Electric storage cell

Abstract

To provide a power storage cell capable of suppressing a load from being locally applied to a wound electrode body.SOLUTION: The electric storage cell 100 includes a wound electrode body 1 and a case 2 that houses the wound electrode body 1. The wound-electrode body 1 includes an outer peripheral surface 1c on which a swelling part 1a is formed. The case 2 includes an inner peripheral surface 1a facing the outer peripheral surface 2c. On the 2c of the inner peripheral surface, a groove portion 1a (concave portion) is provided at a position facing the swelling portion 2e.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to an energy storage cell. [Background technology]

[0002] International Publication No. 2020 / 137547 (Patent Document 1) discloses an electricity storage device including a wound electrode body provided with a tab lead. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 137547 Summary of the Invention [Problem to be solved by the invention]

[0004] The wound electrode body of Patent Document 1 is provided with a tab lead. The provision of the tab lead may cause a bulge to 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 a case or the like, a load is locally applied to the wound electrode body (bulge).

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide an energy storage cell that can suppress localized loads on a wound electrode body. [Means for solving the problem]

[0006] An energy storage cell according to one aspect of the present disclosure includes a wound electrode assembly including an electrode sheet and a separator, and a case that houses the wound electrode assembly. The wound electrode assembly is formed by winding the electrode sheet and the separator around a winding axis. The wound electrode assembly includes an outer peripheral surface on which a bulge portion is formed. The case includes an inner peripheral surface that faces the outer peripheral surface. The inner peripheral surface has a recess provided at a position facing the bulge portion.

[0007] In the energy storage cell according to one aspect of the present disclosure, as described above, a recess is provided on the inner circumferential surface of the case at a position facing the bulge. This allows the distance between the inner circumferential surface of the case and the bulge to be greater than when no recess is provided. As a result, the pressure that the wound electrode body receives from the inner circumferential surface of the case at the location where the bulge is provided can be reduced compared to when no recess is provided. This makes it possible to suppress localized pressure on the wound electrode body.

[0008] In the energy storage cell according to the above aspect, the bulge is preferably formed to extend in the axial direction of the wound electrode body, and the recess includes a groove provided to extend along the bulge. With this configuration, it is possible to easily reduce the pressure that the axially extending bulge receives from the inner peripheral surface of the case compared to a case in which no groove is formed.

[0009] In the energy storage cell according to the above aspect, the outer peripheral surface preferably includes a terminal end of the wound electrode body. The wound electrode body includes a tape attached to the terminal end so as to maintain the wound state of the wound electrode body. The bulge is formed by the tape. The recess is provided at a position facing the tape. With this configuration, it is possible to reduce the pressure that the tape attached to the terminal end receives from the inner peripheral surface of the case compared to a case in which a recess is not formed. As a result, it is possible to suppress localized pressure on the wound electrode body while maintaining the wound state of the wound electrode body with the tape.

[0010] In the energy storage cell according to the above aspect, the bulge is preferably formed by an adhesive applied between the outer peripheral surface and the recess. With this configuration, the adhesive can reduce pressure from the inner peripheral surface of the case compared to when no recess is formed. As a result, the vibration resistance of the wound electrode body can be improved by fixing the case and the wound electrode body with the adhesive while suppressing localized pressure on the wound electrode body.

[0011] In this case, preferably, the outer peripheral surface includes a terminal end of the wound electrode body, and the adhesive is applied between the outer peripheral surface and a recess provided at a position facing the terminal end. With this configuration, the wound state of the wound electrode body can be maintained by adhering the terminal end with the adhesive while improving the vibration resistance, etc. of the wound electrode body. Furthermore, because the wound state of the wound electrode body can be maintained by the adhesive, tape or the like for maintaining the wound state of the wound electrode body can be omitted.

[0012] In the energy storage cell according to the above aspect, the electrode sheet preferably includes a sheet-shaped current collector and a tab lead protruding in the axial direction from the current collector. The bulge is formed by the tab lead. The recess is located radially outward of the wound electrode body relative to the tab lead. With this configuration, it is possible to reduce the pressure that the bulge formed by the thickness of the tab lead receives from the inner peripheral surface of the case compared to a case in which no recess is formed. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to suppress a load from being applied locally to a wound electrode body in which a bulge portion is formed. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing the configuration of a storage cell according to a first embodiment. [Figure 2] FIG. 1 is a schematic perspective view showing the configuration of a wound electrode body according to a first embodiment. [Figure 3] FIG. 2 is a partial enlarged view of the positive electrode side of FIG. [Figure 4] FIG. 2 is a partially enlarged view of the negative electrode side of FIG. [Figure 5] FIG. 2 is a diagram showing a state in which the wound electrode body and the case according to the first embodiment are separated. [Figure 6] FIG. 4 is a partially enlarged plan view of the vicinity of the groove according to the first embodiment, as viewed from the Z1 side. [Figure 7]FIG. 11 is a partially enlarged plan view of the vicinity of a groove according to a second embodiment, as viewed from the Z1 side. [Figure 8] FIG. 10 is a perspective view showing the configuration of a wound electrode body according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing the configuration of a storage cell according to a third embodiment. [Figure 10] FIG. 11 is a schematic perspective view showing the configuration of a wound electrode body according to a third embodiment. [Figure 11] FIG. 10 is a plan view showing the configuration of a positive electrode plate according to a third embodiment. [Figure 12] FIG. 10 is a plan view showing the configuration of a negative electrode plate according to a third embodiment. [Figure 13] FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. [Figure 14] FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG. [Figure 15] FIG. 11 is a partially enlarged plan view of the vicinity of a groove according to a third embodiment, as viewed from the Z1 side. [Figure 16] FIG. 11 is a partially enlarged plan view of the vicinity of a groove according to a third embodiment, as viewed from the Z2 side. [Figure 17] FIG. 10 is a diagram showing a state in which the wound electrode body and the case are separated according to a modified example of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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 designated by the same reference numerals, and description thereof will not be repeated.

