Electricity storage device and spacer used in same

Abstract

The invention relates to an electricity storage device and a separator used for the electricity storage device, and provides a technology capable of preventing electrolyte from flowing out of an electrode body from the inside of the electrode body without preventing the electrolyte from entering the electrode body from the outside of the electrode body to the inside of the electrode body. An electricity storage device disclosed herein is provided, in one embodiment, with: an electrode body (20) including a positive electrode (22), a negative electrode (24), and a separator (26); an electrolyte; and a case (10) that houses the electrode body (20) and the electrolyte solution. The electricity storage device has a backflow prevention groove (27) on the surface of the spacer (26). The backflow prevention groove (27) is a groove through which the electrolyte flows from the outside to the inside of the electrode body (20), and is a groove formed in a pattern which prevents the electrolyte from flowing from the inside to the outside of the electrode body (20).

Description

Technical Field

[0001] The present disclosure relates to an electricity storage device and a separator used for the electricity storage device. Background Art

[0002] Japanese Patent Application Publication No. 2022-12289 discloses a non-aqueous electrolyte secondary battery, which includes an electrode body on which a positive electrode, a negative electrode, and a separator are superimposed, and a non-aqueous electrolyte that permeates the interior of the electrode body. The positive electrode and the negative electrode are each formed by applying an electrode mixture layer containing an electrode active material to the surface of a strip-shaped electrode collector foil. The electrode body has a flow path for the non-aqueous electrolyte to flow inside and outside the electrode body, namely, an electrolyte flow path. When the area in the negative electrode mixture layer that contacts the electrolyte flow path is set as a barrier portion, and the area located closer to the center than the barrier portion is set as a liquid holding portion, the barrier portion has a higher potential relative to the positive electrode active material than the negative electrode active material contained in the liquid holding portion, and contains a negative electrode active material with a larger expansion and contraction rate associated with the increase or decrease of the SOC. The publication states that: through this structure, it is possible to properly prevent the shortage of non-aqueous electrolyte inside the electrode body and to maintain the battery performance of the non-aqueous electrolyte secondary battery in an appropriate state.

[0003] The electrode disclosed in Japanese Patent Application Publication No. 2023-100057 includes a substrate and an active material layer arranged on the surface of the substrate. One or more grooves are formed on the surface of the active material layer. The grooves extend linearly along the surface of the active material layer and include an inlet region, an intermediate region and an outlet region when viewed from above. The inlet region includes an inlet opening at the periphery of the active material layer. The outlet region includes an outlet opening at the periphery of the active material layer. The intermediate region is arranged between the inlet region and the outlet region and connects the inlet region and the outlet region. The inlet region and the outlet region are respectively configured so that the first pressure loss when the fluid flows in the forward direction is smaller than the second pressure loss when the fluid flows in the reverse direction. The forward direction refers to the direction from the inlet region toward the outlet region, and the reverse direction refers to the direction from the outlet region toward the inlet region. The publication states that: through this structure, the flow of the electrolyte in the groove of the electrode is made directional, thereby making it easy to discharge bubbles.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-12289

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2023-100057 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] The present inventors have considered that it is desirable to prevent the electrolyte from penetrating from the outside of the electrode body into the inside of the electrode body and to suppress the electrolyte from flowing out from the inside of the electrode body to the outside.

[0010] Means for solving problems

[0011] According to the technology disclosed herein, a storage device is disclosed, comprising: an electrode body including a positive electrode, a negative electrode, and a separator; an electrolyte; and a housing that accommodates the electrode body and the electrolyte. The storage device has a backflow prevention groove on the surface of the separator. The backflow prevention groove is a groove that allows the electrolyte to flow from the outside to the inside of the electrode body, and is a groove formed in a pattern that prevents the electrolyte from flowing from the inside to the outside of the electrode body. According to this structure, it is possible to prevent the electrolyte from penetrating from the outside of the electrode body into the inside of the electrode body and to suppress the electrolyte from flowing out from the inside of the electrode body to the outside.

[0012] According to the technology disclosed herein, a separator is disclosed, which is used for an electrical storage device, wherein the electrical storage device includes: an electrode body, the electrode body including a positive electrode, a negative electrode, and a separator; an electrolyte; and a shell, the shell accommodating the electrode body and the electrolyte. The separator has a backflow prevention groove on its surface. The backflow prevention groove is a groove for allowing the electrolyte to flow from the outside to the inside of the electrode body, and is a groove formed in a pattern that prevents the electrolyte from flowing from the inside to the outside of the electrode body. According to this structure, it is possible to prevent the electrolyte from penetrating from the outside of the electrode body into the inside of the electrode body and to suppress the electrolyte from flowing out from the inside of the electrode body to the outside. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a perspective view schematically showing the battery 1 .

[0014] Figure 2 yes Figure 1 II-II sectional view.

[0015] Figure 3 It is a perspective view showing the electrode assembly 20 attached to the sealing plate 14 .

[0016] Figure 4 It is a perspective view showing the electrode body 20 to which the second current collecting portion 52 is attached.

[0017] Figure 5 is a schematic diagram of the electrode body 20 .

[0018] Figure 6 2 is a top view of the spacer 26 .

[0019] Figure 7 It is an explanatory diagram of the shape of the backflow prevention groove 27.

[0020] Figure 8 yes Figure 6 IIX-IIX cross-sectional view.

[0021] Figure 9 is a top view of the spacer 226 .

[0022] Figure 10 is a schematic diagram of the electrode body 320.

[0023] Figure 11 It is a perspective view of the electrode body 420 .

[0024] Description of Reference Numerals

[0025] 1Battery (electricity storage device)

[0026] 10 shell

[0027] 20 electrode body

[0028] 201 First End

[0029] 202 Second End

[0030] 22 positive electrode

[0031] 24 negative electrode

[0032] 26 spacers

[0033] 26A First Floor

[0034] 26B Second Floor

[0035] 26S substrate

[0036] 261 First Area

[0037] 262 Second Area

[0038] 27 Backflow prevention groove

[0039] 27A Supervisor

[0040] 27B Deputy pipe

[0041] 27C1 first connection part

[0042] 27C2 second connection part

[0043] 28 slots

[0044] 30 positive terminal

[0045] 40 negative terminal

[0046] 35, 45 external conductive components

[0047] 50 positive electrode current collecting component

[0048] 60 negative electrode current collecting component

[0049] P first direction

[0050] QSecond direction

[0051] 320, 420 electrode body

[0052] 226, 326, 426 spacers

[0053] 227 Backflow prevention groove. DETAILED DESCRIPTION

[0054] Hereinafter, an embodiment of the technology disclosed herein will be described. The embodiment described herein is not intended to particularly limit the technology disclosed herein. Unless otherwise specified, the technology disclosed herein is not limited to the embodiment described herein. The drawings are schematically depicted and do not necessarily reflect the actual objects. Components and parts that perform the same function are appropriately marked with the same figure marks, and repeated descriptions are sometimes omitted. Figure marks such as "F", "Rr", "R", "L", "U" and "D" in the drawings represent front, back, right, left, top and bottom, respectively. Unless otherwise specified, expressions such as "A to B" indicating a numerical range mean "above A and below B", and include the meaning of "exceeding A and below B".

