Energy storage devices

Abstract

The electrolyte is efficiently permeated into the electrode body. [Solution] The energy storage device 1 disclosed herein comprises a case 10 having an electrolyte injection section 19, an electrode body 30, a resin film 50 arranged to surround the electrode body 30, and an electrolyte. The case 10 includes a bottom wall 11, an upper wall 12, and a first side wall 17. The electrolyte injection section 19 is provided at a position close to the upper wall 12 of the first side wall 17. The electrode body 30 has a bottom portion 30C including a permeability region 38 into which the electrolyte can penetrate, and the bottom portion 30C is positioned opposite the bottom wall 11. The resin film 50 has a first end portion 52 that extends from one side to cover a portion of the bottom portion 30C of the electrode body 30 in a predetermined direction, and a second end portion 54 that extends from the opposite direction to the first end portion 52 along the predetermined direction to cover a portion of the bottom portion 30C of the electrode body 30. A portion of the second end portion 54 overlaps the first end portion 52 on the bottom wall 11 side of the case 10.

Description

Technical Field

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

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2007-42628 discloses a secondary battery including an electrode body group in a jelly roll form. The secondary battery has a configuration in which a positive electrode terminal is provided at one end of a case and a negative electrode terminal is provided on the opposite side. <000001​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​One aspect of the technology disclosed herein is an energy storage device comprising a case having a liquid injection section, an electrode body housed in the case, a resin film disposed between the case and the electrode body so as to surround the electrode body, and an electrolyte housed in the case. The case includes a bottom wall, an upper wall facing the bottom wall, and a first side wall extending from the edge of the bottom wall to the edge of the upper wall. The liquid injection section is provided on the first side wall at a position closer to the upper wall than to the bottom wall. The electrode body is positioned so that its bottom faces the bottom wall. The resin film has a first end extending from one side in a predetermined direction to cover a portion of the bottom of the electrode body, and a second end extending from the opposite direction to the first end along the predetermined direction to cover a portion of the bottom of the electrode body. A portion of the second end overlaps the first end with the bottom wall side of the case.

[0007] In the above-described energy storage device, the electrolyte can be efficiently permeated into the electrode body. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view of an energy storage device according to one embodiment. [Figure 2] Figure 2 is a perspective view of an energy storage device according to one embodiment, viewed from a different viewpoint than in Figure 1. [Figure 3] Figure 3 is a schematic cross-sectional view showing the internal structure of the energy storage device shown in Figure 1. [Figure 4] Figure 4 is a schematic cross-sectional view showing the structure of an electrode body according to one embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view showing the internal structure of the energy storage device in Figure 1 from a different perspective than that shown in Figure 3. [Figure 6] Figure 6 is a schematic cross-sectional view showing the configuration of the region between the electrode body and the bottom wall. [Modes for carrying out the invention]

[0009] Hereinafter, several embodiments of the technology disclosed herein will be described in detail with reference to the drawings. Matters other than those specifically mentioned herein but necessary for implementation (e.g., general configuration and manufacturing processes of energy storage devices not characterizing this disclosure) can be understood as design matters for those skilled in the art based on the prior art. This disclosure can be implemented based on the contents disclosed herein and common technical knowledge in the art. In the following drawings, the same reference numerals are used to denote components and parts that perform the same function. Also, the dimensional relationships (length, width, thickness, etc.) in each drawing do not necessarily reflect the actual dimensional relationships.

[0010] In this specification, "energy storage device" is a concept that encompasses devices in which a charge-discharge reaction occurs through the movement of a charge carrier between a pair of electrodes (positive electrode and negative electrode). In other words, energy storage devices include batteries such as secondary batteries (e.g., lithium-ion secondary batteries, nickel-metal hydride batteries, nickel-cadmium batteries) and capacitors (physical batteries) such as lithium-ion capacitors and electric double-layer capacitors.

[0011] In this specification, "rectangular tube" refers to a tube shape in which the opening is polygonal (for example, a quadrilateral) in a cross-section perpendicular to the axial direction. The corners where the sides of the polygon meet may be rounded (R-shaped).

[0012] In this specification, "approximately rectangular" is a term that includes not only a perfect rectangle, but also shapes such as those in which the corners connecting the long and short sides of a rectangle are rounded, or shapes with notches at the corners.

[0013] <Energy storage devices> Hereinafter, an energy storage device 1 will be described as one embodiment. Figure 1 is a schematic perspective view showing the energy storage device according to one embodiment. Figure 2 is a perspective view of the energy storage device according to one embodiment from a different viewpoint than that in Figure 1. Figure 3 is a schematic cross-sectional view showing the internal structure of the energy storage device in Figure 1. In this specification, the reference numerals X, Y, and Z in the drawings are referred to as the first direction, second direction, and third direction, respectively. Also, X1, X2, Y1, Y2, Z1, and Z2 in the drawings are reference numerals used to indicate the correspondence of orientations in each drawing. However, these directions are defined for the convenience of explanation and do not limit the installation method of the energy storage device in any way.

