JP2001338688A - Terminal bundling structure of flat laminated cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable electrode terminals to surely and tightly bundle, at the terminal bundling structure of a flat laminated cell, and to improve the productivity of the flat laminated cell. SOLUTION: Electrode terminals 13A, which are the lamination of a plurality of flat plate-shaped unit cell elements 10, are stacked and bundled by a rivet 14A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat plate type battery in which a plurality of flat unit battery elements are stacked, and the pole terminals of each unit battery element are superposed and bound. The present invention relates to a battery terminal binding structure.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for miniaturization of portable devices such as cellular phones and portable terminals. However, in portable devices, the proportion of batteries occupying both dimensions and weight is large. In other words, miniaturization of the battery can be said. Against this background, recently, a flat plate type battery that can be made thin has attracted attention.

[0003] A flat plate type battery is formed by stacking flat unit battery elements. In addition to thinning, the capacity can be easily increased by increasing the number of stacked unit battery elements. Unlike a wound battery formed by winding battery elements, attention is also paid to the fact that batteries having various shapes can be formed by changing the flat shape of the unit battery element to an arbitrary one.

[0004]

By the way, a metal tab for extracting electricity is provided on each of the positive electrode and the negative electrode of each battery element constituting the flat plate type battery. Are connected in parallel, the tabs on the positive electrode side of each battery element are respectively superposed and bound, and similarly, the tabs on the negative electrode side of each battery element are each superposed and bound.

[0005] The binding portion of the tab on the positive electrode side and the binding portion of the tab on the negative electrode side also function as coupling terminals for leads connected to external devices, and are constituted by the tabs on the positive electrode side inside the battery. The coupling terminal and the lead on the positive electrode side are polymerized and bound, and similarly, the coupling terminal formed by the tab on the negative electrode side and the lead on the negative electrode side are polymerized and bound.

As a method of binding the tab and the lead, for example, there are soldering, welding, ultrasonic welding and the like. However, all of these binding methods have problems. In other words, there is a problem that the soldering may have a thermal effect on the battery, and the efficiency of the processing operation is low, and the productivity of the battery is reduced. Also, welding may have a thermal effect on the battery as in the case of soldering. Further, for example, in a lithium battery in which lithium ions are used as an electromotive substance, aluminum (Al) is generally provided on the tab and lead of the positive electrode. However, aluminum is difficult to be welded, and even if bound by welding, there is a risk that the binding may become unstable. Also, in ultrasonic welding, if the number of layers of tabs to be polymerized increases, welding becomes insufficient,
As in the case of welding, the binding may be unstable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to securely and firmly bind tabs (polar terminals) and improve productivity of a flat plate type battery. It is another object of the present invention to provide a terminal binding structure for a flat plate type battery.

[0008]

For this reason, the terminal binding structure of the flat plate type battery according to the present invention (Claim 1) is a flat plate type battery constructed by stacking a plurality of flat unit battery elements. A terminal bundling structure of a flat plate type battery in which each of the pole terminals of each unit battery element is superposed and bound, wherein each of the pole terminals is bound by a rivet.

It is preferable that the rivet is made of the same material as the pole terminal. Also,
It is preferable that the rivet is provided with a rotation stopping mechanism so that the rivet does not rotate with respect to the pole terminal. The rotation stopping mechanism may be constituted by a projection provided on a surface of the rivet head that is in contact with the pole terminal.

[0010] Further, the rotation stopping mechanism may be constituted by a groove provided on a surface of the rivet in contact with the pole terminal of the head portion. The groove may be an annular groove formed around the axis of the rivet. Further, the groove may be a cross-shaped groove formed around the axis of the rivet. Further, the pole terminals may be bound by using a plurality of the rivets.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 to FIG. 10 are diagrams showing a terminal binding structure of a flat plate type battery as one embodiment of the present invention. In this embodiment, an example will be described in which the terminal binding structure of the flat-plate stacked battery of the present invention is applied to a lithium secondary battery.

A flat-plate lithium secondary battery (hereinafter simply referred to as a battery) according to the present invention has a battery element 1 (see FIG. 1) housed in a flexible housing 2 as shown in FIG. The housing 2 is formed by housing the battery element 1 and then sealing the outer edges 21 and 21.
Further, the leads 3A and 3B are exposed from the housing 2. As shown in FIGS. 1 and 2, each of the leads 3A and 3B has one end inside the housing 2 and the tabs 13A and 1B.
3B (tabs 13A and 13B will be described later) are respectively joined to binding terminals formed by binding, and the other end is electrically connected to an external device (not shown) outside the housing 2. ing. Each of the leads 3A and 3B has a tab 13 so as not to cause electrolytic corrosion.
The leads 3A and the tabs 13A are made of an aluminum material, and the leads 3B and the tabs 13B are made of a copper material.

The battery element 1 is constructed by stacking a plurality (three in this case) of unit battery elements 10 in a plate shape as shown in FIG. 1 in order to increase the capacity of the battery. Each unit battery element 10 includes a positive electrode 10A, a negative electrode 10B, and an electrolyte layer 10C interposed between the positive electrode 10A and the negative electrode 10B. In FIG. 1, the unit battery element 10 has a forward posture in which the positive electrode 10A is on the upper side and the negative electrode 10B is on the lower side. On the contrary, the unit battery element 10 has the negative electrode 10B on the upper side and the positive electrode 10A on the lower side. Some of the posture.