[0055] In this specification, an "electrical storage device" refers to a device that generates charge and discharge by moving charge carriers between a pair of electrodes (a positive electrode and a negative electrode) via an electrolyte. Such electrical storage devices include secondary batteries such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries; and capacitors such as lithium-ion capacitors and electric double-layer capacitors. Below, as an example of the above-mentioned electrical storage device, an embodiment is described with a lithium-ion secondary battery as the target. Therefore, the electrical storage device in the following description is sometimes referred to as a "battery."

[0056] Figure 1 It is a perspective view schematically showing the battery 1 . Figure 2 yes Figure 1 II-II sectional view. Figure 1 and Figure 2 As shown, the battery 1 includes a housing 10, an electrode body 20, a positive electrode terminal 30, a negative electrode terminal 40, external conductive members 35 and 45, a positive electrode current collecting member 50, a negative electrode current collecting member 60, an insulating member 70, a gasket 90, and an external insulating member 92. Although not shown in the figure, the battery 1 includes, for example, an electrolyte. As the electrolyte, an electrolyte used as an electrolyte for this type of lithium-ion secondary battery can be used without particular limitation. Since the composition of the electrolyte does not contribute to the characteristics of the technology disclosed herein, a detailed description thereof is omitted.

[0057] In this embodiment, the housing 10 is a frame that houses the electrode assembly 20 and the electrolyte. Here, the housing 10 has a flat, bottomed rectangular parallelepiped (square) shape. The material of the housing 10 can be the same as that used in the past and is not particularly limited. The housing 10 is preferably made of metal, more preferably aluminum, an aluminum alloy, iron, or an iron alloy.

[0058] In this embodiment, the housing 10 includes an outer body 12 and a sealing plate (lid) 14. Figure 1 As shown, the outer body 12 has a flat rectangular bottom 12a, a pair of first side walls 12b extending from a pair of opposite sides of the bottom 12a in the vertical direction Z and facing each other, and a pair of second side walls 12c extending from a pair of opposite sides of the bottom 12a in the vertical direction Z and facing each other. In this embodiment, the first side wall 12b is a long side wall extending from a pair of opposite long sides of the bottom 12a. In addition, the second side wall 12c is a short side wall extending from a pair of opposite short sides of the bottom 12a. In this embodiment, the area of the second side wall 12c is smaller than that of the first side wall 12b. The portion facing the bottom 12a and surrounded by the pair of first side walls 12b and the pair of second side walls 12c is the opening 12h. The sealing plate 14 is a component that seals the opening 12h of the outer body 12. The sealing plate 14 faces the bottom 12a of the outer body 12. The sealing plate 14 has a roughly rectangular shape when viewed from above. The housing 10 is integrated by joining the sealing plate 14 to the periphery of the opening of the exterior body 12. The joining means is welding such as laser welding, for example. The housing 10 is hermetically sealed.

[0059] The sealing plate 14 is provided with a liquid injection hole 15 and a vent valve 17. The liquid injection hole 15 is used to inject the electrolyte after the sealing plate 14 is assembled to the outer body 12. The liquid injection hole 15 is sealed by a sealing member 16. The vent valve 17 is a thin-walled portion configured to rupture when the pressure inside the housing 10 exceeds a predetermined value, thereby discharging the gas inside the housing 10 to the outside.

[0060] In this embodiment, the positive electrode terminal 30 and the negative electrode terminal 40 are attached to the sealing plate 14. In this embodiment, the positive electrode terminal 30 is arranged at an end portion ( Figure 1 and Figure 2 In this embodiment, the negative electrode terminal 40 is arranged at the end portion on the other side of the longitudinal direction Y of the sealing plate 14 ( Figure 1 and Figure 2 the right end of the ).

[0061] like Figure 2 As shown, the positive electrode terminal 30 is connected to the positive electrode 22 of the electrode body 20 (see FIG. Figure 5) is electrically connected. The positive terminal 30, for example, passes through the terminal lead-out hole 18 and is led out from the interior of the sealing plate 14 to the outside. The positive terminal 30 is insulated from the sealing plate 14 by an insulating member 70 and a gasket 90. The positive terminal 30 is preferably made of metal, more preferably aluminum or an aluminum alloy. An external conductive member 35 is fixed to the positive terminal 30. The positive terminal 30 is bonded to the external conductive member 35.

[0062] like Figure 2 As shown, the negative electrode terminal 40 is connected to the negative electrode 24 of the electrode body 20 (see FIG. Figure 5 ) is electrically connected. The negative electrode terminal 40, for example, passes through the terminal lead-out hole 19 and is led out from the interior of the sealing plate 14 to the outside. The negative electrode terminal 40 is insulated from the sealing plate 14 by an insulating member 70 and a gasket 90. The negative electrode terminal 40 is preferably made of metal, more preferably copper or a copper alloy. An external conductive member 45 is fixed to the negative electrode terminal 40. The negative electrode terminal 40 is bonded to the external conductive member 45.

[0063] The positive electrode current collecting member 50 is a member that electrically connects the positive electrode 22 and the positive electrode terminal 30 inside the outer casing 12. Figure 2 As shown, the positive electrode current collecting member 50 includes a first current collecting portion 51 and a second current collecting portion 52. The first current collecting portion 51 is formed in an L-shaped cross section, for example. The first current collecting portion 51 includes a base 51a and a lead 51b, for example. Figure 2 As shown, the base 51a is arranged along the inner surface of the sealing plate 14. The lead 51b extends from one end of the base 51a in the width direction Y toward the bottom 12a (see FIG. Figure 1 For example, the second power collecting portion 52 is connected to the lead 51b.

[0064] Figure 3 It is a perspective view showing the electrode assembly 20 attached to the sealing plate 14 . Figure 4 : is a perspective view showing the electrode body 20 with the second current collecting portion 52 mounted thereon. Figures 1 to 4 As shown, the second collector portion 52 extends toward the bottom 12a of the outer casing 12. In the present embodiment, the second collector portion 52 has a first connecting piece 52a and a second connecting piece 52b. The first connecting piece 52a is, for example, a portion electrically connected to the first collector portion 51. In the present embodiment, the first connecting piece 52a is connected to the first collector portion 51 via a connecting portion 521. The connecting portion 521 is, for example, a thin-walled portion. The first connecting piece 52a extends, for example, along the up-down direction Z. In the present embodiment, the first connecting piece 52a is arranged approximately perpendicular to the winding axis WL of each electrode body 20. Although not particularly limited, a fuse portion 52f may be formed on the first connecting piece 52a. The fuse portion 52f is configured to melt when a current of 1000A or more (for example, a short-circuit current) flows through the battery 1.

