JP2001256960A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery in which short-circuit between a battery element and a lead is prevented, and also the lead can be easily bent. SOLUTION: A flat laminated type battery element 1 is interposed between armored members 2, 3, by joining their peripheries 2a, 3a to seal the battery element 1. The battery element 1 is provided by laminating a plurality of unit cells. Tabs 4a, 4b of each unit cell are bundled to form terminal portions, to which leads 21 are joined. This lead 21 is provided with insulated coating 20. At portions where the lead is bent, a recess 18 or breaks 19 are provided on this insulated coating 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery in which a battery element is wrapped with an exterior material, and more particularly to a battery in which a short circuit between a lead and a battery element is prevented. More specifically, the present invention relates to a battery suitable for a non-aqueous secondary battery such as a lithium secondary battery.

[0002]

2. Description of the Related Art As a thin battery, as disclosed in JP-A-8-83596, a thin battery element (for example, a power generation element composed of a laminate of a positive electrode, a separator, and a negative electrode) covered with a laminated composite material is known. . After the battery element is inserted into the exterior material made of the laminated composite material, the inside of the laminated composite material is depressurized, and a compressive force is applied to the battery element in the stacking direction to increase the adhesion between the layers. In this case, the laminated composite material is obtained by laminating a metal layer and a synthetic resin layer, and generally has both surfaces of an aluminum layer covered with a synthetic resin layer.

[0003]

In a battery using such a laminated composite material, there is a problem that a short circuit easily occurs through a metal layer of an exterior material. FIG.
FIG. 2 is a schematic cross-sectional view showing a state near a lead of such a battery. It has a positive electrode lead 142 electrically connected to the positive electrode of the battery element (not shown) and a negative electrode lead (not shown) electrically connected to the negative electrode.
The negative electrode lead is drawn out from the bonding surface 145 of the two laminated composite materials 143 and 144. Each of the laminate composites 143 and 144 has a synthetic resin 42 as an innermost layer, a metal layer 40 made of aluminum, and a synthetic resin layer 41 as an outermost layer. The battery elements are encapsulated by bonding the synthetic resin layers to each other. In such a battery, since the metal layer 40 is exposed at the end surfaces 146 and 147 of the laminated composite materials 143 and 144, the positive electrode lead 1
42 and the negative electrode lead are in a state of easy contact,
When such a situation occurs, a short circuit occurs.

Therefore, it has been proposed to provide an insulating film on the lead in order to separate the lead from the metal layer exposed on the end face of the exterior material. FIG. 15 is a schematic cross-sectional view showing such a state.
The components denoted by the same reference numerals as those in FIG. 14 indicate the same components as those in FIG. In FIG. 15, unlike FIG. 14, an insulating film 151 is provided on the lead between the positive electrode lead 142 and the synthetic resin layer 42 as the innermost layer, and this is the end face of the laminated composite materials 143 and 144. 146 and 147
Rather, it extends in the lead tip direction. As a result, it is possible to more effectively prevent a short circuit resulting from the exposure of the metal layer on the end face of the laminated composite material as described above.

However, when the insulating film is provided in this manner, the rigidity of the entire lead including the insulating film is increased, the lead is difficult to bend, and the assembling workability of the battery is deteriorated. Even if you do not bend,
This type of insulating film lacks flexibility and is vulnerable to impact.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem and to provide a battery in which a short circuit in a lead is prevented and the lead is easily bent.

[0007]

A battery according to the present invention is a battery in which a battery element is wrapped with two or two pieces of exterior material made of a laminated composite material in which a metal layer and a synthetic resin layer are laminated. In a battery in which a lead connected to the battery element is drawn out from between two or two pieces of the exterior material, an insulating film for separating the lead from the metal layer exposed at the end face of the exterior material is formed on the lead. The insulating film is provided with a concave portion or a cut at a bent portion or a portion to be bent of the lead.

