Method for manufacturing an electricity storage device, and electricity storage device

Abstract

To provide technology that increases the efficiency of impregnating a wound electrode body with an electrolytic solution.SOLUTION: According to the technology disclosed here, a manufacturing method for a power storage device 1 comprising an electrode body 20, a case 10, and an electrolytic solution is provided. The case 10 is of a rectangular parallelepiped shape, and has an outer package 12 having a wide rectangular first wall 12a and an opening 12h facing the first wall 12a, and a wide rectangular sealing plate 14 for sealing the opening 12h and facing the first wall 12a. The manufacturing method includes an accommodation step, a liquid injection step, and a sealing step. In the accommodation step, the electrode body 20 is accommodated in the outer package 12 so that the wide face 20a and the first wall 12a face each other. In the liquid injection step, an electrolytic solution is injected into the outer package 12 after the accommodation step. In the sealing step, the opening 12h of the outer package 12 is sealed with the sealing plate 14 after the liquid injection step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electricity storage device, and to an electricity storage device. [Background technology]

[0002] In the lithium-ion battery disclosed in Patent Document 1, spacers are disposed at each corner between the prismatic battery case and the spiral-shaped electrode element, with at least a portion of the spacer being in close contact with the electrode element. Furthermore, a space is provided behind each spacer as an escape route for air bubbles. This document describes how, when a lithium-ion battery receives an external impact from the prismatic battery case, the impact is concentrated at the top of the rounded portion of the short side of the electrode element. However, with the above-described configuration, the spacer disperses the impact, reducing transmission of the impact to the electrode element and improving the impact resistance of the lithium-ion battery. Furthermore, when pouring electrolyte into the prismatic battery case, air bubbles escape not only from the top surface of the electrode element but also from the space provided behind the spacer. This improves the permeability of the electrolyte into the electrode element and shortens the pouring time.

[0003] The nonaqueous electrolyte secondary battery disclosed in Patent Document 2 includes an electrode stack and a case that houses the electrode stack, and a pressure member is attached to apply pressure to the electrode stack in the electrode stacking direction. This nonaqueous electrolyte secondary battery uses a thin flat spring processed into a shape that generates elasticity in a direction perpendicular to the plate surface as the pressure member. The thin flat spring is disposed in the gap between the inner surface of the case and the electrode stack. This document describes how the electrode stack can be compressed by a simple configuration in which a thin flat spring is processed into a predetermined shape and disposed in the gap between the inner surface of the case and the electrode stack. It also describes how this configuration can extend the charge / discharge cycle life of the nonaqueous electrolyte secondary battery.

[0004] In the flat prismatic battery disclosed in Patent Document 3, the main case is formed as a half-shell made of a processed metal plate with a flange around the opening of the recess. A plate assembly is housed in the recess. A metal cover plate is disposed with its peripheral portion overlapping the flange and welded to the flange. Furthermore, in this battery, a recess is formed in the main case and / or cover plate in a direction that reduces the thickness of the battery. This publication states that when the plate assembly housed in the case expands or internal pressure increases, causing a force in the bulging direction to act on the case, the recess in the cover plate, which has a lower deformation strength than the main case, bulges outward. This does not affect the overall thickness of the case, and the bulging does not affect the device in which the flat prismatic battery is installed. Therefore, it is stated that this configuration can contribute to achieving thinner devices. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-216239 [Patent Document 2] Japanese Patent Application Publication No. 10-334879 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-103368 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors wish to improve the efficiency with which the wound electrode body is impregnated with the electrolyte. [Means for solving the problem]

[0007] The disclosed method for manufacturing an electricity storage device includes an electrode assembly having a pair of opposing wide surfaces, an outer casing having a wide rectangular first wall and an opening facing the first wall, and a wide rectangular sealing plate facing the first wall and sealing the opening, and an electrolyte. The manufacturing method includes a housing step of housing the electrode assembly in the outer casing so that the wide surface faces the first wall, a liquid injection step of injecting the electrolyte into the outer casing after the housing step, and a liquid sealing step of sealing the opening of the outer casing with the liquid injection step. This manufacturing method can improve the efficiency of impregnation of the electrolyte into the electrode assembly (wound electrode assembly).

[0008] In a preferred embodiment of the manufacturing method disclosed herein, the liquid injection step is carried out under a negative pressure state, which can further increase the efficiency of impregnation of the electrode assembly with the electrolyte.

[0009] In another preferred aspect of the manufacturing method disclosed herein, in the liquid injection step, the electrolyte solution is injected into the exterior body through the opening. With this configuration, in addition to the above-mentioned effects, liquid injection can be performed more easily.

[0010] In another preferred aspect of the manufacturing method disclosed herein, in the sealing step, the opening of the exterior body is sealed while pressing the wide surface of the electrode assembly with the sealing plate. With this configuration, it is possible to reduce the inter-electrode distance in the electrode assembly after it has been sufficiently impregnated with the electrolyte.

[0011] In another preferred embodiment of the manufacturing method disclosed herein, the sealing step uses a sealing plate having a protrusion, which makes it possible to maintain a small inter-electrode distance.

[0012] In another preferred embodiment of the manufacturing method disclosed herein, a pressing force of at least 6 kN is applied to the wide surface of the electrode assembly in the sealing step, which makes it possible to maintain a desirable inter-electrode distance.