[0016] [First embodiment] 1 is a cross-sectional view showing the overall configuration of an energy storage cell 100 according to an embodiment of the present disclosure. The energy storage cell 100 is, for example, a lithium-ion battery mounted on a vehicle. Note that the uses and types of the energy storage cell 100 are not limited to the above examples.

[0017] The energy storage cell 100 includes a wound electrode body 1, a case 2, a positive electrode terminal 3, a positive electrode current collector plate 4, an external gasket 5, an internal gasket 6, and a negative electrode current collector plate .

[0018] The wound electrode body 1 is housed in a case 2. The case 2 has a cylindrical shape. That is, the energy storage cell 100 is a cylindrical battery. The case 2 is made of copper, aluminum, or the like.

[0019] The wound electrode body 1 includes a positive electrode plate 10, a negative electrode plate 20, and a separator 30. The separator 30 is provided between the positive electrode plate 10 and the negative electrode plate 20. The separator 30 separates the positive electrode plate 10 and the negative electrode plate 20 while allowing ions (e.g., lithium ions) to move between the positive electrode plate 10 (positive electrode active material) and the negative electrode plate 20 (negative electrode active material). The wound electrode body 1 is composed of an electrode plate group in which the positive electrode plate 10 and the negative electrode plate 20 are wound with the separator 30 interposed therebetween. Each of the positive electrode plate 10 and the negative electrode plate 20 is an example of an "electrode sheet" of the present disclosure.

[0020] As shown in Fig. 2, the wound electrode body 1 is formed by winding a positive electrode plate 10, a negative electrode plate 20, and a separator 30 around a winding axis α. In Fig. 2, the wound electrode body 1 is shown in a slightly unwound state so that the wound state of the wound electrode body 1 can be easily understood.

[0021] 1, the positive electrode terminal 3 includes a disk portion 3a and a rivet portion 3b. The rivet portion 3b is connected to the disk portion 3a. The rivet portion 3b is provided so as to extend from the center of the disk portion 3a toward the Z2 side. The positive electrode terminal 3 is made of aluminum.

[0022] 3, the disk portion 3a is disposed on the upper surface 2a (surface on the Z1 side) of the case 2. A through hole 2b is provided in the upper surface 2a of the case 2. The rivet portion 3b extends from the disk portion 3a, which is disposed outside the case 2, through the through hole 2b to the inside of the case 2.

[0023] The positive current collector 4 is housed in the case 2. The positive current collector 4 is welded to a positive electrode uncoated portion 11b (described later) of the positive plate 10 on the Z1 side of the wound electrode body 1. As a result, the positive current collector 4 is positively charged. The positive current collector 4 is welded to an end 3c on the Z2 side of the rivet portion 3b. As a result, the positive terminal 3 is positively charged.

[0024] The external gasket 5 is disposed between the disk portion 3a of the positive electrode terminal 3 and the upper surface 2a of the case 2. This insulates the positive electrode terminal 3 from the case 2.

[0025] The internal gasket 6 is disposed inside the case 2, between the case 2 and the positive current collector plate 4. This insulates the case 2 from the positive current collector plate 4. The rivet portion 3b penetrates the internal gasket 6 and comes into contact with the positive current collector plate 4.

[0026] The positive electrode plate 10 includes a positive electrode current collector 11 and a positive electrode composite layer 12. The positive electrode composite layer 12 is applied to both surfaces in the radial direction (R direction) of the positive electrode current collector 11 (a positive electrode coated portion 11a described later). The positive electrode composite layer 12 faces the separator 30 in the R direction.

[0027] Positive electrode current collector 11 is made of, for example, aluminum. Positive electrode mixture layer 12 is formed by applying a positive electrode slurry to the surface of positive electrode current collector 11 and drying it. The positive electrode slurry is prepared by kneading materials for positive electrode mixture layer 12 (such as a positive electrode active material and a binder) with a solvent. Positive electrode mixture layer 12 is in close contact with separator 30. The thickness of positive electrode mixture layer 12 is, for example, 0.1 μm or more and 1000 μm or less.