[0014] As shown in Figures 1 to 3, the energy storage device 1 comprises a case 10, a positive electrode terminal 22, a negative electrode terminal 24, an electrode body 30, a first spacer 42, a second spacer 44, a resin film 50, and an electrolyte (not shown). The case 10 has an injection section 19 for injecting the electrolyte into the interior. The energy storage device 1 is a lithium-ion secondary battery in this case. The respective components will be described below.

[0015] (1) Case As shown in Figures 1 and 2, the case 10 includes a bottom wall 11, a top wall 12, and a first side wall 17. In this embodiment, the case 10 comprises a case body 10A, a first lid 10B, and a second lid 10C. The case body 10A includes a bottom wall 11, a top wall 12, a first wide side wall 13, and a second wide side wall 14. The first lid 10B is positioned as the first side wall 17. When impregnating the electrode body 30 with electrolyte, the case 10 is installed such that the bottom wall 11 is positioned vertically lower than the top wall 12.

[0016] The case body 10A is a rectangular tubular member having a first opening 15 at one end (X1 side in Figure 1) and a second opening 16 at the other end (X2 side in Figure 1). The bottom wall 11 and the top wall 12 face each other in the third direction Z. The bottom wall 11 and the top wall 12 are each formed in a plate shape. The bottom wall 11 and the top wall 12 are each substantially rectangular in plan view. The bottom wall 11 and the top wall 12 each have a long side extending along the first direction X.

[0017] The first wide side wall 13 and the second wide side wall 14 face each other in the second direction Y. The first wide side wall 13 and the second wide side wall 14 have areas larger than those of the bottom wall 11 and the upper wall 12. The first wide side wall 13 extends from the edge (long side) 11a of the bottom wall 11 to the edge (long side) 12a of the upper wall 12. The second wide side wall 14 extends from the edge (long side) 11b of the bottom wall 11 to the edge (long side) 12b of the upper wall 12. The first wide side wall 13 and the second wide side wall 14 are each formed in a plate shape. The first wide side wall 13 and the second wide side wall 14 are each substantially rectangular. The first wide side wall 13 and the second wide side wall 14 each have a long side extending along the first direction X.

[0018] [[ID=?]] The case body ʺAʺ can be manufactured, for example, by bending a single metal plate into a cylindrical shape and joining the seams (for example, by welding). Therefore, in the case body ʺAʺ shown in FIG. <<1>>, a welding joint 18 extending along the first direction X is formed on the upper wall 12. The material of the case body ʺAʺ can be a metal material such as aluminum, an aluminum alloy, iron, or an iron alloy. From the viewpoint of ease of processing, the case body ʺAʺ is preferably composed of aluminum or an aluminum alloy.

[0019] A safety valve 70 is provided on the bottom wall 11. The safety valve 70 is a thin-walled part designed to break when the inside of the case 10 reaches a predetermined pressure and release the internal pressure. In some embodiments, the safety valve 70 can be provided on the upper wall ʺ2ʺ or the side wall instead of the bottom wall 11 of the case 10. Two or more safety valves 70 may be provided.

[0020] Note: There seems to be an error in the reference number in the translation of paragraph . It should be "FIG. 1" instead of "<<1>>". Also, there seems to be an error in the reference number in the translation of paragraph . It should be "upper wall 12" instead of "upper wall ʺ2ʺ". These are likely typos in the original text you provided.As shown in FIG. 3, the first side wall 17 extends from the edge (short side) 11c of the bottom wall 11 to the edge (short side) 12c of the upper wall 12. In the present embodiment, the first lid body 10B is disposed as the first side wall 17. The first lid body 10B is attached to the first opening 15 and closes the first opening 15. The first lid body 10B is a substantially rectangular plate-shaped member. As shown in FIG. 3, the first lid body 10B extends from the edge (short side) 11c of the bottom wall 11 to the edge (short side) 12c of the upper wall 12. The first lid body 10B is overlapped and joined to the respective end faces of the bottom wall 11, the upper wall 12, the first wide side wall 13, and the second wide side wall 14 of the case body 10A. The joining method is not particularly limited. For example, the case body 10A and the first lid body 10B are joined by welding. The material of the first lid body 10B is preferably the same kind of metal material (aluminum, aluminum alloy, iron, iron alloy, etc.) as that of the case body 10A. [[ID=​​​​​​​​​​The second lid 10C is fitted onto the second opening 16 and closes the second opening 16. The second lid 10C is a substantially rectangular plate-like member. The second lid 10C faces the first lid 10B. As shown in Figure 3, the second lid 10C extends from the edge (short side) 11d of the bottom wall 11 to the edge (short side) 12d of the top wall 12. The second lid 10C faces the first lid 10B. The first lid 10B is joined to the end faces of the bottom wall 11, top wall 12, first wide side wall 13, and second wide side wall 14 of the case body 10A by overlapping them. The joining method is not particularly limited, but for example, the case body 10A and the second lid 10C are joined by welding. The material of the second lid 10C is preferably the same type of metal material as the case body 10A (aluminum, aluminum alloy, iron, iron alloy, etc.). The second lid 10C is an example of a second side wall that faces the first side wall 17 of the case 10.

