JP6736264B2 - Secondary battery - Google Patents

Description

Embodiments of the present invention relate to a secondary battery.

Some secondary batteries have a structure in which an electrode group, an electrolytic solution, and the like are covered with a laminate having an outer film, a metal layer, and an inner film. In such a secondary battery, the lead terminal connected to the electrode group is formed so as to project from the laminate, and the lead terminal and the metal layer are formed with the inner film sandwiched therebetween. The demand for secondary batteries that can be charged and discharged with large current is increasing, and it is necessary to increase the cross-sectional area of the lead terminals. It may be possible to increase the thickness of the lead terminal in order to increase the cross-sectional area of the lead terminal. Conventionally, in the secondary battery, it is necessary to make the inner film thick so that the lead terminal and the metal layer are not short-circuited. If the inner film is made thick, there is a problem that the amount of moisture infiltrated into the battery from the outside increases.

JP 2005-141955 A

In order to solve the above problems, a secondary battery that effectively prevents a short circuit is provided.

According to the embodiment, the secondary battery includes an electrode group, a metal plate, a resin layer, an inner film, a metal layer, and an outer film. The electrode group includes electrodes. Metal plate is electrically connected to the electrode, the first direction and parallel to the front and back surfaces projecting from the electrode, as well as adjacent to a the surface parallel to the first direction, extends between the surface and the back surface And a pair of surfaces in the thickness direction . The resin layer covers the metal plate. The inner film covers the resin layer and is bonded to the resin layer by heat fusion. The metal layer covers the inner film and adheres to the inner film. The outer film covers the metal layer and adheres to the metal layer. The resin layer includes a first portion, a second portion, and a third portion. The first portion is adjacent to the inside of the portion where the inner films contact each other. The second portion is provided between the first portion and the surface of the metal plate in the thickness direction, and forms a step between the second portion and the first portion . The third portion is a third portion provided between the surfaces of the pair in the thickness direction is provided in an upper surface, projecting with respect to the second portion on the side facing the surface, and, A protrusion that is provided on the back surface and that projects toward the second portion is provided on the side facing the back surface .

FIG. 1 is a diagram showing a configuration example of a secondary battery according to an embodiment. FIG. 2 is an example of a cross-sectional view of the secondary battery according to the embodiment. FIG. 3A is a diagram showing a configuration example of the laminate film according to the embodiment. FIG. 3B is a diagram showing another configuration example of the laminate film according to the embodiment. FIG. 4 is a diagram showing an example of the positive electrode lead terminal according to the embodiment. FIG. 5A is an example of a cross-sectional view of the positive electrode lead terminal according to the embodiment. FIG. 5B is an example of a cross-sectional view of the positive electrode lead terminal according to the embodiment. FIG. 6 is a diagram showing an example of a method for manufacturing a secondary battery according to the embodiment. FIG. 7 is another example of a cross-sectional view of the secondary battery according to the embodiment. FIG. 8 is a diagram showing another configuration example of the secondary battery according to the embodiment.

Hereinafter, embodiments will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration example of a secondary battery 10 according to the embodiment. The portion hidden by the laminate exterior 4 is indicated by a dotted line. FIG. 2 is an example of a cross-sectional view taken along the line AA′ of the secondary battery 10 according to the embodiment.
The secondary battery 10 shown in FIG. 1 is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, and is configured as a laminated secondary battery. The secondary battery 10 includes an electrode group 1, a positive electrode lead terminal 2, a negative electrode lead terminal 3, and a laminate exterior 4 and the like.

The electrode group 1 is formed into a flat rectangular parallelepiped by, for example, stacking a positive electrode, a separator, and a negative electrode in this order, winding them into a coil, and pressing them.

The positive electrode of the electrode group 1 is, for example, one in which a positive electrode active material is applied to both surfaces of a metal foil as a current collector. The positive electrode is produced, for example, by applying a slurry containing a positive electrode active material to a current collector made of aluminum foil or aluminum alloy foil. The positive electrode active material is not particularly limited, but oxides, sulfides, polymers or the like capable of inserting and extracting lithium can be used. Preferred active materials include lithium-manganese composite oxide, lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium iron phosphate and the like, which can provide a high positive electrode potential.