[0013] The technology disclosed herein also provides an electricity storage device comprising: an electrode assembly in which a long, sheet-like positive electrode and a long, sheet-like negative electrode are wound in the sheet longitudinal direction with a separator interposed therebetween, the electrode assembly having a pair of opposing wide surfaces; a rectangular parallelepiped case that houses the electrode assembly, the case having a wide, rectangular first wall and an opening facing the first wall, and a wide, rectangular sealing plate facing the first wall and sealing the opening; and an electrolyte. This electricity storage device does not have a liquid injection hole for injecting the electrolyte into the case. In an electricity storage device configured as described above, since no liquid injection hole is provided, the electrolyte is injected through the opening in the exterior body. This improves the efficiency of impregnation of the electrolyte into the electrode assembly.

[0014] In a preferred aspect of the electricity storage device disclosed herein, the sealing plate has a protrusion that protrudes toward the wide surface of the electrode assembly. With this configuration, a preferred inter-electrode distance can be maintained in the electrode assembly.

[0015] Preferably, the convex portion is further provided with a rib portion that protrudes toward the wide surface. With this configuration, the above-mentioned effect can be enhanced. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view of an electricity storage device 1. FIG. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Figure 3] FIG. 3 is an exploded perspective view of the case 10. As shown in FIG. [Figure 4] FIG. 4 is a schematic diagram of the electrode body 20. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the technology disclosed herein will be described below. The embodiment described herein is not intended to limit the technology disclosed herein. The technology disclosed herein is not limited to the embodiment described herein unless otherwise specified. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, members and parts that perform the same function are appropriately designated by the same reference numerals, and redundant explanations will be omitted. Furthermore, the notation "A to B" indicating a numerical range means "greater than or equal to A and less than or equal to B" unless otherwise specified, and also encompasses the meaning of "greater than A and less than B."

[0018] In this specification, the term "electricity storage device" refers to a device in which charging and discharging occur by the movement of charge carriers between a pair of electrodes (positive and negative electrodes) via an electrolyte. Such electricity 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. In the following, an embodiment will be described in which a lithium ion secondary battery is used as an example of the above-mentioned electricity storage device.

[0019] Fig. 1 is a perspective view of the electricity storage device 1. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 2 shows a cross-sectional view along the first wall 12a of the case 10. Fig. 3 is an exploded perspective view of the case 10. Fig. 3 shows the exterior body 12 and the sealing plate 14 removed from the opening 12h of the exterior body 12.

[0020] <Electricity storage device 1> The technology disclosed herein provides an electricity storage device 1. As shown in Figures 1 and 2, the electricity storage device 1 includes a case 10, an electrode assembly 20, a positive electrode terminal 30, a negative electrode terminal 40, a positive electrode current collector 50, a negative electrode current collector 60, an electrolyte (not shown), and various insulating members.

[0021] -Case 10- The case 10 is, for example, a rectangular parallelepiped (hexahedral) member that houses the electrode assembly 20. As shown in FIG. 1, the case 10 includes an exterior body 12 and a sealing plate 14. The exterior body 12 is, for example, the main body of the case 10 that houses the electrode assembly 20 therein. As shown in FIGS. 1 to 3, the exterior body 12 has an opening 12h, a first wall 12a, a pair of opposing second walls 12b and 12c, and a pair of opposing third walls 12d and 12e. In this embodiment, the first wall 12a has a wide rectangular shape and faces the opening 12h. The pair of second walls 12b and 12c extend from a pair of opposing long sides of the first wall 12a. As shown in FIGS. 1 and 2, the lower second wall 12c forms the bottom surface of the electricity storage device 1. The upper second wall 12b is the top surface facing the bottom surface and serves as an attachment surface for electrode terminals. The pair of third walls 12d, 12e extend from a pair of opposing short sides of the first wall 12a. In this specification, the term "rectangular" includes shapes in which linear long and short sides are joined to each other via curves, and shapes in which at least one of the long and short sides is not linear but is curved, uneven, or bent and composed of multiple straight or curved lines.

[0022] Opening 12h is, for example, a portion where sealing plate 14 is attached. Here, opening 12h is formed by being surrounded by the upper edges of the pair of second walls 12b and 12c and the upper edges of the pair of third walls 12d and 12e, and has a wide rectangular shape. As shown in FIG. 3, opening 12h has a recessed step 121 along its inner edge. Here, sealing plate 14 is fitted into step 121. Furthermore, by joining (e.g., welding) sealing plate 14 to step 121, exterior body 12 and sealing plate 14 are integrated, and case 10 is airtightly sealed.

[0023] In the embodiment shown in FIG. 3, the first wall 12a is provided with a protrusion 122 and a rib portion 123. The protrusion 122 is, for example, a portion that protrudes from the first wall 12a toward the inside of the case 10. Here, the protrusion 122 has a pair of opposing short side walls 122a, a pair of opposing long side walls 122b, and a flat surface 122c. As shown in FIG. 3, the short side walls 122a rise from the first wall 12a toward the inside of the case 10 along a pair of opposing short sides of the first wall 12a. The long side walls 122b rise from the first wall 12a toward the inside of the case 10 along a pair of opposing long sides of the first wall 12a. Here, the flat surface 122c is surrounded by the tips of the pair of opposing short side walls 122a and the tips of the pair of opposing long side walls 122b. The flat surface 122c faces, for example, the wide surface 20a of the electrode body 20 (see FIGS. 1 to 3). From the viewpoint of efficiently applying a pressing force to the electrode body 20, when the area of ​​the wide surface 20a is taken as 1, the area of ​​the flat surface 122c is, for example, 0.7 or more, preferably 0.8 or more, and more preferably 0.9 or more, and is not particularly limited to, but may be 1.3 or less, 1.2 or less, or 1.1 or less.