[0028] Positive electrode current collector 11 includes positive electrode coated portion 11a and positive electrode uncoated portion 11b. Positive electrode coated portion 11a is a portion of positive electrode current collector 11 that is coated with positive electrode composite layer 12. Positive electrode coated portion 11a is sandwiched between separators 30.

[0029] The positive electrode uncoated portion 11b is a portion of the positive electrode current collector 11 that is not coated with the positive electrode composite material layer 12. The positive electrode uncoated portion 11b is located closer to the Z1 side than the positive electrode coated portion 11a. Specifically, the positive electrode uncoated portion 11b protrudes from the positive electrode coated portion 11a toward the Z1 side.

[0030] The positive electrode uncoated portion 11b includes a portion 11c extending along the Z direction and a portion 11d extending along the R direction. The positive electrode uncoated portion 11b is bent radially inward. The positive electrode uncoated portion 11b is bent into an L shape. The portion 11d of the positive electrode uncoated portion 11b is in contact with the positive electrode current collector plate 4. This causes the positive electrode current collector plate 4 to be positively charged. The positive electrode uncoated portion 11b (portion 11d) is joined to the positive electrode current collector plate 4 by welding.

[0031] A plurality of positive electrode uncoated portions 11b are arranged side by side along the winding direction. A slit (not shown) is provided between adjacent positive electrode uncoated portions 11b in the winding direction. Among the plurality of positive electrode uncoated portions 11b, adjacent positive electrode uncoated portions 11b in the R direction are arranged so as to partially overlap each other.

[0032] As shown in FIG. 4, the negative electrode current collector 7 is housed in the case 2. The negative electrode current collector 7 is welded to a negative electrode uncoated portion 21b (described later) of the negative electrode plate 20 on the Z2 side of the wound electrode body 1. As a result, the negative electrode current collector 7 is negatively charged. The negative electrode current collector 7 is in contact with the case 2. As a result, the case 2 is negatively charged.

[0033] The negative electrode plate 20 includes a negative electrode current collector 21 and a negative electrode composite layer 22. The negative electrode composite layer 22 is applied to both surfaces in the radial direction (R direction) of the negative electrode current collector 21 (a negative electrode coated portion 21a described later). The negative electrode composite layer 22 faces the separator 30 in the R direction.

[0034] Negative electrode current collector 21 is made of, for example, copper. Negative electrode mixture layer 22 is formed by applying a negative electrode slurry to the surface of negative electrode current collector 21 and drying the coating. The negative electrode slurry is prepared by kneading materials for negative electrode mixture layer 22 (negative electrode active material, binder, etc.) with a solvent. Negative electrode mixture layer 22 is in close contact with separator 30. The thickness of negative electrode mixture layer 22 is, for example, 0.1 μm or more and 1000 μm or less.

[0035] The negative electrode current collector 21 includes a negative electrode coated portion 21a and a negative electrode uncoated portion 21b. The negative electrode coated portion 21a is a portion of the negative electrode current collector 21 that is coated with a negative electrode composite material layer 22. The negative electrode coated portion 21a is sandwiched between separators 30.

[0036] Negative electrode uncoated portion 21b is a portion of negative electrode current collector 21 that is not coated with negative electrode composite material layer 22. Negative electrode uncoated portion 21b is located on the Z2 side of negative electrode coated portion 21a. Specifically, negative electrode uncoated portion 21b protrudes from negative electrode coated portion 21a to the Z2 side.

[0037] The negative electrode uncoated portion 21b includes a portion 21c extending along the Z direction and a portion 21d extending along the R direction. The negative electrode uncoated portion 21b is bent radially inward. The negative electrode uncoated portion 21b is bent into an L shape. The portion 21d of the negative electrode uncoated portion 21b is in contact with the negative electrode current collector plate 7. As a result, the negative electrode current collector plate 7 is negatively charged. The negative electrode uncoated portion 21b (portion 21d) is joined to the negative electrode current collector plate 7 by welding.

[0038] Furthermore, a plurality of negative electrode uncoated portions 21b are arranged side by side along the winding direction. A slit (not shown) is provided between adjacent negative electrode uncoated portions 21b in the winding direction. Furthermore, among the plurality of negative electrode uncoated portions 21b, adjacent negative electrode uncoated portions 21b in the R direction are provided so as to partially overlap each other.

[0039] Fig. 5 is a schematic perspective view showing a state in which the wound electrode body 1 and the case 2 are separated. As shown in Fig. 5, the wound electrode body 1 includes an outer peripheral surface 1a and an end portion 1b. The end portion 1b is the end portion of the winding of the wound electrode body 1. The end portion 1b is provided so as to extend along the axial direction (Z direction).

