JP2020030899A - Secondary battery - Google Patents

Abstract

To provide a secondary battery in which the occurrence of reaction unevenness in a peripheral edge part of an electrode active material layer is prevented, accordingly a battery capacity can be improved.SOLUTION: The secondary battery comprises: an electrode assembly including a first electrode plate and a second electrode plate; and an outermost insulation sheet. The outermost insulation sheet includes a first outermost part covering a first outermost main surface of the electrode assembly. A second electrode active material layer includes an edge part deviated to an outside from a first electrode active material layer when viewing in a main direction. The first sheet outermost part of the outermost insulation sheet includes a first convex part abutting on the first outermost main surface. A first convex part is overlapped with the edge part of the second electrode active material layer when viewing in the main direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a secondary battery.

  For example, as proposed in Patent Document 1, a stacked battery (secondary battery) in which a positive electrode plate and a negative electrode plate are alternately stacked is widely used. As an example of the stacked battery, a lithium ion secondary battery can be exemplified. One of the features of the lithium ion secondary battery is that it has a larger capacity than other types of stacked batteries. Lithium ion secondary batteries having such characteristics are expected to be widely used in various applications such as in-vehicle applications and stationary housing applications.

  When performing initial charging of the manufactured stacked battery, the electrode stacked body is charged while being pressed, and gas generated by charging is extracted from the inside. This prevents gas from stagnating in the electrolytic solution and facilitates impregnation of the electrolytic solution into the positive electrode active material layer provided on the positive electrode plate and the negative electrode active material layer provided on the negative electrode plate.

WO 2015/064721

  However, when pressing the stacked battery, there is a problem that the edge of the negative electrode active material layer protruding from the positive electrode active material layer is hardly pressed. In this case, the gas stagnates around the edge, making it difficult for the edge to be impregnated with the electrolyte. As a result, reaction unevenness occurs in the negative electrode active material layer, and there is a concern that the battery capacity may be reduced.

  The present invention has been made in view of such a point, and provides a secondary battery capable of preventing a reaction unevenness from occurring at an edge of an electrode active material layer and improving a battery capacity. The purpose is to:

The present invention
An electrode body including a first electrode plate and a second electrode plate facing each other in the main direction;
And an outermost insulating sheet,
The electrode body has a first outermost main surface and a second outermost main surface located on opposite sides in the main direction,
The outermost insulating sheet includes a first sheet outermost portion that covers the first outermost main surface,
A first electrode current collector including a connection region and an effective region adjacent to the connection region; a first electrode active material layer positioned on the first electrode current collector in the effective region; , And
A second electrode current collector including a connection region and an effective region adjacent to the connection region; a second electrode active material layer positioned on the second electrode current collector in the effective region; , And
The second electrode active material layer includes an edge protruding outside the first electrode active material layer when viewed in the main direction,
The outermost portion of the first sheet of the outermost insulating sheet includes a first protrusion abutting on the first outermost main surface,
A secondary battery, wherein the first protrusion overlaps the edge of the second electrode active material layer when viewed in the main direction,
I will provide a.

In the secondary battery according to the present invention,
The first electrode plate and the second electrode plate are each formed in a sheet-like shape, and are alternately stacked in the main direction,
When viewed in the main direction, the edge of the second electrode active material layer is formed around the first electrode active material layer,
The first projection is formed in a frame shape so as to overlap the edge of the second electrode active material layer when viewed in the main direction,
You may do so.

In the secondary battery according to the present invention,
The first electrode plate and the second electrode plate are wound around a winding axis extending in a direction orthogonal to the main direction,
When viewed in the main direction, the edge of the second electrode active material layer is formed on both sides of the first electrode active material layer in a direction along the winding axis,
The outermost insulating sheet includes a pair of the first protrusions overlapping the edge of the second electrode active material layer when viewed in the main direction,
You may do so.

In the secondary battery according to the present invention,
The outermost insulating sheet includes a second sheet outermost portion that covers the second outermost main surface,
The outermost portion of the second sheet of the outermost insulating sheet includes a second convex portion abutting on the second outermost main surface,
The second projection overlaps the edge of the second electrode active material layer when viewed in the main direction;
You may do so.

In the secondary battery according to the present invention,
The outermost insulating sheet includes a folded portion formed to be folded at one side in a predetermined direction perpendicular to the main direction with respect to the electrode body,
The folded portion connects the first sheet outermost portion and the second sheet outermost portion,
You may do so.

In the secondary battery according to the present invention,
The first sheet outermost portion and the second sheet outermost portion are connected to each other by a joining tape located on the other side in the predetermined direction orthogonal to the main direction with respect to the electrode body,
You may do so.

In the secondary battery according to the present invention,
The outermost insulating sheet has a sheet tab portion extending from the outermost portion of the first sheet to the opposite side to the folded portion, and the sheet tab portion located on the opposite side of the folded portion for the outermost portion of the second sheet. A tab insertion portion inserted to lock the outermost portion of the first sheet and the outermost portion of the second sheet with each other,
You may do so.

In the secondary battery according to the present invention,
Further comprising a second outermost insulating sheet formed separately from the outermost insulating sheet,
The second outermost insulating sheet includes a second sheet outermost portion that covers the second outermost main surface,
The outermost portion of the second sheet of the outermost insulating sheet includes a second convex portion abutting on the second outermost main surface,
The second projection overlaps the edge of the second electrode active material layer when viewed in the main direction;
You may do so.

In the secondary battery according to the present invention,
The first projection overlaps an edge of the first electrode active material layer when viewed in the stacking direction;
You may do so.

In the secondary battery according to the present invention,
The second projection overlaps an edge of the first electrode active material layer when viewed in the stacking direction.
You may do so.

In the secondary battery according to the present invention,
An exterior body for housing the electrode body is further provided,
The exterior body has a pair of support substrates, and a seal layer laminated on each of the inner surfaces of the support substrates facing each other.
You may do so.

In the secondary battery according to the present invention,
An exterior body for housing the electrode body is further provided,
The exterior body has an opening, a battery can that houses the electrode body, and a battery lid that seals the opening.
You may do so.

  According to the secondary battery of the present invention, it is possible to prevent the occurrence of reaction unevenness at the edge of the electrode active material layer, and to improve the battery capacity.

FIG. 1 is a view for explaining the first embodiment of the present invention, and is a perspective view showing a stacked battery. FIG. 2 is a plan view showing a membrane electrode assembly included in the stacked battery of FIG. FIG. 3 is a sectional view taken along line AA of FIG. FIG. 4 is a sectional view taken along line BB of FIG. FIG. 5 is an exploded perspective view of a part of the membrane / electrode assembly of FIG. FIG. 6 is a cross-sectional view showing the membrane electrode assembly to which the outermost insulating sheet is attached. FIG. 7 is a plan view of the insulating sheet shown in FIGS. FIG. 8 is a cross-sectional view showing a pressed state of the stacked battery of FIG. FIG. 9 is a plan view showing a first modification of the outermost insulating sheet of FIG. FIG. 10 is a sectional view showing a membrane electrode assembly to which the outermost insulating sheet of FIG. 9 is attached. FIG. 11 is a cross-sectional view showing a second modified example of the membrane / electrode assembly shown in FIG. 7 to which an outermost insulating sheet is attached. FIG. 12 is a view for explaining the second embodiment of the present invention, and is a perspective view showing a secondary battery. FIG. 13 is an exploded perspective view showing the secondary battery of FIG. FIG. 14 is an exploded perspective view showing the battery lid of FIG. FIG. 15 is a cross-sectional view showing the battery lid of FIG. FIG. 16 is a partial cross-sectional view showing the secondary battery of FIG. FIG. 17 is a view for explaining the third embodiment of the present invention, and is a perspective view showing a membrane electrode assembly of a secondary battery. FIG. 18 is a perspective view showing the wound electrode body shown in FIG. FIG. 19 is a partial cross-sectional view showing the secondary battery shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, the scale and the vertical and horizontal dimensional ratios and the like are appropriately changed and exaggerated for convenience of understanding.

(First Embodiment)
First, the secondary battery according to the first embodiment of the present invention will be described. In the present embodiment, as an example of a secondary battery, a stacked battery in which a positive electrode plate and a negative electrode plate are alternately stacked and housed in an outer package having a pair of supporting base materials will be described. Here, FIG. 1 to FIG. 8 are views for explaining the stacked battery according to the present invention. 1 and 2 are a perspective view and a plan view, respectively, showing a specific example of a stacked battery.

  As shown in FIGS. 1 and 2, a stacked battery 1 (secondary battery) according to the present embodiment includes an outer package 2, a membrane electrode assembly 5 housed in the outer package 2, and a membrane electrode assembly. And a pair of tabs 3 connected to each other. The exterior body 2 accommodates the membrane electrode assembly 5 therein. The tab 3 extends from the inside of the exterior body 2 to the outside. In the field of vehicles such as electric vehicles, a module configured by combining a plurality of stacked batteries 1 is mounted on a vehicle. Electrical connection between the plurality of stacked batteries 1 is realized via the tab 3.

  Hereinafter, each component of the stacked battery 1 will be described.

(Exterior)
The outer package 2 is a packaging material for sealing the membrane / electrode assembly 5. The exterior body 2 may have flexibility. The outer package 2 has, as an example, a support base 2a (see FIG. 8) and an adhesive layer 2b laminated on inner surfaces of the support base 2a facing each other. The support base 2a preferably has high gas barrier properties and moldability. As such a supporting base material 2a, an aluminum foil or a stainless steel foil can be used. The adhesive layer 2b is located on the inner surface of the support substrate 2a and functions as a seal layer for joining the support substrate 2a. The adhesive layer 2b preferably has insulation, chemical resistance, thermoplasticity, and the like in addition to adhesiveness. As such an adhesive layer 2b, polypropylene, modified polypropylene, low density polypropylene, ionomer, ethylene / vinyl acetate can be used. In the present embodiment, the membrane electrode assembly 5 is disposed between the pair of support base materials 2a, and the adhesive layer 2b formed on each inner surface is thermally welded around the membrane electrode assembly 5 by sealing. A part is formed. In this manner, the support bases 2a are joined to each other to seal the inside of the exterior body 2.

(Membrane electrode assembly)
The membrane electrode assembly 5 includes an electrode laminate 7 (electrode body) and an outermost insulating sheet 40. The electrode stack 7 has a first electrode plate 10 and a second electrode plate 20 that face each other in the stacking direction dL (main direction). In the present embodiment, an example in which the membrane electrode assembly 5 forms a lithium ion secondary battery will be described. In this example, the first electrode plate 10 constitutes a positive electrode plate 10X, and the second electrode plate 20 constitutes a negative electrode plate 20Y. However, as can be understood from the description of the operation and effect described below, the present embodiment described here is not limited to the lithium ion secondary battery, and the first electrode plate 10 and the second electrode plate It can be widely applied to the membrane electrode assembly 5 in which 20 are alternately stacked.

  FIG. 3 is a cross-sectional view of the membrane electrode assembly 5 along a first direction d1 described later, and FIG. 4 is a cross-sectional view of the membrane electrode assembly 5 along a second direction d2 described later. FIG. 5 is an exploded perspective view of the membrane electrode assembly 5. As shown in FIGS. 1 to 5, the electrode stack 7 of the membrane electrode assembly 5 has a plurality of positive plates 10X (first electrode plates 10) and a plurality of negative plates 20Y (second electrode plates 20). . The positive electrode plate 10X and the negative electrode plate 20Y are each formed in a sheet shape, and are alternately arranged and laminated along the laminating direction dL. The electrode stack 7 has a first outermost main surface 7a and a second outermost main surface 7b (see FIG. 6) located on opposite sides in the stacking direction dL as main surfaces. The stacking direction dL (main direction) in the present embodiment corresponds to the normal direction of the first outermost main surface 7a and the second outermost main surface 7b. The stacked battery 1 and the membrane electrode assembly 5 have a flat shape as a whole, have a small thickness in the stacking direction dL, and extend in directions d1 and d2 perpendicular to the stacking direction dL. Here, the principal surface means a flat surface having a relatively large area that defines a flat shape when viewed globally.