[0024] The rib portion 123 is, for example, a portion that protrudes from the flat surface 122c toward the inside of the case 10 (toward the wide surface 20a of the electrode assembly 20). In the embodiment shown in FIG. 3, the rib portion 123 may be provided, for example, in the form of stripes arranged in a predetermined pattern. The shape of each rib that constitutes the rib portion 123 may be the same as or different from the shape of each rib in the rib portion 142 of the sealing plate 14. Here, the tip of the rib portion 123 contacts the wide surface 20a of the electrode assembly 20. By providing the protrusions 122 and the rib portion 123, for example, it is possible to apply a pressing force to the wide surface 20a of the electrode assembly 20, thereby maintaining a preferable inter-electrode distance in the electrode assembly 20. Note that the protrusions 122 and the rib portion 123 are not essential and may be omitted in other embodiments.

[0025] As shown in FIGS. 1 to 3, the second wall 12b is provided with a discharge valve 126, a first terminal mounting portion 124, and a second terminal mounting portion 125. The discharge valve 126 is, for example, a thin-walled portion. Here, the discharge valve 126 is configured to break when the pressure inside the case 10 reaches a predetermined value or higher, thereby discharging gas inside the case 10 to the outside. The first terminal mounting portion 124 is, for example, a portion to which the positive electrode terminal 30 is attached. In the embodiment shown in FIGS. 1 to 3, the first terminal mounting portion 124 is a step recessed from the second wall 12b. A through-hole 18 through which the positive electrode terminal 30 is inserted is provided at the bottom of the first terminal mounting portion 124. The second terminal mounting portion 125 is, for example, a portion to which the negative electrode terminal 40 is attached. In the embodiment shown in FIGS. 1 to 3, the second terminal mounting portion 125 is a step recessed from the second wall 12b. The second terminal attachment portion 125 has a bottom provided with a through-hole 19 through which the negative electrode terminal 40 is inserted.

[0026] The sealing plate 14 is, for example, a flat plate-like member that seals the opening 12h. Therefore, the shape of the sealing plate 14 may correspond to the shape of the opening 12h. In this embodiment, the sealing plate 14 is a wide rectangle. Here, when the sealing plate 14 is attached to the opening 12h, the sealing plate 14 faces the first wall 12a. As shown in FIG. 3, the sealing plate 14 has a pair of opposing long sides 14a, 14b and a pair of opposing short sides 14c, 14d. Here, the long side 14a rests on the bottom of the step 121 in the second wall 12b. The long side 14b rests on the bottom of the step 121 in the second wall 12c. The short side 14c rests on the bottom of the step 121 in the third wall 12d. The short side portion 14d rests on the bottom of the step 121 in the third wall 12e.

[0027] As shown in FIGS. 1 and 3, the sealing plate 14 has a protrusion 141, a rib portion 142, and an edge portion 143. The protrusion 141 has, for example, a pair of opposing short side walls 141a, a pair of opposing long side walls 141b, and a flat surface 141c. As shown in FIG. 3, the short side wall 141a rises from the edge portion 143 toward the inside of the case 10 along a pair of opposing short sides 14c and 14d of the sealing plate 14. The long side wall 141b rises from the edge portion 143 toward the inside of the case 10 along a pair of opposing long sides 14a and 14b of the sealing plate 14. Here, the flat surface 141c is surrounded by the tips of the pair of opposing short side walls 141a and the tips of the pair of opposing long side walls 141b. The flat surface 141c faces, for example, the wide surface 20a of the electrode body 20 (see FIGS. 1 to 3). From the viewpoint of efficiently applying a pressing force to the electrode body 20, the area of ​​the flat surface 141c is, for example, 0.7 to 0.9 when the area of ​​the wide surface 20a is 1. The height of the protrusion 141 is not particularly limited and can be set appropriately.

[0028] The rib portion 142 is, for example, a portion that protrudes from the flat surface 141c toward the inside of the case 10. In the embodiment shown in FIGS. 1 and 3, the rib portion 142 is formed on the flat surface 141c. The rib portion 142 protrudes from the flat surface 141c toward the wide surface 20a of the electrode body 20 (toward the inside of the case 10). The rib portion 142 may be provided, for example, in the form of stripes arranged in a predetermined pattern. In the embodiment shown in FIG. 1, the rib portion 142 has a first rib 142a, a pair of second ribs 142b, a pair of third ribs 142c, a pair of fourth ribs 142d, a pair of fifth ribs 142e, a pair of sixth ribs 142f, and a pair of seventh ribs 142g, which have mutually different shapes.