In such a battery, the short circuit of the lead is prevented by the insulating film. In addition, since the concave portion or the cut is provided in the insulating film, the lead can be easily bent along the concave portion or the cut.

It is preferable that the insulating film is present from the surface where two or two pieces of the exterior material are bonded to the outside. As a result, by selecting the material of the insulating film, it becomes possible to enhance the adhesiveness between the lead and the synthetic resin layer.

The insulating film is preferably made of a synthetic resin having a high heat-fusibility, such as a modified polyolefin.

In the present invention, it is preferable that a recess or a cut is provided along the outer edge of the exterior material. as a result,
The bending of the lead can be performed along the outer edge of the exterior material.

The battery of the present invention is useful even when the lead is not bent. That is, as described above, the insulating film of the lead lacks flexibility and may be weak to impact, but if a cut or recess is provided in the insulating film of the lead,
When a shock is applied to the lead, the lead is deformed along the portion provided with the cut or the recess, and the shock can be absorbed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A battery according to an embodiment will be described below with reference to the drawings. 1A is a perspective view of a lead portion, FIG. 1B is a cross-sectional view taken along line BB of FIG. 1A, and FIG. 1C is a diagram in which a concave portion is provided in the insulating film instead of a cut. 2A is an exploded perspective view of the battery according to the embodiment, FIG. 2B is a cross-sectional view of a main part of the battery, and FIG. 3 is a schematic perspective view of a battery element. 4 (a) and 4 (b) are perspective views of the battery.

In this battery, after the battery element 1 is accommodated in the concave portion 2a of the exterior member 2, the terminal portions (tabs 4a, 4
b) An insulating material 5 such as an epoxy resin is injected into the vicinity, and then the exterior material 3 is covered on the exterior material 2 so that the leads 21 extend outward, and the peripheral portions of the exterior materials 2 and 3 are vacuum-sealed. 2
a and 3a are joined.

As shown in FIG. 2A, the exterior member 2 has a flat plate shape. The exterior material 3 includes a housing portion 3b formed of a rectangular box-shaped recess,
It has a shallow open box shape having a peripheral portion 3a that protrudes outward in a flange shape from four peripheral edges of the housing portion 3b.

As shown in FIGS. 2B and 3, the battery element 1
Is a stack of a plurality of unit battery elements. The tab 4a or 4b is extended from the unit battery element. The tabs 4a from the positive electrode are bundled (that is, overlapped with each other), and the positive electrode lead 21 is joined. The tabs 4b from the negative electrode are also bundled together, and the negative electrode lead 2
1 are joined.

An insulating film 20 is provided on the positive electrode lead 21 and the negative electrode lead 21 from the bonding surface of the exterior materials 2 and 3 to the outside of the exterior material.

The battery element 1 is housed in the housing part 3b of the exterior material 3, and the insulating material 5 is injected near the tabs 4a and 4b,
Preferably, before curing, the cladding material 2 is covered. A pair of leads 21 extending from the battery element 1 are drawn out through the bonding surfaces of the peripheral edges 2a, 3a of one side of the exterior materials 2, 3, respectively. Then, the outer peripheral parts 2 of the outer peripheral members 2 and 3 in a reduced pressure (preferably vacuum) atmosphere
a and 3a are hermetically joined together by a method such as thermocompression bonding or ultrasonic welding, and the battery element 1 is sealed in the exterior materials 2 and 3.

The insulating film 20 is also provided on portions of the leads 21 protruding from the outer packaging materials 2 and 3. A cut 19 extending in the width direction of the lead 20 is formed in a portion of the insulating film 20 along the outer edge of the outer packaging materials 2 and 3.
(FIGS. 1A and 1B) or a recess 18 (FIG. 1C). The notch 19 is preferably provided by a knife or laser irradiation after joining the peripheral portions 2a and 3a, but is provided in advance when the dimensional accuracy and positional accuracy of the lead 21 and the exterior materials 2 and 3 are high. May be.