[0024] (2) Electrode terminal The positive electrode terminal 22 is attached to the first cover 10B. A portion of the positive electrode terminal 22 is exposed to the outside of the case 10. The positive electrode terminal 22 is preferably made of metal, and more preferably of aluminum or an aluminum alloy. As shown in Figure 3, the positive electrode terminal 22 is electrically connected to the positive electrode sheet 32 ​​(more specifically, the positive electrode tab 33 described later) of the electrode body 30 via the positive electrode current collector 23 inside the case 10. The positive electrode current collector 23 may be a part of the positive electrode terminal 22, or it may be another metal component.

[0025] The negative electrode terminal 24 is attached to the second cover 10C. The negative electrode terminal 24 is located on the opposite side of the positive electrode terminal 22 in the first direction X. A portion of the negative electrode terminal 24 is exposed to the outside of the case 10. The negative electrode terminal 24 is preferably made of metal, and more preferably of copper or a copper alloy. As shown in Figure 3, the negative electrode terminal 24 is electrically connected to the negative electrode sheet 34 (more specifically, the negative electrode tab 35 described later) of the electrode body 30 via the negative electrode current collector 25 inside the case 10. The negative electrode current collector 25 may be a part of the negative electrode terminal 24, or it may be another metal component.

[0026] (3) Electrode body The electrode body 30 is a power generation element in the energy storage device 1. As shown in Figure 3, the electrode body 30 is housed inside the case 10. Figure 4 is a schematic cross-sectional view showing the structure of the electrode body 30. Figure 5 is a schematic cross-sectional view showing the internal structure of the energy storage device of Figure 1 from a different viewpoint than Figure 3. In Figure 5, the detailed structure of the electrode body 30 is omitted. The electrode body 30 has a first wide surface 30A, a second wide surface 30B, a bottom 30C, and an upper part 30D. The first wide surface 30A faces the first wide side wall 13 of the case 10 inside the case 10. The second wide surface 30B is the surface facing the first wide surface 30A. The second wide surface 30B faces the second wide side wall 14 of the case 10 inside the case 10. The bottom 30C faces the bottom wall 11 of the case 10 inside the case 10. The upper part 30D faces the bottom part 30C. Inside the case 10, the upper part 30D faces the upper wall 12 of the case 10.

[0027] As shown in Figure 4, the electrode body 30 comprises a positive electrode sheet 32, a negative electrode sheet 34, and a separator sheet 36. The positive electrode sheet 32 ​​and the negative electrode sheet 34 are alternately stacked with the separator sheet 36 in between. In this embodiment, the electrode body 30 is stacked along the direction in which the first wide surface 30A and the second wide surface 30B face each other. In this specification, the stacking direction is also referred to as the thickness direction of the electrode body 30.

[0028] In this embodiment, the separator sheet 36 is folded in a zigzag pattern (also called a bellows pattern) by being folded back alternately at predetermined intervals. The electrode sheets (positive electrode sheet 32 ​​and negative electrode sheet 34) are sandwiched between the folded separator sheet 36 on both sides (the laminated surfaces) in the thickness direction of the electrode sheets. The separator sheet 36 is wrapped around the outermost part of the zigzag structure and forms the outer surface of the electrode body 30. A winding stopper tape 39 is attached to the end portion 36e of the separator sheet 36 to prevent winding slack.

[0029] The electrode body 30 has a penetration region 38 that serves as an inlet for the electrolyte to penetrate from the outside to the inside of the electrode body 30. The penetration region 38 includes an inflow passage 37 through which the electrolyte can penetrate between the positive electrode sheet 32 ​​and the negative electrode sheet 34 (inside the electrode body 30). In this embodiment, the surface perpendicular to the stacking direction of the electrode sheets (positive electrode sheet 32, negative electrode sheet 34) includes the penetration region 38. In the penetration region 38, the end face of the electrode sheet (the surface perpendicular to the thickness direction of the electrode sheet) may be exposed. In this embodiment, the bottom 30C, the top 30D, the surface facing the first lid 10B, and the surface facing the second lid 10C of the electrode body 30 include the penetration region 38. The bottom 30C, which includes the penetration region 38, faces the bottom wall 11 of the case 10 inside the case 10. This allows the electrolyte to penetrate into the inside of the electrode body 30 from the bottom wall 11 side of the case 10.