[0029] In this embodiment, the first rib 142a and the pair of second ribs 142b to the pair of sixth ribs 142f each have straight line segments L1 to L6 aligned along the pair of opposing long sides 14a, 14b of the sealing plate 14. The first rib 142a and the pair of second ribs 142b to the pair of sixth ribs 142f each have curved portions R1 to R6 extending from one end of the straight line segments L1 to L6 toward the long side 14a (the long side on the second wall 12b side, which is the terminal mounting surface side of the exterior body 12) of the sealing plate 14 toward the opposite long side 14b. Here, the first rib 142a is generally T-shaped and includes a straight line segment LA in addition to the straight line segment L1 and curved portion R1. The straight line segment LA extends from the curved portion R1 toward the long side 14b. Furthermore, a recess 142a1 having a substantially triangular shape in plan view is provided at a connecting portion between the straight portion L1, the curved portion R1, and the LA. Here, the recess 142a1 is recessed from the inside toward the outside of the case 10. By providing the recess 142a1, no pressing force is applied to the connecting portion. This makes it possible to suppress a decrease in performance of the electricity storage device 1. The pair of third ribs 142c are substantially L-shaped and have a straight portion LB in addition to the straight portion L3 and the curved portion R3. The straight portion LB extends from the curved portion R3 toward the long side portion 14b. Here, the pair of seventh ribs 142g have a substantially rectangular shape in plan view. The pair of seventh ribs 142g are arranged so that their long sides are aligned with the long side portion 14b. In FIG. 1, the pair of seventh ribs 142g are provided so as to be surrounded by the pair of sixth ribs 142f, one short side portion 14c or the other short side portion 14d, and the long side portion 14b.

[0030] 1, the end of the curved portion R2 of the second rib 142b (the end opposite the straight portion L2) is sandwiched between the curved portion R1 of the first rib 142a and the curved portion R3 of the third rib 142c. Also, the end of the curved portion R4 of the fourth rib 142d (the end opposite the straight portion L4) is sandwiched between the curved portion R3 of the third rib 142c and the curved portion R5 of the fifth rib 142e. In addition, the end of the straight portion LA of the first rib 142a (one end opposite the curved portion R1), the end of the straight portion LB of the pair of third ribs 142c (one end opposite the curved portion R3), the end of the curved portion R5 of the pair of fifth ribs 142e (one end opposite the straight portion L5), the end of the curved portion R6 of the pair of sixth ribs 142f (one end opposite the straight portion L6), and the pair of seventh ribs 142g are arranged along the long side portion 14b.

[0031] The rib portion 142 having the above-described shape can efficiently apply a pressing force to the wide surface 20a, thereby realizing a preferable inter-electrode distance. In addition, the linear pressure can prevent the electrolyte from being pushed out from the inside to the outside of the electrode body 20 due to expansion and contraction of the electrode body 20. Therefore, the rib portion 142 can prevent the electrolyte from being depleted in the electrode body 20 when the electricity storage device 1 is charged and discharged.

[0032] Here, the protruding tips of each rib constituting the rib portion 142 contact the wide surface 20a of the electrode assembly 20. When the opening 12h is sealed with the sealing plate 14, the rib portion 142 applies a pressing force to the wide surface 20a of the electrode assembly 20. When the area of ​​the flat surface 141c is 1, the contact area between the rib portion 142 and the wide surface 20a (the total area of ​​the protruding tips of each rib in the rib portion 142) is, for example, 0.2 to 0.8, preferably 0.3 or more, more preferably 0.4 or more, or 0.7 or less, preferably 0.6 or less. This allows a suitable inter-electrode distance to be maintained. The height of each rib is not particularly limited and can be set as appropriate.

[0033] Here, edge portion 143 is a portion provided on the periphery of sealing plate 14. As shown in FIGS. 1 and 3, edge portion 143 is provided along a pair of long sides 14a, 14b and a pair of short sides 14c, 14d. Edge portion 143 is also provided around protrusion 141. Here, edge portion 143 does not have any irregularities, through holes, or the like.

[0034] In this embodiment, the case 10 is not provided with a liquid injection hole for injecting the electrolyte into the case 10. As will be described later in the description of the manufacturing method, when the electrolyte is injected into the case 10, it is injected through the opening 12h.

[0035] -Electrode body 20- The electrode assembly 20 is a power generating element of the electricity storage device 1, having, for example, a positive electrode and a negative electrode. FIG. 4 is a schematic diagram of the electrode assembly 20. As shown in FIG. 4, the electrode assembly 20 is a wound electrode assembly in which a long sheet-like positive electrode 22 and a long sheet-like negative electrode 24 are wound in the sheet longitudinal direction LD with a separator 23 interposed therebetween. The electrode assembly 20 can be produced, for example, by winding the positive electrode 22, the negative electrode 24, and the separator 23 into a cylindrical body and press-molding the cylindrical body. Therefore, the electrode assembly 20 has a flat shape and has a pair of wide surfaces 20a (see FIG. 2).

[0036] As shown in FIGS. 2 and 4, the electrode assembly 20 is housed in the exterior housing 12 so that the winding axis direction WD is approximately parallel to the up-down direction of the electricity storage device 1. In this embodiment, the winding axis WL of the electrode assembly 20 is approximately parallel to the first wall 12a, the third walls 12d and 12e, and the sealing plate 14, and is approximately perpendicular to the second walls 12b and 12c. The wide surface 20a of the electrode assembly 20 faces the first wall 12a and the sealing plate 14. One end face of the electrode assembly 20 faces the second wall 12b, and the other end face faces the second wall 12c. Here, the end faces of the electrode assembly 20 are the stacking surfaces of the positive electrode 22, the negative electrode 24, and the separator 23, and are open surfaces.