Although the cut 19 is provided in FIGS. 1A and 1B, a recess 18 extending in the width direction of the lead may be provided as shown in FIG. 1C. The recess 18 can be formed by, for example, applying a heated wire or a knife edge.

The joining pieces 4A, 4F, 4G are formed by joining the peripheral parts 2a, 3a to each other. The joining pieces 4A, 4F, 4G project outward from the enclosing part 4B enclosing the battery element 1. Therefore, FIG.
As shown in (a), the joint pieces 4A and 4G are bent along the envelope 4B and fastened to the side surface of the envelope 4B with an adhesive or an adhesive tape (not shown). Thereafter, the lead 21 is bent as required.

As shown in FIG. 4B, the lead piece 21 may be bent by further bending the joint piece 4F along the enclosing part 4B. The two-dot chain line 21 'in FIG.
When the lead 21 is bent only once at the base as shown in FIG. 1, the cut 19 or the concave portion 18 may be provided only in the vicinity of the outer edges of the exterior materials 2 and 3 as shown in FIG.

As shown by the solid line in FIG.
Is bent one more time, a similar cut or recess is provided in advance in the insulating coating of the lead (or after the sealing of the exterior members 2 and 3) at the portion to be bent.

The insulating film 20 is preferably formed by attaching a synthetic resin such as a modified polyolefin or polyolefin which is easily welded to the lead 21 by heat welding.

The insulating material 5 is preferably a fluid synthetic resin having curability, and examples thereof include an epoxy resin, an acrylic resin, and a silicone resin. Among them, an epoxy resin and / or an acrylic resin are preferable. Most preferred.

In FIG. 2, the exterior materials 2 and 3 are separate bodies. However, in the present invention, the exterior materials 2 and 3 may be integrally formed as shown in FIG. In FIG. 5, one side of the exterior material 3 and one side of the exterior material 2 are continuous, and the exterior material 2 has a lid shape that is connected to the exterior material 3 in a bendable manner. A concave portion of the housing portion 3b is formed from one side where the exterior materials 2 and 3 are continuous,
This one side has the same configuration as the joining piece except that no joining piece is formed.

Although FIGS. 1 and 5 show the exterior material 3 having the accommodation portion 3b and the flat exterior material 2, in the present invention, as shown in FIG. , 7b,
Peripheral portions 6a, 6a, which protrude from four peripheral edges of the housing portions 6b, 7b
The battery element 1 may be enveloped by the outer packaging materials 6 and 7 having the outer member 7a. In FIG. 6, the exterior materials 6 and 7 are integrated in a series, but they may be separate as in FIG. 1.

In the present invention, as shown in FIG. 7, one flat sheet-like exterior material 8 is folded in two along the central side 8a to form two pieces of a first piece 8A and a second piece 8B. The battery element 1 is interposed between the first piece 8A and the second piece 8B, and the peripheral portion 8 of the first piece 8A and the second piece 8B is formed as shown in FIG.
The battery elements 1 may be encapsulated by bonding b to each other.

In the batteries of FIGS. 5 to 7 as well, it is preferable that after the battery element is sealed with an exterior material, a cut 19 or a concave portion 18 is formed in the insulating film provided on the lead 21. A concave portion may be provided.

The above-mentioned exterior materials 2, 3, 6, 7, and 8 are laminated composite materials formed by laminating a metal layer and a synthetic resin layer. Such an exterior material usually has shape changeability, so that the shape of the battery can be easily changed in various ways. Further, after the interior of the exterior material is evacuated, by sealing the peripheral portion of the exterior material, a pressing force can be applied to the battery element 1, and as a result, battery characteristics such as cycle characteristics are improved. be able to. Further, by using the laminated composite material, the thickness and weight of the case member can be reduced, and the capacity of the battery as a whole can be improved.