  In the illustrated non-limiting example, the positive electrode plate 10X and the negative electrode plate 20Y have a rectangular outer contour. The positive electrode plate 10X and the negative electrode plate 20Y have a longitudinal direction in a first direction d1, which is a direction perpendicular to the laminating direction dL and in which the tabs 3 extend (or in which the pair of tabs 3 are arranged). It has a short direction (width direction) in a second direction d2 orthogonal to both of the one direction d1. The positive electrode plate 10X and the negative electrode plate 20Y are displaced in the first direction d1. More specifically, the plurality of positive electrode plates 10X are arranged closer to one side (the right side in FIG. 2) in the first direction d1, and the plurality of negative electrode plates 20Y are arranged on the other side (in FIG. 2) in the first direction d1. (Left side). The positive electrode plate 10X and the negative electrode plate 20Y overlap in the laminating direction dL at the center (first effective area b1 and second effective area b2 described later) in the first direction d1.

  The positive electrode plate 10X (first electrode plate 10) has a sheet-like outer shape as illustrated. The positive electrode plate 10X (first electrode plate 10) includes a positive electrode current collector 11X (first electrode current collector 11) and a positive electrode active material layer 12X (first electrode active material layer) provided on the positive electrode current collector 11X. 12). The positive electrode active material layer 12X has a rectangular outer contour. In the lithium ion secondary battery, the positive electrode plate 10X emits lithium ions when discharging and occludes lithium ions when charging.

  The positive electrode current collector 11X has a first surface 11a and a second surface 11b located on opposite sides as main surfaces. The positive electrode active material layer 12X is formed on at least one of the first surface 11a and the second surface 11b of the positive electrode current collector 11X. When the first surface 21a or the second surface 21b of the negative electrode current collector 21Y described later defines the first outermost main surface 7a or the second outermost main surface 7b in the stacking direction dL of the electrode stack 7, a stacked type The plurality of positive electrode plates 10X included in the battery 1 may have the same configuration as one having a pair of positive electrode active material layers 12X provided on both sides of the positive electrode current collector 11X.

The positive electrode current collector 11X and the positive electrode active material layer 12X can be manufactured by various manufacturing methods using various materials applicable to the stacked battery 1 (lithium ion secondary battery). As an example, the positive electrode current collector 11X can be formed of an aluminum foil. The positive electrode active material layer 12X contains, for example, a positive electrode active material, a conductive additive, and a binder serving as a binder. The positive electrode active material layer 12X is formed by applying a positive electrode slurry obtained by dispersing a positive electrode active material, a conductive auxiliary agent, and a binder in a solvent onto a material forming the positive electrode current collector 11X and solidifying the slurry. Can be done. As the positive electrode active material, for example, a lithium metal oxide compound represented by a general formula LiM _x O _y (where M is a metal and x and y are the composition ratio of metal M to oxygen O) is used. Specific examples of the lithium metal oxide compound include lithium cobaltate, lithium nickelate, lithium manganate and the like. Acetylene black or the like can be used as the conductive assistant. As the binder, polyvinylidene fluoride or the like can be used.

  As shown in FIG. 2, the positive electrode current collector 11X (first electrode current collector 11) has a first connection region a1 and a first effective region b1 adjacent to the first connection region a1. The positive electrode active material layer 12X (first electrode active material layer 12) is disposed only in the first effective region b1 of the positive electrode current collector 11X. The first effective region b1 has a rectangular outer contour, and is a region where the positive electrode active material layer 12X is provided as a whole. The first connection region a1 and the first effective region b1 are arranged in the first direction d1 of the positive electrode plate 10X. The first connection region a1 is located outside the first effective region b1 in the first direction d1 of the positive electrode plate 10X (the right side in FIG. 2). The plurality of positive electrode current collectors 11X are joined and electrically connected in the first connection region a1 by resistance welding, ultrasonic welding, sticking with tape, fusion, or the like. On the other hand, the first effective region b1 is located in a region of the negative electrode plate 20Y facing a negative electrode active material layer 22Y described later. With such an arrangement of the first effective region b1, precipitation of lithium from the positive electrode active material layer 12X can be prevented.

  Next, the negative electrode plate 20Y (second electrode plate 20) will be described. The negative electrode plate 20Y also has a sheet-like outer shape, similarly to the positive electrode plate 10X. The negative electrode plate 20Y (second electrode plate 20) includes a negative electrode current collector 21Y (second electrode current collector 21) and a negative electrode active material layer 22Y (second electrode active material layer) provided on the negative electrode current collector 21Y. 22). The negative electrode active material layer 22Y has a rectangular outer contour. In the lithium ion secondary battery, the negative electrode plate 20Y occludes lithium ions during discharging and releases lithium ions during charging.

  The negative electrode current collector 21Y has a first surface 21a and a second surface 21b located on opposite sides as main surfaces. The negative electrode active material layer 22Y is formed on at least one of the first surface 21a and the second surface 21b of the negative electrode current collector 21Y. Specifically, the case where the first surface 21a or the second surface 21b of the negative electrode current collector 21Y defines the first outermost main surface 7a or the second outermost main surface 7b in the stacking direction dL of the electrode stack 7 The negative electrode active material layer 22Y is not provided on the surface of the negative electrode current collector 21Y. Except for the negative electrode current collector 21Y forming the first outermost main surface 7a and the negative electrode current collector 21Y forming the second outermost main surface 7b, the plurality of negative electrode plates 20Y included in the stacked battery 1 are: As having a pair of negative electrode active material layers 22Y provided on both sides of the negative electrode current collector 21Y, they can be configured identically to each other.

  The negative electrode current collector 21Y and the negative electrode active material layer 22Y can be manufactured by various manufacturing methods using various materials applicable to the stacked battery 1. As an example, the negative electrode current collector 21Y is formed of, for example, a copper foil. The negative electrode active material layer 22Y includes, for example, a negative electrode active material made of a carbon material and a binder functioning as a binder. The negative electrode active material layer 22Y forms, for example, a negative electrode slurry formed by dispersing a negative electrode active material composed of carbon powder, graphite powder, and the like and a binder such as polyvinylidene fluoride in a solvent, as a negative electrode current collector 21Y. It can be produced by coating and solidifying on a material.

  As shown in FIG. 2, the negative electrode current collector 21Y (second electrode current collector 21) has a second connection region a2 and a second effective region b2 adjacent to the second connection region a2. The negative electrode active material layer 22Y (second electrode active material layer 22) is disposed only in the second effective area b2 of the negative electrode current collector 21Y. The second effective region b2 has a rectangular outer contour, and is a region where the negative electrode active material layer 22Y is provided as a whole. The second connection region a2 and the second effective region b2 are arranged in the first direction d1 of the negative electrode plate 20Y. The second connection region a2 is located outside the second effective region b2 in the first direction d1 of the negative electrode plate 20Y (left side in FIG. 2). The plurality of negative electrode current collectors 21Y are joined and electrically connected to each other in the second connection region a2 by resistance welding, ultrasonic welding, tape bonding, fusion, or the like. On the other hand, the second effective region b2 extends to a region facing the positive electrode active material layer 12X of the positive electrode plate 10X.

  As shown in FIG. 2, the length of the negative electrode active material layer 22Y along the first direction d1 is longer than the length of the positive electrode active material layer 12X along the first direction d1. The width of the negative electrode active material layer 22Y along the second direction d2 is longer than the width of the positive electrode active material layer 12X along the second direction d2. The negative electrode active material layer 22Y includes an edge that protrudes outside the positive electrode active material layer 12X (outside in a direction perpendicular to the stacking direction dL) when viewed in the stacking direction dL. In the present embodiment, since the positive electrode plate 10X and the negative electrode plate 20Y are each formed in the shape of a single sheet, the edge portion surrounds the entire periphery of the positive electrode active material layer 12X when viewed in the stacking direction dL. It is formed over. The dimension of the edge of the negative electrode active material layer 22Y is, for example, 1 mm. This edge is hereinafter referred to as a peripheral edge 22a.

  As shown in FIG. 3, at least one of the positive electrode plate 10X (the first electrode plate 10) and the negative electrode plate 20Y (the second electrode plate 20) may have an insulator (insulating layer) 30. The insulator 30 prevents a short circuit between the positive electrode plate 10X (the first electrode plate 10) and the negative electrode plate 20Y (the second electrode plate 20). In the illustrated example, the negative electrode plate 20Y has the insulator 30. The insulator 30 is provided so as to cover the pair of negative electrode active material layers 22Y included in each negative electrode plate 20Y. The surface of the negative electrode plate 20Y facing the positive electrode active material layer 12X of the positive electrode plate 10X in the stacking direction dL is formed by the insulator 30. However, the insulator 30 that covers the pair of positive electrode active material layers 12X included in each positive electrode plate 10X can be provided instead of the illustrated insulator 30 or in addition to the illustrated insulator 30.

  In the illustrated example, the insulator 30 also functions as the electrolyte layer 30A. The electrolyte layer 30A is a layer formed by solidifying or gelling the electrolytic solution applied on the active material layers 12X, 22Y on the active material layers 12X, 22Y. As the electrolytic solution, for example, a polymer matrix and a non-aqueous electrolyte solution (that is, a non-aqueous solvent and an electrolyte salt) which are gelled to cause stickiness on the surface, or a polymer matrix and a non-aqueous solvent , A solid electrolyte can be used.

  As shown in FIGS. 3 to 6, the outermost insulating sheet 40 includes a first sheet outermost portion 41 that covers the first outermost main surface 7 a of the electrode stack 7 and a second sheet that covers the second outermost main surface 7 b. And a two-sheet outermost portion 42. FIG. 6 is a cross-sectional view along the second direction d2 of the membrane electrode assembly 5 to which the outermost insulating sheet 40 is attached.

  The first sheet outermost portion 41 includes a first convex portion 43 that contacts the first outermost main surface 7a of the electrode stack 7. The first convex portion 43 is located so as to overlap the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL.

  In the present embodiment, the first convex portion 43 is formed in a rectangular frame shape so as to overlap the peripheral portion 22a of the negative electrode active material layer 22Y. The first convex portion 43 faces and is in contact with the first surface 21a of the negative electrode current collector 21Y that defines the first outermost main surface 7a. The first convex portion 43 overlaps the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL, and also has a peripheral portion 12a of the positive electrode active material layer 12X (a region near the peripheral edge of the positive electrode active material layer 12X). ) May also overlap. The width of the first convex portion 43 may be a value in consideration of the protrusion size of the negative electrode active material layer 22Y and a manufacturing error. In this case, the width is, for example, 2 mm to 5 mm, and preferably 2 mm to 3 mm. Further, in FIGS. 3 and 4, the first convex portion 43 is shown not to protrude outside the peripheral edge portion 22a of the negative electrode active material layer 22Y, but the present invention is not limited thereto. The negative electrode active material layer 22 </ b> Y may extend beyond the peripheral edge portion 22 a and straddle the outer peripheral edge of the negative electrode active material layer 22 </ b> Y. In this case, the protrusion size of the first protrusion 43 is, for example, 5 mm to 10 mm.

  As shown in FIG. 6, the outermost portion 42 of the second sheet includes a second convex portion 44 that contacts the second outermost main surface 7b of the electrode stack 7. The second convex portion 44 is located so as to overlap the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL.