[0065] The second connecting piece 52b is, for example, a portion joined to the positive electrode tab group 23. In this embodiment, the second connecting piece 52b extends along the up-down direction Z. The second connecting piece 52b is arranged approximately perpendicular to the winding axis WL of each electrode body 20. The surface of the second connecting piece 52b connected to the plurality of positive electrode tabs 22t is arranged approximately parallel to the second side wall 12c of the outer body 12. From the viewpoint of sufficiently ensuring the width of the second connecting piece 52b and reducing the battery resistance of the battery 1, the second connecting piece 52b is connected to the plurality of positive electrode tabs 22t (see Figure 5 ) is configured to face the first end portion 201 of the electrode body 20.

[0066] The negative electrode current collecting member 60 is a member that electrically connects the negative electrode 24 and the negative electrode terminal 40 inside the outer casing 12. Figures 2-4 As shown, the negative electrode current collecting member 60 includes a first current collecting portion 61 and a second current collecting portion 62. The first current collecting portion 61 includes a base 61a and a lead 61b. The second current collecting portion 62 includes a first connecting piece 62a and a second connecting piece 62b. Since the structure of the negative electrode current collecting member 60 is the same as that of the positive electrode current collecting member 50 described above, a detailed description thereof will be omitted. In addition, regarding the negative electrode current collecting member 60, Figure 4 The reference numeral “621” in the figure is a connection portion, and the reference numeral “62f” is a fuse portion.

[0067] like Figure 3 As shown, the battery 1 includes three electrode bodies 20. Figure 3 and Figure 4 As shown, the second current collecting portion 52 of the positive electrode current collecting member 50 is arranged on one side in the longitudinal direction Y ( Figure 3 and Figure 4 The second current collecting portion 62 of the negative electrode current collecting member 60 is arranged on the other side in the longitudinal direction Y ( Figure 3 and Figure 4 The right side of the Figure 2 As shown, one or more electrode bodies 20 are arranged inside the outer body 12 while being covered by an electrode body holder 29 made of a resin sheet such as polypropylene (PP). The number of electrode bodies 20 housed in the battery 1 is not particularly limited, and may be one, two, or four or more.

[0068] Figure 5 is a schematic diagram of the electrode body 20. Figure 5 As shown, the electrode body 20 includes a positive electrode 22, a negative electrode 24, and a separator 26 that insulates the positive electrode 22 from the negative electrode 24. Figure 5 As shown, the electrode body 20 is an electrode body (wound electrode body) produced by stacking a positive electrode 22 and a negative electrode 24 with a separator 26 interposed therebetween and winding them.

[0069] like Figures 2 to 4 As shown, the electrode body 20 includes a main body 20a, a positive electrode tab group 23 and a negative electrode tab group 25. The main body 20a is a portion where the positive electrode 22, the negative electrode 24 and the separator 26 are stacked, and is, for example, flat in shape. The width of the main body 20a is, for example, more than 10 cm. The width of the main body 20a can be, for example, more than 15 cm or more than 20 cm. The width of the main body 20a can be, for example, less than 50 cm or less than 40 cm. In this specification, "the width of the main body 20a" refers to, for example, the width of the positive electrode 22 and the negative electrode 24 in the short side direction (in Figure 5 ( ) is the length of the main body 20a in the width direction Y) along the winding axis direction.

[0070] like Figure 1 、 Figure 2 and Figure 5 As shown, the electrode body 20 is arranged inside the outer body 12 with the winding axis WL parallel to the width direction Y. In this embodiment, the electrode body 20 is arranged inside the outer body 12 with the winding axis WL parallel to the bottom 12a and perpendicular to the second side wall 12c. In addition, the two end portions of the electrode body 20 along the direction of the winding axis WL (hereinafter also referred to as the "winding axis direction") face the second side wall 12c of the outer body 12. In this specification, the side close to the positive electrode current collecting member 50 ( Figure 2 and Figure 4 The end of the electrode body 20 (e.g., the main body 20a) facing the second side wall 12c (on the left side in the width direction Y) is referred to as the "first end 201". Figure 2 and Figure 4 The end of the electrode body 20 (e.g., the main body 20a) facing the second side wall 12c (on the right side in the width direction Y) is referred to as the "second end 202." In this embodiment, the first end 201 and the second end 202 of the electrode body 20 are the stacked surfaces (open surfaces) of the positive electrode 22, the negative electrode 24, and the separator 26, and are open to the outside of the electrode body 20. For example, the electrolyte flows in or out of the first end 201 and the second end 202.

[0071] The positive electrode 22 comprises, for example, a long strip of positive electrode current collector foil 22c (e.g., aluminum foil) and a positive electrode active material layer 22a fixed to at least one surface of the positive electrode current collector foil 22c. Although not particularly limited, a protective layer 22p may be provided on one side edge of the positive electrode 22 in the width direction Y, as needed. Furthermore, the materials constituting the positive electrode active material layer 22a and the protective layer 22p can be any materials used in batteries of this type (lithium-ion secondary batteries in this embodiment) without particular limitation.

[0072] At one end portion of the positive electrode current collector foil 22c in the width direction Y ( Figure 5 A plurality of positive electrode tabs 22t are provided at the left end portion of the positive electrode. The plurality of positive electrode tabs 22t are respectively oriented to one side in the width direction Y ( Figure 5 The plurality of positive electrode tabs 22t are arranged at intervals (intermittently) along the longitudinal direction of the positive electrode 22. The positive electrode tab 22t is a part of the positive electrode collector foil 22c, and is a part of the positive electrode collector foil 22c where the positive electrode active material layer 22a and the protective layer 22p are not formed (the collector foil exposed part). In this embodiment, the plurality of positive electrode tabs 22t protrude further than the spacer 26 in the width direction Y. For example, the end portion of the plurality of positive electrode tabs 22t on one side in the width direction Y ( Figure 5 The left end portion of the positive electrode tab group 23 is stacked to form the positive electrode tab group 23 (refer to Figures 2 to 4 ).like Figure 2 As shown in FIG. 2 , a positive electrode current collecting member 50 is joined to the positive electrode tab group 23. Figures 1 to 3 As shown, the positive electrode tab group 23 joined to the positive electrode current collecting member 50 is bent so that the front ends of the plurality of positive electrode tabs 22t constituting the positive electrode tab group 23 are arranged along the second side wall 12c. Figure 5 , although the positive electrode tabs 22 t are shown to have substantially the same length and shape, the lengths and shapes of the positive electrode tabs 22 t may be different from each other.

[0073] The negative electrode 24 includes, for example, a long strip of negative electrode current collector foil 24 c (e.g., copper foil) and a negative electrode active material layer 24 a fixed to at least one surface of the negative electrode current collector foil 24 c. The negative electrode active material layer 24 a may be made of any material used in batteries of this type (lithium-ion secondary batteries in this embodiment) without particular limitation.