[0030] The inlet passage 37 may be the entrance portion of a communication hole that extends into the interior of the electrode body 30. The separator sheet 36 may be a porous sheet to which the electrolyte can permeate. Therefore, in this embodiment, the separator sheet 36, which is positioned between the positive electrode sheet 32 ​​and the adjacent negative electrode sheet 34, has the inlet passage 37. In some embodiments, the inflow passage 37 may be a slit or gap provided on the surface of the separator sheet 36 or the electrode sheet.

[0031] In the electrode body 30 shown in Figure 4, the separator sheet 36 is wrapped around the outermost part of the zigzag structure. That is, the bottom portion 30C, including the penetration region 38, is covered by the outer surface of the separator sheet 36. However, the separator sheet 36 has communication holes through which the electrolyte can penetrate. Therefore, the electrolyte on the outside of the electrode body 30 can pass through the separator sheet 36 and reach the penetration region 38.

[0032] The positive electrode sheet 32 ​​comprises a positive electrode current collector foil and a positive electrode active material layer formed on at least one surface of the positive electrode current collector foil. The material of the positive electrode current collector foil is a conductive metallic material. For example, aluminum, aluminum alloy, etc., can be used as the positive electrode current collector foil. As shown in Figure 3, a positive electrode tab 33 extending from the electrode body 30 is provided at the end of the positive electrode current collector foil (X1 side in the figure). The positive electrode tab 33 faces the first cover body 10B. The positive electrode tab 33 has a current collector foil exposed portion in which the positive electrode current collector foil is exposed. The current collector foil exposed portion is joined to the positive electrode current collector portion 23. The positive electrode active material layer contains a positive electrode active material. The positive electrode active material is a material that can reversibly absorb and release charge carriers. The positive electrode active material may be the same as conventional materials and is not particularly limited. The positive electrode active material may be, for example, a lithium transition metal composite oxide such as lithium nickel cobalt manganese composite oxide. The positive electrode active material layer may contain optional components other than the positive electrode active material, such as a binder or conductive material.

[0033] The negative electrode sheet 34 comprises a negative electrode current collector foil and a negative electrode active material layer formed on at least one surface of the negative electrode current collector foil. The material of the negative electrode current collector foil is a conductive metallic material. For example, copper, copper alloys, etc., can be used as the negative electrode current collector foil. As shown in Figure 3, a negative electrode tab 35 extending from the electrode body 30 is provided at the end of the negative electrode current collector foil (X2 side in the figure). The negative electrode tab 35 faces the second cover body 10C. The negative electrode tab 35 has a current collector foil exposed portion in which the negative electrode current collector foil is exposed. The current collector foil exposed portion is joined to the negative electrode current collector portion 25. The negative electrode active material layer contains a negative electrode active material. The negative electrode active material is a material that can reversibly absorb and release charge carriers. The negative electrode active material may be the same as conventional materials and is not particularly limited. The negative electrode active material may be, for example, a carbon material such as graphite or a silicon-based material. The negative electrode active material layer may contain optional components other than the negative electrode active material, such as a binder, thickener, dispersant, etc.

[0034] The separator sheet 36 may be the same as in the conventional design and is not particularly limited. The separator sheet 36 may have a single-layer structure, or it may have a structure of two or more layers with different properties and characteristics (such as thickness and porosity), for example, a three-layer structure. The separator sheet 36 is made of resin, for example, and preferably of a polyolefin resin. As the polyolefin resin, polyethylene, polypropylene, or a mixture thereof is preferred.

[0035] (4) Electrolyte The electrolyte can be the same as in the conventional method and is not particularly limited. The electrolyte is, for example, a non-aqueous electrolyte containing a non-aqueous solvent (organic solvent) and a supporting salt (electrolyte salt, such as a lithium salt or sodium salt). Examples of non-aqueous solvents include carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts include fluorine-containing lithium salts such as lithium hexafluoride phosphate (LiPF6).

[0036] (5) Spacer As shown in Figure 3, the first spacer 42 is positioned between the first lid 10B and the electrode body 30. The first spacer 42 has a bottom surface 42a facing the bottom wall 11 and an upper surface 42b facing the top wall 12. The first spacer 42 has a base portion 42c extending from the bottom surface 42a to the upper surface 42b. The base portion 42c is positioned to cover the surface of the electrode body 30 facing the first lid 10B. The first spacer 42 prevents direct contact between the electrode body 30 and the first lid 10B, thereby preventing damage to the electrode body 30.