In the battery element 1, by alternately stacking the unit battery elements 10 having these different postures, the unit battery elements 10, 10 adjacent in the stacking direction have the same polarity (that is, the positive electrode 10A and the positive electrode 10A). 10A or the negative electrode 10B and the negative electrode 10B). The number of stacked unit battery elements 10 is usually 2 or more, preferably 5 or more,
The effect of the present invention is more preferably set to 10 or more. In other words, in the ultrasonic welding or soldering as in the prior art, if the number of stacked unit cell elements 10 increases, the tab 1
While the binding power and productivity of the leads 3A and 13B and the leads 3A and 3B are significantly reduced, according to the present invention, the tabs 13A and 13B and the leads 3A and 3B are connected by rivets 14A and 14B as described later. In connection with such rivets 14A and 14B, the unit battery element 1
Even if the number of laminations of 0 increases, such binding power and productivity hardly decrease. However, it is not realistic that the number of stacked unit battery elements 10 is too large.
The number of laminations of 0 is usually 100 or less.

As described above, the positive electrode 10A is provided with an aluminum tab (pole terminal) 13A, and the negative electrode 10B is provided with a copper tab (pole terminal) 13B.
The tab 13A is connected to the positive electrode 10A as described later with reference to FIG.
Is formed by extending the current collector 12A constituting the
B is formed by extending a current collector 12B constituting the negative electrode 10B, and the current collectors 12A and 12B, and thus the tab 1 are formed.
The materials of 3A and 13B are determined based on the compatibility with a positive electrode active material 11A and a negative electrode active material 11B described later.

The battery has a configuration in which a plurality of stacked unit battery elements 10 are connected in parallel. For this reason, as shown in FIG. 1, each of the stacked unit battery elements 10 has a positive electrode side. Similarly, each of the stacked unit battery elements 10 is similarly stacked so that the tabs 13A of the
Here, in each of the unit battery elements 10, the tabs 13 </ b> B on the negative electrode side are easily polymerized and bound.
Each unit battery element 10 is formed such that each positive electrode tab 13A is on the lower side in the figure and each negative electrode tab 13B is on the upper side in the figure when viewed from above shown in FIG.

Therefore, as described above, the unit cell element 1
0 includes a stack in a forward orientation and a stack in a reverse orientation.
When the tabs 13A and 13B are viewed from above in a posture in which the tabs 13A and 13B are directed upward with the negative electrode 10B facing downward, the positive electrode side tab 13A
Is formed on the right side (therefore, this unit battery element 10 is referred to as a light type (hereinafter, simply referred to as an R type) or an R type unit battery element 10).
The tabs 13A, 1A are stacked in the reverse orientation, with the positive electrode 10A facing upward and the negative electrode 10B facing downward.
When viewed with 3B facing upward, the positive electrode side tab is formed on the left side (therefore, this unit battery element 10 is referred to as a left type (hereinafter abbreviated as L type) or an L type unit battery element 10). . Such a a a R type and L type, disposed between the positive electrode tab 13A and the negative electrode tab 13B has a symmetrical structure with respect to the center line C _L.

With such a structure, as described above, when these unit cell elements 10 are stacked upside down (in the thickness direction), that is, when the
When the positive electrode is set to the upper side and the negative electrode is set to the upper side for the L type, or the negative electrode is set to the upper side for the R type and the positive electrode is set to the upper side for the L type). Each has a structure that is easily concentrated and concentrated on one side.

Then, the tabs 13A and 13B and the lead 3
A and 3B are rivets 14 as shown in FIGS.
A, 14B. Here rivets 14
A and 14B will be described.
B has rivets 14A and 14B so as not to cause electrolytic corrosion.
Tabs 13A, 13B and lead 3 bound by B
The rivets 14A on the positive electrode side are made of an aluminum material, and the rivets 14B on the negative electrode side are made of a copper material.

The rivets 14A and 14B include:
Here, as shown in FIG.
A, 140B are flat, and the shaft portions 141A, 141
1B having a hollow tip is used. As shown in FIG. 4, in order to insert the rivets 14A and 14B, oblong holes 131A and 131B are respectively formed in the tabs 13A and 13B, respectively, and the leads 3A and 3B are formed.
In B, perfect circular holes 31A and 31B are formed in advance. Holes 131A, 1 of tabs 13A, 13B
By making the 31B an elliptical shape, the insertion of the rivets 14A and 14B becomes easier and the productivity is improved as compared with the case where the 31B is made a perfect circular shape.

