JP2016225118A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery which effectively prevents short-circuiting.SOLUTION: The secondary battery comprises an electrode group, a metal plate, a resin layer, an inner film, a metal layer and an outer film. The electrode group includes electrodes. The metal plate is electrically connected to the electrodes and includes a first face that protrudes from the electrodes and is in parallel with a first direction, and a second face that is in parallel with the first direction and neighboring to the first face. The resin layer includes: a protrusion that is formed so as to protrude from a position opposite to the first face in a second direction that is orthogonal to the first face; and a release step that is formed at a position opposite to the second face. The resin layer covers the metal plate. The inner film covers the resin layer and is adhered with the resin layer by heat-sealing. The metal layer covers the inner film and is adhered with the inner film. The outer film covers the metal layer and is adhered with the metal layer.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a secondary battery.

  Some secondary batteries have a structure in which an electrode group and an electrolytic solution 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 protrude from the laminate, and the lead terminal and the metal layer are formed with an inner film interposed therebetween. The demand for a secondary battery that charges and discharges with a large current increases, and the cross-sectional area of the lead terminal needs to be increased. In order to increase the cross-sectional area of the lead terminal, it is conceivable to increase the thickness of the lead terminal. Conventionally, in the secondary battery, it is necessary to increase the thickness of the inner film so that the lead terminal and the metal layer are not short-circuited. When the inner film is thickened, there is a problem that the amount of moisture entering from the outside into the battery 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. The metal plate is electrically connected to the electrode, and has a first surface parallel to the first direction protruding from the electrode and a second surface parallel to the first direction and adjacent to the first surface. . The resin layer includes: a protrusion formed to protrude in a second direction perpendicular to the first surface from a position facing the first surface; and a relief step formed in a position facing the second surface. The metal plate is covered. The inner film covers the resin layer and adheres 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.

FIG. 1 is a diagram illustrating a configuration example of the secondary battery according to the embodiment. FIG. 2 is an example of a cross-sectional view of the secondary battery according to the embodiment. FIG. 3A is a diagram illustrating a configuration example of a laminate film according to the embodiment. FIG. 3B is a diagram illustrating another configuration example of the laminate film according to the embodiment. FIG. 4 is a diagram illustrating 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 illustrating an example of a method for manufacturing the 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 illustrating 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 illustrating a configuration example of a secondary battery 10 according to the embodiment. A portion hidden in the laminate exterior 4 is indicated by a dotted line. FIG. 2 is an example of a cross-sectional view taken along line AA ′ of the secondary battery 10 according to the embodiment.
A 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 laminate-type 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 sheath 4.

  The electrode group 1 is formed in a flat rectangular parallelepiped shape, for example, by sequentially stacking a positive electrode, a separator, and a negative electrode, winding the coil, and pressing it.

  The positive electrode of the electrode group 1 is obtained by, for example, applying a positive electrode active material on 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 an aluminum foil or an aluminum alloy foil. Although it does not specifically limit as a positive electrode active material, The oxide, sulfide, polymer, etc. which can occlude / release lithium can be used. Preferable active materials include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium iron phosphate, and the like that can obtain a high positive electrode potential.

  For example, the positive electrode includes a positive electrode tab made of a metal foil portion to which no positive electrode active material is applied. The positive electrode tab protrudes from the separator to one side of the electrode group 1 in the winding axis direction. The positive electrode tabs protrude from the separator while being overlapped with each other.

  The negative electrode of the electrode group 1 is obtained by applying a negative electrode active material on both sides of a metal foil as a current collector. The negative electrode is produced 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, and metal oxides, metal sulfides, metal nitrides, alloys, and the like that can occlude and release lithium can be used. Preferably, the lithium ion occlusion and release potential is metal lithium. It is a substance that becomes 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 a negative electrode current collector and a negative electrode related component. 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 includes a negative electrode tab made of a metal foil portion to which no negative electrode active material is applied. The negative electrode tab protrudes 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, a laminate of the same material or different materials among these can be used. Examples of the material for forming the separator include polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-butene copolymer.