[0037] The first spacer 42 is preferably made of an insulating resin. Examples of insulating resins include polyamide resin and polyolefin resin (e.g., polypropylene, polyethylene). The insulating properties of the first spacer 42 prevent electrical conductivity between the electrode body 30 and the first cover 10B.

[0038] As shown in Figure 3, the second spacer 44 is positioned between the second cover 10C and the electrode body 30. The second spacer 44 has a bottom surface 44a facing the bottom wall 11 and an upper surface 44b facing the top wall 12. The second spacer 44 has a base portion 44c extending from the bottom surface 44a to the upper surface 44b. The base portion 44c is positioned to cover the surface of the electrode body 30 facing the second cover 10C. The second spacer 44 prevents direct contact between the electrode body 30 and the second cover 10C, thereby preventing damage to the electrode body 30.

[0039] The second spacer 44 is preferably made of an insulating resin. The insulating resin may be the same as that used for the first spacer 42 described above.

[0040] (6) Resin film As shown in Figures 3 and 5, the resin film 50 is an insulating member placed between the case 10 and the electrode body 30. The resin film 50 is positioned to surround the outer circumference of the electrode body 30. In this embodiment, the resin film 50 has a cylindrical shape. The electrode body 30 is housed inside the cylindrical resin film 50. The resin film 50 covers the first wide surface 30A, the second wide surface 30B, the bottom 30C, and the top 30D. This prevents electrical conductivity between the electrode body 30 and the case body 10A.

[0041] In this embodiment, at least a portion of the first spacer 42 and at least a portion of the second spacer 44 are arranged inside the resin film 50. This makes it possible to more effectively prevent electrical conductivity between the electrode body 30 and the case 10.

[0042] In this embodiment, an electrode body 30, with a first spacer 42 and a second spacer 44 attached to both sides, is placed on a single film. Then, the film is folded into a cylindrical shape to surround the electrode body 30, the first spacer 42, and the second spacer 44, thereby creating a resin film 50. In some embodiments, the resin film 50 may be composed of two or more films.

[0043] The material of the resin film 50 may be, for example, polyamide resin, polyolefin resin (e.g., polypropylene, polyethylene), etc. The resin film 50 may also be a porous material that allows the electrolyte to permeate.

[0044] Incidentally, the inventors of this invention want to make it easier for the electrolyte that has accumulated at the bottom of the case to penetrate into the electrode body. The impregnation process, in which the electrolyte penetrates into the inside of the electrode body, is a particularly time-consuming process in the manufacturing process of energy storage devices. Therefore, if the electrolyte can penetrate into the electrode body more easily, the manufacturing time of energy storage devices can be shortened.

[0045] Figure 6 is a schematic cross-sectional view showing the configuration of the region between the electrode body 30 and the bottom wall 11. As shown in Figures 5 and 6, the resin film 50 has a first end 52 and a second end 54. The first end 52 and the second end 54 are located between the bottom wall 11 of the case 10 and the bottom 30C of the electrode body 30. The second end 54 and the first end 52 are located between the bottom 30C of the electrode body 30 and the bottom wall 11.

[0046] The first end portion 52 covers a part of the bottom portion 30C of the electrode body 30. The first end portion 52 is a part of the resin film 50 that is positioned between the bottom portion 30C of the electrode body 30 and the bottom wall 11 of the case 10, and refers to a portion that extends from one side to the other in a predetermined direction. In this embodiment, the first end portion 52 extends in the thickness direction (second direction Y) of the electrode body 30 from the second wide surface 30B side (Y1 side) to the first wide surface 30A side (Y2 side) of the electrode body 30.

[0047] The second end portion 54 covers a part of the bottom portion 30C of the electrode body 30. The second end portion 54 is a part of the resin film 50 that is positioned between the bottom portion 30C of the electrode body 30 and the bottom wall 11 of the case 10, and refers to a portion that extends from one side to the other in a predetermined direction. In this embodiment, the second end portion 54 extends in the thickness direction (second direction Y) of the electrode body 30 from the first wide surface 30A side (Y2 side) to the second wide surface 30B side (Y1 side) of the electrode body 30.

[0048] The resin film 50 has an overlapping portion 56 in which at least a part of the first end 52 and a part of the second end 54 overlap. In the overlapping portion 56, the first end 52 is located on the bottom 30C side of the electrode body 30, and the second end 54 is located on the bottom wall 11 side of the case 10. In the overlapping portion 56, the opposing region 57 between the first end 52 and the second end 54 is not completely closed. The opposing region 57 includes a gap through which the electrolyte can pass.