[0074] At one end portion of the negative electrode current collector foil 24c in the width direction Y ( Figure 5 A plurality of negative electrode tabs 24t are provided on the right end portion of the negative electrode. The plurality of negative electrode tabs 24t face one side in the width direction Y ( Figure 5 The plurality of negative electrode tabs 24t are arranged at intervals (intermittently) along the longitudinal direction of the negative electrode 24. Here, the negative electrode tab 24t is a part of the negative electrode collector foil 24c, and is a part of the negative electrode collector foil 24c where the negative electrode active material layer 24a is not formed (the collector foil exposed part). In this embodiment, the negative electrode tab 24t protrudes further than the separator 26 in the width direction Y. For example, the end portion of the plurality of negative electrode tabs 24t on one side in the width direction Y ( Figure 5 The right end portion of the negative electrode tab group 25 is stacked to form the negative electrode tab group 25 (refer to Figures 2 to 4 ).like Figure 2As shown, the negative electrode current collecting member 60 is joined to the negative electrode tab group 25. The negative electrode tab group 25 joined to the negative electrode current collecting member 60 is bent so that the front ends of the plurality of negative electrode tabs 24t constituting the negative electrode tab group 25 are arranged along the second side wall 12c. Figure 5 In the figure, the negative electrode tabs 24t are shown as having substantially the same length and shape, but the lengths and shapes of the negative electrode tabs 24t may be different from each other.

[0075] Figure 6 2 is a top view of the separator 26. The separator 26 is a member that insulates the positive electrode active material layer 22a of the positive electrode 22 from the negative electrode active material layer 24a of the negative electrode 24. The separator 26 constitutes the outer surface of the electrode body 20. In this embodiment, as shown in FIG. Figure 5 and Figure 6 As shown, the separator 26 is a long strip-shaped separator. The width of the separator 26 (the length in the width direction Y along the winding axis) is greater than either the length of the positive electrode 22 excluding the positive electrode tab 22t in this direction or the length of the negative electrode 24 excluding the negative electrode tab 24t in this direction.

[0076] Figure 7 2 is an explanatory diagram of the shape of the backflow prevention groove 27. Figure 7 , the planar shape of the backflow prevention groove 27 is partially shown. Here, the spacer 26 has the backflow prevention groove 27 (refer to Figure 6 and Figure 7 ). Here, the backflow prevention groove 27 is a groove on the surface of the separator 26 that allows the electrolyte to flow from the outside to the inside of the electrode body 20, and is formed into a pattern that hinders the electrolyte from flowing from the inside to the outside of the electrode body 20. In the present embodiment, the backflow prevention groove 27 is both a flow path for the electrolyte to flow from the outside to the inside of the electrode body 20, and a flow path for the electrolyte to flow from the inside to the outside of the electrode body 20. However, the backflow prevention groove 27 is configured so that the electrolyte flows relatively easily in the direction from the outside to the inside of the electrode body 20, and it is relatively difficult for the electrolyte to flow in the direction from the inside to the outside of the electrode body 20. In addition, in the following description, the direction from the outside to the inside of the electrode body 20 is sometimes referred to as the first direction P, and the direction from the inside to the outside of the electrode body 20 is sometimes referred to as the second direction Q (refer to Figure 6 and Figure 7 ).

[0077] exist Figure 7 In the embodiment shown, the backflow prevention groove 27 is configured in the shape of a Tesla valve. Figure 7As shown, the backflow prevention groove 27 includes a main pipe 27A and an annular sub-pipe 27B. The main pipe 27A, for example, constitutes a flow path for the electrolyte to flow from the outside to the inside of the electrode body 20 and a flow path for the electrolyte to flow from the inside to the outside of the electrode body 20. The sub-pipe 27B is, for example, a pipe that branches from the main pipe 27A and merges with the main pipe 28A after branching from the main pipe 27A. Figure 7 As shown in FIG, a plurality of sub-pipes 27B are connected to the main pipe 27A. Figure 7 In the illustrated embodiment, each sub-tube 27B is connected to the main tube 27A at two locations. The main tube 27A and the sub-tube 27B are connected at two locations: a first connection point 27C1 and a second connection point 27C2. The first connection point 27C1 is located outside the electrode body 20, facing each other. The second connection point 27C2 is located inside the electrode body 20, facing each other, at the two connection points between the main tube 27A and the sub-tube 27B.

[0078] In this embodiment, when the electrolyte flows along the first direction P (refer to Figure 7 At the first connection portion 27C1, the electrolyte flowing in the main pipe 27A is diverted from the main pipe 27A to the auxiliary pipe 27B. However, due to the structure, the amount of electrolyte diverted to the auxiliary pipe 27B is relatively small compared to the main pipe 27A, so the flow in the direction P is less likely to be blocked. In addition, at the second connection portion 27C2, the electrolyte flowing in the auxiliary pipe 27B also merges with the electrolyte flowing in the main pipe 27A along the flow direction of the electrolyte flowing in the main pipe 27A (here, the first direction P), so the flow in the direction P is not blocked. On the other hand, when the electrolyte flows in the second direction Q (refer to Figure 7 At the second connection point 27C2, the electrolyte flowing in the main pipe 27A is diverted from the main pipe 27A to the sub-pipe 27B. However, due to the structure, the amount of electrolyte diverted to the sub-pipe 27B is relatively greater than that to the main pipe 27A, thus easily obstructing the flow in the direction Q. Furthermore, at the first connection point 27C1, the electrolyte flowing in the sub-pipe 27B merges with the electrolyte flowing in the main pipe 27A from a direction opposite to the flow direction of the electrolyte flowing in the main pipe 27A (here, the second direction Q), thereby obstructing the flow of electrolyte in the main pipe A in the direction Q.

[0079] like Figure 4 and Figure 6 As shown, the separator 26 has a first region 261 and a second region 262. The first region 261 is, for example, a region at the edge of the separator 26 that is open to the outside of the electrode body 20. Here, the "region open to the outside of the electrode body 20" refers to a region that allows the electrolyte to flow in from the outside of the electrode body 20 and the electrolyte to flow out to the inside of the electrode body 20. Figure 4 In the illustrated embodiment, the first region 261 is adjacent to the first end 201 and the second end 202 of the electrode body 20 in the separator 26 . Figure 6 In the embodiment shown, the first region 261 is a strip-shaped region provided at both ends of the spacer 26 in the short direction and along the long direction of the spacer 26. The second region 262 is, for example, a region of the spacer 26 other than the first region 261. Figure 4 In the embodiment shown, the second region 262 is sandwiched between the first regions 261. Figure 6 In the illustrated embodiment, the second region 262 is a band-shaped region sandwiched between the first regions 261 and extending along the longitudinal direction of the spacer 26 .

[0080] Although not particularly limited, Figure 6 The ratio of the width W1 of the first region 261 (on one side) to the width Wt of the spacer 26 (W1 / Wt) is approximately 1 / 8 to 1 / 2, preferably 1 / 4 to 1 / 3. The ratio of the width W2 of the second region 262 to the width Wt of the spacer 26 (W2 / Wt) is approximately 3 / 4 or less, preferably 1 / 3 to 1 / 2.