  The positive electrode lead terminal 2 includes a metal plate 21 and a resin layer 22.

  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.

  In addition, when the raw material of the metal plate 21 is aluminum, in order to improve the adhesiveness with the resin layer 22 to the metal plate 21, and in order to improve the chemical resistance with respect to electrolyte solution, thickness 0.05 micrometer or more, You may perform the surface treatment which consists of a 0.2 micrometer or less layer of organic substance. As the surface treatment, the surface of the metal plate 21 may be formed with aluminum oxide by chemical conversion treatment. However, because of the metal oxide insulating layer, charge / discharge inspection, voltage inspection, resistance inspection, etc. in the battery manufacturing process. In the electrical inspection, it is necessary to remove the metal oxide insulating layer. 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 still attached. .

The metal plate 21 has a substantially rectangular parallelepiped shape. The metal plate 21 has surfaces 21a to 21d.
The surface 21 a is a predetermined surface parallel to the first direction in which the metal plate 21 protrudes 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 parallel to the first direction and is 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 superimposed positive electrode tab by laser welding or ultrasonic welding.

  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 thermal bonding (thermocompression bonding).

The resin layer 22 after heat sealing has a protruding portion 22a, a protruding portion 22b, a relief step portion 22c, a relief step portion 22d, and the like.
The protrusion 22 a is provided on the surface 21 a of the metal plate 21. The protrusion 22a is formed to protrude in a second direction perpendicular to the surface 21a from a position facing the surface 21a. The protrusion 22a is formed with a dimension that covers at least the surface 21a.

  Moreover, the protrusion part 22b is provided on the surface 21b which is the back surface of the surface 21a. Since the protrusion 22b has the same configuration as the protrusion 22a, detailed description thereof is 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.

Further, the relief step portion 22d is formed on the surface 21d. Since the escape step portion 22d is the same as the escape step portion 22c, detailed description thereof is omitted.
The negative electrode lead terminal 3 includes a metal plate 31 and a resin layer 32.

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

  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 superimposed negative electrode tab by laser welding or ultrasonic welding.

  Since the resin layer 32 has the same configuration as that of the resin layer 22, detailed description thereof is 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 thermal bonding.

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

  The laminate film constituting the laminate exterior 4 has flexibility. As shown in FIG. 3A, the laminate film includes 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 and the like from entering the inside of the secondary battery 10 from the outside, and further preventing the electrolytic solution and the like inside the secondary battery 10 from leaking to the outside. Yes, it is a conductor foil made 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 laminate 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 sealing 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 edges of two laminate films, and a storage portion 4b formed inside the seal portion 4a. Furthermore, one end of the metal plate 21 that is not connected to the positive electrode tab and one end of the metal plate 31 that is 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, electrolyte solution, etc.

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

  Usually, before injection of the electrolytic solution, a part of the seal portion 4a has a portion that is not thermally fused, and the electrolytic solution is injected from the portion, and is thermally fused after a predetermined amount of electrolytic solution is injected. By the seal portion 4a, the accommodating portion 4b is kept airtight with the outside air (outside of the battery).

  As the electrolytic solution, a nonaqueous electrolytic solution prepared by dissolving an electrolyte (for example, lithium salt) in a nonaqueous 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), ethyl methyl carbonate (EMC), γ-butyrolactone (γ -BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. Nonaqueous solvents 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 arsenic hexafluoride (LiAsF6), lithium trifluorometasulfonate ( Lithium salts such as LiCF3SO3) can be mentioned. The electrolyte may be used alone or in combination of two or more. The amount of electrolyte dissolved in the non-aqueous solvent is desirably 0.2 mol / L to 3 mol / L.

  The electrolytic solution is injected into the housing portion 4b so that the positive electrode, the negative electrode, the separator of the electrode group 1, and the gaps 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 a resin layer 22 before heat sealing. For example, the metal plate 21 is covered with two resin films (the resin layer 22 before heat sealing) from the surface 21a side and the surface 21b side. Further, the two resin films cover the metal plate 21 along the surface 21c and the surface 21d.