The tabs 13A and 13B may be provided with holes in a perfect circle, or the leads 3A and 3B may be provided with holes in an oval shape. By the way, in such a configuration, the rivets 14A and 14B rotate with respect to the tabs 13A and 13B, thereby increasing the conduction resistance between the rivets 14A and 14B and the tabs 13A and 13B and deteriorating the battery performance. There is a risk of doing this. Therefore, the rivets 14A, 1
4B does not rotate with respect to the tabs 13A and 13B,
Although omitted in FIGS. 1, 3 and 4, the rivet 14
5A, the back surfaces of the head portions 140A and 140B of A and 14B (the surfaces in contact with the tabs 13A and 13B).
As shown in (B), a plurality (three in this case) of projections (rotation stopping mechanisms) 143A and 143B are provided as rotation stopping mechanisms.

That is, the rivets 14A, 1
When the tabs 13A, 13B and the leads 3A, 3B are bound by the 4B, these projections 143A, 143B
A, 13B, respectively, rivets 14A, 1
4B is prevented from rotating with respect to the tabs 13A and 13B. Now, FIG.
As shown in the figure, the tabs 13A, 13B and the leads 3A, 3A
B is a state in which the holes 131A, 131B, 31A, and 31B are superposed so that the holes 131A, 131B, 31A, and 31B are put together.
The rivet 14A is inserted into the hole 1A.
The rivets 14B are inserted into the rivets 14B and 31B, and thereafter, the shaft ends 142A and 142B of the rivets 14A and 14B are crushed by a hammer, a press or the like, as shown in FIG. As shown by the dashed line, the head portion 140A and the shaft end 142A are pushed outward.
The tab 13A and the lead 3B are pressed and bound, and similarly, the tab 13B and the lead 3B are pressed and bound between the head part 140B and the shaft end 142B. As shown in FIG. 4, here, the leads 3A and 3B move outward (from the battery) as shown by a two-dot chain line in the figure after the shaft ends 142A and 142B of the rivets 14A and 14B are crushed. (To separate).

The shapes of the heads 140A and 140B and the shafts 141A and 141B of the rivets 14A and 14B are not limited to the flat shape and the hollow shape as shown in FIG. Rivet 1 shown in)
As in 4 ', a round head 140' may be used, or a solid shaft portion 141 'may be used. In addition, each rivet 14A, 14
The rotation stopping mechanism for preventing B from rotating with respect to the tabs 13A and 13B is not limited to those shown in FIGS. 5A and 5B described above. For example, the number of projections 143A and 143B is not limited to three, and is not limited to one using projections.

For example, as shown in FIGS. 6A and 6B, tabs 13A and 13B of the heads 140A and 140B.
May be provided by providing a groove on the surface on the side in contact with. 6A, an annular groove 144 formed concentrically with the shafts 141A and 141B is provided.
In (B), a groove portion 145 is provided in a cross shape around the axis of the shaft portions 141A and 141B. By providing such grooves 144 and 145, the head 140A,
The contact area between the head 140A and the tabs 14A and 14B is reduced.
4A and 14B, the contact pressure with each rivet 14 is increased.
A and 14B can be prevented from rotating with respect to the tabs 13A and 13B.

Alternatively, the binding of the tabs 13A and the leads 3A and the binding of the tabs 13B and the leads 3B are not performed with one rivet, but are performed with a plurality of rivets. 14A and 14B may be configured not to rotate. Now, the housing 2, the positive electrode 10A, the negative electrode 10B, and the electrolyte layer 10C will be described.

First, the housing 2 will be described.
The structure of the housing 2 may be any structure as long as it has mechanical strength and sealing properties. In addition to the structure shown in FIG. 8 described above, for example, the housing 4 shown in FIG. May be used. In the housing 4, a part of the sheet-shaped housing member is subjected to drawing processing to form a housing part 41 for housing the battery element 1. After the battery element 1 is housed in the housing part 41, the housing member is folded back. It is superimposed and sealed.

As shown in FIGS. 8 and 9, it is preferable to seal the overlapped housings 2 and 4 in terms of battery performance such as ease of manufacture and battery capacity. In this case, the leads 3A and 3B can be easily exposed to the outside from the sealing portions of the housings 2 and 4. Exposing the leads from the sealing portion of the housing is a preferable aspect in that the electrical connection with the battery element 1 housed therein is easy, and as a result, the yield and safety of the battery are improved.

Further, the housings 2 and 4 preferably have shape changeability because it is easy to change the shape of the battery in various ways. Further, the battery element 1 is connected to the housing 2,
4, when sealing the outer edges of the housings 2 and 4
It is preferable that the inside of the housings 2 and 4 be evacuated before the sealing. Thereby, a pressing force can be applied to the battery element 1, and battery characteristics such as cycle characteristics can be improved.

The materials of the housings 2 and 4 are as follows.
Aluminum or nickel-plated metal such as iron or copper or synthetic resin can be used. However, since it is lightweight, has high moisture resistance and is easy to process, it is a flexible film-like composite in which metal and synthetic resin are laminated. It is preferable to use a material [for example, a laminated composite material (laminated film)]. By using the laminated composite material, the members constituting the housings 2 and 4 can be made thinner and lighter, and the capacity of the whole battery can be improved.

FIG. 10 shows a laminated composite material.
As shown in (A), a laminate in which a metal layer 5 and a synthetic resin layer 6 are laminated can be used. The metal layer 5 is for preventing infiltration of water or maintaining shape retention, and is a single metal such as aluminum, iron, copper, nickel, titanium, molybdenum and gold, an alloy such as stainless steel and Hastelloy, or aluminum oxide. Or the like, but aluminum is particularly preferable because of its excellent workability. The metal layer 5 can be formed by a metal foil, a metal deposition film, a metal sputter, or the like.