[0081] In this embodiment, the backflow prevention groove 27 is provided in the first region 261. For example, the backflow prevention groove 27 can be provided in the first region 261 so that the main pipe 27A is arranged along the short side direction of the spacer 26. In this embodiment, the groove 28 having a pattern different from that of the backflow prevention groove is provided in the second region 262 (see Figure 8 The pattern of the grooves 28 provided in the second region 262 is not particularly limited, and examples thereof include dot patterns, stripes along the short side direction of the spacer 26, and stripes along the long side direction of the spacer 26.

[0082] Figure 8 yes Figure 6 IIX-IIX cross-sectional view. Figure 8 , the cross-sectional structure of the first region 261 and the second region 262 of the spacer 26 is partially shown. Figure 8 As shown, the separator 26 includes a substrate 26S, a first layer 26A, and a second layer 26B. As the substrate 26S, any conventionally known porous sheet used as a separator for such a battery can be used without particular limitation. The substrate 26S can have a single-layer structure or a multilayer structure having two or more layers (e.g., a three-layer structure). The substrate 26S is preferably a porous sheet made of a polyolefin such as polyethylene (PE) or polypropylene (PP).

[0083] like Figure 8As shown, the first layer 26A is provided on the surface of the substrate 26S. In this embodiment, the first layer 26A is provided in the first region 261. Figure 8 In the embodiment shown, the backflow prevention groove 27 is provided in the first layer 26A. Figure 8 As shown, the second layer 26B is provided on the surface of the substrate 26S. In this embodiment, the second layer 26B is provided in the second region 262. Figure 8 In the illustrated embodiment, the grooves 28 are provided in the second layer 26B.

[0084] In the present embodiment, the first layer 26A and the second layer 26B are adhesive layers. The adhesive layer is, for example, a layer composed of an adhesive. Examples of adhesives include acrylic resins; fluorine resins such as polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE); rubber resins such as styrene butadiene rubber (SBR); polyurethane resins; silicone resins; epoxy resins, etc. Resins may be used alone or in combination of two or more. From the viewpoint of excellent flexibility and improved adhesion to the electrode, fluorine resins, acrylic resins, etc. may be preferably used as adhesives. The adhesive constituting the first layer 26A and the adhesive constituting the second layer 26B may be the same or different.

[0085] The method for forming the first layer 26A having the backflow prevention groove 27 is not particularly limited, and a conventionally known method can be used. As a method for forming the first layer 26A, for example, inkjet printing can be cited. In this case, a slurry for forming the first layer 26A by mixing the above-mentioned adhesive and a solvent or a dispersion medium (for example, an aqueous solvent, an organic solvent) is applied to the substrate 26S in a prescribed pattern. Next, by drying the coating, the first layer 26A having the backflow prevention groove 27 can be formed. The method for forming the second layer 26B having the groove 28 can be the same as the above method except that the groove 28 is formed instead of the backflow prevention groove 27.

[0086] The electrolyte solution includes, for example, an electrolyte salt and a non-aqueous solvent. Examples of the electrolyte salt include LiPF6. The concentration of the electrolyte salt in the electrolyte solution is, for example, 0.7 mol / L to 1.3 mol / L. The non-aqueous solvent may be, for example, a carbonate ester. Examples of the carbonate ester include ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), monofluoroethylene carbonate (MFEC), difluoroethylene carbonate (DFEC), monofluoromethyl difluoromethyl carbonate (F-DMC), dimethyl trifluorocarbonate (TFDMC), etc. They can be used alone or in combination of two or more.

[0087] Battery 1 is used in various applications, and is particularly preferably used as a power source (driving power source) for motors mounted on vehicles such as passenger cars and trucks. The type of vehicle is not particularly limited, but preferred examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0088] As described above, battery 1 includes: an electrode assembly 20 containing a positive electrode 22, a negative electrode 24, and a separator 26 that insulates the positive electrode 22 from the negative electrode 24; an electrolyte; and a case 10 that houses the electrode assembly 20 and the electrolyte. Battery 1 includes backflow prevention grooves 27 on the surface of separator 26. Backflow prevention grooves 27 are grooves that allow electrolyte to flow from the outside to the inside of electrode assembly 20 and are formed in a pattern that prevents electrolyte from flowing from the inside to the outside of electrode assembly 20.

[0089] As described above, the backflow prevention groove 27 is a groove that allows the electrolyte to flow from the outside of the electrode body 20 to the inside, while also preventing the electrolyte from flowing from the inside of the electrode body 20 to the outside. In other words, the backflow prevention groove 27 promotes the penetration of the electrolyte into the electrode body 20 while preventing the electrolyte from flowing out of the electrode body 20. By providing the separator 26 with the backflow prevention groove 27, the battery 1 can prevent the electrolyte from penetrating from the outside of the electrode body 20 to the inside of the electrode body 20 while preventing the electrolyte from flowing out of the inside of the electrode body 20. As a result, the uniformity of the electrolyte distribution within the electrode body 20 can be improved.

[0090] Alternatively, the battery 1 may include a backflow prevention groove 27 in a first region 261 that is open to the outside of the electrode body 20 at the edge of the separator 26. In other words, the separator 26 may include a backflow prevention groove 27 in the first region 261 that constitutes the edge. The first region 261 is, for example, a region in the electrode body 20 where the electrolyte flows into and out of the electrode body 20. Providing the backflow prevention groove 27 in the first region 261 can further prevent the electrolyte that has flowed (permeated) into the electrode body 20 from flowing out (backflowing) outside the electrode body 20.

[0091] Alternatively, the separator 26 may include a substrate 26S and a first layer 26A located on a surface of the substrate 26S. Alternatively, the first layer 26A may be provided in the first region 261. Alternatively, the backflow prevention groove 27 may be provided in the first layer 26A. By providing the first layer 26A with the backflow prevention groove 27 in the first region 261, in addition to preventing the outflow of the electrolyte, other effects (such as an adhesive effect) can be imparted to the separator 26.

[0092] Alternatively, the spacer 26 may have a second region 262 in addition to the first region 261. Alternatively, a second layer 26B may be provided on the surface of the substrate 26S in the second region 262. Alternatively, a groove 28 having a pattern different from the backflow prevention groove 27 may be provided in the second layer 26B. By providing the groove 28 having a pattern different from the backflow prevention groove 27 in the second region 262, it is easy to retain the electrolyte in the second region 262. As a result, the uniformity of the electrolyte distribution in the electrode body 20 can be improved. In addition, by providing the groove structure in the first region 261 and the second region 262, the uniformity of the thickness of the electrode body 20 can be improved.

[0093] Alternatively, the battery 1 may include a wound electrode body as the electrode body 20. This wound electrode body is formed by stacking a long sheet of positive electrode 22 and a long sheet of negative electrode 24 with a long sheet of separator 26 interposed therebetween, and then winding the electrode body along the longitudinal direction of the sheet. For example, compared to a stacked electrode body, a wound electrode body is more likely to have uneven electrolyte distribution. By using a separator 26 having the above-described structure in the wound electrode body 20, the effects of the technology disclosed herein can be further enhanced.