[0037] 4, the positive electrode 22 has a long, strip-shaped 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 portion in the winding axis direction WD of the positive electrode 22, as necessary. Note that, as the constituent materials of the positive electrode active material layer 22a and the protective layer 22p, materials used in this type of electricity storage device (in this embodiment, a lithium ion secondary battery) may be used without particular limitation.

[0038] A plurality of positive electrode tabs 22t are provided at one end of the positive electrode current collector foil 22c in the winding axis direction WD (the upper end in FIG. 4). The plurality of positive electrode tabs 22t protrude toward one end of the winding axis direction WD (the upper end in FIG. 4). The plurality of positive electrode tabs 22t are provided at intervals (intermittently) along the longitudinal direction LD of the positive electrode 22. The positive electrode tabs 22t are part of the positive electrode current collector foil 22c and are portions of the positive electrode current collector foil 22c where the positive electrode active material layer 22a is not formed (active material layer unformed portions). In the embodiment shown in FIG. 4, a protective layer 22p is provided on the base end side of the positive electrode tab 22t. In this embodiment, the plurality of positive electrode tabs 22t protrude further in the winding axis direction WD than the separator 23. The plurality of positive electrode tabs 22t are stacked at one end of the winding axis direction WD (the upper end in FIG. 4) to form a positive electrode tab group. Therefore, the height (length in the winding axis direction WD) of each positive electrode tab 22t and the width (length in the longitudinal direction LD) of each positive electrode tab 22t do not need to be the same. As shown in Fig. 2, a positive electrode current collector 50 is joined to the stacked positive electrode tabs 22t (positive electrode tab group).

[0039] 4, the negative electrode 24 has a long, strip-shaped negative electrode current collector foil 24c (e.g., copper foil) and a negative electrode active material layer 24a fixed to at least one surface of the negative electrode current collector foil 24c. Note that, as a constituent material of the negative electrode active material layer 24a, any material used in this type of electricity storage device (in this embodiment, a lithium ion secondary battery) may be used without any particular limitation.

[0040] A plurality of negative electrode tabs 24t are provided at one end of the negative electrode current collector foil 24c in the winding axis direction WD (the upper end in FIG. 4). The plurality of negative electrode tabs 24t protrude toward one end of the winding axis direction WD (the upper end in FIG. 4). The plurality of negative electrode tabs 24t are provided at intervals (intermittently) along the longitudinal direction LD of the negative electrode 24. The negative electrode tabs 24t are part of the negative electrode current collector foil 24c, and are portions of the negative electrode current collector foil 24c where the negative electrode active material layer 24a is not formed (active material layer unformed portions). In this embodiment, the plurality of negative electrode tabs 24t protrude further in the winding axis direction WD than the separator 23. For example, the plurality of negative electrode tabs 24t are stacked at one end of the winding axis direction WD (the upper end in FIG. 4) to form a negative electrode tab group. Therefore, the height (length in the winding axis direction WD) of each negative electrode tab 24t and the width (length in the longitudinal direction LD) of each negative electrode tab 24t do not need to be the same. As shown in Fig. 2, a negative electrode current collector 60 is joined to the stacked negative electrode tabs 24t (negative electrode tab group).

[0041] The separator 23 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. In this embodiment, the separator 23 forms the outer surface of the electrode body 20. The separator 23 is, for example, a porous sheet made of a resin such as a polyolefin resin, such as polyethylene (PE) or polypropylene (PP).

[0042] 4, in the electrode assembly 20, the lower end P3 of the separator 23 is the lowest, followed by the lower end P2 of the negative electrode 24, and the lower end P1 of the positive electrode 22 is the highest. The widths of the sheets (in FIG. 4, the length in the winding axis direction WD, excluding the positive electrode tab 22t and the negative electrode tab 24t) are largest in the order of the separator 23, the negative electrode 24, and the positive electrode 22.

[0043] -Positive terminal 30- The positive electrode terminal 30 is, for example, a member electrically connected to the positive electrode 22 of the electrode assembly 20. As shown in FIG. 2, the positive electrode terminal 30 is inserted through the through-hole 18 and exposed to the outside of the exterior body 12. Here, the positive electrode terminal 30 has a first conductive member 31 and a second conductive member 32. In this embodiment, the first conductive member 31 has a shaft portion 31a and a base portion 31b. The shaft portion 31a is, for example, cylindrical and is a portion inserted into the through-hole 18 and the through-hole of the second conductive member 32. The base portion 31b is, for example, flat and is a portion disposed along the outer surface of the exterior body 12 (here, the second wall 12b). The second conductive member 32 is, for example, flat and is a portion connected to a bus bar when constructing a battery pack. In this embodiment, the second conductive member 32 is rectangular. The first conductive member 31 and the second conductive member 32 are connected to each other outside the case 10. The first conductive member 31 is made of, for example, aluminum or an aluminum alloy. The second conductive member 32 is made of, for example, aluminum, an aluminum alloy, copper, a copper alloy, or the like.

[0044] The negative electrode terminal 40 is, for example, a member electrically connected to the negative electrode 24 of the electrode body 20. As shown in FIG. 2, the negative electrode terminal 40 is inserted into the through-hole 19 and exposed to the outside of the exterior body 12. Here, the negative electrode terminal 40 has a first conductive member 41 and a second conductive member 42. The first conductive member 41 is made of, for example, copper or a copper alloy. The negative electrode terminal 40 may have a configuration similar to that of the positive electrode terminal 30, for example. Therefore, a description of the configuration of the negative electrode terminal 40 will be omitted here.