The synthetic resin 6 is used to prevent contact between the metal layer 5 and the battery element 1 or to protect the metal layer 5, and the elastic modulus and the tensile elongation are particularly limited. However, it also includes what is generally called an elastomer. As the synthetic resin 6, a thermoplastic, a thermoplastic elastomer, a thermosetting resin and a plastic alloy are used. These resins include those in which a filler such as a filler is mixed.

The laminated composite material is shown in FIG.
As shown in (B), a synthetic resin layer 6A functioning as an outer protective layer is provided on the outer surface of the metal layer 5, and corrosion by the electrolyte and contact between the metal layer 5 and the battery element 1 are prevented on the inner surface. 5 may be formed as a three-layer structure in which a synthetic resin layer 6B functioning as an inner protective layer for protecting the protective layer 5 is laminated.
In this case, as the resin 6A used for the outer protective layer, a resin excellent in chemical resistance and mechanical strength such as polyethylene, polypropylene, modified polyolefin, ionomer, amorphous polyolefin, polyethylene terephthalate, and polyamide is used. desirable. On the other hand, as the resin 6B used for the inner protective layer, a chemically resistant synthetic resin is used, and for example, polyethylene, polypropylene, modified polyolefin, ionomer, ethylene-vinyl acetate copolymer, or the like can be used.

The laminated composite material is shown in FIG.
As shown in (C), between each of the metal layer 5, the protective layer forming synthetic resin 6A, and the inner protective layer synthetic resin layer 6B,
An adhesive 7 may be interposed. Furthermore, an adhesive layer made of a weldable resin such as polyethylene or polypropylene may be provided on the innermost surface of the composite material in order to bond the connection portion (sealing portion) of the housing member.

The housings 2 and 4 may be formed by fusing the periphery of the film-like body, or the sheet-like body may be drawn and formed by vacuum forming, pressure forming, press forming or the like. Further, it can be molded by injection molding a synthetic resin. When injection molding is used, the metal layer is usually formed by sputtering or the like.

Next, the positive electrode 10A and the negative electrode 10B will be described with reference to FIG. 7. The positive electrode 10A is obtained by coating one surface of the positive electrode current collector 12A with a positive electrode active material 11A using the positive electrode current collector 12A as a core material. Similarly, the negative electrode 10B is formed by coating one surface of the negative electrode current collector 12B with the negative electrode active material 11B using the negative electrode current collector 12B as a core material. A positive electrode tab 13A extends from each positive electrode current collector 12A, and a negative electrode tab 13B similarly extends from each negative electrode current collector 12B. The active materials 11A, 1A are provided on both surfaces of the current collectors 12A, 12B.
1B may be configured to be coated respectively.

As the current collectors 12A and 12B, generally, a foil made of metal is used.
Due to compatibility with 11B, aluminum is used as the positive electrode current collector 12A (including the tab 13A) and copper is used as the negative electrode current collector 12B (including the tab 13B). The thickness of the current collectors 12A and 12B is appropriately selected. However, if the thickness is too small, the mechanical strength becomes weak, so that processing becomes difficult and the productivity is lowered. The energy density is preferably in the range of 1 to 30 μm because there is a possibility of lowering the energy density as a whole.

The current collectors 12A and 12B and the active material 11
Active materials 11A, 11A,
Before coating 11B, current collectors 12A, 12B
It is preferable to previously perform a surface roughening treatment. Examples of such a surface roughening method include a mechanical polishing method,
There are an electrolytic polishing method and a chemical polishing method. As the mechanical polishing method, for example, there is a method of polishing the surface of the current collector with a wire cloth provided with a polishing cloth paper, a grindstone, an emery buff, a steel wire or the like to which abrasive particles are fixed. In addition, each current collector 12
A and 12B are made of a plate-like member, a net-like member, a punching metal, or the like.

As the positive electrode active material 11A, an inorganic compound or an organic compound can be used as long as it can occlude and release lithium ions. Transition metal oxides as inorganic compounds,
Chalcogen compounds such as composite oxides of lithium and transition metals, transition metal sulfides, and the like can be given. Here, Fe, Co, Ni, Mn, or the like is used as the transition metal. _{Specifically, MnO, V 2 O 5,} V 6 0 13. , Transition metal oxides such as TiO ₂ , lithium nickelate, lithium cobaltate,
Examples thereof include a composite oxide of lithium and a transition metal such as lithium manganate, and a transition metal sulfide such as TiS ₂ , FeS, and MoS ₂ . These compounds may be partially substituted with elements in order to improve their properties.
Examples of the organic compound include polyaniline, polypyrrole, polyacene, disulfide-based compounds, and polysulfide-based compounds. As the positive electrode active material 11A,
These inorganic compounds and organic compounds may be used as a mixture. Preferred is a composite oxide of lithium and at least one transition metal selected from the group consisting of cobalt, nickel and manganese.