[0049] As shown in Figures 5 and 6, the second end portion 54 includes an electrode body facing portion 60 that faces the bottom portion 30C of the electrode body 30 without passing through the first end portion 52. The electrode body facing portion 60 is provided continuously with the overlapping portion 56. A first space 62 is formed between the electrode body facing portion 60 and the bottom portion 30C of the electrode body 30. In this embodiment, the first space 62 is a space created because the thickness of the second end portion 54 is smaller than the thickness of the overlapping portion 56. The first space 62 faces the bottom portion 30C of the electrode body 30 and communicates with the penetration region 38.

[0050] In this technology, as described above, the resin film 50 has an overlapping portion 56 where the first end 52 and the second end 54 overlap at the bottom 30C of the electrode body 30. In addition, there is an electrode body facing portion 60 where the second end 54 faces the electrode body 30 without passing through the first end 52. A first space 62 exists between the electrode body facing portion 60 and the bottom 30C of the electrode body 30. At the overlapping portion 56 between the second end 54, the space between the first end 52 and the second end 54 is not blocked, so the electrolyte can pass through and enter the first space 62. The electrolyte that enters the first space 62 penetrates into the electrode body 30 from the penetration region 38. Therefore, the electrolyte can be efficiently penetrated into the electrode body 30.

[0051] As shown in Figure 6, the average length L2 of the second end 54 may be longer than the average length L1 of the first end 52. The average length L1 of the first end 52 and the average length L2 of the second end 54 are the arithmetic mean of the lengths in the direction in which they extend. In this embodiment, as shown in Figure 6, the average lengths L1 and L2 are the lengths in the thickness direction (second direction Y) of the electrode body 30. As a result, the first space 62 is formed to be wider compared to the case where the average length L1 of the second end 54 is shorter than the average length L2 of the first end 52, so that the electrolyte can penetrate into the inside of the electrode body 30 more efficiently.

[0052] The ratio of the area of ​​the electrode body opposing portion 60 to the area of ​​the bottom portion 30C of the electrode body 30, which is set to 100%, is not particularly limited, but is preferably 50% or more, 60% or more, 70% or more, or 80% or more. The larger the area of ​​the electrode body opposing portion 60, the wider the area of ​​the electrolyte present in the first space 62 can come into contact with the penetration region 38, which can improve the impregnation efficiency. On the other hand, from the viewpoint of securing the area of ​​the overlapping portion 56 and preventing misalignment between the first end portion 52 and the second end portion 54, the ratio of the above area of ​​the electrode body opposing portion 60 is not particularly limited, but is preferably 95% or less, or 90% or less.

[0053] The ratio of the area of ​​the overlapping portion 56 to the area of ​​the bottom portion 30C of the electrode body 30, which is set to 100%, is not particularly limited, but is preferably 50% or less, 40% or less, 30% or less, or 20% or less. The smaller the ratio of the area of ​​the overlapping portion 56, the easier it is for the electrolyte to pass through the gap in the opposing region 57 of the overlapping portion 56, thus making it easier for the electrolyte to enter the first space 62. On the other hand, from the viewpoint of ensuring the area of ​​the overlapping portion 56 and preventing misalignment between the first end portion 52 and the second end portion 54, the above ratio of the area of ​​the overlapping portion 56 is not particularly limited, but is preferably 5% or more, or 10% or more.

[0054] As shown in Figure 6, the average length L1 of the second end portion 54 when the thickness T of the electrode body 30 (see Figure 6) is 100 is not particularly limited, but is preferably 70 or more, 80 or more, or 90 or more. The longer the second end portion 54, the narrower the space between the first end portion 52 and the bottom wall 11 can be. Such a space should not be too wide, as there is a risk of electrolyte stagnation. On the other hand, if such a space becomes too narrow, it may become difficult for the electrolyte to enter the first space 62 through the gap in the overlapping portion 56. Therefore, the average length L2 of the second end portion 54 is not particularly limited, but is preferably 98 or less, or 95 or less.

[0055] As shown in Figure 6, the average length L1 of the first end portion 52 when the thickness T of the electrode body 30 (see Figure 6) is 100 is not particularly limited, but is preferably 50 or less, 40 or less, 30 or less, or 20 or less. The shorter the first end portion 52, the wider the first space 62 can be. A wider first space 62 allows more electrolyte to be held in the first space 62, thus improving impregnation efficiency. On the other hand, if the first end portion 52 is too short, it becomes more prone to curling. Therefore, although the average length L1 of the first end portion 52 is not particularly limited, is preferably 5 or more, or 10 or more.