For example, the positive electrode comprises a positive electrode tab consisting of a metal foil portion not coated with the positive electrode active material. The positive electrode tab projects from the separator to one side in the winding axis direction of the electrode group 1. The positive electrode tabs protrude from the separator in a state where they overlap each other.

The negative electrode of the electrode group 1 is a metal foil as a current collector coated with a negative electrode active material on both sides. The negative electrode is prepared by applying a slurry containing a negative electrode active material to a current collector made of an aluminum foil or an aluminum alloy foil. The negative electrode active material is not particularly limited, but metal oxides, metal sulfides, metal nitrides, alloys and the like capable of occluding and releasing lithium can be used, and preferably the lithium ion occluding and releasing potential is metallic lithium. It is a substance that has a potential of 0.4 V or more with respect to the potential. Since the negative electrode active material having such a lithium ion storage/release potential can suppress the alloy reaction between aluminum or an aluminum alloy and lithium, it is possible to use aluminum or an aluminum alloy for the negative electrode current collector and the negative electrode-related constituent members. And For example, there are titanium oxide, lithium titanium oxide, tungsten oxide, amorphous tin oxide, tin silicon oxide, silicon oxide, etc. Among them, lithium titanium composite oxide is preferable.

For example, the negative electrode comprises a negative electrode tab consisting of a metal foil portion not coated with the negative electrode active material. The negative electrode tab projects from the separator to the other side in the winding axis direction of the electrode group 1. The negative electrode tabs protrude from the separator in a state where they overlap each other.

As the separator, a microporous film, a woven fabric, a non-woven fabric, or a laminate of the same material or different materials among them can be used. Examples of the material forming the separator include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, and the like.

The positive electrode lead terminal 2 is composed of a metal plate 21, a resin layer 22, and the like.

The metal plate 21 is a conductor made of metal. The metal plate 21 is, for example, 1000 series pure aluminum. The metal plate 21 is, for example, aluminum having a purity of 99% or more.

When the material of the metal plate 21 is aluminum, in order to improve the adhesiveness of the metal plate 21 to the resin layer 22 and the chemical resistance to the electrolytic solution, for example, the thickness is 0.05 μm or more, You may perform the surface treatment which consists of a 0.2-micrometer or less organic substance layer. As the surface treatment, the surface of the metal plate 21 may be formed into a film by aluminum oxide by chemical conversion treatment, but due to the insulating layer of the metal oxide, charge/discharge inspection, voltage inspection, resistance inspection, etc. in the battery manufacturing process. When conducting an electrical inspection of, it is necessary to remove the insulating layer of metal oxide. In the case of an organic substance layer, by making the tip of the inspection terminal sharp and sharp, the organic substance layer can be easily penetrated, so that an electrical inspection can be performed with the organic substance layer attached. ..

The metal plate 21 has a substantially rectangular parallelepiped shape. The metal plate 21 has surfaces 21a to 21d.
The surface 21a is a predetermined surface parallel to the first direction in which the metal plate 21 projects from the electrode group 1. The surface 21b is a surface facing the surface 21a. That is, the surface 21b is the back surface of the surface 21a.

The surface 21c is a surface parallel to the first direction and adjacent to the surface 21a. The surface 21d is a surface facing the surface 21c. That is, the surface 21d is the back surface of the surface 21c.

One end of the metal plate 21 is electrically connected to the positive electrode tab. For example, the metal plate 21 is joined to the stacked positive electrode tabs by laser welding, ultrasonic welding, or the like.

That is, the resin layer 22 has a predetermined width in the first direction and is formed in an annular shape that covers the outer periphery of the metal plate 21 in the direction orthogonal to the first direction. The resin layer 22 is bonded to the metal plate 21 by heat bonding (heat compression bonding).

The resin layer 22 after heat fusion has a protrusion 22a, a protrusion 22b, a relief step 22c, and a relief step 22d.
The protrusion 22 a is provided on the surface 21 a of the metal plate 21. The protrusion 22a is formed so as to protrude from a position facing the surface 21a in a second direction orthogonal to the surface 21a. The protrusion 22a is formed to have a size that covers at least the surface 21a.

Further, the protruding portion 22b is provided on the surface 21b which is the back surface of the surface 21a. The protruding portion 22b has the same configuration as the protruding portion 22a, and thus detailed description thereof will be omitted.