The particle size of the positive electrode active material 11A may be appropriately selected depending on the balance with the other components of the battery. The initial efficiency and cycle characteristics are usually 1 to 100, especially 2 to 60 μm. This is preferable because battery characteristics such as the above are improved. As the negative electrode active material 11B, as a material capable of occluding and releasing lithium ions, a carbon-based material such as graphite or coke is usually used. Such a carbon-based material can also be used in the form of a mixture or coating with a metal, metal salt, oxide, or the like. Examples of the negative electrode material include oxides and sulfates of silicon, tin, zinc, manganese, iron, nickel, etc., metallic lithium, Li-A1, Li-Bi-C
d, Li-Sn-Cd and other lithium alloys, lithium transition metal nitrides, silicon and the like can also be used. Preferably, it is graphite or coke in terms of capacity.

If the particle size of the negative electrode active material 11B is too large, the electron conductivity deteriorates, and from the viewpoint of improving the battery characteristics such as initial efficiency, late characteristics and cycle characteristics, the average particle size of the negative electrode active material 11B has an upper limit. Is usually 12 μm or less, preferably 10 μm or less, and the lower limit is usually 0.5 μm or more, preferably 7 μm or more. The positive electrode active material 11A and the negative electrode active material 11B are bonded to the current collectors 12A and 12B, respectively, and are bonded to each other.
It is preferable to mix a binder with 1B. As the binder, inorganic compounds such as silicate and glass, and various resins mainly composed of polymers can be used. Examples of the resin include alkane-based polymers such as polyethylene, polypropylene, and poly-1,1-dimethylethylene; unsaturated polymers such as polybutadiene and polyisoprene; polystyrene, polymethylstyrene, polyvinylpyridine, and poly-N-vinylpyrrolidone. Acrylic polymers such as polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid, polymethacrylic acid, polyacrylamide; polyfluorinated Fluorinated resins such as vinyl, polyvinylidene fluoride, and polytetrafluoroethylene; CN group-containing polymers such as polyacrylonitrile and polyvinylidene cyanide; polyvinyl acetates such as polyvinyl acetate and polyvinyl alcohol Alcohol polymers; polyvinyl chloride, halogen-containing polymers such as polyvinylidene chloride;
A conductive polymer such as polyaniline can be used.
Further, a mixture of the above-mentioned polymers and the like, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer and the like can also be used.

If the amount of the binder is too small, the strength of the electrode may be reduced. On the other hand, if the amount of the binder is too large, the capacity may be reduced or the rate characteristics may be reduced. The amount of the binder relative to parts by weight is preferably 0.1 to 30 parts by weight, and 1 to 15 parts by weight.
It is more preferred to use parts by weight. Also, active material 11A,
11B may contain additives, such as a conductive material and a reinforcing material, which exhibit various functions, a powder or a filler, if necessary. As the conductive material, active materials 11A and 11B
No particular limitation is imposed as long as it can impart conductivity by mixing in an appropriate amount with carbon powder. Usually, carbon powders such as acetylene black, carbon black, and graphite, and fibers and foils of various metals are exemplified. As additives, trifluoropropylene carbonate, vinylene carbonate, 1,
6-Dioxaspiro [4,4] nonane-
2,7-dion, 12-crown-4-ether and the like can be used to increase the stability and life of the battery. As the reinforcing material, various inorganic or organic spherical or fibrous fillers can be used.

The active materials 11A and 11B are combined with the current collectors 12A and 1
As a method of forming on the 2B, for example, powdered active materials 11A and 11B are mixed with a solvent together with a binder, and this is formed into a dispersion paint using a ball mill, a sand mill, a twin-screw kneader, or the like. There is a method of applying and drying on the current collectors 12A and 12B. In this case, the type of the solvent used is not particularly limited as long as it is inert to the active materials 11A and 11B and can dissolve the binder.
For example, any of commonly used inorganic solvents and organic solvents such as N-methylpyrrolidone can be used.

The active material 11A, 11B is mixed with a binder and heated to soften the current collector 1A.
The layers of the active materials 11A and 11B can also be formed on the current collectors 12A and 12B by pressing or spraying on the 2A and 12B. Alternatively, the active materials 11A and 11B may be used alone and the current collector 12A,
By sintering on the current collectors 12A and 12B,
A layer of the active materials 11A and 11B can be formed on B.

The active materials 11A and 11B have the same material (electrolytic material) as the material of an electrolyte layer 10C described later in order to facilitate the movement of ions within the active materials 11A and 11B.
Are mixed. The larger the amount of the mixed electrolyte, the more easily the ions can move in the active materials 11A and 11B, which is preferable in terms of the rate characteristics. On the other hand, the smaller the amount of the electrolyte, the higher the energy density. For this reason, the mixing ratio of the electrolyte to the active materials 11A and 11B is 10 to
It is preferred to be 50% by volume.

The thickness of each of the active materials 11A and 11B is
Thickness is preferred in terms of capacity, while thinness is preferred in terms of late characteristics. Therefore, the lower limit of the film thickness of each of the active materials 11A and 11B is usually 20 μm or more, preferably 30 μm or more.
μm or more, more preferably 50 μm or more, and most preferably 80 μm or more, while the upper limit is usually 2 μm or more.
It is not more than 00 μm, preferably not more than 150 μm.

