Electricity storage unit

Abstract

The utility model provides an electric power storage unit capable of inhibiting local application of a load to a wound electrode body. An electricity storage unit is provided with: a wound electrode body in which an electrode sheet and a separator, which are stacked on each other, are wound around a winding axis; a buffer member provided so as to surround the wound electrode body from the outer peripheral side of the wound electrode body; and a case that accommodates the wound electrode body and the buffer member.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power storage unit. BACKGROUND

[0002] A power storage device having a wound electrode body provided with a tab lead is disclosed in Patent Literature 1.

[0003] Patent Literature 1: Japanese Patent No. 4225639

[0004] The tab lead is provided in the wound electrode body of Patent Literature 1 described above. Due to the provision of the tab lead, an expanded portion can be formed in the outer peripheral surface of the wound electrode body due to the thickness of the tab lead. In this case, when the wound electrode body is restrained by a case or the like, a load can be locally applied to the wound electrode body (the expanded portion). SUMMARY

[0005] The present utility model is completed in order to solve the above problem, and aims to provide a power storage unit capable of suppressing a load from being locally applied to a wound electrode body.

[0006] The power storage unit of the first aspect includes: a wound electrode body wound with electrode sheets and separators that are stacked with each other around a winding axis; a buffer member provided from an outer peripheral side of the wound electrode body so as to surround the wound electrode body; and a case that accommodates the wound electrode body and the buffer member.

[0007] The power storage unit of the second aspect is the power storage unit of the first aspect, in which the buffer member is composed of a porous member.

[0008] The power storage unit of the third aspect is the power storage unit of the first aspect or the second aspect, in which a concave-convex portion is formed in an outer peripheral surface of the case.

[0009] The power storage unit of the fourth aspect is the power storage unit of the third aspect, in which the winding axis extends in an axial direction; and the concave-convex portion is provided at least from one end to the other end of a range in the axial direction in which the wound electrode body is provided.

[0010] The power storage unit of the fifth aspect is the power storage unit of the third aspect or the fourth aspect, in which the concave-convex portion is provided so as to surround the wound electrode body in a circumferential shape.

[0011] According to the present disclosure, a load can be suppressed from being locally applied to a wound electrode body. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 A perspective view showing the configuration of the power storage unit of the first embodiment.

[0013] Figure 2 A schematic perspective view showing the configuration of the wound electrode body of the first embodiment.

[0014] Figure 3 is a perspective view showing the configuration of the power storage unit of the third embodiment.

[0015] Figure 4 is a plan view of the power storage unit of the third embodiment viewed from the Z1 side.

[0016] Figure 5 is a cross-sectional view along the V-V line. Figure 4

[0017] Figure 6 is a perspective view showing another configuration of the power storage unit of the third embodiment. DETAILED DESCRIPTION

[0018] Embodiments of the present disclosure will be explained in detail below with reference to the drawings. Note that the same symbols are attached to parts that are the same or equivalent in the drawings, and the explanation thereof will be omitted.

[0019] Figure 1 is a perspective view showing the configuration of the power storage unit 100 according to the first embodiment of the present disclosure. The power storage unit 100 is, for example, a lithium ion battery mounted on a vehicle. Note that the use and the kind of the power storage unit 100 are not limited to the above example.

[0020] The power storage unit 100 includes a wound electrode body 10, a buffer member 11, and a case 12. The wound electrode body 10 and the buffer member 11 are housed in the case 12.

[0021] 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 plate 110, a negative electrode plate 111, and a separator 112. The separator 112 is provided between the positive electrode plate 110 and the negative electrode plate 111. That is, the positive electrode plate 110, the separator 112, and the negative electrode plate 111 are stacked with each other. The separator 112 separates the positive electrode plate 110 and the negative electrode plate 111 while allowing ions (e.g., lithium ions) to pass between the positive electrode plate 110 (positive electrode active material) and the negative electrode plate 111 (negative electrode active material). The wound electrode body 10 is configured of a group of electrode plates in which the positive electrode plate 110 and the negative electrode plate 111 are wound with the separator 112 interposed therebetween. The positive electrode plate 110, the separator 112, and the negative electrode plate 111 are wound with a winding axis a as the center. Note that in the present specification, the direction in which the winding axis extends is set as the Z direction. Further, the positive electrode plate 110 and the negative electrode plate 111 are each an example of an "electrode sheet" of the present disclosure. Further, the Z direction is an example of an "axial direction" of the present disclosure.