FIG. 12 shows a laminated composite material.
As shown in (A), a laminate in which a metal layer 40 and a synthetic resin layer 41 are laminated can be used. This metal layer 40
Is for preventing infiltration of water or maintaining shape retention, and may be a simple metal such as aluminum, iron, copper, nickel, titanium, molybdenum, gold, or an alloy such as stainless steel, Hastelloy, or a metal oxide such as aluminum oxide. . Particularly, aluminum having excellent workability is preferable.

The formation of the metal layer 40 can be performed using a metal foil, a metal deposition film, a metal sputter, or the like.

The synthetic resin layer 41 is used to protect the case member, prevent invasion by the electrolyte, prevent contact between the metal layer and the battery element, or protect the metal layer. In the present invention, the elastic modulus and the tensile elongation of the synthetic resin are not limited. Therefore, the synthetic resin in the present invention includes what is generally called an elastomer.

As the synthetic resin, thermoplastics, thermoplastic elastomers, thermosetting resins, and plastic alloys 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 41 for functioning as an outer protective layer is provided on the outer surface of the metal layer 40, and corrosion on the inner surface and contact between the metal layer and the battery element are prevented on the inner surface. A three-layer structure in which the synthetic resin layers 42 functioning as inner protective layers for protecting the layers can be formed.

In this case, the resin used for the outer protective layer is
Preferably, resins excellent in chemical resistance and mechanical strength, such as polyethylene, polypropylene, modified polyolefin, ionomer, amorphous polyolefin, polyethylene terephthalate, and polyamide are desirable.

As the inner protective layer, a synthetic resin having chemical resistance is used. For example, polyethylene, polypropylene, modified polyolefin, ionomer, ethylene-vinyl acetate copolymer and the like can be used.

Further, as shown in FIG. 13, the composite material may be provided with an adhesive layer 43 between the metal layer 40, the synthetic resin layer 41 for forming the protective layer, and the synthetic resin layer 42 for forming the corrosion-resistant layer. Furthermore, in order to adhere the case members to each other,
An adhesive layer made of a resin such as polyethylene or polypropylene that can be welded can be provided on the innermost surface of the composite material. The case may be formed by fusing the periphery of the film-like body, or the sheet-like body may be drawn 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.

In order to provide a housing portion formed of a concave portion in the exterior material, drawing can be performed.

In the battery of the present invention configured as described above, since the insulating film 20 is provided on the lead 21, short-circuiting due to contact with the metal layer of the laminated composite material is prevented. Moreover, the cut 19 or the concave portion 1 is formed on the insulating film.
Since the lead 8 is provided, the lead 21 can be easily bent along the cut 19 or the recess 18.

In this embodiment, the tab 4
a and 4b are filled with the insulating material 5, so that the tab 4
A short circuit between a and 4b and the unit battery element is prevented.

Further, in this embodiment, since the bent joint piece is fixed along with the encased portion with an adhesive or an adhesive tape, the strength and rigidity of the side surface of the battery are high. . Of course, the bent joint piece is also prevented from separating from the envelope. Further, since the strength and rigidity of the side surface of the battery are high, even when the side surface receives an impact, the active material is prevented from peeling off.

The battery element of the present invention is suitable for being applied to a flat plate type battery element in which a plurality of flat unit battery elements each having a positive electrode and a negative electrode are stacked in the thickness direction, particularly to a lithium secondary battery. Therefore, a preferred configuration when the above-mentioned battery element is a lithium secondary battery element will be described below.

FIG. 9 shows a preferred example of a unit battery element of the lithium secondary battery element. This unit battery element is formed by stacking a positive electrode current collector 22, a positive electrode active material 23, a spacer (electrolyte layer) 24, a negative electrode active material 25, and a negative electrode current collector 26. Usually, the positive electrode active material 23 is bound on one side of the positive electrode current collector 22, and the negative electrode active material 25 is bound on one side of the negative electrode current collector 26.