[0040] The wound electrode body 1 also includes a tape 8 attached to the outer peripheral surface 1a. The tape 8 is provided at the terminal end 1b to maintain the wound state of the wound electrode body 1. The tape 8 is provided so as to extend in the axial direction (Z direction). That is, the tape 8 is provided so as to follow the terminal end 1b extending along the Z direction. The tape 8 is provided so as to cover the terminal end 1b from the radially outer side (R2 side).

[0041] The tape 8 has a thickness t1 (see FIG. 6) in the radial direction (R direction). As a result, a bulge 1c is formed on the outer peripheral surface 1a of the wound electrode body 1 due to the tape 8 being attached to the outer peripheral surface 1a. In other words, the bulge 1c is formed by the tape 8.

[0042] The case 2 also includes an inner circumferential surface 2c. The inner circumferential surface 2c is arranged to face the outer circumferential surface 1a of the wound electrode body 1 in the R direction (the radial direction of the wound electrode body 1). The wound electrode body 1 is inserted into the case 2 through an opening 2d on the Z1 side of the case 2. The opening 1d is closed with a lid (not shown) after the wound electrode body 1 is placed. This forms the upper surface 2a (see FIG. 1).

[0043] In a conventional energy storage cell, the provision of a tab lead may cause a bulge to form 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 constrained by a case or the like, a load is locally applied to the wound electrode body (bulge).

[0044] Therefore, in the first embodiment, a groove 2e is provided on the inner circumferential surface 2c of the case 2 at a position facing the bulge 1c (tape 8). The groove 2e is provided so as to extend along the bulge 1c (tape 8) extending in the Z direction (axial direction). In other words, the groove 2e extends in the Z direction. The tape 8 has a length L1 in the Z direction. The groove 2e has a length L2 in the Z direction. The length L2 of the groove 2e is greater than the length L1 of the tape 8. The groove 2e is an example of a "recess" in the present disclosure.

[0045] 6 is a plan view of the vicinity of the bulge 1c as viewed from the Z1 side with the wound electrode body 1 placed in the case 2. As shown in FIG. 6, the tape 8 has a width W1 in the C direction (circumferential direction). The groove 2e has a width W2 in the C direction. The width W1 of the tape 8 is smaller than the width W2 of the groove 2e. For example, the width W1 is 0.5 to 0.9 times the width W2.

[0046] Specifically, the C1-side end 2f of the groove 2e is positioned closer to the C1 side than the C1-side end 8a of the tape 8. The C2-side end 2g of the groove 2e is positioned closer to the C2 side than the C2-side end 8b of the tape 8.

[0047] The tape 8 has a thickness t1 in the R direction. The groove 2e has a depth d1 in the R direction. The depth d1 of the groove 2e is greater than the thickness t1 of the tape 8. This allows the entire tape 8 to be accommodated in the groove 2e.

[0048] The distance D1 between the outer peripheral surface 1a of the wound electrode body 1 and the inner peripheral surface 2c of the case 2 is smaller than the thickness t1 of the tape 8. As a result, at least a portion of the tape 8 (at least a portion on the case 2 side) is arranged to fit inside the groove 2e. Note that the distance D1 corresponds to a circumferential position where the bulge 1c and the groove 2e are not provided.

[0049] As described above, in the first embodiment, the groove 2e is provided on the inner circumferential surface 2c of the case 2 at a position facing the bulge 1c (tape 8). This allows the bulge 1c to escape into the groove 2e. As a result, it is possible to prevent a load from being locally applied from the case 2 to the wound electrode body 1 (bulge 1c).

[0050] [Second embodiment] Next, a second embodiment of the present disclosure will be described with reference to Figures 7 and 8. In the second embodiment, an adhesive material 18 is used instead of the tape 8 of the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and a repeated description will not be given.

[0051] 7 is a partially enlarged plan view showing the configuration of the energy storage cell 200. The energy storage cell 200 includes a wound electrode body 31 and a case 2. The wound electrode body 31 includes an outer peripheral surface 31a, an end portion 31b, and a bulge portion 31c.

[0052] In the second embodiment, the bulge 31c is formed by an adhesive 18 applied between the outer peripheral surface 31a and the groove 2e. The adhesive 18 is arranged, for example, by filling a liquid adhesive 18 into a gap S formed between the inner peripheral surface 2c corresponding to the groove 2e and the outer peripheral surface 31a when the wound electrode body 31 is inserted (arranged) in the case 2. That is, the adhesive 18 is arranged so as to fill the groove 2e and the space between the groove 2e and the outer peripheral surface 31a. The filled liquid adhesive 18 is later cured. Note that the wound electrode body 31 and the case may be assembled with the adhesive 18 applied in advance to the groove 2e or the outer peripheral surface 31a.

[0053] The wound electrode body 31 differs in configuration from the wound electrode body 1 of the first embodiment only in that an adhesive material 18 is provided instead of the tape 8.

[0054] The groove 2e is provided at a position facing the terminal end 31b in the radial direction (R direction). The terminal end 31b is covered from the radially outer side (R2 side) by an adhesive 18 provided between the groove 2e and the outer circumferential surface 31a. As a result, the terminal end 31b is fixed by the adhesive 18.