  In the present embodiment, the second convex portion 44 is formed in a rectangular frame shape so as to overlap the peripheral portion 22a of the negative electrode active material layer 22Y. The second convex portion 44 faces and is in contact with the second surface 21b of the negative electrode current collector 21Y that defines the second outermost main surface 7b. The second convex portion 44 may overlap with the peripheral portion 22a of the negative electrode active material layer 22Y and also with the peripheral portion 12a of the positive electrode active material layer 12X when viewed in the stacking direction dL. The width of the second convex portion 44 is, for example, 2 mm to 5 mm, preferably 2 mm to 3 mm, like the first convex portion 43. Further, in FIGS. 3 and 4, the second convex portion 44 is shown not to protrude outside the peripheral portion 22a of the negative electrode active material layer 22Y, but the present invention is not limited to this. The negative electrode active material layer 22 </ b> Y may extend beyond the peripheral edge portion 22 a and straddle the outer peripheral edge of the negative electrode active material layer 22 </ b> Y. In this case, the protrusion size of the second convex portion 44 is, for example, 5 mm to 10 mm.

  As shown in FIGS. 3 to 6, the outermost insulating sheet 40 includes a folded portion 45 formed to be folded on one side (the right side in FIG. 6) of the electrode laminate 7 in the second direction d2. The folded portion 45 is formed so as to straddle the entire electrode laminate 7 in the laminating direction dL, and connects the first sheet outermost portion 41 and the second sheet outermost portion 42. That is, the outermost portion 41 of the first sheet, the folded portion 45, and the outermost portion 42 of the second sheet are integrally formed continuously.

  FIG. 7 is a plan view of the outermost insulating sheet 40. FIG. The outermost insulating sheet 40 includes a sheet base material 46, first convex portions 43, and second convex portions 44. In the present embodiment, the sheet base 46 is formed of a film having a rectangular planar shape, and is formed from the outermost portion 41 of the first sheet to the outermost portion 42 of the second sheet. The first convex portion 43 is joined to the outermost portion 41 of the first sheet of the sheet base material 46, and the second convex portion 44 is joined to the outermost portion 42 of the second sheet. The first convex portion 43 and the second convex portion 44 are each formed of a film having the same rectangular frame-like planar shape. By folding such an outermost insulating sheet 40 in a region between the first sheet outermost portion 41 and the second sheet outermost portion 42, a folded portion 45 is formed.

  The sheet base material 46 of the outermost insulating sheet 40 has high ion permeability (air permeability), predetermined mechanical strength, and durability against an electrolyte, a positive electrode active material, a negative electrode active material, and the like. preferable. As such a sheet base material 46, for example, a porous body or a nonwoven fabric formed of an insulating material can be used. For example, as the sheet base material 46, a resin porous film can be used. More specifically, a porous film made of a thermoplastic resin having a melting point of about 80 to 140 ° C. can be used as the sheet base 46. Polyolefin-based polymers such as polypropylene and polyethylene can be used as the thermoplastic resin. The thickness of the sheet base material 46 is preferably, for example, 10 μm to 150 μm in consideration of preventing a decrease in the energy density of the stacked battery 1 due to an increase in the internal volume of the outer package 2 and mechanical strength. Is 10 μm to 30 μm.

  The material used for the first protrusion 43 and the second protrusion 44 is preferably the same as that of the sheet base material 46. The first protrusion 43 and the second protrusion 44 may be bonded to the sheet base 46 with an adhesive. In this case, an acrylic adhesive may be used as the adhesive. The thickness of the first projection 43 and the second projection 44 is, for example, 50 μm to 500 μm, and preferably 50 to 100 μm.

  As shown in FIG. 6, the outermost portion 41 of the first sheet and the outermost portion 42 of the second sheet are separated from each other by a bonding tape 50 located on the other side (the left side in FIG. 6) of the electrode laminate 7 in the second direction d2. They may be connected. In the present embodiment, the bonding tape 50 is located on the opposite side of the folded portion 45 with respect to the electrode laminate 7. One end of the joining tape 50 is joined to the bent end of the outermost portion 41 of the first sheet, and the other end is joined to the bent end of the outermost portion 42 of the second sheet. The joining tape 50 may be configured to have, for example, a tape base 50a and an adhesive layer 50b laminated on the tape base 50a. In the example shown in FIG. 6, the joining tape 50 includes an edge portion on the opposite side (left side in FIG. 6) of the folded portion 45 of the outermost portion 41 of the first sheet and a folded portion 45 of the outermost portion 42 of the second sheet. And the edge on the opposite side (the left side in FIG. 6). As a material forming the tape base material 50a, for example, polyethylene terephthalate, polypropylene, or the like can be used. The thickness of the tape base 50a is, for example, 5 μm to 20 μm in consideration of preventing a decrease in the energy density of the stacked battery 1 due to an increase in the internal volume of the outer package 2 and considering mechanical strength and the like. As a material constituting the adhesive layer 50b, for example, an acrylic resin can be used. The thickness of the adhesive layer 50b is, for example, 5 μm to 20 μm.

  Next, a method for manufacturing the stacked battery 1 according to the present embodiment configured as a lithium ion secondary battery will be described. The manufacturing method of the stacked battery 1 described below includes an electrode stacked body preparing step of preparing the electrode stacked body 7 and an insulating sheet in which the outermost insulating sheet 40 is attached to the electrode stacked body 7 to form the membrane electrode assembly 5. A mounting step, a sealing step of sealing the membrane electrode assembly 5 with the outer package 2, an initial charging step of performing initial charging of the stacked battery 1, and a resealing step of resealing the outer package 2 are provided. . Hereinafter, each step will be described.

(Electrode laminate preparation step)
The electrode laminate preparing step includes the steps of manufacturing the positive electrode plate 10X (first electrode plate 10) and the negative electrode plate 20Y (second electrode plate 20), respectively, and the positive electrode plate 10X (first electrode plate 10) and the negative electrode plate 20Y ( Alternately laminating the second electrode plates 20).

  First, the steps of manufacturing the positive electrode plate 10X (the first electrode plate 10) and the negative electrode plate 20Y (the second electrode plate 20) will be described. The positive electrode plate 10X and the negative electrode plate 20Y may be manufactured at different timings by different processes. Also, the positive electrode plate 10X and the negative electrode plate 20Y are manufactured simultaneously in parallel, and the manufactured positive electrode plate 10X and the negative electrode plate 20Y are sequentially supplied to the step of alternately stacking the positive electrode plate 10X and the negative electrode plate 20Y. It may be.

  For example, the positive electrode plate 10X solidifies by coating a composition (slurry) that will form the positive electrode active material layer 12X on a long aluminum foil that will form the positive electrode current collector 11X, Next, it can be produced by cutting into a desired size. Similarly, the negative electrode plate 20Y is formed by, for example, applying a composition (slurry) that will form the negative electrode active material layer 22Y on a long copper foil that will form the negative electrode current collector 21Y. It can be made by solidifying and then cutting to the desired size. In addition, when the insulator 30 functioning as the electrolyte layer 30A is provided to at least one of the positive electrode plate 10X and the negative electrode plate 20Y, on the long material before cutting or after cutting which becomes the electrode plates 10 and 20 The insulator 30 can be manufactured by applying and solidifying or gelling the electrolytic solution on the sheet material.

  Next, a step of alternately stacking the positive electrode plates 10X and the negative electrode plates 20Y is performed. In this step, the positive electrode plate 10X and the negative electrode plate 20Y are stacked such that the positive electrode active material layer 12X of the positive electrode plate 10X and the negative electrode active material layer 22Y of the negative electrode plate 20Y face each other.

  After the positive electrode plates 10X and the negative electrode plates 20Y are alternately stacked, the plurality of positive electrode plates 10X are joined to each other in the first connection region a1 of the positive electrode current collector 11X and become conductive. Then, the tab 3 is electrically connected to the first connection region a1 of the positive electrode current collector 11X. Similarly, the plurality of negative electrode plates 20Y are connected to each other in the second connection region a2 of the negative electrode current collector 21Y and become conductive. Then, the tab 3 is electrically connected to the second connection region a2 of the negative electrode current collector 21Y. 1 and 2, the tab 3 on the positive electrode plate 10X side is connected to the second surface 11b (lower surface) of the lowermost positive electrode plate 10X, and the tab 3 on the negative electrode plate 20Y is connected to the lowermost position. Is connected to the second surface 21b (lower surface) of the negative electrode plate 20Y located at the second position.

  In this way, it is possible to obtain the electrode laminate 7 in which the plurality of positive plates 10X and the plurality of negative plates 20Y are alternately stacked.

(Insulation sheet mounting process)
In the sheet attaching step, for example, first, an outermost insulating sheet 40 as shown in FIG. 7 is prepared. Subsequently, the electrode laminate 7 is placed on the outermost portion 42 of the second sheet of the outermost insulating sheet 40. In this case, the second convex portion 44 located at the outermost portion 42 of the second sheet overlaps the peripheral portion 22a of the negative electrode active material layer 22Y of the negative electrode plate 20Y when viewed in the stacking direction dL of the electrode stack 7. The electrode laminate 7 is positioned at the position.

  Next, the region between the second outermost portion 42 of the outermost insulating sheet 40 and the outermost portion 41 of the first sheet is bent, and the outermost portion 41 of the first sheet is folded into the first outermost portion of the electrode laminate 7. It covers over the negative electrode plate 20Y which defines the outer main surface 7a (top surface). In this case, the first convex portion 43 located at the outermost portion 41 of the first sheet overlaps the peripheral portion 22a of the negative electrode active material layer 22Y of the negative electrode plate 20Y when viewed in the stacking direction dL of the electrode stack 7. , The first sheet outermost portion 41 is positioned. As a result, a folded portion 45 as shown in FIG. 6 is formed between the outermost portion 41 of the first sheet and the outermost portion 42 of the second sheet.

  Thereafter, the outermost portion 41 of the first sheet and the outermost portion 42 of the second sheet are connected to each other by the joining tape 50. Note that the outermost insulating sheet 40 may be attached to the electrode laminate 7 with another bonding tape or the like.

  Thus, the membrane electrode assembly 5 in which the outermost insulating sheet 40 is attached to the electrode laminate 7 can be obtained. The attachment of the outermost insulating sheet 40 to the electrode laminate 7 may be performed before the tab 3 is connected to the current collectors 11X and 21Y.

(Sealing process)
In the sealing step, first, the membrane electrode assembly 5 to which the tab 3 is attached is disposed inside the exterior body 2. For example, the membrane electrode assembly 5 is mounted on one support substrate 2a of the outer package 2, and another support substrate 2a is mounted on the membrane electrode assembly 5. Subsequently, with the tab 3 extended to the outside, the inner surfaces of the outer package 2 are joined together by heat welding or the like along the outer edge of the outer package 2. Thereby, a seal portion for sealing the inside of the exterior body 2 from the outside can be formed along the outer edge of the exterior body 2.

(Initial charging process)
In the initial charging process,

As shown in FIG. 8, a pressure plate 61 is brought into contact with the upper surface of the stacked battery 1 sealed in the sealing step, and the stacked battery 1 is pressed by the pressure plate 61. Here, when the first convex portion 43 located at the first sheet outermost portion 41 of the outermost insulating sheet 40 and the second convex portion 44 located at the second sheet outermost portion 42 are viewed in the stacking direction dL. In addition, it overlaps with the peripheral portion 22a of the negative electrode active material layer 22Y of each negative electrode plate 20Y. Thus, the pressing force of the pressure plate 61 is applied to the peripheral portion 22a of the negative electrode active material layer 22Y, and the peripheral portion 22a is pressed. That is, as described above, the negative electrode active material layer 22Y is positioned so as to protrude outside the positive electrode active material layer 12X (outside in a direction orthogonal to the stacking direction dL) over the entire circumference. As a result, when the outermost insulating sheet 40 does not include the first protrusion 43 or the second protrusion 44, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y tends to be reduced. is there. However, in the present embodiment, since the outermost insulating sheet 40 includes the first protrusion 43, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y can be increased. Then, the outermost portion 41 of the first sheet is deformed by receiving a pressing force from the pressing plate 61, and the outermost portion 41 of the first sheet abuts on a portion other than the peripheral portion 22 a of the negative electrode plate 20 </ b> Y, and the pressure is applied. Is done. Thus, the electrode stack 7 can be uniformly pressed.