A plurality of the unit battery elements are stacked to form a battery element. In this stacking, a unit battery element in a forward posture (FIG. 9) with the positive electrode on the upper side and the negative electrode on the lower side is used. On the other hand, unit battery elements in an inverted posture (not shown) with the positive electrode on the lower side and the negative electrode on the upper side are alternately stacked. That is, the unit battery elements adjacent in the stacking direction are stacked such that the same electrodes face each other (that is, the positive electrodes and the negative electrodes face each other).

A positive electrode tab 4a extends from the positive electrode current collector 22 of this unit battery element, and a negative electrode tab 4b extends from the negative electrode current collector 26.

As shown in FIG. 9, instead of a unit battery element in which a positive electrode active material, a spacer and a negative electrode active material are laminated between a positive electrode current collector and a negative electrode current collector, as shown in FIG. A positive electrode 11 and a negative electrode 12 are prepared by laminating a positive electrode active material 11a or a negative electrode active material 12a on both surfaces of the body 15a or the negative electrode current collector 15b as a core material.
May be alternately stacked via a spacer (electrolyte layer) 13 as shown in FIG. 11 to form a unit battery element. in this case,
A combination of a pair of the positive electrode 11 and the negative electrode 12 (strictly, from the center in the thickness direction of the current collector 15a of the positive electrode 11 to the center in the thickness direction of the current collector 15b of the negative electrode 12) corresponds to a unit battery element.

As the positive electrode current collectors 15a and 22, metal foils such as aluminum, stainless steel, and nickel can be used, and aluminum is particularly preferable.
As the material, metal foils such as copper, stainless steel and nickel can be used, and copper is particularly preferable. The thickness of the current collector is 1 to 30
It is preferably about μm.

The positive electrode active material absorbs lithium ions.
Use either inorganic or organic compounds if they can be stored and released.
Can be used. As inorganic compounds, transition metal oxides, lithium
Complex oxide of transition metal and transition metal, transition metal sulfide, specific
Contains MnO, V₂O₅, V ₆O1₁₃, TiO₂Etc.
Transition metal oxide, lithium nickelate, lithium cobaltate
And transition metals such as lithium and lithium manganate
Composite oxide, TiS ₂, FeS, MoS₂Transitions such as
Metal sulfide and the like. These compounds have properties
Which is partially elementally substituted to improve
Is also good. Examples of the organic compound include polyaniline and polyaniline.
Lipyrrole, polyacene, disulfide compound, poly
And sulfide compounds. The positive electrode active material
These inorganic compounds and organic compounds may be used as a mixture.
Particularly preferred are cobalt, nickel and manganese.
At least one transition metal selected from the group consisting of
It is a composite oxide with titanium.

The particle size of the positive electrode active material may be appropriately selected in accordance with the other components of the battery.
0 μm, especially 1 to 10 μm is preferable because battery characteristics such as initial efficiency and cycle characteristics are improved.

As the negative electrode active material, a carbon-based material such as graphite and coke is usually used. This carbon-based material may be used as a mixture with a metal, a metal salt, an oxide, or the like, or in the form of a coating. As the negative electrode active material, silicon, tin, zinc, manganese, iron, nickel and other oxides and sulfates, lithium metal, Li-Al, Li-Bi-Cd,
A lithium alloy such as Li-Sn-Cd, a lithium transition metal nitride, silicon and the like can also be used. Preferably, it is graphite or coke in terms of capacity. The average particle size of the negative electrode active material is usually 12 μm or less, preferably 10 μm or less, from the viewpoint of improving battery characteristics such as initial efficiency, late characteristics, and cycle characteristics. If the particle size is too large, the electron conductivity deteriorates. Also, usually 0.5 μm or more,
Preferably it is 7 μm or more.