Next, the electrolyte layer 10C will be described. As described above, the electrolyte layer 10C
And a negative electrode 10B, for example, is configured by impregnating a porous sheet with an electrolyte described later, and the thickness of the electrolyte layer 10C is generally 1 to 200 μm, preferably 5 to 200 μm.
５０50 μm. As the porous sheet, a sheet having a porosity of 10 to 95% is usually used.
It is preferable to use one of about 85%. The material of the porous sheet may be a polyolefin or a polyolefin in which some or all of the hydrogen atoms have been substituted with fluorine (specifically, a microporous film formed using a synthetic resin such as polyolefin). A membrane, a nonwoven fabric, a woven fabric, or the like is used. Also, regarding the thickness of the porous sheet,
Usually 1 to 200 μm, preferably 5 μm to 100 μm
Is used.

As the electrolyte impregnated in the porous sheet, various electrolytes such as a fluid electrolyte (hereinafter referred to as an electrolyte) and a non-fluid electrolyte such as a gel electrolyte and a completely solid electrolyte are used. You. From the viewpoint of the characteristics of the battery, it is preferable to use an electrolyte or a gel electrolyte, and from the viewpoint of safety, it is preferable to use a non-fluid electrolyte. In particular, when a non-fluid electrolyte is used, the liquid leakage can be more effectively prevented with respect to a battery using a conventional electrolytic solution. Therefore, as described above, the housing 2 containing the battery element 1 including the electrolyte layer 10C is used. It is possible to use a material having a low strength, but a thin film and a variable shape, such as a laminate film, for example.

A description will be given of such an electrolytic solution, a gel electrolyte, and a completely solid electrolyte. First, the electrolyte layer 10C
The electrolytic solution applicable to the present invention will be described. The electrolytic solution is usually produced by dissolving a supporting electrolyte in a non-aqueous solvent.
As a supporting electrolyte, a non-electrolyte that is stable as an electrolyte with respect to the positive electrode active material 11A and the negative electrode active material 11B and that can perform movement for lithium ions to undergo an electrochemical reaction with the positive electrode active material 11A or the negative electrode active material 11B. Any water substance can be used. LiPF ₆ in particular, LiAsF _6, LiSbF _6, LiB
F ₄ , LiClO ₄ , LiI, LiBr, LiCl, Li
Lithium salts such as AlCl, LiHF ₂ , LiSCN, and LiSO ₃ CF ₂ can be used. Of these, LiPF ₆ and LiClO ₄ are particularly preferably used.

When a non-aqueous solvent is used as a solvent for these supporting electrolytes, the concentration is generally 0.5 to 2.5 m
An ol / L concentration of electrolyte is used. The non-aqueous solvent that dissolves these supporting electrolytes is not particularly limited,
It is preferable to use a solvent having a relatively high dielectric constant. Specifically, cyclic carbonates such as ethylene carbonate and propylene carbonate, acyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, glymes such as tetrahydrofuran, 2-methyltetrahydrofuran and dimethoxyethane, and γ
Lactones such as butyrolactone, sulfur compounds such as sulfolane, nitriles such as acetonitrile, and the like are used. These solvents can be used alone or as a mixture of two or more.

In particular, any one of cyclic carbonates such as ethylene carbonate and propylene carbonate, and acyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate is used, or any one of these is used. It is preferable to use a mixture of two or more. In addition, those in which some of the hydrogen atoms in the molecules of these solvents are substituted with halogen or the like can also be used.

Further, additives and the like may be added to these solvents. Examples of the additive include trifluoropropylene carbonate, vinylene carbonate, 1,6-
Dioxaspiro [4,4] nonane-2,7
-Dione, 12-crown-4-ether and the like,
It can be used to enhance the stability, performance and life of batteries.

Next, a gel electrolyte applicable to the electrolyte layer 10C will be described. The gel electrolyte is usually generated by holding the above-mentioned electrolytic solution with a polymer. That is, the gel electrolyte is generally one in which the electrolyte is held in a polymer network and the fluidity as a whole is significantly reduced. In such a gel electrolyte, the properties such as ion conductivity and the like are close to those of the above-mentioned electrolyte solution, but the fluidity and volatility are significantly suppressed and the safety is enhanced. If the ratio of the polymer in the gel electrolyte is too low, the electrolyte solution cannot be held, and there is a risk of liquid leakage. On the other hand, if the ratio is too high, the ionic conductivity tends to decrease and the battery characteristics tend to deteriorate. , 1
Preferably it is in the range of 50% by weight.

The polymer used in the gel electrolyte is not particularly limited as long as it is a polymer capable of forming a gel together with the electrolytic solution, and those produced by polycondensation of polyester, polyamide, polycarbonate, polyimide, etc. Polyurethane, polyurea, etc., produced by polyaddition, acrylic derivative polymers such as poly (methyl methacrylate), and addition polymerization of polyvinyls such as polyvinyl acetate, polyvinyl chloride, polyvinylidene fluoride, etc. Some are done.

