reduced diameter section, 23a Uneven section, 30 Insulating tape (first insulating tape), 40 Insulating tape (second insulating tape), 100 Energy storage cell, Z direction (axial direction), α Winding axis.

Claims

1. A wound electrode body is formed by winding an electrode sheet and a separator around a winding axis, A cylindrical case is formed to house the wound electrode body and to extend in the axial direction of the wound electrode body, A first insulating tape is disposed on the outer circumferential surface of one end of the wound electrode body in the axial direction, The winding electrode body comprises a second insulating tape disposed on the outer circumferential surface of the other end in the axial direction, The aforementioned case is, A cylindrical first portion provided at the axial position corresponding to the first insulating tape, A cylindrical second portion provided at the axial position corresponding to the second insulating tape, It includes a cylindrical reduced-diameter portion provided between the first portion and the second portion, which is radially reduced in diameter compared to each of the first and second portions, The reduced diameter portion has an uneven surface formed therein. The aforementioned uneven portion includes a plurality of protrusions arranged in the axial direction, A storage cell in which the distance between the outer peripheral ends of adjacent protrusions in the axial direction is smaller than the width of the first insulating tape in the axial direction.

2. The energy storage cell according to claim 1, wherein the diameter of the reduced diameter portion gradually decreases from the end of the reduced diameter portion toward the center in the axial direction.

3. The energy storage cell according to claim 2, wherein the reduced diameter portion is curved so as to be convex toward the wound electrode body.

4. A wound electrode body formed by winding an electrode sheet and a separator around a winding axis, A cylindrical case is formed to house the wound electrode body and to extend in the axial direction of the wound electrode body, A first insulating tape is disposed on the outer circumferential surface of one end of the wound electrode body in the axial direction, The winding electrode body comprises a second insulating tape disposed on the outer circumferential surface of the other end in the axial direction, The aforementioned case is, A cylindrical first portion provided at the axial position corresponding to the first insulating tape, A cylindrical second portion provided at the axial position corresponding to the second insulating tape, It includes a cylindrical reduced-diameter portion provided between the first portion and the second portion, which is radially reduced in diameter compared to each of the first and second portions, The reduced diameter portion has an uneven surface formed therein. The reduced diameter portion is, The curved surface is formed such that the diameter of the reduced diameter portion gradually decreases from the end to the center in the axial direction, and is curved convexly toward the wound electrode body. An energy storage cell in which the central part of the curved surface in the axial direction is in local contact with the central part of the wound electrode body in the axial direction.

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