It is preferable to use a binder in order to bind the positive electrode active material and the negative electrode active material on the current collector. As the binder, inorganic compounds such as silicate and glass, and various resins mainly composed of polymers can be used. As the resin, for example, polyethylene,
Alkane-based polymers such as polypropylene and poly-1,1-dimethylethylene; unsaturated polymers such as polybutadiene and polyisoprene; polymers having a ring such as polystyrene, polymethylstyrene, polyvinylpyridine and poly-N-vinylpyrrolidone; Acrylic polymers such as methyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid, polymethacrylic acid, polyacrylamide; polyvinyl fluoride, polyvinylidene fluoride, polytetra Fluorine resins such as fluoroethylene; CN group-containing polymers such as polyacrylonitrile and polyvinylidene cyanide; polyvinyl alcohol polymers such as polyvinyl acetate and polyvinyl alcohol; polyvinyl chloride Halogen-containing polymers such as polyvinylidene chloride; and conductive polymers such as polyaniline can be used. Also, a mixture of the above polymers, etc.,
Modified products, derivatives, random copolymers, alternating copolymers, graft copolymers, block copolymers and the like can also be used.

The amount of the binder relative to 100 parts by weight of the active material is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight. If the amount of the resin is too small, the strength of the electrode may decrease. If the amount of the resin is too small, the capacity may decrease, or the late characteristics may decrease.

The positive electrode active material and the negative electrode active material may contain additives, such as conductive materials and reinforcing materials, which exhibit various functions, powders, fillers, and the like, if necessary.

The conductive material is not particularly limited as long as it can impart conductivity by mixing an appropriate amount with the above-mentioned active material. Usually, carbon powder such as acetylene black, carbon black and graphite, and various kinds of metals are used. Fibers, foils and the like can be mentioned. Additives include trifluoropropylene carbonate, vinylene carbonate, 1,6-Di
oxaspiro [4,4] nonane-2,7-d
ion, 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 and organic spherical and fibrous fillers can be used.

As a method of forming an electrode on a current collector,
For example, a method of mixing a powdered active material with a solvent together with a binder, dispersing the active material with a ball mill, a sand mill, a twin-screw kneader, or the like, coating the resultant on a current collector, and drying the resultant is preferably performed. In this case, the kind of the solvent used is not particularly limited as long as it is inert to the electrode material and can dissolve the binder. For example, any of commonly used inorganic and organic solvents such as N-methylpyrrolidone and the like can be used. Can also be used.

Further, the electrode material layer may be formed by a method of pressing or spraying the active material on a current collector in a state where the active material is mixed with a binder and heated to be softened. Furthermore, it can be formed by firing the active material alone on the current collector.

An ion mobile phase is usually formed in the positive and negative electrodes. The proportion of the ion mobile phase in the electrode is
The higher the value, the easier the ion migration becomes. The preferable is the rate characteristic, while the lower the value, the higher the capacitance. Preferably 1
0 to 50% by volume. As materials for the ion mobile phase,
The same material as the electrolyte phase material described later can be used.

It is preferable that the positive electrode active material and the negative electrode active material be thicker in terms of capacity and thinner in terms of rate. The film thickness is usually at least 20 μm, preferably at least 30 μm, more preferably at least 50 μm, most preferably at least 80 μm. The thickness of the positive electrode and the negative electrode is usually 200 μm or less, preferably 150 μm or less.

The spacers (electrolyte layers) 13 and 24 usually contain various electrolytes such as an electrolyte having fluidity and a non-fluid electrolyte such as a gel electrolyte and a completely solid electrolyte.
An electrolyte or a gel electrolyte is preferable in terms of battery characteristics, and a non-fluid electrolyte is preferable in terms of safety. In particular, when a non-fluid electrolyte is used, liquid leakage can be more effectively prevented with respect to a battery using a conventional electrolytic solution, so that the advantage of using a case having a shape changeability such as a laminated film described later is advantageous. You can make the most of it.

The electrolyte used for the electrolyte layer is usually a solution obtained by dissolving a supporting electrolyte in a non-aqueous solvent.