Preferred polymers include polyacrylonitrile and polyvinylidene fluoride.
Here, the polyvinylidene fluoride includes not only a homopolymer of vinylidene fluoride but also a copolymer with another monomer component such as hexafluoropropylene. Also, acrylic acid, methyl acrylate, ethyl acrylate, ethoxyethyl acrylate, methoxyethyl acrylate, ethoxyethoxyethyl acrylate, polyethylene glycol monoacrylate, ethoxyethyl methacrylate, methoxyethyl methacrylate, ethoxyethoxyethyl methacrylate, polyethylene glycol monomethacrylate, N , N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, glycidyl acrylate, allyl acrylate, acrylonitrile, N-vinylpyrrolidone, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, Diethylene glycol Dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, it is also preferable to use an acrylic polymer obtained by polymerizing an acrylic derivative such as polyethylene glycol dimethacrylate.

If the ratio of the weight average molecular weight of the polymer to the concentration of the polymer in the electrolyte is too low, the retention of the electrolyte is reduced (it becomes difficult to form a gel) and the electrolyte flows from the housing 2 to the outside. On the other hand, if it is too high, the viscosity becomes excessively high, which causes difficulty in the manufacturing process, or the ratio of the electrolytic solution is low, so that the ion conductivity is low and the battery characteristics (for example, lateness) are low. Characteristic) may be reduced. For this reason, the weight average molecular weight is usually 1
It is preferable to use a polymer in the range of from 000 to 5,000,000, and the concentration of the polymer in the electrolytic solution is preferably in the range of from 0.1% by weight to 30% by weight.

Next, a complete solid electrolyte applicable to the electrolyte layer 10C will be described. As the complete solid electrolyte, various solid electrolytes known so far can be used. For example, it can be formed by mixing the polymer used in the gel electrolyte and the supporting electrolyte salt at an appropriate ratio. In this case, in order to increase the conductivity, it is preferable to use a polymer having a high polarity and to have a skeleton having many side chains.

In the terminal binding structure of the flat plate type battery according to one embodiment of the present invention, as described above, the tabs 13A,
Since the binding of the lead 13B and the leads 3A and 3B is performed by the rivets 14A and 14B, respectively, there are the following advantages. In other words, the tabs 13A, 13B and the leads 3A, 3B can be firmly and securely bound by the rivets 14A, 14B, and the tabs 13A, 13B
And rivets 14 in the holes formed in the leads 3A and 3B.
Since it has a simple configuration in which only A and 14B are attached, there is an advantage that the work of binding the tabs 13A and 13B and the leads 3A and 3B can be simplified and the productivity of the battery can be improved.

The tab 13A on the positive electrode side and the lead 3A
Is made of an aluminum material that is difficult to weld, but can be easily bound by the rivets 14A.
That is, there is also an advantage that the binding can be performed firmly and reliably regardless of the material of the tab or the lead. Also, unlike soldering and welding, tabs 13A, 13B
In addition, there is an advantage that when the leads 3A and 3B are bound, there is no thermal effect on the battery.

The rivet 14A is a rivet 14A.
The rivet 14B is formed of the same aluminum material as the tab 13A and the lead 3A bound by the rivet 14B.
Since it is made of the same copper material as B, there is an advantage that electrolytic corrosion can be prevented. In addition, the tab 1
Since the rotation of the rivets 14A, 14B with respect to 3A, 13B is regulated, the tabs 13A, 13B and the rivets 14
There is also an advantage that the contact with the rivets 14A and 14B can be prevented from increasing by making the contact with the rivets 14A and 14B stable with the contacts with the rivets 14A and 14B, respectively.

It should be noted that the terminal binding structure of the flat plate type battery of the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist of the invention.
For example, in the above embodiment, each unit battery element 10
Although the unit battery element 10 is formed in a square shape, the shape of the unit battery element 10 is appropriately set according to design conditions, and may be, for example, a polygon other than a square, or a circle.

In the above-described embodiment, an example is described in which the terminal binding structure of the flat plate type battery of the present invention is applied to a lithium battery using lithium ions as an electromotive substance. Is applicable to various batteries using other substances as electromotive substances.

[0062]

As described above in detail, according to the terminal binding structure of the flat plate type battery according to the first aspect of the present invention, regardless of the material of the pole terminal, the pole terminal of each unit battery element is rivet. Since it is possible to securely and firmly bind the terminals and to use a simple configuration in which the pole terminals are bound by rivets, there is an advantage that the terminal bundling operation can be simplified and the productivity of the flat plate type battery can be improved. .

Further, by forming the rivet with the same material as the pole terminal, there is an advantage that electrolytic corrosion can be prevented (claim 2). Furthermore, by providing a rotation stopping mechanism on the rivet so that the rivet does not rotate with respect to the pole terminal, there is an advantage that an increase in the conduction resistance of the pole terminal can be prevented (claim 3).

Further, by providing a projection on the surface of the rivet which is in contact with the pole terminal of the head, there is an advantage that the rotation stopping mechanism can be easily configured (claim 4). Similarly,
Provision of the groove on the surface of the rivet in contact with the pole terminal of the rivet has an advantage that the rotation stopping mechanism can be easily configured (claim 5). Further, by forming the groove with an annular groove or a cross-shaped groove formed around the axis of the rivet, there is an advantage that the rivet can be reliably prevented from rotating with respect to the pole terminal. (Claims 6 and 7).