[0045] -Positive electrode current collector 50- The positive electrode current collector 50 is, for example, a member that electrically connects the positive electrode tab 22t and the positive electrode terminal 30. The positive electrode current collector 50 is, for example, a plate-shaped conductive member. As shown in FIG. 2, the positive electrode current collector 50 extends along the inner surface of the exterior body 12 (here, the inside of the second wall 12b) in the direction of the longer side of the second wall 12b. The positive electrode tab 22t (here, a group of positive electrode tabs) is connected to one end (the right end in FIG. 2) of the positive electrode current collector 50. Furthermore, the lower end of the shaft portion 31a of the positive electrode terminal 30 is inserted into a through-hole 50h at the other end (the left end in FIG. 2) of the positive electrode current collector 50 and crimped. The positive electrode current collector 50 is made of, for example, aluminum or an aluminum alloy.

[0046] -Negative electrode current collector 60- The negative electrode current collector 60 is, for example, a member that electrically connects the negative electrode tab 24t and the negative electrode terminal 40. The negative electrode current collector 60 is, for example, a plate-shaped conductive member. As shown in FIG. 2, the negative electrode current collector 60 extends along the inner surface of the exterior body 12 (here, the inside of the second wall 12b) in the direction of the longer side of the second wall 12b. The negative electrode tab 24t (here, a group of negative electrode tabs) is connected to one end (the left end in FIG. 2) of the negative electrode current collector 60. Furthermore, the lower end of the negative electrode terminal 40 is inserted into a through-hole 60h at the other end (the right end in FIG. 2) of the negative electrode current collector 60 and crimped. The negative electrode current collector 60 is made of, for example, copper or a copper alloy.

[0047] -Electrolyte- The electrolyte solution contains, 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. Examples of carbonates 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), trifluorodimethyl carbonate (TFDMC), etc. These may be used alone or in combination of two or more.

[0048] -Insulating materials- Various insulating members are used in the electricity storage device 1. For example, as shown in FIG. 2 , an external insulating member 91 is disposed on the outside of the case 10 between the second conductive member 32 of the positive electrode terminal 30 and the second wall 12b, and between the second conductive member 42 of the negative electrode terminal 40 and the second wall 12b. Also, on the outside of the case 10, a gasket 92 is disposed between the first conductive member 31 and the second wall 12b, and between the first conductive member 41 and the second wall 12b. The gasket 92 has a cylindrical portion 921 disposed on the inner periphery of the through hole 18 and the inner periphery of the through hole 19. Also, an internal insulating member 93 is disposed on the inside of the case 10 between the positive electrode current collector 50 and the second wall 12b, and between the negative electrode current collector 60 and the second wall 12b.

[0049] The electricity storage device 1 can be used for a variety of purposes, and is particularly preferably used as a power source (driving power source) for motors mounted on vehicles such as passenger cars, trucks, etc. The type of vehicle is not particularly limited, but suitable examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0050] As described above, the electricity storage device 1 includes an electrode assembly 20, a case 10, and an electrolyte. The electrode assembly 20 is an electrode assembly in which a long, sheet-like positive electrode 22 and a long, sheet-like negative electrode 24 are wound in the sheet longitudinal direction with a separator 23 interposed therebetween, and has a pair of opposing wide surfaces 20a. The case 10 is a rectangular parallelepiped case that houses the electrode assembly 20. The case 10 also has an exterior body 12 that has a wide, rectangular first wall 12a and an opening 12h facing the first wall 12a, and a wide, rectangular sealing plate 14 that faces the first wall 12a and seals the opening 12h. The electricity storage device 1 does not have a liquid injection hole for injecting an electrolyte into the case 10.

[0051] In the electricity storage device 1 having such a configuration, no liquid injection hole is provided, and therefore the electrolyte is injected through the opening 12h of the exterior body 12. Therefore, the exterior body 12 is sealed after the electrolyte is injected. This can increase the efficiency of impregnation of the electrolyte into the electrode body 20. Furthermore, since the step of providing a liquid injection hole can be omitted, the productivity of the electricity storage device 1 can be improved.

[0052] Furthermore, in the electricity storage device 1, the sealing plate 14 is provided with a protrusion 141 that protrudes toward the wide surface 20a of the electrode body 20. By using the sealing plate 14 provided with the protrusion 141, a pressing force can be applied to the wide surface 20a of the electrode body 20. This makes it possible to maintain a preferable inter-electrode distance.

[0053] Furthermore, the protrusions 141 are further provided with ribs 142 that protrude toward the wide surface 20a. By using a sealing plate 14 provided with the ribs 142 as well as the protrusions 141, it is possible to apply a pressing force to the wide surface 20a of the electrode body 20 more efficiently. This enhances the effect of maintaining a desirable inter-electrode distance.

[0054] <Method of manufacturing electricity storage device 1> The technology disclosed herein provides a method for manufacturing the electricity storage device 1. This manufacturing method includes, for example, a housing step, a bonding step, a liquid injection step, and a sealing step.