FIG. 5B shows another example of a cross-sectional view taken along line BB ′.
In the example shown in FIG. 5B, the resin layer 22 before heat-sealing includes 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 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. 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 set to 0.5 mm or more, and the thickness TP before the heat bonding of the inner film 43 of the laminate outer package 4 is set to 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 before the heat sealing of the inner film 43 of the laminate outer package 4 is set to 0.07 mm or less.

The thickness of the inner film 43 before heat sealing 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 for manufacturing the secondary battery 10 will be described.
FIG. 6 is a diagram illustrating a method for manufacturing the secondary battery 10.
FIG. 6 is a cross-sectional view showing the positional relationship between the cross section of the heat fusion portion of the positive electrode lead terminal 2 after the heat fusion shown in FIG. The pressing surfaces (seal surfaces) of the jig 51 and the jig 52 have a thickness that is the same as the width of the seal portion 4a, and are elongated.

  The jig 51 includes a top surface and a bottom surface that is a 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 accommodated. 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 be heated by an external heater.

  The jig 52 includes a recess 52a. The jig 52 and the recess 52a have the same configuration as the jig 51 and the recess 51a, respectively, and thus description thereof is omitted.

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

  The positive electrode lead terminal 2 is set so that the width direction of the metal plate 21 is positioned 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 recess 51a and the recess 52a face each other.

  In this state, when the laminate film is pressed with the heated jig 51 and the jig 52, the heat of the jig 51 and the jig 52 is transferred to the inner film 43 and the resin layer 22 by heat conduction, 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 molten resin flows into the gap between the surface 21 a and the inner film 43 and between the surface 21 b and the inner film 43. The melted resin also flows into the gap from the resin layer 22 sandwiched between the inner films 43 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 a relief step portion 22c and a relief step portion 22d. In the relief step portion, the shapes of the concave portion 51a of the jig 51 and the concave portion 52a of the jig 52 are not transferred as they are, and there are cases in which the shape is slightly deviated as shown in FIG. 6, but the airtightness is not affected.

  Further, the inner film 43 and the resin layer 22 are thermally fused 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 is not present, the inner films 43 are heat-sealed. As a result, the seal part 4a and the accommodating part 4b are formed.

  The press surface of the jig for heat-sealing two laminated films without the positive electrode lead terminal 2 or the negative electrode lead terminal 3 is an elongated flat surface with 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 sealing is Wf as shown in FIG. When the width of 21 is WL, and the thickness of the laminate film of the laminate outer sheath 4 before heat fusion as shown in FIG. 3A or 3B is TF, for example,
TL + Tf <Da + Db <TL + Tf × 2 Formula (2)
(TF + Tf) × 2 + WL <W <Wf Equation (3)
Meet.

According to the formula (2), the thickness of the region where the laminate films are fused is T1, and the thickness between the two laminate films after the heat fusion of the region including the metal plate 21 (from the surface 21a to the surface 21b direction). If length is T2, for example,
TL + Tf <T2-T1 <TL + Tf × 2 Formula (4)
Meet.
The secondary battery configured as described above includes a protrusion made 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 exterior. 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 films constituting the laminate exterior, there are regions where the metal plate and the resin layer of the positive electrode lead terminal are present and regions where they are absent. Therefore, the laminate film is not flat and has irregularities.

  The heat adhesion of the laminated film having irregularities improves the adhesion by providing a concave relief step 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 a gap is likely to be generated on the fusion 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 press processing, short circuit failure between the metal plate and the metal layer in the laminate exterior is likely to occur. Therefore, normally, when the thickness of the metal plate of the lead terminal is increased, it is necessary to increase the thickness of the inner film of the laminate exterior.

  In the secondary battery according to the embodiment, the metal plate of the lead terminal and the metal layer in the laminate exterior are short-circuited by forming the protruding portion and the relief step portion in the resin layer at the time of hot pressing as described above. 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.