[0094] Alternatively, the backflow prevention groove 27 may include a main pipe 27A and an annular sub-pipe 27B connected to the main pipe 27A at two locations. Alternatively, the main pipe 27A may constitute a flow path for the electrolyte to flow from the outside to the inside of the electrode body 20 and a flow path for the electrolyte to flow from the inside to the outside of the electrode body 20. The backflow prevention groove 27 may be configured as follows when the electrolyte flows from the outside to the inside of the electrode body 20 and when the electrolyte flows from the inside to the outside of the electrode body 20. Alternatively, when the electrolyte flows from the outside to the inside of the electrode body 20, the electrolyte flowing in the main pipe 27A may be diverted from the main pipe 27A to the sub-pipe 27B at the first connection location 27C1 of the two connection locations 27C1 and 27C2 of the main pipe 27A and the sub-pipe 27B, which is arranged opposite to each other on the outside of the electrode body 20. In this case, the electrolyte flowing in the secondary pipe 27B may merge with the electrolyte flowing in the main pipe 27A at the second connection point 27C2, located opposite to the main pipe 27A and the secondary pipe 27B, located inside the electrode body 20. Alternatively, when the electrolyte flows from the interior of the electrode body 20 to the exterior, the electrolyte flowing in the main pipe 27A may be diverted from the main pipe 27A to the secondary pipe 27B at the second connection point 27C2. Alternatively, at the first connection point 27C1, the electrolyte flowing in the secondary pipe 27B may merge with the electrolyte flowing in the main pipe 27A from a direction opposite to the direction of the electrolyte flowing in the main pipe 27A (herein, the second direction Q). This configuration of the backflow prevention groove 27 is preferred for achieving the effects of the technology disclosed herein.

[0095] The backflow prevention groove 27 may also be provided in a Tesla valve shape. This structure in the backflow prevention groove 27 is preferable for achieving the effects of the technology disclosed herein.

[0096] The above descriptions of embodiments of the technology disclosed herein are merely illustrative and do not limit the scope of the claims. The technical solutions described in the claims include various variations and modifications of the aforementioned embodiments. Other embodiments of the technology disclosed herein are described below. In the following embodiments, the structures other than those described above are the same as those described in the aforementioned embodiments. Therefore, any repetitive descriptions are omitted.

[0097] In the above embodiment, the backflow prevention groove 27 is provided in a Tesla valve shape. However, the shape of the backflow prevention groove is not limited to the Tesla valve shape as long as the effects of the technology disclosed herein can be achieved. Figure 9 is a top view of the spacer 226. Figure 9 , the planar structure of the spacer 226 is partially enlarged. Figure 9 As shown, the spacer 226 has a backflow prevention groove 227. In this embodiment, the backflow prevention groove 227 has a main pipe 227A and a valve 227B. The main pipe 227A can, for example, constitute a flow path for the electrolyte to flow from the outside to the inside of the electrode body 20 and a flow path for the electrolyte to flow from the inside to the outside of the electrode body 20. The valve 227B is, for example, a portion that prevents the electrolyte from flowing from the inside to the outside of the electrode body 20. Figure 9 In the embodiment shown, valve 227B is disposed within main pipe 227A. Figure 9 In the embodiment, a plurality of valves 227B are provided in one main pipe 227A, but the number of valves 227B in one main pipe 227A is not particularly limited and can be appropriately changed. In addition, a valve can also be provided inside the backflow prevention groove 27 in the above-mentioned embodiment as needed.

[0098] The open surfaces (first end portion 201 and second end portion 202) of the electrode body 20 in the above embodiment are arranged to face the second side wall 12c of the case 10. However, the shape of the electrode body is not limited thereto. Figure 10 is a schematic diagram of the electrode body 320. Figure 10 As shown, the electrode body 320 is a wound electrode body. Figure 10 In the embodiment shown, in the electrode body 320, a long sheet-shaped positive electrode 322 and a long sheet-shaped negative electrode 324 are stacked with a long sheet-shaped separator 326 interposed therebetween and wound along the longitudinal direction of the sheet. In this embodiment, the electrode body 320 is housed in the case 10 (see FIG. 1 ) so that the winding axis WL3 of the electrode body 320 is substantially parallel to the vertical direction Z of the case 10. Figure 1 and Figure 2 ).

[0099] In this embodiment, the electrode body 320 is housed in the outer casing 12 in such a manner that the winding axis direction WD3 is substantially parallel to the first side wall 12b and the second side wall 12c and substantially perpendicular to the bottom 12a and the sealing plate 14. Therefore, the first end 3201 of the electrode body 20 faces the bottom 12a, and the second end 3202 faces the sealing plate 14. Here, the first end 3201 and the second end 3202 are the stacking surfaces of the positive electrode 322, the negative electrode 324, and the separator 326, and are open surfaces. Figure 10 As shown, the positive electrode tab 322t and the negative electrode tab 324t are both provided at the second end portion 3202 of the electrode body 320. Therefore, the positive electrode tab 322t and the negative electrode tab 324t face the sealing plate 14 (see Figure 2 ).

[0100] exist Figure 10 In the illustrated embodiment, the first region 3261 is adjacent to the first end 3201 and the second end 3202 of the electrode body 320 in the spacer 326 . Figure 10 In the embodiment shown, the first region 3261 is a strip-shaped region provided at both ends of the short side direction of the spacer 326 and along the long side direction of the spacer 326. The second region 3262 is, for example, a region of the spacer 326 other than the first region 3261. Figure 10 In the embodiment shown, the second region 3262 is sandwiched between the first regions 3261. In this embodiment, the second region 3262 is a strip-shaped region sandwiched between the first regions 3261 and along the long side direction of the spacer 326. For example, the backflow prevention groove can be provided in the first region 3261. Figure 10 , reference numeral “ 322 a ” denotes a positive electrode active material layer, reference numeral “ 322 c ” denotes a positive electrode current collector foil, reference numeral “ 322 p ” denotes a protective layer, reference numeral “ 324 a ” denotes a negative electrode active material layer, and reference numeral “ 324 c ” denotes a negative electrode current collector foil.

[0101] The electrode body 20 in the above embodiment is a wound electrode body, but the structure of the electrode body is not limited thereto. Figure 11 is a three-dimensional diagram of the electrode body 420. Figure 11 As shown, the electrode body 420 is a stacked electrode body. Figure 11 As shown, the electrode body 420 has a rectangular sheet-shaped positive electrode 422, a rectangular sheet-shaped negative electrode 424 and a rectangular sheet-shaped separator 426. In the present embodiment, the positive electrode 422 and the negative electrode 424 are alternately stacked with the separator 426 between them. In the present embodiment, the positive electrode 422 has a collector foil exposed portion 422t on which no positive electrode active material layer is provided at an end portion on one side in the long side direction. The negative electrode 424 has a collector foil exposed portion 424t on which no negative electrode active material layer is provided at an end portion on one side in the long side direction. In the electrode body 420, the collector foil exposed portions 422t of the positive electrode 422 overlap with each other, and the collector foil exposed portions 424t of the negative electrode 424 overlap with each other. In the present embodiment, the electrode body 420 is housed in the shell 10 (refer to) in such a manner that the short side direction of the electrode is substantially parallel to the up-down direction Z of the shell 10 and the long side direction of the electrode is substantially parallel to the long side direction Y of the shell 10. Figure 1 and Figure 2 ).