[0056] As shown in Figure 6, the average length L3 of the overlapping portion 56 when the thickness T of the electrode body 30 (see Figure 6) is 100 is not particularly limited, but for example, it is preferable to have a length of 50 or less, 40 or less, 30 or less, or 20 or less. The shorter the average length L3 of the overlapping portion 56, the easier it is for the electrolyte to pass through the gap in the overlapping portion 56, and thus easier for the electrolyte to enter the first space 62. On the other hand, from the viewpoint of securing the area of ​​the overlapping portion 56 and preventing misalignment between the first end 52 and the second end 54, the ratio of the average length L3 of the overlapping portion 56 is not particularly limited, but for example, it is preferable to have a ratio of 5 or more, or 10 or more.

[0057] The thickness of the resin film 50 is not particularly limited, but for example, it may be 50 μm or more, 100 μm or more, or 150 μm or more. The greater the thickness of the resin film 50, the wider the first space 62 can be secured, and the better the impregnation efficiency may be. On the other hand, a greater thickness of the resin film 50 reduces the capacity of the energy storage device 1. Therefore, the thickness of the resin film 50 may be, for example, 300 μm or less, 250 μm or less, or 200 μm or less.

[0058] In the overlapping portion 56, the second end portion 54 and the first end portion 52 may be partially welded together, but it is preferable that the overlapping portion 56 is not welded in the region where the electrode body 30 and the bottom wall 11 face each other. This is because the electrolyte can be supplied to the first space 62 more efficiently. In this embodiment, the resin film 50 is welded to the bottom surface 42a of the first spacer 42 and the bottom surface 44a of the second spacer 44. This allows the resin film 50 to be fixed around the electrode body 30 without welding the overlapping portion 56 in the region where the electrode body 30 and the bottom wall 11 face each other.

[0059] The energy storage device 1 can be used for various applications. Suitable applications include automotive applications, specifically as a power source for vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). The energy storage device 1 can also be used as a battery for small-scale power storage devices. The energy storage device 1 can typically be used in the form of a battery module, which consists of multiple devices connected in series and / or parallel.

[0060] Although several embodiments have been described above, these embodiments are merely examples. This technology can be implemented in various other forms. The technologies described in the claims include various modifications and changes to the embodiments exemplified above. For example, it is possible to replace parts of the above embodiments with other variations, and it is also possible to add other variations to the above embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0061] In the above-described embodiment, the first lid 10B was used as the first side wall 17 having the liquid injection section 19. However, in some embodiments, the first side wall having the liquid injection section may be part of the case body.

[0062] In the above-described embodiment, the case 10 had two lids 10B and 10C, but in this technology, the number of lids is not particularly limited. In some embodiments, there may be only one lid. Also, the case may not include any lids.

[0063] In the embodiments described above, each wall constituting the case was a substantially rectangular plate-like portion; however, in some embodiments, each wall constituting the case may be square or polygonal.

[0064] In the above-described embodiment, the electrode body 30 was a laminated electrode body having a zigzag structure using strip-shaped separator sheets 36, but it is not limited to this as long as the electrode body has a penetration region 38. For example, the electrode body may be a laminated electrode body prepared by preparing a plurality of separator sheets and stacking them with one or more separator sheets sandwiched between a positive electrode sheet and a negative electrode sheet. Alternatively, it may be a wound electrode body in which a strip-shaped positive electrode sheet and a strip-shaped negative electrode sheet are overlapped via a strip-shaped separator sheet and wound up. In the case of a wound electrode body, the penetration region may be formed on both sides in the direction of the winding axis.

[0065] In the above-described embodiment, one electrode body 30 was housed in the case 10, but in some embodiments, there may be multiple electrode bodies 30.

[0066] As described above, specific embodiments of the technology disclosed herein include those described in the following sections.