Further, by binding the pole terminals by using a plurality of rivets, there is an advantage that rotation of the rivet with respect to the pole terminals can be prevented and an increase in the conduction resistance of the pole terminals can be suppressed ( Claim 8).

[Brief description of the drawings]

FIG. 1 is an enlarged schematic cross-sectional view of a main part of a terminal stacking structure of a flat plate type battery according to an embodiment of the present invention (FIG. 2).
(A1-A1 cross-sectional view).

FIG. 2 is a schematic plan view showing a configuration of a battery element according to a terminal binding structure of a flat plate type battery as one embodiment of the present invention.

FIG. 3 is a view showing a rivet according to the terminal binding structure of the flat plate type battery as one embodiment of the present invention;
(A) is an enlarged schematic side view showing the structure of a rivet having a flat-type head portion and a hollow-type shaft portion, and (B) is a diagram illustrating a round-shaped head portion and a solid-type shaft portion. It is a typical side view which expands and shows the structure of the rivet which has.

FIG. 4 is a view showing a terminal binding structure of the flat plate type battery as one embodiment of the present invention, and is a schematic arrow view showing a main part thereof cut away.

FIG. 5 is a diagram showing a structure of a head portion of a rivet according to a terminal binding structure of the flat plate type battery as one embodiment of the present invention, wherein (A) is an enlarged schematic side view,
(B) is a sectional view taken along the line A2-A2 of (A).

FIGS. 6A and 6B show a modified example of a head portion of a rivet according to a terminal binding structure of a flat plate type battery according to an embodiment of the present invention, corresponding to FIG. 5B. It is a typical enlarged view shown.

FIG. 7 is a schematic cross-sectional view of a main part (a cross-sectional view taken along the line A1-A1 in FIG. 2) showing an enlarged structure of a unit battery element according to a terminal binding structure of a flat plate type battery as one embodiment of the present invention FIG.

FIG. 8 is a schematic perspective view showing the entire configuration of a battery to which the terminal binding structure of the flat plate type battery according to one embodiment of the present invention is applied.

FIG. 9 is a schematic perspective view showing an overall configuration of an example of a forming process of a housing according to a terminal binding structure of a flat plate type battery as one embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view showing, in an enlarged manner, the configuration of components of a housing relating to a terminal binding structure of a flat plate type battery as one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery element 2, 4 Housing 3A Positive side lead 3B Negative side lead 5 Metal layer 6, 6A, 6B Synthetic resin layer 7 Adhesive material 10 Unit battery element 10A Positive electrode 10B Negative electrode 10C Electrolyte layer 11A Positive electrode active material 11B Negative electrode active material 12A, 12B Current collector 13A Positive side tab (polar terminal) 13B Negative side tab (polar terminal) 14 ', 14A, 14B Rivet 31A, 31B Lead hole 41 Housing 131A, 131B Tab hole 140', 140A, 140B Rivet head 141 ', 141A, 141B Rivet shaft 142A, 142B Rivet shaft end 143A, 143B Projection 144 Annular groove 145 Cross-shaped groove

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masaaki Mita 3-10, Ushidori, Kurashiki-shi, Okayama Prefecture Mizushima Works, Mitsubishi Chemical Corporation F-term (reference) 5H022 AA09 BB03 CC02 CC04 CC09 CC10 5H029 AJ14 AK02 AK03 AK05 AK16 AL02 AL06 AL07 AL08 AL12 AM00 AM03 AM04 AM05 AM16 BJ04 BJ12 CJ01 DJ05

Claims (8)

[Claims] 1. A flat battery having a plurality of flat unit battery elements stacked on each other, and a terminal bundling structure of the flat battery stack in which the pole terminals of each unit battery element are superimposed and bound. The terminal bundling structure of a flat plate type battery, wherein the pole terminals are bound by rivets. 2. The terminal binding structure for a flat plate type battery according to claim 1, wherein the rivet is made of the same material as the pole terminal. 3. The terminal bundling of a flat plate type battery according to claim 1, wherein the rivet is provided with a rotation stopping mechanism to prevent the rivet from rotating with respect to the pole terminal. Construction. 4. The flat plate type battery according to claim 3, wherein the rotation stopping mechanism is constituted by a projection provided on a surface of the rivet head portion which is in contact with the pole terminal. Terminal binding structure. 5. The terminal of a flat plate type battery according to claim 3, wherein the rotation stopping mechanism is constituted by a groove provided on a surface of the rivet head portion which comes into contact with the pole terminal. Unity structure. 6. The groove according to claim 5, wherein the groove is an annular groove formed around the axis of the rivet.
A terminal binding structure of the flat plate type battery according to the above. 7. The terminal binding structure according to claim 5, wherein the groove is a cross-shaped groove formed around an axis of the rivet. 8. The terminal binding structure for a flat plate type battery according to claim 1, wherein the pole terminals are bound using a plurality of the rivets.