[0102] In this embodiment, in the electrode body 420, the two stacking surfaces of the electrode and the separator (here, the stacking surface at the first end 4201 and the stacking surface at the second end 4202), the stacking surface of the collector foil exposed portion 422t of the positive electrode 422, and the stacking surface of the collector foil exposed portion 424t of the negative electrode 424 are open surfaces. These four open surfaces are respectively opposite to the bottom 12a, the first side wall 12b or the second side wall 12c of the shell 10. Among them, the stacking surface of the collector foil exposed portion 422t of the positive electrode 22 is opposite to the second side wall 12c on one side. The stacking surface of the collector foil exposed portion 424t of the negative electrode 24 is opposite to the second side wall 12c on the other side (refer to Figure 2 ).

[0103] exist Figure 11 In the illustrated embodiment, the first region 4261 is provided along a pair of opposing long sides and a pair of opposing short sides in the spacer 426. The second region 4262 is, for example, a region of the spacer 426 other than the first region 4261. Figure 11 In the illustrated embodiment, the second region 4262 is surrounded by the first region 4261. The backflow prevention groove may be provided in the first region 4261, for example.

[0104] In the above embodiment, in the spacer 26, the first layer 26A and the second layer 26B serving as adhesive layers are provided on one side of the base material 26S. However, the structure of the spacer is not limited to this. For example, the first layer 26A and the second layer 26B serving as adhesive layers may be provided on both sides of the base material 26S. Alternatively, a heat-resistant layer may be provided between the base material 26S and the adhesive layer. In the case where a heat-resistant layer is provided, only the adhesive layer may be provided on the surface of one side of the base material 26S, and only the heat-resistant layer may be provided on the surface of the other side. Alternatively, only the adhesive layer may be provided on the surface of one side of the base material 26S, and both the heat-resistant layer and the adhesive layer may be provided on the surface of the other side. Alternatively, only the heat-resistant layer may be provided on the surface of one side of the base material 26S, and both the heat-resistant layer and the adhesive layer may be provided on the surface of the other side. In the case where both the heat-resistant layer and the adhesive layer are provided, the heat-resistant layer is preferably provided between the base material 26S and the adhesive layer. Furthermore, the structure of the heat-resistant layer may be any heat-resistant layer used in such applications without particular limitation. Since the structure of the heat-resistant layer itself does not contribute to the characteristics of the technology disclosed herein, its description is omitted here.

[0105] The technology disclosed herein may include the aspects described in the following items.

[0106] Item 1: An electricity storage device comprising:

[0107] an electrode body comprising a positive electrode, a negative electrode, and a separator for insulating the positive electrode from the negative electrode;

[0108] electrolyte; and

[0109] a housing for housing the electrode assembly and the electrolyte;

[0110] in,

[0111] The electricity storage device has a backflow prevention groove on the surface of the separator. The backflow prevention groove is a groove for the electrolyte to flow from the outside to the inside of the electrode body and is formed in a pattern to prevent the electrolyte from flowing from the inside to the outside of the electrode body.

[0112] Item 2: The power storage device according to Item 1, wherein

[0113] The electricity storage device includes the backflow prevention groove in a first region on the edge of the separator that is open to the outside of the electrode body.

[0114] Item 3: The power storage device according to Item 2, wherein:

[0115] The spacer comprises a substrate and a first layer located on a surface of the substrate.

[0116] The first layer is provided in the first area,

[0117] The backflow prevention groove is provided on the first layer.

[0118] Item 4: The power storage device according to Item 2 or 3, wherein

[0119] The spacer has a second region other than the first region,

[0120] The surface of the substrate in the second region is provided with a second layer,

[0121] The second layer is provided with grooves having a pattern different from that of the backflow prevention grooves.

[0122] Item 5: The power storage device according to any one of Items 1 to 4, wherein

[0123] The electricity storage device includes a wound electrode body as the electrode body, wherein the long sheet-shaped positive electrode and the long sheet-shaped negative electrode are stacked with the long sheet-shaped separator interposed therebetween and wound in the longitudinal direction of the sheet.

[0124] Item 6: The power storage device according to any one of Items 1 to 4, wherein

[0125] The electricity storage device includes, as the electrode body, a laminated electrode body in which the rectangular sheet-shaped positive electrodes and the rectangular sheet-shaped negative electrodes are alternately laminated with the rectangular sheet-shaped separator interposed therebetween.

[0126] Item 7: The power storage device according to any one of Items 1 to 6, wherein

[0127] The backflow prevention groove includes a main pipe and an annular sub-pipe connected to the main pipe at two locations.

[0128] The main pipe constitutes a flow path for the electrolyte to flow from the outside to the inside of the electrode body and a flow path for the electrolyte to flow from the inside to the outside of the electrode body.

[0129] The backflow prevention groove is composed of:

[0130] When the electrolyte flows from the outside to the inside of the electrode body,

[0131] At a first connection point, which is disposed opposite to the outside of the electrode body, of the two connection points between the main pipe and the sub-pipe, the electrolyte flowing in the main pipe is branched from the main pipe to the sub-pipe.

[0132] At the second connection point, which is located on the inner side of the electrode body and faces each other, the electrolyte flowing in the sub-pipe merges with the electrolyte flowing in the main pipe along the flow direction of the electrolyte flowing in the main pipe.

[0133] When the electrolyte flows from the inside to the outside of the electrode body,

[0134] At the second connection portion, the electrolyte flowing in the main pipe is branched from the main pipe to the sub-pipe.

[0135] At the first connection portion, the electrolyte flowing in the sub-pipe merges with the electrolyte flowing in the main pipe from a direction opposite to the flow direction of the electrolyte flowing in the main pipe.

[0136] Item 8: The power storage device according to any one of Items 1 to 6, wherein

[0137] The backflow prevention groove is configured in a Tesla valve shape.

[0138] Item 9: A separator used for an electricity storage device, the electricity storage device comprising:

[0139] an electrode body comprising a positive electrode, a negative electrode, and a separator for insulating the positive electrode from the negative electrode;

[0140] electrolyte; and

[0141] a housing for housing the electrode assembly and the electrolyte;

[0142] in,

[0143] The separator has a backflow prevention groove on its surface. The backflow prevention groove is a groove through which the electrolyte solution flows from the outside to the inside of the electrode body and is formed in a pattern that prevents the electrolyte solution from flowing from the inside to the outside of the electrode body.

[0144] Item 10: The spacer according to Item 9, wherein:

[0145] The spacer includes the backflow prevention groove in a first region constituting an edge portion.