[0055] The adhesive material 18 is provided so as to extend in the circumferential direction (C direction) from an end 2f on the C1 side of the groove 2e to an end 2g on the C2 side.

[0056] Fig. 8 is a perspective view showing the configuration of the wound electrode body 31. As shown in Fig. 8, the adhesive 18 is provided on the outer peripheral surface 31a of the wound electrode body 31 so as to extend from an end 31d on the Z1 side of the wound electrode body 31 to an end 31e on the Z2 side of the wound electrode body 31.

[0057] The other configurations are the same as those in the first embodiment, and therefore will not be described repeatedly.

[0058] [Third embodiment] Next, a third embodiment of the present disclosure will be described with reference to Figures 9 to 16. In the third embodiment, unlike the first and second embodiments, a bulge portion is formed by a tab lead.

[0059] 9 is a cross-sectional view showing the overall configuration of a storage cell 300 according to a third embodiment of the present disclosure. The storage cell 300 is, for example, a lithium-ion battery mounted on a vehicle. Note that the use and type of the storage cell 300 are not limited to the above examples.

[0060] The energy storage cell 300 includes a wound electrode body 301 , a case 302 , a CID (Current Interrupt Device) 303 , a positive-side insulating plate 304 , a negative-side insulating plate 305 , and an insulating layer 306 .

[0061] The wound electrode body 301 is housed in a case 302. The case 302 has a cylindrical shape. That is, the power storage cell 300 is a cylindrical battery. The case 302 is made of, for example, copper or aluminum.

[0062] The wound electrode assembly 301 includes a positive electrode plate 310, a negative electrode plate 320, and a separator 330. The separator 330 is provided between the positive electrode plate 310 and the negative electrode plate 320. The separator 330 separates the positive electrode plate 310 and the negative electrode plate 320 while allowing ions (e.g., lithium ions) to move between the positive electrode plate 310 (positive electrode active material) and the negative electrode plate 320 (negative electrode active material). The wound electrode assembly 301 is composed of an electrode plate group in which the positive electrode plate 310 and the negative electrode plate 320 are wound with the separator 330 interposed therebetween. Each of the positive electrode plate 310 and the negative electrode plate 320 is an example of an "electrode sheet" of the present disclosure.

[0063] As shown in Fig. 10, the wound electrode body 301 is formed by winding a positive electrode plate 310, a negative electrode plate 320, and a separator 330 around a winding axis β. In Fig. 10, the wound electrode body 301 is shown in a slightly unwound state so that the wound state of the wound electrode body 301 can be easily seen.

[0064] Positive electrode plate 310 includes a sheet-shaped positive electrode current collector 311 (see FIG. 11), a positive electrode composite layer 312 (see FIG. 11), and a positive electrode tab lead 313. Negative electrode plate 320 includes a sheet-shaped negative electrode current collector 321 (see FIG. 12), a negative electrode composite layer 322 (see FIG. 12), and a negative electrode tab lead 323. Each of positive electrode current collector 311 and negative electrode current collector 321 is an example of a "current collector" in the present disclosure. Each of positive electrode tab lead 313 and negative electrode tab lead 323 is an example of a "tab lead" in the present disclosure.

[0065] 9 again, the positive side insulating plate 304 is housed in the case 302. The positive side insulating plate 304 is provided to insulate the wound electrode body 301 (the negative electrode plate 320 and the separator 330) from the case 302. The positive side insulating plate 304 is provided to cover the positive electrode current collector 311, the negative electrode plate 320, and the separator 330 from the Z1 side.

[0066] The positive insulating plate 304 has a through-hole 304a. The positive electrode tab lead 313 passes through the through-hole 304a and is in contact with (welded to) a conductive film 303b (described later), thereby electrically connecting the positive electrode tab lead 313 and the conductive film 303b.

[0067] The negative side insulating plate 305 is housed in the case 302. The negative side insulating plate 305 is provided to insulate the wound electrode body 301 (positive electrode plate 310 and separator 330) from the case 302. The negative side insulating plate 305 is provided to cover the positive electrode plate 310, the negative electrode current collector 321, and the separator 330 from the Z2 side.

[0068] The negative insulating plate 305 has a through hole 305a. The negative electrode tab lead 323 passes through the through hole 305a and is in contact with the bottom 302a of the case 302. This electrically connects the negative electrode tab lead 323 to the bottom 302a of the case. As a result, the side surface 302b of the case 302 connected to the bottom 302a of the case 302 is negatively charged. The side surface 302b is in contact with the negative electrode current collector 321 of the negative electrode plate 320 provided on the outermost periphery of the wound electrode body 301.

[0069] CID 303 is an element that interrupts the current path by utilizing an increase in the internal cell pressure caused by gas generated due to overcharging of energy storage cell 300. CID 303 is provided to seal the opening on the Z1 side of case 302. CID 303 has an outer cap 303a, a conductive film 303b, a gasket 303c, and a bottom disk 303d.