  Next, a predetermined voltage is applied to each positive electrode plate 10X, and each negative electrode plate 20Y is electrically grounded. As a result, the electrode stack 7 is initially charged. During this time, gas (bubbles) generated by charging accumulates inside the exterior body 2. Further, when the stacked battery 1 is pressed by the pressure plate 61, the gas generated in the region between the positive electrode plate 10 </ b> X and the negative electrode plate 20 </ b> Y hardly stays in the region, The plate 61 moves to a portion where the plate 61 is not in contact (a gap between the membrane electrode assembly 5 and the outer package 2 when viewed in the stacking direction dL) and stays in the portion. Since the peripheral portion 22a of the negative electrode active material layer 22Y is pressed, the entire electrolyte including the peripheral portion 22a of the negative electrode active material layer 22Y is easily impregnated with the electrolytic solution.

  When the state of charge (SOC) of the stacked battery 1 reaches a predetermined value (for example, 100%), the initial charging is completed. Thereafter, the stacked battery 1 is discharged until the charging rate reaches a predetermined value (for example, 0%). The pressure plate 61 is removed.

(Reseal process)
In the resealing step, first, a gas vent opening (not shown) is formed in the outer package 2 of the stacked battery 1 that has been discharged until the charging rate reaches a predetermined value (for example, 0%). As the gas vent opening, for example, a hole may be formed inside the seal part formed by heat welding in the exterior body 2, or a part of the seal part may be cut to make the interior of the exterior body 2 May be communicated with.

  Subsequently, the stacked battery 1 in which the gas vent opening is formed is housed in the decompression chamber 60, and the inside of the exterior body 2 is depressurized. During this time, gas staying in the above-described portion (gap) inside the exterior body 2 can be removed. Under the reduced pressure, the exterior body 2 is resealed, and the membrane electrode assembly 5 is sealed with the exterior body 2. For example, the inner surfaces of the exterior body 2 are joined by heat welding or the like inside the above-described gas vent opening. This makes it possible to form a seal portion for sealing the inside of the exterior body 2 from the outside again. The portion of the exterior body 2 where the gas vent opening is formed may be cut and removed.

  In this manner, the stacked battery 1 including the membrane electrode assembly 5 sealed by the outer package 2 having the pair of support bases 2a can be manufactured.

  As described above, according to the present embodiment, first sheet outermost portion 41 of outermost insulating sheet 40 covering first outermost main surface 7a of electrode laminate 7 abuts on first outermost main surface 7a. The first convex portion 43 includes the first convex portion 43, and the first convex portion 43 overlaps the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL. Thus, when the stacked battery 1 is pressed in the stacking direction dL during the initial charging, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y can be increased. Therefore, the electrolytic solution can be efficiently impregnated even in the peripheral portion 22a of the negative electrode active material layer 22Y. As a result, it is possible to prevent the occurrence of reaction unevenness in the peripheral portion 22a of the negative electrode active material layer 22Y, and to improve the battery capacity of the stacked battery 1.

  Further, according to the present embodiment, the second sheet outermost portion 42 of the outermost insulating sheet 40 covering the second outermost main surface 7b of the electrode laminate 7 is in contact with the second outermost main surface 7b. The second protrusion 44 overlaps the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL. Thus, when the stacked battery 1 is pressed in the stacking direction dL during the initial charging of the stacked battery 1, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y can be further increased. Therefore, the electrolytic solution can be efficiently impregnated even in the peripheral portion 22a of the negative electrode active material layer 22Y.

  Further, according to the present embodiment, the outermost insulating sheet 40 includes the folded portion 45 formed so as to be folded at one side in the second direction d2 orthogonal to the laminating direction dL of the electrode laminate 7, 45 connects the first sheet outermost portion 41 and the second sheet outermost portion 42. Thus, the outermost insulating sheet 40 can be formed integrally from the outermost portion 41 of the first sheet to the outermost portion 42 of the second sheet. Therefore, the workability of attaching the outermost insulating sheet 40 to the electrode stack 7 can be improved.

  Further, according to the present embodiment, the outermost portion 41 of the first sheet and the outermost portion 42 of the second sheet are bonded to each other on the other side in the second direction d2 perpendicular to the lamination direction dL of the electrode laminate 7. At 50 they are connected to each other. This prevents the first sheet outermost portion 41 and the second sheet outermost portion 42 from being displaced with respect to the electrode stack 7. For this reason, the first protrusion 43 located at the outermost portion 41 of the first sheet and the second protrusion 44 located at the outermost portion 42 of the second sheet are displaced from the peripheral edge 22a of the negative electrode active material layer 22Y. Can be prevented. In particular, according to the present embodiment, the bonding tape 50 is located on the opposite side to the folded portion 45 of the outermost insulating sheet 40 with respect to the electrode laminate 7. Thus, the outermost insulating sheet 40 is formed so as to wrap around the electrode laminate 7 one round, and the displacement of the outermost insulating sheet 40 with respect to the electrode laminate 7 can be further prevented.

  Further, according to the present embodiment, the first convex portion 43 overlaps with the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL, and also on the peripheral portion 12a of the positive electrode active material layer 12X. overlapping. Thus, when the stacked battery 1 is pressed in the stacking direction dL during the initial charging of the stacked battery 1, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y can be further increased. Further, the pressing force applied to the peripheral portion 12a of the positive electrode active material layer 12X can be increased. Therefore, the electrolytic solution can be more efficiently impregnated even in the peripheral portion 22a of the negative electrode active material layer 22Y.

  According to the present embodiment, the second convex portion 44 overlaps with the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL, and also on the peripheral portion 12a of the positive electrode active material layer 12X. overlapping. Thus, when the stacked battery 1 is pressed in the stacking direction dL during the initial charging of the stacked battery 1, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y can be further increased. Further, the pressing force applied to the peripheral portion 12a of the positive electrode active material layer 12X can be further increased. Therefore, the electrolytic solution can be more efficiently impregnated even in the peripheral portion 22a of the negative electrode active material layer 22Y.

  Further, according to the present embodiment, membrane electrode assembly 5 has outermost insulating sheet 40 including first convex portion 43 overlapping peripheral portion 22a of negative electrode active material layer 22Y. Thus, the electrolyte solution can be efficiently impregnated into the negative electrode active material layer 22Y even after the resealing step. In particular, the membrane electrode assembly 5 having the electrode laminate 7 is housed in the exterior body 2 having the pair of support base materials 2a joined to each other by the adhesive layer 2b. Even after the re-sealing step, the inside of the exterior body 2 is depressurized, so that a pressing force due to a pressure difference from the atmospheric pressure can be applied to the outermost insulating sheet 40 via the exterior body 2. Therefore, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y can be increased, and the electrolytic solution can be efficiently impregnated also in the peripheral portion 22a of the negative electrode active material layer 22Y.

  In the above, one embodiment has been described with reference to a specific example, but the above-described specific example is not intended to limit the embodiment. The above-described embodiment can be carried out in various other specific examples, and various omissions, replacements, and changes can be made without departing from the gist of the embodiment.

  Hereinafter, an example of a modification will be described with reference to the drawings. In the following description and the drawings used in the following description, portions that can be configured in the same manner as the above-described specific example will be denoted by the same reference numerals used for corresponding portions in the above-described specific example, and will be described in duplicate. Is omitted.

(First Modification)
In the above description, the first sheet outermost portion 41 and the second sheet outermost portion 42 of the outermost insulating sheet 40 have been described based on a specific example in which the first sheet outermost portion 41 and the second sheet outermost portion 42 are connected to each other by the joining tape 50. The manner of connection between the outer portion 41 and the outermost portion 42 of the second sheet is not limited to the specific example shown in FIG. For example, as shown in FIGS. 9 and 10, a sheet tab portion 70 is provided on one side of the first sheet outermost portion 41, and a slit into which the sheet tab portion 70 is inserted is provided on the other side of the second sheet outermost portion 42. May be provided. FIG. 9 is a plan view of the outermost insulating sheet 40 in the first modification, and FIG. 10 is a cross-sectional view of the membrane electrode assembly 5 to which the outermost insulating sheet 40 of FIG. 9 is attached.

  In the first modification, the first sheet extension 72 extends from the outermost portion 41 of the first sheet to the opposite side (left side in FIG. 10) from the side of the folded portion 45. A sheet tab portion 70 further extends from the first sheet extension portion 72 to a side opposite to the folded portion 45 side. On the other hand, the second sheet extension 73 extends from the outermost portion 42 of the second sheet to the side opposite to the folded portion 45, and the tab insertion portion 71 is located in the second sheet extension 73. The tab insertion portion 71 is formed in a slit shape so as to extend in a direction (up and down direction in FIG. 9) orthogonal to the direction in which the sheet tab portion 70 extends (left and right direction in FIG. 9).

  As shown in FIG. 10, the first sheet outermost portion 41 is positioned on the first outermost main surface 7 a of the electrode stack 7, and the second sheet outermost portion 42 is positioned on the second outermost main surface 7 b of the electrode stack 7. Then, the sheet outermost portion 41 and the outermost portion 42 of the second sheet can be locked by inserting the sheet tab portion 70 into the tab insertion portion 71.

  According to the present modification, the sheet tab portion 70 on the side of the first sheet outermost portion 41 is inserted into the slit on the side of the second sheet outermost portion 42, so that the first sheet outermost portion 41 and the second sheet The outermost portion 42 can be connected. Thereby, the workability of attaching the outermost insulating sheet 40 can be improved.

(Second Modification)
In the above description, the first sheet outermost portion 41 and the second sheet outermost portion 42 of the outermost insulating sheet 40 are described based on a specific example in which the outermost insulating sheet 40 is integrally formed by being connected by the folded portion 45. It is not limited to this specific example. For example, as shown in FIG. 11, the second outermost insulating sheet 80 formed separately from the outermost insulating sheet 40 (here, described as the first outermost insulating sheet 40) is a second sheet. It may be formed so as to include the outermost portion 42. FIG. 11 is a cross-sectional view of the membrane electrode assembly 5 according to the second modification.

  In the second modification, the first outermost insulating sheet 40 including the first sheet outermost portion 41 is located on the first outermost main surface 7a of the electrode stack 7. The second outermost insulating sheet 80 including the second sheet outermost portion 42 is located on the second outermost main surface 7b of the electrode laminate 7. The first outermost insulating sheet 40 and the second outermost insulating sheet 80 are formed as individual sheet members. That is, the membrane electrode assembly 5 in the second modified example includes the electrode laminate 7, the first outermost insulating sheet 40 covering the first outermost main surface 7 a of the electrode laminate 7, and the electrode laminate 7. And a second outermost insulating sheet 80 covering the second outermost main surface 7b. In this case, the joining tape 50 may connect the first outermost insulating sheet 40 and the second outermost insulating sheet 80 on one side and the other side in the second direction d2 of the electrode laminate 7. Good.

  According to the present modification, as shown in FIG. 11, the first outermost insulating sheet 40 and the second outermost insulating sheet 80 are formed separately so that the first outermost insulating sheet 40 is located at the outermost portion 41 of the first sheet. The position of the first convex portion 43 and the position of the second convex portion 44 located on the outermost portion 42 of the second sheet can be prevented from affecting each other, and the first outermost insulating sheet 40 and the second 2, the workability of attaching the outermost insulating sheet 80 can be improved.