[0146] Item 11: The spacer according to Item 10, wherein

[0147] The separator includes a base material and a first layer located on a surface of the base material in the first region, and the first layer includes the backflow prevention groove.

[0148] Item 12: The spacer according to Item 10 or 11, wherein

[0149] The separator includes a second layer in a second region other than the first region, and grooves having a pattern different from that of the backflow prevention grooves are provided in the second layer.

[0150] Item 13: The spacer according to any one of Items 9 to 12, wherein

[0151] The backflow prevention groove includes a main pipe and an annular sub-pipe connected to the main pipe at two locations.

[0152] The main pipe constitutes a flow path for the electrolyte to flow from the outside to the inside of the electrode body and a flow path for the electrolyte to flow from the inside to the outside of the electrode body.

[0153] The backflow prevention groove is composed of:

[0154] When the electrolyte flows from the outside to the inside of the electrode body,

[0155] At a first connection point, which is disposed opposite to the outside of the electrode body, of the two connection points between the main pipe and the sub-pipe, the electrolyte flowing in the main pipe is branched from the main pipe to the sub-pipe.

[0156] At the second connection point, which is located on the inner side of the electrode body and faces each other, the electrolyte flowing in the sub-pipe merges with the electrolyte flowing in the main pipe along the flow direction of the electrolyte flowing in the main pipe.

[0157] When the electrolyte flows from the inside to the outside of the electrode body,

[0158] At the second connection portion, the electrolyte flowing in the main pipe is branched from the main pipe to the sub-pipe.

[0159] At the first connection portion, the electrolyte flowing in the sub-pipe merges with the electrolyte flowing in the main pipe from a direction opposite to the flow direction of the electrolyte flowing in the main pipe.

[0160] Item 14: The spacer according to any one of Items 9 to 13, wherein

[0161] The backflow prevention groove is configured in a Tesla valve shape.

Claims

1. An electricity storage device comprising: an electrode body comprising a positive electrode, a negative electrode, and a separator for insulating the positive electrode from the negative electrode; electrolyte; and a housing for housing the electrode assembly and the electrolyte; in, The electricity storage device has a backflow prevention groove on the surface of the separator. The backflow prevention groove is a groove for the electrolyte to flow from the outside to the inside of the electrode body and is formed in a pattern to prevent the electrolyte from flowing from the inside to the outside of the electrode body.

2. The power storage device according to claim 1, wherein The electricity storage device includes the backflow prevention groove in a first region on the edge of the separator that is open to the outside of the electrode body.

3. The power storage device according to claim 2, wherein The spacer comprises a substrate and a first layer located on a surface of the substrate. The first layer is provided in the first area, The backflow prevention groove is provided on the first layer.

4. The power storage device according to claim 3, wherein The spacer has a second region other than the first region, The surface of the substrate in the second region is provided with a second layer, The second layer is provided with grooves having a pattern different from that of the backflow prevention grooves.

5. The power storage device according to any one of claims 1 to 4, wherein The electricity storage device includes a wound electrode body as the electrode body, wherein the long sheet-shaped positive electrode and the long sheet-shaped negative electrode are stacked with the long sheet-shaped separator interposed therebetween and wound in the longitudinal direction of the sheet.

6. The power storage device according to any one of claims 1 to 4, wherein The electricity storage device includes, as the electrode body, a laminated electrode body in which the rectangular sheet-shaped positive electrodes and the rectangular sheet-shaped negative electrodes are alternately laminated with the rectangular sheet-shaped separator interposed therebetween.

7. The power storage device according to any one of claims 1 to 4, wherein The backflow prevention groove includes a main pipe and an annular sub-pipe connected to the main pipe at two locations. The main pipe constitutes a flow path for the electrolyte to flow from the outside to the inside of the electrode body and a flow path for the electrolyte to flow from the inside to the outside of the electrode body. The backflow prevention groove is composed of: When the electrolyte flows from the outside to the inside of the electrode body, At a first connection point, which is disposed opposite to the outside of the electrode body, of the two connection points between the main pipe and the sub-pipe, the electrolyte flowing in the main pipe is branched from the main pipe to the sub-pipe. At the second connection point, which is located on the inner side of the electrode body and faces each other, the electrolyte flowing in the sub-pipe merges with the electrolyte flowing in the main pipe along the flow direction of the electrolyte flowing in the main pipe. When the electrolyte flows from the inside to the outside of the electrode body, At the second connection portion, the electrolyte flowing in the main pipe is branched from the main pipe to the sub-pipe. At the first connection portion, the electrolyte flowing in the sub-pipe merges with the electrolyte flowing in the main pipe from a direction opposite to the flow direction of the electrolyte flowing in the main pipe.

8. The power storage device according to claim 7, wherein The backflow prevention groove is configured in a Tesla valve shape.

9. A separator used for an electricity storage device, the electricity storage device comprising: an electrode body comprising a positive electrode, a negative electrode, and a separator for insulating the positive electrode from the negative electrode; electrolyte; and a housing for housing the electrode assembly and the electrolyte; in, The separator has a backflow prevention groove on its surface. The backflow prevention groove is a groove through which the electrolyte solution flows from the outside to the inside of the electrode body and is formed in a pattern that prevents the electrolyte solution from flowing from the inside to the outside of the electrode body.

10. The spacer according to claim 9, wherein The spacer includes the backflow prevention groove in a first region constituting an edge portion. The spacer according to claim 10 , wherein: The separator includes a base material and a first layer located on a surface of the base material in the first region, and the first layer includes the backflow prevention groove.

12. The spacer according to claim 11, wherein The separator includes a second layer in a second region other than the first region, and grooves having a pattern different from that of the backflow prevention grooves are provided in the second layer.

13. The spacer according to any one of claims 9 to 12, wherein The backflow prevention groove includes a main pipe and an annular sub-pipe connected to the main pipe at two locations. The main pipe constitutes a flow path for the electrolyte to flow from the outside to the inside of the electrode body and a flow path for the electrolyte to flow from the inside to the outside of the electrode body. The backflow prevention groove is composed of: When the electrolyte flows from the outside to the inside of the electrode body, At a first connection point, which is disposed opposite to the outside of the electrode body, of the two connection points between the main pipe and the sub-pipe, the electrolyte flowing in the main pipe is branched from the main pipe to the sub-pipe. At the second connection point, which is located on the inner side of the electrode body and faces each other, the electrolyte flowing in the sub-pipe merges with the electrolyte flowing in the main pipe along the flow direction of the electrolyte flowing in the main pipe. When the electrolyte flows from the inside to the outside of the electrode body, At the second connection portion, the electrolyte flowing in the main pipe is branched from the main pipe to the sub-pipe. At the first connection portion, the electrolyte flowing in the sub-pipe merges with the electrolyte flowing in the main pipe from a direction opposite to the flow direction of the electrolyte flowing in the main pipe.

14. The spacer according to claim 13, wherein The backflow prevention groove is configured in a Tesla valve shape.

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