  The inner film of the laminate outer sheath is a path through which moisture from the outside of the battery passes (permeates) and enters the battery, so there is no need to increase the thickness of the inner film. The airtightness between the two can be improved. Moreover, the material of an inner film can be decreased and the manufacturing cost of a 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 tact 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 an example of another cross-sectional view of the secondary battery 10.
As shown in FIG. 7, one surface (the 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 laminate exterior 4 is formed along the surfaces 21a, 21c and 21d of the metal plate 21. The seal portion 4a to which the laminate films of the laminate exterior 4 are bonded is formed on the surface 21b side.

  The resin layer 22 includes a protrusion 22a, a relief step 22c, 22d, and the like. The protrusion 22 a is provided on the surface 21 a of the metal plate 21. The protrusion 22a is formed to protrude in a second direction perpendicular to the surface 21a from a position facing the surface 21a. The protrusion 22a is formed with a dimension that covers at least the surface 21a.

  For example, the secondary battery 10 is formed using a jig provided with a recess and a flat jig. For example, the secondary battery 10 is formed by placing the metal plate 21 covered with a resin film and a laminate film on a flat jig, and pressing both jigs with a jig provided with a recess from the top. May be. That is, in FIG. 6, the depth of the recess 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 illustrating another configuration example of the secondary battery 10. A portion hidden in 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 the coil, and pressing it.

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

  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, for example, by stacking the positive electrode lead terminal 2 and the negative electrode lead terminal 3 between two laminated films and fusing the peripheral edges together.

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

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

Further, the surface 21c of the metal plate 21 may not 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 with respect to the first direction. In this case, the metal plate 21 may not be a rectangular parallelepiped.
Moreover, the laminate exterior 4 may be formed by folding back one long laminate film in the middle and pressing it with a heated jig in a superposed state. Moreover, the laminate exterior 4 may be formed by pressing a laminated film formed in a cup shape with a heated jig.

In addition, the jigs 51 and 52 may each include a recess formed so that the metal plate 31 of the negative electrode lead terminal 3 can be accommodated.
Although several embodiments of the present invention have been described, these embodiments are presented by way of example 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 scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Electrode group, 2 ... Positive electrode lead terminal, 3 ... Negative electrode lead terminal, 4 ... Laminate exterior, 4a ... Sealing part, 21 ... Metal plate, 21a thru | or ... Surface, 22 ... Resin layer, 22a and b ... Projection part, 22c and d ... relief step portion, 31 ... metal plate, resin layer ... 32, 41 ... metal layer, 42 ... outer film, 43 ... inner film, 43a ... adhesive layer, 43b ... heat fusion layer, 221 ... adhesive layer, 222: Heat-resistant layer.

Claims (8)

An electrode group comprising electrodes;
A metal plate electrically connected to the electrode and having a first surface parallel to the first direction protruding from the electrode and a second surface parallel to the first direction and adjacent to the first surface;
A protrusion formed so as to protrude in a second direction perpendicular to the first surface from a position facing the first surface, and a relief step portion formed in a position facing the second surface, A resin layer covering the metal plate;
An inner film that covers the resin layer and adheres to the resin layer by thermal 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 comprising: The metal plate is connected to a positive electrode of the electrode group;
The secondary battery according to claim 1. The metal plate is made of aluminum having a purity of 99.0% or more.
The secondary battery according to claim 1 or 2. The metal plate is surface-treated with an organic substance of 0.05 μm or more and 0.2 μm or less,
The secondary battery according to claim 3. 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
Meet,
The secondary battery according to any one of claims 1 to 4. The TL is 0.5 mm or more, and the TP is 0.09 mm or less.
The secondary battery according to claim 5. The TL is 0.4 mm or more, and the TP is 0.07 mm or less.
The secondary battery according to claim 5. Resin film and resin that heats two jigs provided with recesses formed so that at least one of the metal layers can be accommodated, and forms the metal plate and the resin layer using the two heated jigs Formed by pressing the inner film, the metal layer and the outer film covering the film,
The secondary battery according to any one of claims 1 to 7.