  In the second modification shown in FIG. 11, the first convex portion 43 of the first outermost insulating sheet 40 covering the first outermost main surface 7 a of the electrode stack 7 allows the negative electrode active material layer 22 </ b> Y to be formed. As long as the peripheral portion 22a can be pressed, the second convex portion 44 may not be provided, and further, the second outermost insulating sheet 80 may not be provided. In this case, as shown in FIGS. 1 and 2, the tab 3 on the positive electrode plate 10X side is connected to the second surface 11b (lower surface) of the lowermost positive electrode plate 10X, and the tab 3 on the negative electrode plate 20Y side. 3 is preferably connected to the second surface 21b (lower surface) of the lowermost negative electrode plate 20Y.

(Third Modification)
In the above description, a description has been given based on a specific example in which the second sheet outermost portion 42 of the outermost insulating sheet 40 includes the second convex portion 44, but is not limited thereto. For example, if the peripheral portion 22a of the negative electrode active material layer 22Y can be pressed by the first convex portion 43 of the outermost insulating sheet 40 covering the first outermost main surface 7a of the electrode laminate 7, the outermost second sheet will be described. The second convex portion 44 may not be provided on the portion 42. In this case, as shown in FIGS. 1 and 2, the tab 3 on the positive electrode plate 10X side is connected to the second surface 11b (lower surface) of the lowermost positive electrode plate 10X, and the tab 3 on the negative electrode plate 20Y side. 3 is preferably connected to the second surface 21b (lower surface) of the lowermost negative electrode plate 20Y.

(Fourth modification)
Further, in the above description, an example is shown in which at least one of the positive electrode plate 10X and the negative electrode plate 20Y has the insulator 30, but the present invention is not limited to this example. Instead of including at least one of the positive electrode plate 10X and the negative electrode plate 20Y including the insulator 30, or in addition to including at least one of the positive electrode plate 10X and the negative electrode plate 20Y including the insulator 30, the positive electrode plate 10X and the negative electrode plate 20Y An insulator (insulating layer) 30 configured as a separate member from the positive electrode plate 10X and the negative electrode plate 20Y may be arranged between them. In this case, the insulator 30 functions as a separator. The length of the insulator 30 along the first direction d1 is longer than the length of the negative electrode active material layer 22Y along the first direction d1, and the width along the second direction d2 is equal to the length of the negative electrode active material layer 22Y. 22Y is formed longer than the width along the second direction d2. The insulator 30 can be formed from, for example, a nonwoven fabric or a porous material. In this example, the electrolyte or the gel electrolyte contained in the exterior body 2 is impregnated into the insulator 30 and held. The insulator 30 and the electrolyte used in this example are not particularly limited, and various insulators and electrolytes applicable to the stacked battery 1, particularly, the lithium ion secondary battery can be used.

(Second embodiment)
Next, a secondary battery according to a second embodiment will be described with reference to FIGS.

  The second embodiment shown in FIGS. 12 to 16 is mainly different in that the exterior body has a battery can and a battery cover, and other configurations are the same as those of the first embodiment shown in FIGS. This is substantially the same as the embodiment. 12 to 16, the same parts as those in the first embodiment shown in FIGS. 1 to 11 are denoted by the same reference numerals, and detailed description is omitted. FIG. 12 is a perspective view showing a specific example of a secondary battery, and FIG. 13 is an exploded perspective view of the secondary battery. 14 is a perspective view of the battery cover, FIG. 15 is a cross-sectional view of the battery cover along the stacking direction dL, and FIG. 16 is a partial cross-sectional view of the secondary battery along the stacking direction dL.

  As shown in FIGS. 12 and 13, the secondary battery 100 according to the present embodiment includes an outer package 2 and a membrane / electrode assembly 5 housed in the outer package 2. The exterior body 2 includes a battery can 101 having an opening 102 and a battery lid 110 for sealing the opening 102 of the battery can 101. The battery can 101 is configured to house the membrane electrode assembly 5. In the present embodiment, the battery can 101 is formed in a rectangular parallelepiped shape, and the first can outer main surface 101a and the second can outer main surface 101b located on opposite sides in the stacking direction dL (main direction) (FIG. 15 and FIG. 16) as main surfaces.

  The battery cover 110 has a cover plate 111 for sealing the opening 102 of the battery can 101, and a positive terminal 112X and a negative terminal 112Y provided on the cover plate 111. Among them, the cover plate 111 has a longitudinal direction along the first direction d1, and the positive electrode terminal 112X and the negative electrode terminal 112Y are arranged separately on both sides in the longitudinal direction of the cover plate 111. The positive electrode terminal 112X and the negative electrode terminal 112Y extend from the inside of the exterior body 2 to the outside. In the field of vehicles such as electric vehicles, a module configured by combining a plurality of secondary batteries 100 is mounted on a vehicle. Electrical connection between the plurality of secondary batteries 100 is realized through the positive terminal 112X and the negative terminal 112Y.

  As shown in FIGS. 14 and 15, the positive electrode terminal 112 </ b> X and the negative electrode terminal 112 </ b> Y are connected to the terminal flat portion 113 a provided on the upper side of the cover plate 111, and from the terminal flat portion 113 a to the battery can 101 side (FIGS. And a shaft portion 113b penetrating the cover plate 111. The cover plate 111 is provided with a through hole 111a through which the shaft portion 113b passes. The lower end of the shaft portion 113b of each of the terminals 112X and 112Y is caulked after assembling a lower packing 116 and current collectors 117X and 117Y, which will be described later, to form a caulked portion 114. By forming the caulking portion 114, the terminals 112X and 112Y and the current collectors 117X and 117Y described below are fixed to the cover plate 111.

  An upper packing 115 for preventing leakage of the electrolyte in the battery can 101 is interposed between the cover plate 111 and the terminal flat portions 113a of the terminals 112X and 112Y. The upper packing 115 is formed of an insulating material. As shown in FIG. 15, a part of the upper packing 115 extends into the through-hole 111a, thereby electrically connecting the cover plate 111 and the terminals 112X and 112Y. Insulated. Similarly, a lower packing 116 for preventing leakage of the electrolyte in the battery can 101 is interposed between the cover plate 111 and the caulked portion 114 of each of the terminals 112X and 112Y. The lower packing 116 is formed of an insulating material like the upper packing 115. Current collecting plates 117X and 117Y are interposed between the caulked portion 114 and the lower packing 116. The terminals 112X and 112Y corresponding to the current collectors 117X and 117Y are electrically connected.

  The current collectors 117X and 117Y extend toward the inside of the battery can 101 (downward in FIGS. 14 and 15). The positive electrode current collector 117X is electrically connected to the first connection region a1 of the positive electrode current collector 11X of the membrane / electrode assembly 5. The negative electrode current collector 117Y is electrically connected to the second connection region a2 of the negative electrode current collector 21Y of the membrane / electrode assembly 5.

  As shown in FIGS. 13 to 15, the cover plate 111 is provided with an injection hole 118 for injecting the electrolyte into the battery can 101. After the injection, the injection hole 118 is sealed with an injection plug 119. Although not shown, the cover plate 111 may be provided with a gas discharge valve. The gas discharge valve may be configured to open when the pressure in the battery can 101 becomes larger than a predetermined value to release the gas in the battery can 101.

  The battery can 101, the cover plate 111, the positive electrode terminal 112X, and the positive electrode current collector plate 117X can be formed of, for example, an aluminum alloy. The negative electrode terminal 112Y and the negative electrode current collector 117Y can be formed of, for example, a copper alloy.

  As shown in FIG. 13, the membrane electrode assembly 5 according to the present embodiment includes the electrode laminate 7 and the outermost insulating sheet 40, as in the first embodiment. The electrode stack 7 has a plurality of positive plates 10X (first electrode plates 10) and a plurality of negative plates 20Y (second electrode plates 20). The positive electrode plate 10X and the negative electrode plate 20Y are each formed in a sheet shape, and are alternately arranged and laminated along the laminating direction dL (main direction). As shown in FIGS. 13 and 16, the electrode laminate 7 has, as main surfaces, a first outermost main surface 7a and a second outermost main surface 7b located on opposite sides in the stacking direction dL. . The stacking direction dL in the present embodiment corresponds to the normal direction of the first outermost main surface 7a and the second outermost main surface 7b. The stacking direction dL also corresponds to the normal direction of the first outer main surface 101a and the second outer main surface 101b of the battery can 101 described above. The first outermost main surface 7a and the second outermost main surface 7b are surfaces facing the first outer main surface 101a and the second outer main surface 101b of the battery can 101. More specifically, the first outermost major surface 7a faces the first outer major surface 101a, and the second outermost major surface 7b faces the second outer major surface 101b. As shown in FIGS. 12 and 13, the secondary battery 100 and the membrane electrode assembly 5 have a flat shape as a whole, have a small thickness in the stacking direction dL, and have a direction d1 perpendicular to the stacking direction dL. Spread to d2.

  In the non-limiting example shown in FIG. 13, the positive electrode plate 10X and the negative electrode plate 20Y have substantially rectangular outer contours. The positive electrode plate 10X and the negative electrode plate 20Y have a longitudinal direction in a first direction d1, which is a longitudinal direction of the lid plate 111, and have a short direction (a short direction in a second direction d2 orthogonal to both the laminating direction dL and the first direction d1). (Up-down direction). The positive electrode plate 10X and the negative electrode plate 20Y overlap in the stacking direction dL at the centers (the first effective area b1 and the second effective area b2) in the first direction d1 and the second direction d2.

  The positive electrode plate 10X (first electrode plate 10) has a sheet-like outer shape as illustrated. The positive electrode plate 10X has a positive electrode current collector 11X (first electrode current collector 11) and a positive electrode active material layer 12X (first electrode active material layer 12) provided on the positive electrode current collector 11X. ing. The positive electrode active material layer 12X has a rectangular outer contour.

  In the present embodiment, the first connection region a1 and the first effective region b1 of the positive electrode plate 10X are arranged in the second direction d2 of the positive electrode plate 10X. The first connection region a1 is located outside the first effective region b1 in the second direction d2 of the positive electrode plate 10X (the side of the lid plate 111, the upper side in FIG. 13). The first connection region a1 is located on one side (the right side in FIG. 13) of the positive electrode plate 20X in the first direction d1. The plurality of positive electrode current collectors 11X are joined and electrically connected to each other in the first connection region a1 by resistance welding, ultrasonic welding, tape bonding, fusion, or the like. The above-described positive electrode current collector 117X is electrically connected to the stacked portion of the positive electrode current collector 11X in the first connection region a1. On the other hand, the first effective region b1 is located in a region of the negative electrode plate 20Y facing a negative electrode active material layer 22Y described later. With such an arrangement of the first effective region b1, precipitation of lithium from the positive electrode active material layer 12Y can be prevented.

  Next, the negative electrode plate 20Y (second electrode plate 20) will be described. The negative electrode plate 20Y also has a sheet-like outer shape, similarly to the positive electrode plate 10X. The negative electrode plate 20Y includes a negative electrode current collector 21Y (second electrode current collector) and a negative electrode active material layer 22Y (second electrode active material layer 22) provided on the negative electrode current collector 21Y. I have. The negative electrode active material layer 22Y has a rectangular outer contour.

  In the present embodiment, the second connection region a2 and the second effective region b2 of the negative electrode plate 20Y are arranged in the second direction d2 of the negative electrode plate 20Y. The second connection region a2 is located outside the second effective region b2 in the second direction d2 of the negative electrode plate 20Y (on the side of the cover plate 111, that is, on the upper side in FIG. 13). Further, the second connection region a2 is located on the other side (the left side in FIG. 13) of the negative electrode plate 20Y in the first direction d1. Thus, the second connection region a2 is separated from the first connection region a1 of the positive electrode plate 10X in the first direction d1. The plurality of negative electrode current collectors 21Y are joined and electrically connected to each other in the second connection region a2 by resistance welding, ultrasonic welding, tape attachment, fusion, or the like. The above-described negative electrode current collector 117Y is electrically connected to the stacked portion of the negative electrode current collector 21Y in the second connection region a2. On the other hand, the second effective region b2 extends to a region facing the positive electrode active material layer 12X of the positive electrode plate 10X.