[0070] The external cap 303a functions as an external terminal by being electrically connected to an external bus bar (not shown). The external cap 303a is provided with a weak portion 303e (thin portion). When the internal pressure of the case 302 increases, the external cap 303a is easily broken starting from the weak portion 303e. This allows gas to be quickly discharged to the outside of the case 302.

[0071] The conductive film 303b is provided so as to seal the opening on the Z1 side of the case 302. The conductive film 303b includes a protruding portion 303f that protrudes toward the wound electrode body 301 side (Z2 side). The protruding portion 303f is in contact with the positive electrode tab lead 313. As a result, the conductive film 303b is positively charged. The conductive film 303b is also electrically connected to the external cap 303a. As a result, the external cap 303a is also positively charged. The protruding portion 303f is provided so as to penetrate each of the gasket 303c and the bottom disk 303d.

[0072] Similar to the external cap 303a, the conductive film 303b has a weak portion 303g (thin portion). The conductive film 303b is easily broken from the weak portion 303g when the internal pressure of the case 302 increases. When the conductive film 303b breaks due to the increase in internal pressure, the contact between the conductive film 303b and the positive electrode tab lead 313 is released. As a result, the positive charge of the conductive film 303b is released, and the positive charge of the external cap 303a is also released. As a result, charging and discharging of the energy storage cell 300 is stopped.

[0073] The case 302 is provided with a crimped portion 302c that is crimped to the outer periphery of the external cap 303a. The insulating layer 306 is provided to insulate the crimped portion 302c from the external cap 303a (and the conductive film 303b).

[0074] FIG. 11 is a view of the positive electrode plate 310 in a sheet-like state, viewed from the Y1 side. The Y direction is a direction perpendicular to the positive electrode current collector 311 that has been spread out into a sheet. The positive electrode current collector 311 has a rectangular shape with long sides extending in the X direction and short sides extending in the Z direction. The X direction corresponds to the winding direction of the wound electrode body 301. The Z direction is an example of the "axial direction" in the present disclosure. The Y direction corresponds to the R direction shown in FIG. 9. The R direction is an example of the "radial direction" in the present disclosure.

[0075] 11, positive electrode composite material layer 312 (hatched portion) is applied to a portion of positive electrode current collector 311. That is, positive electrode current collector 311 includes coated portion 311a coated with positive electrode composite material layer 312 and uncoated portion 311b not coated with the positive electrode composite material layer.

[0076] 11, the uncoated portion 311b is provided at the X1-side end 311c of the positive electrode current collector 311. The uncoated portion 311b is provided so as to extend along the Z direction. In the third embodiment, the X1 side and the X2 side are the winding end side and the winding start side of the wound electrode body 301, respectively.

[0077] Positive electrode current collector 311 is made of, for example, aluminum. Positive electrode mixture layer 312 is formed by applying a positive electrode slurry to the surface of positive electrode current collector 311 and drying the coating. The positive electrode slurry is prepared by kneading the materials of positive electrode mixture layer 312 (such as a positive electrode active material and a binder) with a solvent. Positive electrode mixture layer 312 is in close contact with separator 330 (see FIG. 9). The thickness of positive electrode mixture layer 312 is, for example, 0.1 μm or more and 1000 μm or less.

[0078] The positive electrode tab lead 313 is disposed in the uncoated portion 311b. The positive electrode tab lead 313 is provided so as to protrude in the axial direction (toward the Z1 side) from the positive electrode current collector 311. The positive electrode tab lead 313 is provided in the center of the uncoated portion 311b in the X direction.

[0079] 12 is a view of the negative electrode plate 320 in a sheet-like state, viewed from the Y1 side. As shown in Fig. 12, the negative electrode current collector 321, like the positive electrode current collector 311, has a rectangular shape with long sides extending in the X direction and short sides extending in the Z direction.

[0080] Negative electrode current collector 321 may be made of, for example, copper foil. Negative electrode mixture layer 322 is formed by applying a negative electrode slurry to the surface of negative electrode current collector 321 and drying the coating. The negative electrode slurry is prepared by kneading materials for negative electrode mixture layer 322 (negative electrode active material, binder, etc.) with a solvent. Negative electrode mixture layer 322 is in close contact with separator 330 (see FIG. 9). The thickness of negative electrode mixture layer 322 is, for example, 0.1 μm or more and 1000 μm or less.

[0081] Negative electrode composite material layer 322 is applied to a portion of negative electrode current collector 321. That is, negative electrode current collector 321 includes coated portion 321a that is coated with negative electrode composite material layer 322 and uncoated portion 321b that is not coated with negative electrode composite material layer 322. Uncoated portion 321b is provided to extend along the Z direction.

[0082] The negative electrode tab lead 323 is disposed in the uncoated portion 321b. The negative electrode tab lead 323 is provided so as to protrude in the axial direction (Z2 side) from the negative electrode current collector 321. The negative electrode tab lead 323 is provided in the center of the uncoated portion 321b in the X direction.