The escape step portion 22c is provided on the surface 21c. The escape step portion 22c is formed at a position facing the surface 21c. The escape step portion 22c is formed with a predetermined R on the surface 21c.

The escape step portion 22d is formed on the surface 21d. Since the escape step portion 22d is similar to the escape step portion 22c, detailed description thereof will be omitted.
The negative electrode lead terminal 3 is composed of a metal plate 31, a resin layer 32, and the like.

The metal plate 31 is a substantially rectangular parallelepiped conductor made of metal. The metal plate 31 is, for example, aluminum or nickel-plated copper.

One end of the metal plate 31 is electrically connected to the negative electrode tab. For example, the metal plate 31 is joined to the stacked negative electrode tabs by laser welding, ultrasonic welding, or the like.

The resin layer 32 has the same configuration as the resin layer 22, and thus detailed description thereof will be omitted.

The resin layer 32 has a predetermined width in the first direction and is formed in an annular shape that covers the outer periphery of the metal plate 31 in the direction orthogonal to the first direction. The resin layer 32 is bonded to the metal plate 31 by heat bonding.

The laminated exterior 4 is composed of two laminated films.
FIG. 3A shows a configuration example of a laminate film that constitutes the laminate exterior 4. The laminated film shown in FIG. 3A is in a state before heat fusion.

The laminate film forming the laminate exterior 4 has flexibility. As shown in FIG. 3A, the laminate film is composed of a metal layer 41, an outer film 42, an inner film 43, and the like.

The metal layer 41 is a barrier layer for preventing moisture or the like from entering the inside of the secondary battery 10 from the outside and further preventing the electrolytic solution or the like inside the secondary battery 10 from leaking to the outside. Yes, it is a conductor foil composed of a metal such as aluminum, stainless steel, iron, copper or nickel.

The outer film 42 is formed on a predetermined surface of the metal layer 41 and covers the metal layer 41. The outer film 42 is a film made of an insulating material. For example, the outer film 42 is made of nylon, polyethylene terephthalate, or a film having a two-layer structure of both.

The inner film 43 is a film made of an insulating material.
FIG. 3B shows another configuration example of the laminated film.

As shown in FIG. 3B, the inner film 43 is composed of an adhesive layer 43a, a heat fusion layer 43b, and the like.
The adhesive layer 43 a is formed on the other surface of the metal layer 41 that is not in contact with the outer film 42 and is in contact with the metal layer 41. The adhesive layer 43a is made of, for example, a resin adhesive or a heat adhesive resin such as acid-modified polypropylene or acid-modified polyethylene. The heat fusion layer 43b is made of a resin film such as polypropylene or polyethylene.

The laminate exterior 4 includes a seal portion 4a formed by heat-sealing the outer edge portions of two laminate films, and a housing portion 4b formed inside the seal portion 4a. Further, one end of the metal plate 21 not connected to the positive electrode tab and one end of the metal plate 31 not connected to the negative electrode tab are formed so as to protrude from the seal portion 4a.

The accommodating part 4b accommodates the electrode group 1, the electrolytic solution, and the like.

The seal portion 4a includes the heat-sealing layer 43b of the inner film 43 of the laminate film and the resin layer 22 of the positive electrode lead terminal 2, the heat-sealing layer 43b of the inner film 43 of the laminate film and the resin layer 32 of the negative electrode lead terminal 3, and The inner heat-bonding layers 43b of the inner films 43 of the two laminated films are heat-fused.

Usually, before the injection of the electrolytic solution, a part of the seal portion 4a is not heat-sealed, and the electrolytic solution is injected from that part, and after the predetermined amount of the electrolytic solution is injected, the sealing is performed. By the seal portion 4a, the housing portion 4b is kept airtight with the outside air (outside the battery).

As the electrolytic solution, a non-aqueous electrolytic solution prepared by dissolving an electrolyte (for example, a lithium salt) in a non-aqueous solvent is used. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), γ-butyrolactone (γ. -BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran, and the like. The non-aqueous solvent may be used alone or in combination of two or more. Examples of the electrolyte include lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenide (LiAsF6), and lithium trifluorometasulfonate ( Examples thereof include lithium salts such as LiCF3SO3). The electrolytes may be used alone or in combination of two or more. The amount of the electrolyte dissolved in the non-aqueous solvent is preferably 0.2 mol/L to 3 mol/L.