[0022] The positive electrode plate 110 includes a positive electrode current collector plate and a positive electrode composite layer. The positive electrode current collector plate is formed of, for example, a metal material such as aluminum or an aluminum alloy.

[0023] ​The positive electrode composite layer contains a positive electrode active material or a binder or the like. As the positive electrode active material, for example, LiCoO2, LiNO2, LiMn2O4, or the like is included. The thickness of the positive electrode composite layer is, for example, 0.1 μm or more and 1000 μm or less. The positive electrode composite layer is formed on either of the front and back surfaces of the positive electrode current collector, or can be formed on one surface.

[0024] The negative electrode plate 111 contains a negative electrode current collector and a negative electrode composite layer. The negative electrode current collector contains, for example, a metal material such as copper.

[0025] The negative electrode composite layer contains a negative electrode active material or a binder or the like. As the negative electrode active material, for example, graphite or the like is included. The thickness of the negative electrode composite layer is, for example, 0.1 μm or more and 1000 μm or less. The negative electrode composite layer is formed on either of the front and back surfaces of the negative electrode current collector, or can be formed on one surface.

[0026] The case 12 has a cylindrical shape. That is, the power storage unit 100 is a cylindrical battery. In addition, the case 12 is formed of copper or aluminum or the like.

[0027] Here, in the existing power storage unit, since the tab lead is provided, an expanded portion can be formed on the outer peripheral surface of the wound electrode body due to the thickness of the tab lead. In this case, when the wound electrode body is restrained by the case or the like, a load is locally applied to the wound electrode body (the expanded portion).

[0028] Therefore, in the first embodiment, the buffer member 11 is provided so as to surround the wound electrode body 10 from the outer peripheral side of the wound electrode body 10. Even in the case where the expanded portion is formed on the outer peripheral surface of the wound electrode body 10, by providing the buffer member 11, the buffer member 11 can absorb the expanded portion and suppress the case where the load is locally applied. In addition, the buffer member 11 can reduce the pressure from the case 12. As a result, by fixing the wound electrode body 10 and the case 12 with the buffer member 11 while suppressing the pressure locally applied to the wound electrode body 10, the vibration resistance of the wound electrode body 10 can be improved.

[0029] Referring again to Figure 1 , the case 12 includes a top plate 120, a bottom surface 121, and a side wall 122. The top plate 120 is provided so as to cover the wound electrode body 10 and the buffer member 11 from the Z1 side. The bottom surface 121 is provided so as to support the wound electrode body 10 and the buffer member 11 from the Z2 side. The side wall 122 connects the top plate 120 and the bottom surface 121. The side wall 122 has a circular ring shape with the winding axis a (refer to Figure 2 ) as the center.

[0030] As described above, in the first embodiment, the cushion member 11 is provided between the wound electrode body 10 and the case 12. Thereby, even in the case where the expanded portion is formed in the outer peripheral surface of the wound electrode body 10, the cushion member 11 can absorb the expanded portion. As a result, it is possible to suppress the application of the load to the wound electrode body 10 locally from the case 12.

[0031] Next, the second embodiment of the present disclosure will be described. In the second embodiment, the cushion member 11 is composed of a porous member. For the same configuration as the above first embodiment, the same reference numerals as the above first embodiment are assigned and the description thereof is omitted.

[0032] The case 12 also houses an electrolytic solution which is not illustrated. The cushion member 11 is composed of a porous member, and thus when the electrolytic solution is injected into the wound electrode body 10 from one side in the axial direction, it is possible to introduce the electrolytic solution into the inside of the wound electrode body 10 through the cushion member 11. In addition, the liquid retaining property of the porous member is also excellent, and thus it is possible to prevent the liquid in the power storage unit 100 from drying up.

[0033] In addition, by providing the porous cushion member 11 between the wound electrode body 10 and the case 12, it is possible to contribute to the discharge of gas generated, for example, in the case 12.

[0034] As the porous member, for example, a sponge-like member such as a polyurethane foam can be cited.