[0083] Fig. 13 is a cross-sectional view taken along line XIII-XIII in Fig. 11. As shown in Fig. 13, positive electrode current collector 311 has a thickness t11 in the Y direction. Positive electrode composite layer 312 has a thickness t12 in the Y direction. Positive electrode tab lead 313 has a thickness t13 in the Y direction.

[0084] Thickness t13 of positive electrode tab lead 313 is greater than thickness t12 of positive electrode composite material layer 312. Thickness t12 of positive electrode composite material layer 12 and thickness t13 of positive electrode tab lead 13 are each greater than thickness t11 of positive electrode current collector 311. Thickness difference Δt1 (t13−t12) between thickness t13 of positive electrode tab lead 313 and thickness t12 of positive electrode composite material layer 312 may be greater than thickness t11 of positive electrode current collector 311.

[0085] Fig. 14 is a cross-sectional view taken along line XIV-XIV in Fig. 12. As shown in Fig. 14, negative electrode current collector 321 has a thickness t21 in the Y direction. Negative electrode composite layer 322 has a thickness t22 in the Y direction. Negative electrode tab lead 323 has a thickness t23 in the Y direction.

[0086] Thickness t23 of negative electrode tab lead 323 is greater than thickness t22 of negative electrode composite material layer 322. Note that thickness t22 of negative electrode composite material layer 322 and thickness t23 of negative electrode tab lead 323 are each greater than thickness t21 of negative electrode current collector 321. Furthermore, thickness difference Δt2 (t23−t22) between thickness t23 of negative electrode tab lead 323 and thickness t22 of negative electrode composite material layer 322 may be greater than thickness t21 of negative electrode current collector 321.

[0087] Fig. 15 is a partially enlarged plan view of wound electrode body 301 as viewed from the Z1 side. As shown in Fig. 15, in the third embodiment, bulging portion 301c is formed on outer peripheral surface 301a of wound electrode body 301. Bulging portion 301c is formed by positive electrode tab lead 313. Specifically, bulging portion 301c is formed due to thickness difference Δt1 (see Fig. 13) between thickness t13 of positive electrode tab lead 313 (see Fig. 13) and thickness t12 of positive electrode composite layer 312. In other words, the amount of bulge of bulging portion 301c (the amount of protrusion toward R2) is equal to thickness difference Δt1.

[0088] The positive electrode tab lead 313 has a width W11 in the C direction. The groove 302e has a width W12 in the C direction. The bulge 301c has a width W13 in the C direction. The width W13 of the bulge 301c is larger than the width W11 of the positive electrode tab lead 313. The groove 302e is an example of a "recess" in the present disclosure.

[0089] Groove 302e provided in inner circumferential surface 302d of case 302 is located on the R2 side with respect to positive electrode tab lead 313. Positive electrode tab lead 313 is located in the center of the range in direction C where groove 302e is provided. Note that groove 302e may have the same shape as groove 2e in the first embodiment.

[0090] A width W12 of the groove 302e is greater than a width W13 of the bulge 301c. An end 302f on the C1 side of the groove 302e is located closer to the C1 side than an end 301d on the C1 side of the bulge 301c. An end 302g on the C2 side of the groove 302e is located closer to the C2 side than an end 301e on the C2 side of the bulge 301c. The groove 302f is an example of a "recess" in the present disclosure.

[0091] The groove 302e has a depth d2 in the R direction. The depth d2 of the groove 302e is greater than the thickness difference Δt1 (see FIG. 13). This allows the entire bulge 301c to be accommodated in the groove 302e.

[0092] Distance D2 between outer peripheral surface 301a of wound electrode body 301 and inner peripheral surface 302d of case 302 is smaller than the thickness difference Δt1. As a result, at least a portion of bulge 301c (at least a portion on the case 302 side) is disposed so as to fit inside groove 302e. Note that distance D2 corresponds to a circumferential position where bulge 301c and groove 302e are not provided.

[0093] Although the third embodiment illustrates an example in which only one positive electrode tab lead 313 is provided, the present disclosure is not limited to this. A plurality of positive electrode tab leads 313 may be provided lined up in the R direction. In this case, the amount of bulge of the bulging portion 301c is equal to the value obtained by multiplying the number of positive electrode tab leads 313 lined up in the R direction by the thickness difference Δt1.

[0094] Fig. 16 is a partially enlarged plan view of wound electrode body 301 as viewed from the Z2 side. As shown in Fig. 16, bulging portion 301f is formed on outer peripheral surface 301a of wound electrode body 301. Bulging portion 301f is formed by negative electrode tab lead 323. Specifically, bulging portion 301f is formed due to thickness difference Δt2 (see Fig. 14) between thickness t23 of negative electrode tab lead 323 (see Fig. 14) and thickness t22 of negative electrode composite layer 322. In other words, the amount of bulge of bulging portion 301f (the amount of protrusion toward R2) is equal to thickness difference Δt2.