The electrolytic solution is injected into the accommodating portion 4b so that the positive electrode, the negative electrode of the electrode group 1, the separator, and the voids between the respective layers are sufficiently filled with the electrolytic solution.

Next, the dimensions of each element will be described.
FIG. 4 shows an example of the positive electrode lead terminal 2 before heat fusion. FIG. 5A shows an example of a cross-sectional view taken along line BB′.

As shown in FIGS. 4 and 5A, the metal plate 21 is covered with the resin layer 22 before heat fusion. For example, the metal plate 21 is covered with two resin films (resin layer 22 before heat fusion) from the surface 21a side and the surface 21b side. Further, the two resin films cover the metal plate 21 along the surfaces 21c and 21d.

FIG. 5B shows an example of another cross-sectional view taken along the line BB′.
In the example shown in FIG. 5B, the resin layer 22 before heat fusion is composed of an adhesive layer 221 and a heat resistant layer 222. As shown in FIG. 5B, the adhesive layer 221 is formed so as to contact the metal plate 21. The heat resistant layer 222 is formed so as to contact the outer surface of the adhesive layer 221.

The thickness of the metal plate 21 shown in FIG. 5A or FIG. 5B is TL, the thickness of the resin layer 22 before heat fusion is Tf, and the heat fusion of the inner film 43 of the laminate exterior 4 shown in FIG. 3A or 3B is performed. If the thickness before wearing is TP,
For example,
TL≧0.3 mm Tf>TP TL/TP≧5.5 Formula (1)
Meet

For example, the thickness TL of the metal plate 21 of the positive electrode lead terminal 2 is 0.5 mm or more, and the thickness TP of the inner film 43 of the laminate outer package 4 before heat fusion is 0.09 mm or less. Further, for example, the thickness TL of the metal plate 21 of the positive electrode lead terminal 2 is set to 0.4 mm or more, and the thickness TP of the inner film 43 of the laminate exterior 4 before heat fusion is set to 0.07 mm or less.

The thickness of the inner film 43 before heat fusion is, for example, about 0.03 mm to 0.1 mm.
The thickness of the metal layer 41 is, for example, about 0.03 mm to 0.05 mm.
The thickness of the outer film 42 is, for example, about 0.015 mm to 0.030 mm.

Next, a method of manufacturing the secondary battery 10 will be described.
FIG. 6 is a diagram showing a method of manufacturing the secondary battery 10.
FIG. 6 is a cross-sectional view showing the cross-section of the heat-sealed portion of the positive electrode lead terminal 2 after heat-sealing shown in FIG. 2 and the positional relationship between the jig 51 and the jig 52. The pressing surfaces (sealing surfaces) of the jig 51 and the jig 52 have the same thickness as the width of the sealing portion 4a, and have an elongated shape.

The jig 51 includes a top surface and a bottom surface that is the recess 51a. The recess 51a is formed between the top surfaces. The recess 51a is formed so that the metal plate 21 of the positive electrode lead terminal 2 can be stored therein. The bottom surface, which is the recess 51a, is parallel to the top surface. For example, the jig 51 is made of metal or the like. The jig 51 may include a heater for heating the jig 51 inside. Further, the jig 51 may have a structure heated by an external heater.

The jig 52 has a recess 52a. The jig 52 and the recessed portion 52a have the same configurations as the jig 51 and the recessed portion 51a, respectively, and a description thereof will be omitted.

For example, the surfaces 21a and 21b of the metal plate 21 are covered with two resin films forming the resin layer 22 (resin layer 22 before heat fusion). Further, the outside of each resin layer is sandwiched between two laminated films and covered.

The positive electrode lead terminal 2 is set so that the width direction of the metal plate 21 is located within the width direction of the recess 51a and the recess 52a. The positions of the jig 51 and the jig 52 are adjusted so that the concave portion 51a and the concave portion 52a face each other.