  As shown in FIG. 13, similarly to the first embodiment, the length of the negative electrode active material layer 22Y along the first direction d1 is longer than the length of the positive electrode active material layer 12X along the first direction d1. It is getting longer. The length of the negative electrode active material layer 22Y along the second direction d2 is longer than the length of the positive electrode active material layer 12X along the second direction d2. When viewed in the stacking direction dL, it includes an edge protruding outside the positive electrode active material layer 12X (outside in a direction orthogonal to the stacking direction dL). Also in the present embodiment, since the positive electrode plate 10X and the negative electrode plate 20Y are each formed in a sheet shape, the edge is formed around the entire periphery of the positive electrode active material layer 12X. This edge is hereinafter referred to as a peripheral edge 22a.

  As shown in FIGS. 13 and 16, the outermost insulating sheet 40 includes, as in the first embodiment, a first sheet outermost portion 41 that covers the first outermost main surface 7 a of the electrode laminate 7, It includes a second sheet outermost portion 42 that covers the second outermost main surface 7b, and a folded portion 45. Here, the folded portion 45 is formed to be folded on one side (the lower side in FIG. 16) of the electrode laminate 7 in the second direction d2, but the present invention is not limited to this. The electrode stack 7 may be formed so as to be folded on the other side (upper side in FIG. 16) in the second direction d2, and on one side (left side or right side in FIG. 16) in the first direction d1 of the electrode stack 7. It may be formed so as to be folded back. FIG. 16 shows a partial cross section of the secondary battery along the stacking direction dL between the first connection region a1 of the positive electrode plate 10X and the second connection region a2 of the negative electrode plate 20Y.

  Similarly to the first embodiment, the first sheet outermost portion 41 includes a first convex portion 43 that contacts the first outermost main surface 7a of the electrode stack 7. The first convex portion 43 is located so as to overlap the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL. Also in the present embodiment, the first protrusion 43 is formed in a rectangular frame shape so as to overlap with the peripheral portion 22a of the negative electrode active material layer 22Y. The first convex portion 43 may also overlap the peripheral portion 12a of the positive electrode active material layer 12X.

  The outermost portion 42 of the second sheet includes a second convex portion 44 that contacts the second outermost main surface 7b of the electrode stack 7. The second convex portion 44 is located so as to overlap the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL. Also in the present embodiment, the second convex portion 44 is formed in a rectangular frame shape so as to overlap the peripheral portion 22a of the negative electrode active material layer 22Y. The second convex portion 44 may also overlap the peripheral portion 12a of the positive electrode active material layer 12X.

  As shown in FIG. 16, the joining tape 50 that connects the first sheet outermost part 41 and the second sheet outermost part 42 is located on the other side (the upper side in FIG. 16) of the electrode laminate 7 in the second direction d2. You may make it do. In this case, the joining tape 50 may be disposed between the first connection region a1 of the positive electrode plate 10X and the second connection region a2 of the negative electrode plate 20Y in the first direction d1.

  Next, a method of manufacturing the secondary battery 100 according to the present embodiment configured as a lithium ion secondary battery will be described.

  In the electrode laminate preparing step, the electrode laminate 7 can be prepared in the same manner as in the first embodiment. In addition, the battery lid 110 is prepared separately from the electrode laminate preparing step. Thereafter, the positive electrode current collector plate 117X of the battery lid 110 is electrically connected to the first connection region a1 of the positive electrode current collector 11X. Further, the negative electrode current collector plate 117Y of the battery cover 110 is electrically connected to the second connection region a2 of the negative electrode current collector 21Y.

  Next, the outermost insulating sheet 40 is attached to the electrode laminate 7. In this case, the first convex portion 43 of the outermost portion 41 of the first sheet comes into contact with the first outermost main surface 7a of the electrode laminate 7 while forming the folded portion 45, and the outermost portion 42 of the second sheet 42 The second protrusion 44 contacts the second outermost main surface 7b of the electrode stack 7. The first convex portion 43 and the second convex portion 44 are positioned so as to overlap with the peripheral portion 22a of the negative electrode active material layer 22Y of the negative electrode plate 20Y when viewed in the stacking direction dL. Then, the outermost portion 41 of the first sheet and the outermost portion 42 of the second sheet are connected to each other by the joining tape 50. Thus, the membrane electrode assembly 5 in which the outermost insulating sheet 40 is attached to the electrode laminate 7 can be obtained. The attachment of the outermost insulating sheet 40 to the electrode laminate 7 may be performed before the current collectors 117X and 117Y of the battery lid 110 are connected to the current collectors 11X and 21Y.

  In the step of attaching the battery lid 110 to the battery can 101, the membrane / electrode assembly 5 is housed in the battery can 101 while being connected to the current collectors 117X and 117Y of the battery lid 110. Thereby, the opening 102 of the battery can 101 is covered with the cover plate 111 of the battery cover 110. Subsequently, the peripheral edge of the lid plate 111 is joined to the open end (the upper end in FIGS. 13 and 15) of the battery can 101 by, for example, laser welding. Thus, the opening 102 of the battery can 101 is sealed by the cover plate 111. Next, an electrolytic solution is injected into the battery can 101 from a liquid injection hole 118 provided in the cover plate 111.

  In the initial charging step, first, the battery can 101 is pressed. For example, when the secondary battery 100 is placed on a table of a pressing device (not shown) with the second can outer main surface 101b of the battery can 101 facing down, the pressing plate 61 (see FIG. 8) The battery can 101 is pressed by the pressure plate 61 while being in contact with the outer main surface 101a of one can. Here, the gap between the membrane electrode assembly 5 (more specifically, the outermost insulating sheet 40) accommodated in the battery can 101 and the battery can 101 is small, or substantially free of a gap. It is in a state. Thus, the membrane electrode assembly 5 can be pressed while reducing the amount of deformation of the battery can 101 due to pressure, and the deformation of the battery can 101 can be kept within the elastic deformation range. When the first convex portion 43 located at the first outermost portion 41 of the outermost insulating sheet 40 and the second convex portion 44 located at the outermost portion 42 of the second sheet are viewed in the stacking direction dL. Each of the negative electrode plates 20Y overlaps the peripheral portion 22a of the negative electrode active material layer 22Y. Thus, the pressing force of the pressure plate 61 is applied to the peripheral portion 22a of the negative electrode active material layer 22Y, and the peripheral portion 22a is pressed. Further, the outermost portion 41 of the first sheet is deformed by receiving the pressing force from the pressing plate 61, and the outermost portion 41 of the first sheet abuts on a portion other than the peripheral portion 22a of the negative electrode plate 20Y, and the outermost portion 41 is pressed. Is done. Thus, the electrode stack 7 can be uniformly pressed.

  Next, a predetermined voltage is applied to each positive electrode plate 10X, and each negative electrode plate 20Y is electrically grounded. As a result, the electrode stack 7 is initially charged. During this time, the gas (bubbles) generated by charging is discharged from the battery can 101 to the outside through the liquid injection hole 118, but a part of the generated gas accumulates inside the battery can 101. Further, when the secondary battery 100 is pressed by the pressure plate 61, gas generated in a region between the positive electrode plate 10 </ b> X and the negative electrode plate 20 </ b> Y is unlikely to stay in the region, and The plate 61 moves to a portion where the plate 61 is not in contact (a gap between the membrane electrode assembly 5 and the battery can 101 when viewed in the stacking direction dL) and stays in the portion. Since the peripheral portion 22a of the negative electrode active material layer 22Y is pressed, the entire electrolyte including the peripheral portion 22a of the negative electrode active material layer 22Y is easily impregnated with the electrolytic solution.

  When the state of charge (SOC) of the secondary battery 100 reaches a predetermined value (for example, 100%), the initial charging is completed. Thereafter, the secondary battery 100 is discharged until the charging rate reaches a predetermined value (for example, 0%). The pressure plate 61 is removed.

  In the sealing step of sealing membrane electrode assembly 5 according to the present embodiment, secondary battery 100 is housed in decompression chamber 60 after discharging until the charging rate reaches a predetermined value (for example, 0%). Then, the pressure inside the battery can 101 is reduced. During this time, gas remaining in the above-described portion (gap) inside the battery can 101 can be removed. In this reduced pressure state, the injection plug 119 is inserted into the injection hole 118 and sealed by laser welding or the like.

  In this manner, the secondary battery 100 including the membrane electrode assembly 5 sealed by the outer package 2 having the battery can 101 and the battery lid 110 can be manufactured.

  As described above, according to the present embodiment, first sheet outermost portion 41 of outermost insulating sheet 40 covering first outermost main surface 7a of electrode laminate 7 abuts on first outermost main surface 7a. The first convex portion 43 includes the first convex portion 43, and the first convex portion 43 overlaps the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL. Thus, when the secondary battery 100 is pressed in the stacking direction dL during the initial charging, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y can be increased. Therefore, the electrolytic solution can be efficiently impregnated even in the peripheral portion 22a of the negative electrode active material layer 22Y. As a result, it is possible to prevent the occurrence of reaction unevenness in the peripheral portion 22a of the negative electrode active material layer 22Y, and to improve the battery capacity of the secondary battery 100. Further, according to the present embodiment, the second sheet outermost portion 42 of the outermost insulating sheet 40 covering the second outermost main surface 7b of the electrode stack 7 is in contact with the second outermost main surface 7b. The second protrusion 44 overlaps the peripheral portion 22a of the negative electrode active material layer 22Y when viewed in the stacking direction dL. Thus, when the secondary battery 100 is pressed in the stacking direction dL during the initial charging of the secondary battery 100, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y can be further increased.

  Further, according to the present embodiment, exterior body 2 has battery can 101 and battery lid 110. Thus, the strength of the outer package 2 can be increased, and the reliability of the secondary battery 100 can be improved. In the secondary battery 100 according to the present embodiment, the pressure inside the battery can 101 is reduced, but since the exterior body 2 is constituted by the battery can 101, the battery can 101 has a pressure difference from the atmospheric pressure. Is less likely to be applied to the electrode stack 7. However, the membrane electrode assembly 5 has the outermost insulating sheet 40 including the first convex portion 43 overlapping the peripheral portion 22a of the negative electrode active material layer 22Y. This allows the negative electrode active material layer 22Y to be efficiently impregnated with the electrolytic solution even after the sealing step according to the present embodiment. In particular, when the gap between the membrane electrode assembly 5 and the battery can 101 is substantially non-existent, the battery can 101 exerts a pressing force due to a pressure difference from the atmospheric pressure on the outermost insulating sheet 40. It can be added to the first protrusion 43. Therefore, the pressing force applied to the peripheral portion 22a of the negative electrode active material layer 22Y can be increased, and the negative electrode active material layer 22Y can be impregnated with the electrolyte efficiently.

(Third embodiment)
Next, a secondary battery according to a third embodiment will be described with reference to FIGS.

  The third embodiment shown in FIGS. 17 to 19 is mainly different in that the positive electrode plate and the negative electrode plate are wound around the winding axis, and the other configurations are the same as those in FIGS. 12 to 16. This is substantially the same as the second embodiment shown. 17 to 19, the same parts as those in the second embodiment shown in FIGS. 12 to 16 are denoted by the same reference numerals, and detailed description is omitted. FIG. 17 is a perspective view showing a specific example of a membrane electrode assembly of a secondary battery, and FIG. 18 is a perspective view of a wound electrode body. FIG. 19 is a partial cross-sectional view along the main direction dL of the secondary battery.

  As shown in FIGS. 17 to 19, the membrane / electrode assembly 5 according to the present embodiment has an electrode winding body 130 having a winding structure.