[0055] -Containment process- The accommodation step is, for example, a step of accommodating the electrode assembly 20 in the exterior body 12. Here, the electrode assembly 20 is accommodated in the exterior body 12 so that the wide surface 20a faces the first wall 12a (see FIG. 2). Prior to the accommodation step, it is preferable to attach the positive electrode terminal 30, the negative electrode terminal 40, the positive electrode current collector 50, the negative electrode current collector 60, and various insulating members to the second wall 12b of the exterior body 12.

[0056] -Joining process- The joining step is, for example, a step of joining an electrode tab and an electrode current collector. In this embodiment, after the electrode body 20 is housed in the exterior body 12 (after the housing step), the positive electrode tab 22t is joined to the positive electrode current collector 50, and the negative electrode tab 24t is joined to the negative electrode current collector 60. The means for joining the electrode tabs and the electrode current collectors is, for example, laser welding. The joining step provides a first combined body in which the electrode body 20 and the exterior body 12 are integrated.

[0057] -Liquid injection process- The liquid injection process is, for example, a process of injecting an electrolyte into the exterior body 12 after the accommodation process (here, after the bonding process that follows the accommodation process). In this embodiment, the electrolyte is poured into the exterior body 12 through the opening 12h. By pouring the electrolyte into the exterior body 12 through the opening 12h, it is possible to omit the provision of an injection hole in the exterior body 12. This makes it possible to carry out the liquid injection process more easily. Also, for example, the liquid injection process may be carried out under a negative pressure state. This can increase the efficiency of impregnation of the electrolyte into the electrode body 20. In this case, for example, the first combined body obtained in the bonding process may be placed in a negative pressure environment (such as in a negative pressure chamber), and then the liquid injection process may be carried out.

[0058] -Sealing process- The sealing step is, for example, a step of sealing the opening 12h of the exterior body 12 with a sealing plate 14. In this step, for example, the exterior body 12 and the sealing plate 14 are welded (for example, laser welding) together. This integrates the two and obtains a second combined body that seals the case 10. Here, the sealing step is performed after the liquid injection step. In the sealing step, for example, it is preferable to seal the opening 12h of the exterior body 12 while pressing the wide surface 20a of the electrode body 20 with the sealing plate 14. By pressing the wide surface 20a of the electrode body 20 in the sealing step, the inter-electrode distance can be reduced in an electrode body impregnated with an electrolyte solution.

[0059] As described above, the sealing plate 14 is provided with the protrusions 141 and the rib portions 142. In the sealing process, the electrode body 20 can be pressed by bringing the rib portions 142 into contact with the wide surface 20a of the electrode body 20. By using the sealing plate 14 provided with the protrusions 141 and the rib portions 142 as the sealing plate that seals the exterior body 12, it is possible to continue to apply a pressing force to the wide surface 20a of the electrode body 20 even after the exterior body 12 is sealed. This allows the inter-electrode distance to be maintained small.

[0060] Although not particularly limited, it is preferable to apply a pressing force of at least 6 kN to the wide surface 20a of the electrode assembly 20 in the sealing process. This allows a preferable inter-electrode distance to be achieved. The pressing force may be, for example, 10 kN or less, or may be 8 kN or less. The pressing force is the average pressing force applied to the wide surface 20a. The average pressing force is, for example, a value obtained by dividing the total pressing force applied to the wide surface 20a at room temperature by the area of ​​the wide surface 20a. It is also preferable to appropriately adjust, for example, the height of the convex portion 141, the height of the rib portion 142, etc. so that the desired pressing force is applied to the wide surface 20a.

[0061] Then, the second combined product obtained in the sealing step is subjected to an aging treatment under predetermined conditions, thereby obtaining the electricity storage device 1 in a usable state.

[0062] As described above, the manufacturing method of the electricity storage device 1 includes an accommodation step, a liquid pouring step, and a sealing step. In the accommodation step, the electrode assembly 20 is accommodated in the exterior body 12 so that the wide surface 20a faces the first wall 12a. In the liquid pouring step, an electrolyte solution is poured into the exterior body 12 after the accommodation step. In the sealing step, the opening 12h of the exterior body 12 is sealed with the sealing plate 14 after the liquid pouring step. In this manufacturing method, the exterior body 12 having a wide opening is used, making it easy to accommodate the electrode assembly 20 in the exterior body 12. Therefore, for example, the electrode assembly 20 can be accommodated in the exterior body 12 without a separate process for reducing the thickness. Furthermore, in this manufacturing method, after the electrode assembly 20 is accommodated in the exterior body 12, the electrolyte solution is poured before the opening 12h is sealed. Therefore, in the liquid pouring step, an inter-electrode distance that facilitates impregnation of the electrolyte solution is ensured in the electrode assembly 20. This increases the efficiency with which the electrode body 20 is impregnated with the electrolyte.

[0063] In the above embodiment, the sealing plate 14 is provided with the protrusions 141 and the rib portions 142. However, this is not limiting. For example, the shape of the rib portions 142 does not have to be the shape described above. The rib portions 142 may be configured, for example, with dot-like ribs arranged in a predetermined pattern. Instead of the rib portions 142, protrusions (e.g., protrusions curved in a dome shape from the flat surface 141c toward the wide surface 20a) may be provided. Alternatively, the sealing plate 14 may be provided with only the protrusions 141, without the rib portions 142. Alternatively, the sealing plate 14 may be provided with the rib portions 142 and the protrusions described above, without providing the protrusions 141. Although several examples of the configuration of the sealing plate 14 are given here, this is not limiting. The configuration of the sealing plate 14 is not particularly limited as long as it can achieve the effects of the technology disclosed herein.