As the supporting electrolyte, a non-aqueous substance which is stable as an electrolyte with respect to the positive electrode active material and the negative electrode active material, and which can move to cause an electrochemical reaction of lithium ions with the positive electrode active material or the negative electrode active material. Any one can be used. Specifically, LiPF
_{6, LiAsF 6, LiSbF 6,} LiBF 4, LiC
10 ₄ , LiI, LiBr, LiCl, LiAlCl,
Lithium salts such as LiHF ₂ , LiSCN, and LiSO ₃ CF ₂ are mentioned. Of these, LiPF ₆ ,
LiClO ₄ is preferred.

When these supporting electrolytes are used in the state of being dissolved in a non-aqueous solvent, the concentration is 0.5 to 2.5 mol / L.
Is preferred. The nonaqueous solvent in which these supporting electrolytes are dissolved is not particularly limited, but a solvent having a relatively high dielectric constant is preferably used. Specifically, acyclic carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; glymes such as tetrahydrofuran, 2-methyltetrahydrofuran, and dimethoxyethane;
One or more of lactones such as -butyllactone, sulfur compounds such as sulfolane, and nitriles such as acetonitrile are exemplified.

Among them, one or more solvents selected from cyclic carbonates such as ethylene carbonate and propylene carbonate, and acyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate are particularly preferable. is there. Further, additives and the like may be added to these solvents. Examples of the additive include trifluoropropylene carbonate, vinylene carbonate, 1,6-dioxaspi
ro [4,4] nonane-2,7-dione, 1
2-crown-4-ether and the like can be used for the purpose of increasing the stability and life of the battery.

The gel electrolyte that can be used for the electrolyte layer is usually obtained by holding the above-mentioned electrolyte solution with a polymer. That is,
The gel electrolyte is one in which the electrolyte is generally held in a polymer network, and the fluidity as a whole is significantly reduced. Such a gel electrolyte exhibits properties such as ionic conductivity that are close to those of a normal electrolyte solution, but fluidity, volatility and the like are significantly suppressed, and safety is enhanced. The ratio of the polymer in the gel electrolyte is preferably 1 to 50% by weight. If the temperature is too low, the electrolyte cannot be held, and a liquid leak may occur. If it is too high, the ionic conductivity tends to decrease and battery characteristics tend to deteriorate.

Polymers used for the gel electrolyte include:
There is no particular limitation as long as it is a polymer that can form a gel together with the electrolyte, and polyester, polyamide, polycarbonate, those produced by polycondensation such as polyimide,
Polyurethane, polyurea, etc. produced by polyaddition, acrylic derivative polymers such as polymethyl methacrylate, and polyadditions produced by polyvinyl polymerization such as polyvinyl acetate, polyvinyl chloride, polyvinylidene fluoride, etc. and so on. 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 di Acrylic obtained by polymerizing acrylic monomers such as acrylate, triethylene glycol diacrylate, tetraethylene glycol acrylate, polyethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate. Can be used polymers are also preferred.

The weight average molecular weight of the above polymer is usually 10
000 to 5,000,000. If the molecular weight is low, it is difficult to form a gel. If the molecular weight is high, the viscosity becomes too high and handling becomes difficult. The concentration of the polymer with respect to the electrolytic solution may be appropriately selected according to the molecular weight, but is preferably 0.1 to 30% by weight. If the concentration is too low, it is difficult to form a gel, the retention of the electrolytic solution is reduced, and problems of flow and liquid leakage may occur. If the concentration is too high, the viscosity becomes too high, which causes difficulties in the process, and the proportion of the electrolytic solution is reduced, the ionic conductivity is reduced, and the battery characteristics such as late characteristics may be deteriorated.

A completely solid electrolyte layer can be used as the electrolyte layer. As such a 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.

As the electrolyte layer, a material obtained by impregnating a porous sheet such as a porous membrane with the above electrolyte may be used.

The thickness of the electrolyte layer is usually 1 to 200 μm,
Preferably, it is 5 to 100 μm.