  That is, as shown in FIG. 17, in the present embodiment, the membrane / electrode assembly 5 includes the electrode winding body 130 (electrode body) and the outermost insulating sheet 40. The electrode winding body 130 has a positive electrode plate 10X (first electrode plate 10) and a negative electrode plate 20Y (second electrode plate 20) wound around a winding axis 131 extending along the first direction d1. ing. The positive electrode plate 10X and the negative electrode plate 20Y are each formed in a long shape so as to have a longitudinal direction, and are wound around a winding axis 131. As shown in FIG. 18, between the positive electrode plate 10X and the negative electrode plate 20Y, a first insulator 132 and a second insulator 133 configured as separate members from both the positive electrode plate 10X and the negative electrode plate 20Y are interposed. ing. A first insulator 132 is arranged on one side of the positive electrode plate 10X, and a second insulator 133 is interposed on the other side.

  As shown in FIGS. 17 and 19, the electrode winding body 130 has a first outermost main surface 130a and a second outermost main surface 130b located on opposite sides in the main direction dL as main surfaces. I have. The main direction dL according to the present embodiment corresponds to the normal direction of the first outermost main surface 130a and the second outermost main surface 130b. The main direction dL also corresponds to the normal direction of the first outer main surface 101a (see FIGS. 13 and 15) and the second outer main surface 101b of the battery can 101 described above. The first outermost main surface 130a and the second outermost main surface 130b are surfaces facing the first outer main surface 101a and the second outer main surface 101b of the battery can 101. More specifically, the first outermost main surface 130a faces the first outer main surface 101a, and the second outermost main surface 130b faces the second outer main surface 101b. The first outermost main surface 130a and the second outermost main surface 130b are formed substantially flat, and occupy a large area of the electrode winding body 130 when viewed in the main direction dL. Thereby, the electrode winding body 130 is a winding body having a flat shape as shown in FIG. In the electrode winding body 130, in a region sandwiched between the first outermost main surface 130a and the second outermost main surface 130b, the positive electrode plate 10X and the negative electrode plate 20Y are formed to be substantially flat and stacked. I have. In a region above and below the first outermost main surface 130a and the second outermost main surface 130b, the positive electrode plate 10X and the negative electrode plate 20Y are formed in a curved shape and stacked.

  As shown in FIG. 18, the first connection region a1 and the first effective region b1 of the positive electrode plate 10X (the first electrode plate 10) are arranged in the first direction d1 of the positive electrode plate 10X. The first connection region a1 is located outside one of the first effective regions b1 in the first direction d1 (the right side in FIG. 18). The laminated portion of the first connection region a1 of the positive electrode current collector 11X formed by winding the positive electrode plate 10X and the negative electrode plate 20Y is formed by resistance welding, ultrasonic welding, sticking by tape, fusion, or the like. And are electrically connected. The above-described positive electrode current collector 117X is electrically connected to the stacked portion of the positive electrode current collector 11X in the first connection region a1. On the other hand, the first effective region b1 is located in a region of the negative electrode plate 20Y facing the negative electrode active material layer 22Y. With such an arrangement of the first effective region b1, precipitation of lithium from the positive electrode active material layer 12Y can be prevented.

  The second connection region a2 and the second effective region b2 of the negative electrode plate (second electrode plate 20) are arranged in the first direction d1 of the negative electrode plate. The second connection region a2 is located outside the other side of the second effective region b2 in the first direction d1 (left side in FIG. 18). The laminated portion of the second connection region a2 of the negative electrode current collector 21Y formed by winding the positive electrode plate 10X and the negative electrode plate 20Y is formed by resistance welding, ultrasonic welding, tape bonding, fusion, or the like. And are electrically connected. The above-described negative electrode current collector 117Y is electrically connected to the stacked portion of the negative electrode current collector 21Y in the second connection region a2. On the other hand, the second effective region b2 extends to a region facing the positive electrode active material layer 12X of the positive electrode plate 10X.

  As shown in FIG. 18, the width of the negative electrode active material layer 22Y along the first direction d1 is longer than the width of the positive electrode active material layer 12X along the first direction d1. The negative electrode active material layer 22Y includes an edge portion 22b that protrudes outside the positive electrode active material layer 12X (outside in the first direction d1) when viewed in the main direction dL. In the present embodiment, since the positive electrode plate 10X and the negative electrode plate 20Y are respectively wound, the edge 22b is in the first direction d1 (along the winding axis 131) when viewed in the main direction dL. Direction) on both sides of the positive electrode active material layer 12X. Also, as shown in FIG. 18, the negative electrode active material layer 22Y is formed to be longer than the positive electrode active material layer 12X in the winding circumferential direction (the longitudinal direction of the negative electrode plate 20Y). In this manner, a portion where the negative electrode active material layer 22Y does not face the positive electrode active material layer 12X is not formed.

  Both the first insulator 132 and the second insulator 133 function as separators. The width of the first insulator 132 and the width of the second insulator 133 along the first direction d1 are longer than the width of the negative electrode active material layer 22Y along the first direction d1. Further, the first insulator 132 and the second insulator 133 are longer than the negative electrode active material layer 22Y even in the circumferential direction of the winding. In this manner, a portion where the first insulator 132 or the second insulator 133 does not face the negative electrode active material layer 22Y and the positive electrode active material layer 12X is not formed. Therefore, electrical insulation between the positive electrode plate 10X and the negative electrode plate 20Y is ensured. The portion of the first insulator 132 that is arranged on the outermost periphery of the electrode winding body 130 ensures electrical insulation between the negative electrode plate 20Y and the battery can 101. Such first insulator 132 and second insulator 133 can be formed, for example, from a nonwoven fabric or a porous material.

  As shown in FIGS. 17 and 19, the first sheet outermost portion 41 of the outermost insulating sheet 40 covers the first outermost main surface 130a of the electrode winding body 130, and the second sheet outermost portion 42 is The second outermost main surface 130b is covered. The folded portion 45 is formed to be folded on one side (the lower side in FIG. 19) of the electrode winding body 130 in the second direction d2, but is not limited thereto. It may be formed so as to be folded on the other side (upper side in FIG. 19) of the winding body 130 in the second direction d2, and on one side (left side or right side in FIG. 19) of the electrode winding body 130 in the first direction d1. It may be formed so as to be folded back. FIG. 19 shows a partial cross section of the secondary battery along the main direction dL at a position where the first protrusion 43 and the second protrusion 44 are arranged.

  In the present embodiment, the first sheet outermost portion 41 of the outermost insulating sheet 40 is formed of the first outermost main surface 130a of the electrode winding body 130 (the first outermost surface of the first wound body 132). (A part on the side of the outermost main surface 130a). The pair of first convex portions 43 are located so as to overlap with the edge 22b of the negative electrode active material layer 22Y when viewed in the main direction dL. In the present embodiment, each first protrusion 43 is formed in a linear shape extending in the second direction d2 so as to overlap with the corresponding edge 22b of the edges 22b on both sides of the negative electrode active material layer 22Y. ing. The first protrusion 43 may also overlap an edge of the positive electrode active material layer 12X (a region near both edges of the positive electrode active material layer 12X in the first direction d1).

  The second sheet outermost portion 42 of the outermost insulating sheet 40 is connected to the second outermost main surface 130b of the electrode winding body 130 (on the side of the second outermost main surface 130b arranged on the outermost periphery of the first insulator 132). (A portion of FIG. 2). The pair of second convex portions 44 are located so as to overlap the edge 22b of the negative electrode active material layer 22Y when viewed in the main direction dL. In the present embodiment, each second protrusion 44 is formed in a linear shape extending in the second direction d2 so as to overlap with the corresponding edge 22b of the edges 22b on both sides of the negative electrode active material layer 22Y. ing. The second protrusion 44 may also overlap the edge of the positive electrode active material layer 12X.

  When manufacturing the secondary battery 100 according to the present embodiment, first, the winding axis is set so that the first insulator 132, the negative electrode plate 20Y, the second insulator 133, and the positive electrode plate 10X are stacked in this order. Wind around 131. At this time, the winding is performed so that the positive electrode plate 10X is located closer to the center of the winding axis 131 than the negative electrode plate 20Y. Thus, the first insulator 132 is arranged on the outermost periphery of the electrode winding body 130, and the negative electrode plate 20Y is arranged inside the first insulator 132. Then, the negative electrode plates 20Y and the positive electrode plates 10X are alternately arranged toward the center of the winding axis 131. In order to wind the negative electrode plate 20Y at the innermost periphery of the electrode winding body 130 such that the negative electrode plate 20Y is located closer to the center of the winding axis 131 than the positive electrode plate 10X, for example, The positive electrode plate 10X may be wound together with the positive electrode plate 10X.

  At the time of winding, a winding core having a flat shape (for example, a substantially elliptical shape or a substantially elliptical shape) may be used. As a result, the wound electrode body 130 having the substantially flat first outermost main surface 130a and second outermost main surface 130b is obtained. After winding the positive electrode plate 10X and the negative electrode plate 20Y using the cylindrical winding core, the electrode winding body 130 is pressed, and the substantially flat first outermost main surface 130a and the second outermost main surface 130a are pressed. The electrode winding body 130 having a flat shape may be obtained by forming the outer main surface 130b.

  Subsequently, the above-described positive electrode current collector plate 117X is electrically connected to the first connection region a1 of the positive electrode current collector 11X. Similarly, the above-described negative electrode current collector 117Y is electrically connected to the second connection region a2 of the negative electrode current collector 21Y.

  Next, the outermost insulating sheet 40 is attached to the electrode winding body 130. In this case, while forming the folded portion 45, the pair of first convex portions 43 of the outermost portion 41 of the first sheet abut on the first outermost main surface 130 a of the electrode winding body 130, and the outermost portion of the second sheet is formed. The pair of second convex portions 44 of the portion 42 abut on the second outermost main surface 130b of the electrode winding body 130. The first protrusion 43 and the second protrusion 44 are positioned so as to overlap the edges 22b on both sides of the negative electrode active material layer 22Y of the negative electrode plate 20Y when viewed in the main direction dL. Then, the outermost portion 41 of the first sheet and the outermost portion 42 of the second sheet are connected to each other by the joining tape 50. Thus, the membrane electrode assembly 5 in which the outermost insulating sheet 40 is attached to the electrode winding body 130 can be obtained. The attachment of the outermost insulating sheet 40 to the electrode winding body 130 may be performed before the current collectors 117X and 117Y of the battery lid 110 are connected to the current collectors 11X and 21Y.

  In the step of attaching the battery lid 110 to the battery can 101, the membrane / electrode assembly 5 is housed in the battery can 101 while being connected to the current collectors 117X and 117Y of the battery lid 110. Thereby, the opening 102 of the battery can 101 is covered with the cover plate 111 of the battery cover 110. Subsequently, the peripheral edge of the lid plate 111 is joined to the open end (the upper end in FIGS. 13 and 15) of the battery can 101 by, for example, laser welding. Thus, the opening 102 of the battery can 101 is sealed by the cover plate 111. Next, an electrolytic solution is injected into the battery can 101 from a liquid injection hole 118 provided in the cover plate 111.

  In the initial charging step, first, the battery can 101 is pressed. For example, when the secondary battery 100 is placed on a table of a pressing device (not shown) with the second can outer main surface 101b of the battery can 101 facing down, the pressing plate 61 (see FIG. 8) The battery can 101 is pressed by the pressure plate 61 while being in contact with the outer main surface 101a of one can. Here, the gap between the membrane electrode assembly 5 (more specifically, the outermost insulating sheet 40) accommodated in the battery can 101 and the battery can 101 is small, or substantially free of a gap. It is in a state. Thus, the membrane electrode assembly 5 can be pressed while reducing the amount of deformation of the battery can 101 due to pressure, and the deformation of the battery can 101 can be kept within the elastic deformation range. Then, a pair of first convex portions 43 located on the first sheet outermost portion 41 of the outermost insulating sheet 40 and a pair of second convex portions 44 located on the second sheet outermost portion 42 are formed in the main direction dL. When viewed, they overlap the edges 22b on both sides of the negative electrode active material layer 22Y of each negative electrode plate 20Y. Thus, the pressing force of the pressure plate 61 is applied to each edge 22b of the negative electrode active material layer 22Y, and each edge 22b is pressed. Further, the outermost portion 41 of the first sheet is deformed by receiving the pressing force from the pressing plate 61, and the outermost portion 41 of the first sheet abuts on a portion other than the edge portion 22 b of the negative electrode plate 20 </ b> Y to apply pressure. Is done. In this way, the electrode winding body 130 can be uniformly pressed.