In this state, when the laminated film is pressed by the heated jig 51 and jig 52, the heat of the jig 51 and jig 52 is transferred to the inner film 43 and the resin layer 22 by heat conduction, so that the inner film and The resin layer melts. When the resin layer melts, the melted resin flows into the gap formed between the inner film 43 and the resin layer 22 in the third direction orthogonal to the first direction and the second direction, thereby filling the gap. For example, the melted resin flows into the gap between the surface 21a and the inner film 43 and between the surface 21b and the inner film 43. The melted resin also flows into the gap from the resin layer 22 sandwiched between the inner films 43, which is pressed by the top surface of the jig 51 and the top surface of the jig 52. The resin that has flowed into the gap forms the escape step portion 22c and the escape step portion 22d. The shape of the recess 51a of the jig 51 and the shape of the recess 52a of the jig 52 may not be transferred to the relief step portion as it is, and may have a slightly sloping shape as shown in FIG. 6, but this does not affect the airtightness.

Moreover, the inner film 43 and the resin layer 22 are heat-sealed by the heat of the jigs 51 and 52. Similarly, the inner film 43 and the resin layer 32 are heat-sealed. In the region where the resin layer 22 or the resin layer 32 does not exist, the inner films 43 are heat-sealed to each other. As a result, the seal portion 4a and the housing portion 4b are formed.

The pressing surface of the jig for heat-sealing the two laminated films in which the positive electrode lead terminal 2 or the negative electrode lead terminal 3 does not exist is an elongated flat surface having no recess.

Next, the dimensions of the jigs 51 and 52 will be described.
The width of the recesses 51a and 52a is W, the depth of the recess 51a is Da, the depth of the recess 52a is Db, and the width of the resin layer 22 before heat fusion is Wf as shown in FIG. Assuming that the width of 21 is WL and the thickness of the laminate film of the laminate sheath 4 before heat fusion is TF as shown in FIG. 3A or 3B, for example,
TL+Tf<Da+Db<TL+Tf×2 Formula (2)
(TF+Tf)×2+WL<W<Wf Formula (3)
Meet

According to the formula (2), the thickness of the region where the laminated films are fused to each other is T1, and the thickness between the two laminated films after the heat fusion of the region including the metal plate 21 (in the direction from the face 21a to the face 21b). If (length) is T2, for example,
TL+Tf<T2-T1<TL+Tf×2 Formula (4)
Meet
The secondary battery configured as described above includes the protrusion formed of resin on the metal plate of the positive electrode lead terminal. The protrusion maintains the distance between the metal plate and the metal layer in the laminate outer packaging. As a result, the insulation between the metal plate and the metal layer is improved, and the secondary battery can prevent a short circuit between the metal plate of the positive electrode lead terminal and the metal layer in the laminate exterior.

Between the laminate film forming the laminate exterior, there are an area where the metal plate and the resin layer of the positive electrode lead terminal are present and an area where they are not present. Therefore, the laminated film is not flat and has irregularities.

In heat fusion of a laminated film having irregularities, adhesion is improved by providing concave relief steps on the side surface of the metal plate. When the thickness of the metal plate is increased, it is necessary to increase the concave relief step, and thus a gap is likely to occur on the fusion-bonded surface. In order to eliminate such a gap, it is necessary to apply a large force to the laminate exterior and the resin film during hot pressing. On the other hand, when a large force is applied to the laminate exterior and the resin film during hot pressing, short circuit failure between the metal plate and the metal layer in the laminate exterior is likely to occur. Therefore, normally, when increasing the thickness of the metal plate of the lead terminal, it is necessary to increase the thickness of the inner film of the laminate exterior.

In the secondary battery according to the embodiment, during hot pressing as described above, it is possible to form a short circuit between the metal plate of the lead terminal and the metal layer in the laminate exterior by forming the protrusion and the relief step in the resin layer. To prevent. As a result, in the secondary battery, even when the thickness of the metal plate is increased, it is not necessary to increase the thickness of the inner film of the laminate exterior.

Since the inner film of the laminate outer case is a path through which water from the outside of the battery passes (permeates) and penetrates into the battery, there is no need to increase the thickness of the inner film, so the laminate outer case and the resin layer The airtightness between and can be improved. Further, the material of the inner film can be reduced, and the manufacturing cost of the secondary battery can be suppressed. Further, when the inner film is heat-sealed, the temperature of the contact surface rises in a short period of time, and the takt time during production can be suppressed.