[0064] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Section 1: an electrode body in which a long sheet-like positive electrode and a long sheet-like negative electrode are wound in the sheet longitudinal direction with a separator interposed therebetween, the electrode body having a pair of opposing wide surfaces; a rectangular parallelepiped case that houses the electrode assembly, the case having an exterior body that has a wide rectangular first wall and an opening facing the first wall, and a wide rectangular sealing plate that faces the first wall and seals the opening; An electrolyte; A method for manufacturing an electricity storage device comprising: an accommodating step of accommodating the electrode body in the exterior body so that the wide surface and the first wall face each other; a liquid injection step of injecting the electrolyte into the exterior body after the accommodation step; a sealing step of sealing the opening of the exterior body with the sealing plate after the liquid injection step; The manufacturing method includes the steps of: Section 2: Item 1. The manufacturing method according to Item 1, wherein the liquid injection step is carried out under negative pressure. Section 3: Item 3. The manufacturing method according to item 1 or 2, wherein in the liquid injection step, the electrolyte solution is injected into the exterior body through the opening. Section 4: 4. The manufacturing method according to any one of items 1 to 3, wherein in the sealing step, the opening of the exterior body is sealed while pressing the wide surface of the electrode body with the sealing plate. Section 5: 5. The manufacturing method according to any one of items 1 to 4, wherein a sealing plate provided with a convex portion is used as the sealing plate in the sealing step. Item 6: 6. The manufacturing method according to any one of items 1 to 5, wherein a pressing force of at least 6 kN is applied to the wide surface of the electrode assembly in the sealing step. Section 7: an electrode body in which a long sheet-like positive electrode and a long sheet-like negative electrode are wound in the sheet longitudinal direction with a separator interposed therebetween, the electrode body having a pair of opposing wide surfaces; a rectangular parallelepiped case that houses the electrode assembly, the case having an exterior body that has a wide rectangular first wall and an opening facing the first wall, and a wide rectangular sealing plate that faces the first wall and seals the opening; An electrolyte; An electricity storage device comprising: The electricity storage device does not have a liquid injection hole for injecting the electrolyte into the case. Section 8: Item 8. The electricity storage device according to item 7, wherein the sealing plate is provided with a protrusion that protrudes toward the wide surface of the electrode body. Section 9: Item 9. The electricity storage device according to item 8, wherein the protrusions are further provided with ribs that protrude toward the wide surface.

[0065] Although the embodiments of the technology disclosed herein have been described above, it is not intended that the technology disclosed herein be limited to the above-described embodiments. The technology disclosed herein may also be implemented in other embodiments. The technology described in the claims includes various modifications and alterations of the above-described exemplary embodiments. For example, it is possible to replace part of the above-described embodiments with other modified embodiments, and it is also possible to add other modified embodiments to the above-described embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate. [Explanation of symbols]

[0066] 1. Energy storage devices 10 cases 12 Exterior body 12a 1st wall 12h opening 14 Sealing plate 20 Electrode body 22 Positive electrode 23 Separator 24 Negative electrode 30 Positive terminal 40 Negative terminal 50 Positive electrode current collector 60 Negative electrode current collector 91 External insulating member 92 Gasket 93 Internal insulating material

Claims

1. an electrode body in which a long sheet-like positive electrode and a long sheet-like negative electrode are wound in the sheet longitudinal direction with a separator interposed therebetween, the electrode body having a pair of opposing wide surfaces; a rectangular parallelepiped case that houses the electrode assembly, the case having an exterior body that has a wide rectangular first wall and an opening facing the first wall, and a wide rectangular sealing plate that faces the first wall and seals the opening; An electrolyte; A method for manufacturing an electricity storage device comprising: an accommodating step of accommodating the electrode body in the exterior body so that the wide surface and the first wall face each other; a liquid injection step of injecting the electrolyte into the exterior body after the accommodation step; a sealing step of sealing the opening of the exterior body with the sealing plate after the liquid injection step; It encompasses In the sealing step, the opening of the exterior body is sealed while the wide surface of the electrode body is pressed with the sealing plate.

2. The manufacturing method according to claim 1 , wherein the liquid injection step is carried out under negative pressure.

3. The manufacturing method according to claim 1 , wherein the electrolyte is injected into the exterior body through the opening in the injection step.

4. The manufacturing method according to claim 1 , wherein the sealing step uses a sealing plate having a protrusion.

5. The manufacturing method according to any one of claims 1 to 4, wherein a pressing force of at least 6 kN is applied to the wide surface of the electrode body in the sealing step.

6. an electrode body in which a long sheet-like positive electrode and a long sheet-like negative electrode are wound in the sheet longitudinal direction with a separator interposed therebetween, the electrode body having a pair of opposing wide surfaces; a rectangular parallelepiped case that houses the electrode assembly, the case having an exterior body that has a wide rectangular first wall and an opening facing the first wall, and a wide rectangular sealing plate that faces the first wall and seals the opening; An electrolyte; An electricity storage device comprising: No injection hole is provided for injecting the electrolyte into the case, The sealing plate is provided with a protrusion that protrudes toward the wide surface of the electrode body.

7. The electricity storage device according to claim 6 , wherein the protrusion is further provided with a rib protruding toward the wide surface.

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