  Next, a predetermined voltage is applied to each positive electrode plate 10X, and each negative electrode plate 20Y is electrically grounded. Thereby, the electrode winding body 130 is initially charged. During this time, the gas (bubbles) generated by charging is discharged from the battery can 101 to the outside through the liquid injection hole 118, but a part of the generated gas accumulates inside the battery can 101. Further, when the secondary battery 100 is pressed by the pressure plate 61, gas generated in a region between the positive electrode plate 10 </ b> X and the negative electrode plate 20 </ b> Y is unlikely to stay in the region, and The plate 61 moves to a portion where the plate 61 is not in contact (a gap between the membrane electrode assembly 5 and the battery can 101 when viewed in the main direction dL) and stays in the portion. Since the edges 22b on both sides of the anode active material layer 22Y are pressed, the entire electrolyte including the edge 22b of the anode active material layer 22Y is easily impregnated with the electrolytic solution.

  When the state of charge (SOC) of the secondary battery 100 reaches a predetermined value (for example, 100%), the initial charging is completed. Thereafter, the secondary battery 100 is discharged until the charging rate reaches a predetermined value (for example, 0%). The pressure plate 61 is removed.

  In the sealing step of sealing membrane electrode assembly 5 according to the present embodiment, secondary battery 100 is housed in decompression chamber 60 after discharging until the charging rate reaches a predetermined value (for example, 0%). Then, the pressure inside the battery can 101 is reduced. During this time, gas remaining in the above-described portion (gap) inside the battery can 101 can be removed. In this reduced pressure state, the injection plug 119 is inserted into the injection hole 118 and sealed by laser welding or the like.

  In this manner, the secondary battery 100 including the membrane electrode assembly 5 sealed by the outer package 2 having the battery can 101 and the battery lid 110 can be manufactured.

  Thus, according to the present embodiment, first sheet outermost portion 41 of outermost insulating sheet 40 covering first outermost main surface 130a of electrode winding body 130 abuts on first outermost main surface 130a. The first protrusion 43 includes the first protrusion 43 that is in contact with the first protrusion 43, and the first protrusion 43 overlaps the edge 22b of the negative electrode active material layer 22Y when viewed in the main direction dL. Thereby, when the secondary battery 100 is pressed in the main direction dL during the initial charging, the pressing force applied to the edge 22b of the negative electrode active material layer 22Y can be increased. For this reason, the electrolyte solution can be efficiently impregnated even at the edge portion 22b of the negative electrode active material layer 22Y. As a result, it is possible to prevent the occurrence of reaction unevenness at the edge 22b of the negative electrode active material layer 22Y, and to improve the battery capacity of the secondary battery 100. Further, according to the present embodiment, second sheet outermost portion 42 of outermost insulating sheet 40 covering second outermost main surface 130b of electrode winding body 130 abuts on second outermost main surface 130b. Including the second convex portion 44, the second convex portion 44 overlaps the edge 22b of the negative electrode active material layer 22Y when viewed in the main direction dL. Thus, when the secondary battery 100 is pressed in the main direction dL during the initial charging of the secondary battery 100, the pressing force applied to the edge 22b of the negative electrode active material layer 22Y can be further increased.

  Further, according to the present embodiment, exterior body 2 has battery can 101 and battery lid 110. Thus, the strength of the outer package 2 can be increased, and the reliability of the secondary battery 100 can be improved. In the secondary battery 100 according to the present embodiment, the pressure inside the battery can 101 is reduced, but since the exterior body 2 is constituted by the battery can 101, the battery can 101 has a pressure difference from the atmospheric pressure. Is less likely to be applied to the electrode winding body 130. However, the membrane electrode assembly 5 has the outermost insulating sheet 40 including the first convex portion 43 overlapping the edge 22b of the negative electrode active material layer 22Y. This allows the negative electrode active material layer 22Y to be efficiently impregnated with the electrolytic solution even after the sealing step according to the present embodiment. In particular, when the gap between the membrane electrode assembly 5 and the battery can 101 is substantially non-existent, the battery can 101 exerts a pressing force due to a pressure difference from the atmospheric pressure on the outermost insulating sheet 40. It can be added to the first protrusion 43. Therefore, the pressing force applied to the edge portion 22b of the negative electrode active material layer 22Y can be increased, and the electrolyte solution can be efficiently impregnated in the negative electrode active material layer 22Y as well.

(Fifth Modification)
In the above description, a description will be given based on a specific example in which the first outermost portion 41 of the outermost insulating sheet 40 includes a pair of first convex portions 43 arranged on both sides in the first direction d1. However, it is not limited to this. For example, the first sheet outermost portion 41 may include a further third protrusion 47 so as to connect the pair of first protrusions 43. That is, as described above, the negative electrode active material layer 22Y is formed longer than the positive electrode active material layer 12X also in the circumferential direction of the winding (the longitudinal direction of the negative electrode plate 20Y). As a result, as shown in FIG. 18, when viewed in the main direction dL, the negative electrode active material layer 22Y has an edge portion 22c protruding above or below the positive electrode active material layer 12X. The edge 22c is located on the terminal side of the outermost peripheral portion of the negative electrode active material layer 22Y. Therefore, when the edge portion 22c is present on the first outermost main surface 130a, the third convex portion 47 overlapping the edge portion 22c when viewed in the main direction dL is placed on the first sheet outermost surface. The external part 41 may be additionally included. The position of the third convex portion 47 depends on the position of the edge portion 22c, but as an example in FIG. 17, the edge portion 22c present on the first outermost main surface 130a is disposed at an intermediate position in the second direction d2. An example is shown. The third convex portion 47 is formed in a linear shape extending in the first direction d1. The third protrusion 47 may also overlap the edge of the positive electrode active material layer 12X corresponding to (adjacent to) the edge 22c. By providing such a third convex portion 47, the electrolyte solution can be efficiently impregnated even at the edge portion 22c of the negative electrode active material layer 22Y, and the occurrence of reaction unevenness can be further prevented. The battery capacity can be further improved. When the edge 22c exists on the second outermost main surface 130b, the third convex portion 47 may be provided on the outermost portion 42 of the second sheet.

  Although some embodiments and some modifications to each embodiment have been described, it is obvious that a plurality of embodiments can be at least partially combined as appropriate. Further, a plurality of modified examples can be at least partially appropriately combined.

1 Stacked battery (secondary battery)
2 Outer body 2a Support base material 2b Adhesive layer 7 Electrode laminate 7a First outermost main surface 7b Second outermost main surface 10 First electrode plate 10X Positive electrode plate 11 First electrode current collector 11X Positive electrode current collector 12 1 electrode active material layer 12X Positive electrode active material layer 12a Peripheral edge 12b Edge 20 Second electrode plate 20Y Negative electrode plate 21 Second electrode current collector 21Y Negative electrode current collector 22 Second electrode active material layer 22Y Negative electrode active material layer 22a Perimeter Part 22b Edge part 40 Outermost insulating sheet 41 First sheet outermost part 42 Second sheet outermost part 43 First convex part 44 Second convex part 45 Folding part 50 Joining tape 70 Sheet tab part 71 Tab insertion part 80 Second Outermost insulating sheet 100 Secondary battery 101 Battery can 102 Opening 110 Battery lid 130 Electrode winding body 130a First outermost main surface 130b Second outermost main surface 131 Winding axis a1 First connection area a2 Second connection area b1 First effective area b2 Second effective area

Claims (12)

An electrode body including a first electrode plate and a second electrode plate facing each other in the main direction;
And an outermost insulating sheet,
The electrode body has a first outermost main surface and a second outermost main surface located on opposite sides in the main direction,
The outermost insulating sheet includes a first sheet outermost portion that covers the first outermost main surface,
A first electrode current collector including a connection region and an effective region adjacent to the connection region; a first electrode active material layer positioned on the first electrode current collector in the effective region; , And
A second electrode current collector including a connection region and an effective region adjacent to the connection region; a second electrode active material layer positioned on the second electrode current collector in the effective region; , And
The second electrode active material layer includes an edge protruding outside the first electrode active material layer when viewed in the main direction,
The outermost portion of the first sheet of the outermost insulating sheet includes a first protrusion abutting on the first outermost main surface,
The secondary battery, wherein the first protrusion overlaps the edge of the second electrode active material layer when viewed in the main direction. The first electrode plate and the second electrode plate are each formed in a sheet-like shape, and are alternately stacked in the main direction,
When viewed in the main direction, the edge of the second electrode active material layer is formed around the first electrode active material layer,
2. The secondary battery according to claim 1, wherein the first protrusion is formed in a frame shape so as to overlap with the edge of the second electrode active material layer when viewed in the main direction. 3. The first electrode plate and the second electrode plate are wound around a winding axis extending in a direction orthogonal to the main direction,
When viewed in the main direction, the edge of the second electrode active material layer is formed on both sides of the first electrode active material layer in a direction along the winding axis,
2. The secondary battery according to claim 1, wherein the outermost insulating sheet includes a pair of the first protrusions overlapping the edge of the second electrode active material layer when viewed in the main direction. 3. The outermost insulating sheet includes a second sheet outermost portion that covers the second outermost main surface,
The outermost portion of the second sheet of the outermost insulating sheet includes a second convex portion abutting on the second outermost main surface,
4. The secondary battery according to claim 1, wherein the second protrusion overlaps the edge of the second electrode active material layer when viewed in the main direction. 5. The outermost insulating sheet includes a folded portion formed to be folded at one side in a predetermined direction perpendicular to the main direction with respect to the electrode body,
The secondary battery according to claim 4, wherein the folded portion connects the outermost portion of the first sheet and the outermost portion of the second sheet.   The outermost portion of the first sheet and the outermost portion of the second sheet are connected to each other by a joining tape located on the other side in the predetermined direction orthogonal to the main direction with respect to the electrode body. 6. The secondary battery according to 5.   The outermost insulating sheet has a sheet tab portion extending from the outermost portion of the first sheet to the opposite side to the folded portion, and the sheet tab portion located on the opposite side of the folded portion for the outermost portion of the second sheet. The rechargeable battery according to claim 5, further comprising: a tab insertion portion inserted to lock the outermost portion of the first sheet and the outermost portion of the second sheet with each other. Further comprising a second outermost insulating sheet formed separately from the outermost insulating sheet,
The second outermost insulating sheet includes a second sheet outermost portion that covers the second outermost main surface,
The outermost portion of the second sheet of the outermost insulating sheet includes a second convex portion abutting on the second outermost main surface,
2. The secondary battery according to claim 1, wherein the second protrusion overlaps with the edge of the second electrode active material layer when viewed in the main direction. 3.   The secondary battery according to any one of claims 1 to 8, wherein the first protrusion overlaps an edge of the first electrode active material layer when viewed in the main direction.   The secondary battery according to any one of claims 4 to 8, wherein the second projection overlaps an edge of the first electrode active material layer when viewed in the main direction. An exterior body for housing the electrode body is further provided,
The said exterior body has a pair of support base material, and the sealing layer laminated | stacked on the mutually opposing inner surface of the said support base material, respectively, The two of Claim 1-10 characterized by the above-mentioned. Next battery. An exterior body for housing the electrode body is further provided,
The battery according to any one of claims 1 to 10, wherein the exterior body has an opening, a battery can housing the electrode body, and a battery lid sealing the opening. Rechargeable battery.

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