Next, an example of another cross-sectional view of the secondary battery 10 will be described.
FIG. 7 shows another example of a sectional view of the secondary battery 10.
As shown in FIG. 7, one surface (lower surface in FIG. 7) of the laminate exterior 4 is a flat surface. The other surface (upper surface in FIG. 7) of the laminate exterior 4 is formed along the metal plate 21. The other surface of the laminated exterior 4 is formed along the surfaces 21 a, 21 c and 21 d of the metal plate 21. The seal portion 4a where the laminated films of the laminated outer casing 4 adhere to each other is formed on the surface 21b side.

The resin layer 22 includes a protruding portion 22a and escape step portions 22c and 22d. The protrusion 22 a is provided on the surface 21 a of the metal plate 21. The protrusion 22a is formed so as to protrude from a position facing the surface 21a in a second direction orthogonal to the surface 21a. The protrusion 22a is formed to have a size that covers at least the surface 21a.

For example, the secondary battery 10 is formed using a jig having a recess and a flat jig. For example, the secondary battery 10 is formed by disposing the metal plate 21 covered with the resin film and the laminate film on a flat jig, and pressing both jigs from above with a jig having a recess. May be. That is, in FIG. 6, the depth of the concave portion 52a of the jig 52 is Db=0.

Next, another configuration example of the secondary battery 10 will be described.
FIG. 8 is a diagram showing another configuration example of the secondary battery 10. The portion hidden by the laminate exterior 4 is indicated by a dotted line.
In the secondary battery 10 shown in FIG. 8, the positive electrode lead terminal 2 and the negative electrode lead terminal 3 extend in the same direction.

The electrode group 1 is formed in a flat rectangular parallelepiped shape by, for example, stacking a positive electrode, a separator, and a negative electrode in this order, winding them into a coil, and pressing them.

The positive electrode has a plurality of positive electrode tabs arranged at intervals, and the negative electrode has a plurality of negative electrode tabs arranged at intervals. When wound, the plurality of positive electrode tabs are formed to overlap each other and the plurality of negative electrode tabs are formed to overlap each other. The positive electrode tabs and the negative electrode tabs are alternately arranged so as not to overlap each other. The metal plate 21 of the positive electrode lead terminal 2 is joined to the plurality of positive electrode tabs by laser welding, ultrasonic welding, or the like. The metal plate 31 of the negative electrode lead terminal 3 is joined to the plurality of negative electrode tabs by laser welding, ultrasonic welding, or the like.

The metal plate 21 of the positive electrode lead terminal 2 and the metal plate 31 of the negative electrode lead terminal 3 extend from the electrode group 1 in the same direction along the axial direction (center axis direction). Further, the positive electrode lead terminal 2 and the negative electrode lead terminal 3 are provided in parallel with each other and at intervals.

The laminate sheath 4 is formed by, for example, sandwiching the positive electrode lead terminal 2 and the negative electrode lead terminal 3 between two laminated films, and fusing the peripheral edge portions to each other.

For example, the cross-sectional view of the secondary battery 10 taken along the line C-C′ is the same as the cross-sectional view shown in FIG. 2 or 7.

The electrode group 1 may be configured by alternately stacking a plurality of rectangular plate-shaped positive electrodes and a plurality of rectangular plate-shaped negative electrodes with a separator interposed therebetween.

The surface 21c of the metal plate 21 does not have to be a flat surface. For example, depending on the shape of the metal plate 21, the surface 21c may be curved with a predetermined R in the first direction. In this case, the metal plate 21 does not need to have a rectangular parallelepiped shape.
Further, the laminated outer casing 4 may be formed by folding one long laminated film halfway and pressing it with a heated jig in a state of overlapping. Further, the laminated exterior 4 may be formed by pressing a cup-shaped laminated film with a heated jig.