[0095] Groove 302h provided in inner circumferential surface 302d of case 302 is located on the R2 side with respect to negative electrode tab lead 323. Negative electrode tab lead 323 is located in the center of the range in direction C where groove 302h is provided.

[0096] The relationship (size relationship, positional relationship, etc.) between the negative electrode tab lead 323, the bulge portion 301f, and the groove portion 302h is the same as the relationship between the positive electrode tab lead 313, the bulge portion 301c, and the groove portion 302e described above, and therefore will not be described again.

[0097] The distance D2 between the outer peripheral surface 301a of the wound electrode body 301 and the inner peripheral surface 302d of the case 302 is smaller than the thickness difference Δt2. As a result, at least a portion of the bulge 301f (at least a portion on the case 302 side) is arranged to fit inside the groove 302h.

[0098] Although the third embodiment illustrates an example in which only one negative electrode tab lead 323 is provided, the present disclosure is not limited to this. A plurality of negative electrode tab leads 323 may be provided lined up in the R direction. In this case, the amount of bulge of the bulging portion 301f is equal to the value obtained by multiplying the number of negative electrode tab leads 323 lined up in the R direction by the thickness difference Δt2.

[0099] In the first to third embodiments described above, examples have been shown in which grooves (2e, 302e, 302h) extending in the Z direction are formed on the inner circumferential surface (2c, 302d) of the case (2, 302), but the present disclosure is not limited to this. A recessed portion other than a groove may be formed. For example, in the example shown in FIG. 17, a recessed portion 402b is formed on the inner circumferential surface 402a of the case 402 so as to correspond to a bulging portion 401c formed on the outer circumferential surface 401a of the wound electrode body 401. The recessed portion 402b is formed so that its width W21 in the Z direction is equal to or smaller than its width W22 in the C direction so as to correspond to the bulging portion 401c. Note that while FIG. 17 shows an example in which the bulging portion 401c is formed by tape 28, the bulging portion may be formed by an adhesive material or a tab lead.

[0100] In the first embodiment, an example was shown in which the tape 8 was provided at the terminal end 1b of the winding of the wound electrode body 1, but the present disclosure is not limited to this. The tape 8 may also be provided at a position other than the terminal end 1b. The same applies to the position of the adhesive 18 in the second embodiment.

[0101] In the first and second embodiments, a wound electrode body having a tabless structure without tab leads is shown as an example, but the present disclosure is not limited to this. In the first and second embodiments, a wound electrode body having tab leads may be used, as in the third embodiment.

[0102] In the third embodiment, an example was shown in which the tab lead was provided in an uncoated portion, but the present disclosure is not limited to this. The tab lead may be provided in a coated portion. In this case, the thickness of the tab lead does not have to be greater than the thickness of the positive electrode (negative electrode) composite material layer. Furthermore, in the third embodiment, an example was shown in which the thickness difference Δt1 (Δt2) was smaller than the depth d2 of the groove portion and greater than the distance D2 of the gap between the case 302 and the wound electrode body 301, but this is not a limitation when the tab lead is provided in a coated portion. Regarding the depth d2 and the distance D2, the thickness t13 (t23) of the tab lead may be smaller than the depth d2 and greater than the distance D2.

[0103] The configurations of the above-described embodiment and the above-described modifications may be combined with each other.

[0104] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0105] 1, 31, 301, 401 wound electrode body, 1a, 31a, 301a, 401a outer peripheral surface, 1b, 31b terminal end portion, 2, 302, 402 case, 2c, 302d, 402a inner peripheral surface, 2e, 302e, 302f groove portion (recess), 8, 28 tape, 10, 310 positive electrode plate (electrode sheet), 18 adhesive material, 20, 320 negative electrode plate (electrode sheet), 30, 330 separator, 100, 200, 300 storage cell, 301c, 301f, 401c bulge portion, 311 positive electrode current collector (current collector), 313 positive electrode tab lead (tab lead), 321 negative electrode current collector (current collector), 323 negative electrode tab lead (tab lead), 402b recess, R Direction (radial direction), Z direction (axial direction), α, β winding axis.

Claims

1. a wound electrode body including an electrode sheet and a separator; a case that houses the wound electrode body, The wound electrode body is wound so that the electrode sheet and the separator surround a winding axis, the wound electrode body includes an outer peripheral surface on which a bulge portion is formed, the case includes an inner circumferential surface facing the outer circumferential surface, a recess is provided on the inner circumferential surface at a position opposite the bulge, The electrode sheet is a sheet-like current collector; a tab lead protruding from the current collector in the axial direction of the wound electrode body, the bulge is formed by the tab lead, The recess is located radially outward of the wound electrode body relative to the tab lead.

2. The bulge portion is formed to extend in the axial direction of the wound electrode body, The energy storage cell according to claim 1 , wherein the recess includes a groove portion provided so as to extend along the bulge portion.

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