[0067] Item 1: A case having a liquid injection section, The electrode body housed in the above case, Between the above case and the above electrode body, a resin film is arranged so as to surround the above electrode body, The electrolyte contained in the above case and Equipped with, The above case is, The bottom wall and, The upper wall opposite the bottom wall, A first side wall extending from the edge of the bottom wall to the edge of the top wall, Includes, The liquid injection section is located closer to the upper wall than to the bottom wall of the first side wall. The electrode body is positioned so that its bottom faces the bottom wall. The above resin film is A first end extends from one side in a predetermined direction so as to cover a part of the bottom of the electrode body, A second end extends in the direction opposite to the first end, along the predetermined direction described above, and extends so as to cover a part of the bottom of the electrode body. It has, A portion of the second end is superimposed on the bottom wall side of the case relative to the first end. Energy storage device. Item 2: The energy storage device according to Item 1, wherein, in the predetermined direction described above, the average length of the first end is longer than the average length of the second end. Item 3: The second end has an electrode body facing portion where the second end and the electrode body face each other without passing through the first end. The energy storage device according to item 1 or 2, wherein the ratio of the area of ​​the electrode body's opposing portion to the area of ​​the bottom portion of the electrode body is 50% or more when the area of ​​the bottom portion of the electrode body is taken as 100%. Item 4: The energy storage device according to any one of items 1 to 3, wherein the area ratio of the overlapping portion of the first end and the second end, when the area of ​​the bottom of the electrode body is taken as 100%, is 50% or less. Item 5: The energy storage device according to any one of items 1 to 4, wherein the average length of the second end is 70 or more when the thickness of the electrode body in the predetermined direction is 100. Item 6: The energy storage device according to items 1 to 5, wherein the average length of the first end is 50 or less when the thickness of the electrode body in the predetermined direction is 100. Item 7: The energy storage device according to any one of items 1 to 6, wherein the first end and the second end are not welded together in the portion where they overlap. Item 8: Furthermore, it comprises a positive terminal and a negative terminal, The above electrode body comprises a positive electrode and a negative electrode. The above positive terminal is electrically connected to the above positive electrode of the electrode body. The above negative electrode terminal is electrically connected to the above negative electrode of the electrode body. The above case further comprises a second side wall facing the first side wall, The positive terminal is located on the first side wall or the second side wall. The energy storage device according to any one of claims 1 to 7, wherein the negative electrode terminal is located on the first side wall or the second side wall where the positive electrode terminal is not located. Item 9: The above case is, A cylindrical case body including the bottom wall and the top wall, The first lid, which serves as the first side wall, The second lid as the second side wall and Includes, The above case body has a first opening and a second opening located on the opposite side of the first opening. The first cover is fitted into the first opening. The above-mentioned second cover is attached to the above-mentioned second opening. The energy storage device described in item 8. [Explanation of symbols]

[0068] 1. Energy storage device 10 cases 11 Bottom wall 12 Upper wall 17. First side wall 19. Injection section 30 Electrode body 38 Penetration area 50 resin film 52 First end 54 Second end 56 Overlapping parts 60 Electrode body opposing part 62 1st space

Claims

1. A case having a liquid injection section, The electrode body housed in the aforementioned case, Between the case and the electrode body, a resin film is arranged so as to surround the electrode body, The electrolyte contained in the aforementioned case and Equipped with, The aforementioned case is, The bottom wall and, The upper wall opposite the bottom wall, A first side wall extending from the edge of the bottom wall to the edge of the top wall and Includes, The liquid injection section is provided in a position closer to the upper wall than to the bottom wall of the first side wall, The electrode body is positioned so that its bottom faces the bottom wall. The aforementioned resin film is A first end extends from one side in a predetermined direction so as to cover a portion of the bottom of the electrode body, A second end extends in the same predetermined direction as the first end, from the opposite direction to the first end, and extends so as to cover a part of the bottom of the electrode body. It has, A portion of the second end is superimposed on the bottom wall side of the case relative to the first end. Energy storage device.

2. The energy storage device according to claim 1, wherein in the predetermined direction, the average length of the first end is longer than the average length of the second end.

3. The second end has an electrode body facing portion where the second end and the electrode body face each other without passing through the first end, The energy storage device according to claim 1, wherein the ratio of the area of ​​the electrode body opposing portion to the area of ​​the bottom portion of the electrode body, when the area of ​​the bottom portion of the electrode body is taken as 100%, is 50% or more.

4. The energy storage device according to claim 1, wherein the ratio of the area of ​​the overlapping portion of the first end and the second end to the area of ​​the bottom portion of the electrode body, when the area of ​​the bottom portion is taken as 100%, is 50% or less.

5. The energy storage device according to claim 1, wherein the average length of the second end is 70 or more when the thickness of the electrode body in the predetermined direction is 100.

6. The energy storage device according to claim 1, wherein the average length of the first end is 50 or less when the thickness of the electrode body in the predetermined direction is 100.

7. The energy storage device according to claim 1, wherein the first end and the second end are not welded together in the portion where the first end and the second end overlap.

8. Furthermore, it is equipped with a positive terminal and a negative terminal. The electrode body comprises a positive electrode and a negative electrode. The positive electrode terminal is electrically connected to the positive electrode of the electrode body. The negative electrode terminal is electrically connected to the negative electrode of the electrode body. The case further comprises a second side wall facing the first side wall, The positive terminal is located on the first side wall or the second side wall. The energy storage device according to any one of claims 1 to 7, wherein the negative electrode terminal is located on the first side wall or the second side wall where the positive electrode terminal is not located.

9. The aforementioned case is, A cylindrical case body including the bottom wall and the top wall, The first lid as the first side wall, The second lid as the second side wall and Includes, The case body has a first opening and a second opening located on the opposite side of the first opening. The first cover is fitted into the first opening, The second cover is fitted into the second opening. The energy storage device according to claim 8.

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