Further, the jigs 51 and 52 may each include a recess formed so as to be able to store the metal plate 31 of the negative electrode lead terminal 3.
Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the scope of equivalents thereof.
The matters described in the initial claims of the present application will be additionally described below.
[1] An electrode group including electrodes,
A metal plate electrically connected to the electrode, having a first surface protruding from the electrode and parallel to a first direction, and a second surface parallel to the first direction and adjacent to the first surface;
A protrusion portion formed to protrude from a position facing the first surface in a second direction orthogonal to the first surface; and a relief step portion formed at a position facing the second surface. A resin layer covering the metal plate,
An inner film that covers the resin layer and is bonded to the resin layer by heat fusion,
A metal layer that covers the inner film and adheres to the inner film;
An outer film that covers the metal layer and adheres to the metal layer,
A secondary battery including.
[2] The secondary battery according to [1], wherein the metal plate is connected to the positive electrode of the electrode group.
[3] The secondary battery according to [1] or [2], wherein the metal plate is made of aluminum having a purity of 99.0% or more.
[4] The secondary battery according to [3], wherein the metal plate is surface-treated with an organic substance of 0.05 μm or more and 0.2 μm or less.
[5] When the thickness of the metal plate is TL and the thickness of the inner film before heat fusion is TP, TL/TP≧5.5 is satisfied, and any one of [1] to [4] is satisfied. The secondary battery according to item.
[6] The secondary battery according to [5], wherein the TL is 0.5 mm or more and the TP is 0.09 mm or less.
[7] The secondary battery according to [5], wherein the TL is 0.4 mm or more and the TP is 0.07 mm or less.
[8] A resin film in which at least one jig is provided with a recess formed to accommodate the metal layer, and the metal plate and the resin layer are formed by using the two heated jigs. The secondary battery according to any one of [1] to [7], which is formed by pressing the inner film covering the resin film, the metal layer, and the outer film.

DESCRIPTION OF SYMBOLS 1... Electrode group, 2... Positive electrode lead terminal, 3... Negative electrode lead terminal, 4... Laminated exterior, 4a... Seal part, 21... Metal plate, 21a to d... Surface, 22... Resin layer, 22a and b... Projection part, 22c and d... Escape step portion, 31... Metal plate, resin layer... 32, 41... Metal layer, 42... Outer film, 43... Inner film, 43a... Adhesive layer, 43b... Thermal fusion bonding layer, 221... Adhesive layer, 222... Heat resistant layer.

Claims (9)

An electrode group including electrodes,
It is electrically connected to the electrode, a first direction parallel to the front and back surfaces projecting from the electrode, as well as adjacent to the surface which is parallel to the first direction, between the back surface and the surface A metal plate having a pair of surfaces extending in the thickness direction ,
A resin layer covering the metal plate,
An inner film that covers the resin layer and is bonded to the resin layer by heat fusion,
A metal layer that covers the inner film and adheres to the inner film;
An outer film that covers the metal layer and adheres to the metal layer,
Equipped with,
The resin layer is
A first portion adjacent to the inside of the portion where the inner films contact each other;
A second portion provided between the first portion and the surface of the metal plate in the thickness direction and forming a step between the first portion and the first portion;
A third portion provided between the pair of the thickness direction surface is provided in an upper of said surfaces, and projects from the front Stories second portion on the side where the surface is directed, and the A third portion that is provided on the back surface and that has a protrusion that protrudes with respect to the second portion on the side facing the back surface ;
A secondary battery including. The secondary battery according to claim 1, wherein the metal plate is connected to a positive electrode of the electrode group. The secondary battery according to claim 1, wherein the metal plate is made of aluminum having a purity of 99.0% or more. The secondary battery according to claim 3, wherein the metal plate is surface-treated with an organic substance having a thickness of 0.05 μm or more and 0.2 μm or less. If the thickness of the metal plate is TL and the thickness of the inner film before heat fusion is TP,
TL/TP≧5.5
The secondary battery according to claim 1, which satisfies the above condition. 6. The TL is 0.5 mm or more and the TP is 0.09 mm or less.
The secondary battery according to. The TL is 0.4 mm or more, and the TP is 0.07 mm or less.
The secondary battery according to. A resin film and a resin, which heat two jigs provided with a recess formed in at least one side so as to accommodate the metal layer, and form the metal plate and the resin layer by using the two heated jigs. The secondary battery according to any one of claims 1 to 7, which is formed by pressing the inner film covering the film, the metal layer, and the outer film. Let TF be the thickness of the laminate exterior before heat fusion, Tf be the thickness of the resin layer before heat fusion, W be the dimension between the portions extended along the step, and WL be the width of the metal plate. Then,
TF+Tf<(W-WL)/2
The secondary battery according to claim 1, which satisfies the above condition.