[0035] For other configurations, since the same as the above first embodiment, the description thereof is omitted.

[0036] Next, the third embodiment of the present disclosure will be described with reference to Figures 3 to 6 The third embodiment of the present disclosure will be described. In the third embodiment, the concave-convex portion 122a (convex portion 122b, concave portion 122c) is formed on the outer peripheral surface (side wall 122) of the case 12. For the same configuration as the above first embodiment, the same reference numerals as the above first embodiment are assigned and the description thereof is omitted.

[0037] Figure 3 A perspective view showing the configuration of the power storage unit 100 of the third embodiment of the present disclosure. The concave-convex portion 122a is formed on the side wall 122. The concave-convex portion 122a includes the convex portion 122b and the concave portion 122c which are alternately arranged in the Z direction. That is, a plurality of the convex portion 122b and the concave portion 122c are respectively provided. The concave portion 122c is formed between the convex portions 122b which are arranged in the Z direction. In addition, the concave-convex portion 122a is an example of the "concave-convex portion" of the present disclosure. In addition, the convex portion 122b and the concave portion 122c are examples of the "convex portion" and the "concave portion" of the present disclosure, respectively.

[0038] Figure 4This is a top view of the energy storage unit 100 viewed from the Z1 side. The protrusions 122a are arranged to surround the electrode body 10 in a circumferential manner. In other words, a plurality of protrusions 122b are formed in a circumferentially extending manner and have a ring shape.

[0039] Figure 5 For along Figure 4 A cross-sectional view of the VV line. At least from one end S1 to the other end S2 of the range S in the Z direction where the wound electrode body 10 is located, there is a concave-convex portion 122a of the sidewall 122. The range in the Z direction where the concave-convex portion 122a is located can be wider than the range S where the wound electrode body 10 is located. Furthermore, the concave-convex portion 122a is configured to cover the entire wound electrode body 10 (range S) when viewed radially (R direction).

[0040] The convex portions 122b arranged axially are spaced apart from each other by a distance D1. Furthermore, the distance D1 between the convex portions 122b refers to the distance between the vertices of the convex portions 122b.

[0041] As described above, in this embodiment, a protrusion 122a is formed on the side wall 122 of the housing 12. This increases the strength of the energy storage unit 100, enabling a thinner wall design. Furthermore, the protrusion 122a functions as a spring, absorbing the expansion and contraction of the wound electrode body 10.

[0042] The above embodiment shows an example where the protrusions and recesses 122a of the housing 12 are formed over the entire range S of the wound electrode body 10, but the present invention is not limited thereto. For example... Figure 6 As shown, the uneven portion 122a may also be formed only on the Z1 and Z2 sides of the range S. That is, the uneven portion may not be formed near the center of the range S.

[0043] The above embodiment shows an example where the concave and convex portions 122a of the housing 12 circumferentially surround the wound electrode body 10, but the present invention is not limited thereto. The concave and convex portions 122a may be provided such that they partially surround the wound electrode body 10. That is, the convex portions 122b may also have an arc shape.

[0044] The other configurations are the same as those in the first embodiment described above, so their descriptions are omitted.

[0045] Furthermore, the configurations of the above-described embodiments can also be combined with each other.

[0046] The embodiments disclosed herein should be considered illustrative rather than restrictive in all respects. The scope of this disclosure is set forth not by the description of the above embodiments but by the claims, and is intended to include all modifications of the same meaning and scope as the claims.

Claims

1. An electricity storage unit, characterized by comprising: Possessing: a wound electrode body wound with an electrode sheet and a separator being layered with each other around a winding axis; a cushion member provided from an outer peripheral side of the wound electrode body so as to surround the wound electrode body; and a case that accommodates the wound electrode body and the cushion member.

2. The power storage unit according to claim 1, characterized by, The cushion member is composed of a porous member.

3. The power storage unit according to claim 1 or 2, characterized by, A concavo-convex portion is formed on an outer peripheral surface of the case.

4. The power storage unit according to claim 3, characterized by The winding axis extends in an axial direction; The concavo-convex portion is provided at least from one end to the other end of a range in the axial direction where the wound electrode body is provided.

5. The power storage unit according to claim 3, wherein The concavo-convex portion is provided so as to surround the wound electrode body in a circumferential shape.

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