As the porous sheet, specifically, the thickness is usually 1 μm or more, preferably 5 μm or more, and usually 200 μm or more.
μm or less, preferably 100 μm or less is used. The porosity is usually 10 to 95%, preferably 30 to 8%.
It is about 5%. As a material of the porous sheet, a polyolefin or a polyolefin in which part or all of hydrogen atoms have been substituted with fluorine can be used. Specifically, a microporous film, a nonwoven fabric, a woven fabric, or the like formed using a synthetic resin such as polyolefin can be used.

The planar shape of the electrode is arbitrary, and may be square, circular, polygonal, or the like.

As shown in FIGS. 9 and 11, the current collectors 22, 26 or 15a, 15b are usually provided with tabs 4a,
4b are continuously provided. When the electrode is rectangular, a tab 4a protruding from the positive electrode current collector is formed near one side of one side of the electrode as shown in FIG. 3, and the tab 4b of the negative electrode current collector is formed near the other side. Form.

The stacking of a plurality of battery elements is effective in increasing the capacity of the battery. At this time, however, the tabs 4a and 4b from each of the battery elements are usually arranged as shown in FIG. To form lead connection terminals of the positive electrode and the negative electrode. As a result, a large-capacity battery element 1 can be obtained.

As shown in FIG. 2, the tabs 4a and 4b have
The lead 21 made of a flaky metal is bonded. As a result, the lead 21 and the positive and negative electrodes of the battery element are electrically coupled. The tabs 4a and 4b can be connected to each other by welding using an ultrasonic welding machine.
The connection between the lead 4b and the lead 21 can be performed by resistance welding such as spot welding, ultrasonic welding or laser welding.

In the present invention, it is preferable to use an annealed metal for at least one of the positive electrode lead and the negative electrode lead 21 and preferably for both of the leads. As a result, a battery having excellent bending durability as well as strength can be obtained.

As the kind of metal used for the lead, aluminum, copper, nickel, SUS and the like can be generally used. The preferred material for the positive electrode lead is aluminum. A preferable material for the lead of the negative electrode is copper.

The thickness of the lead 21 is usually at least 1 μm, preferably at least 10 μm, more preferably at least 20 μm.
Most preferably, it is 40 μm or more. If the thickness is too small, the mechanical strength of the lead such as tensile strength tends to be insufficient. The thickness of the lead is usually 1000 μm or less, preferably 500 μm or less, and more preferably 100 μm or less. If the thickness is too large, the bending durability tends to deteriorate, and the case tends to be difficult to seal the battery element. The advantage of using the later-described annealed metal for the lead is more remarkable as the thickness of the lead is larger.

The width of the lead is usually from 1 mm to 20 mm, especially from about 1 mm to 10 mm, and the length of the lead exposed to the outside is usually from about 1 mm to 50 mm.

As described above, the insulating film of the lead is preferably made of a synthetic resin such as a modified polyolefin. The thickness of this insulating film is preferably 5 to 100 μm, particularly preferably 10 to 50 μm. The cuts 19 and the recesses 18 are preferably provided on both sides of the lead, but only one may be provided. The cuts and recesses are preferably provided continuously in the width direction of the lead, that is, traversing the lead, but may be provided partially (for example, in a broken line). The depth of the concave portion 18 is preferably about 90 to 99%, particularly about 95 to 99% of the thickness of the insulating film.

[0081]

As described above, in the battery of the present invention, since the lead is provided with the insulating film, a short circuit is prevented. Also,
By providing the synthetic resin insulating film, the exterior material and the lead can be easily airtightly adhered and joined. In the present invention, since the cuts or recesses are provided in the portion where the insulating film is bent, the lead can be easily bent at the expected bending position.

[Brief description of the drawings]

1A is a perspective view of a main part of a battery according to an embodiment, FIG. 1B is a cross-sectional view taken along line BB in FIG. 1A,
(C) is a cross-sectional view of the same portion as (b) of the battery according to another embodiment.

FIG. 2A is an exploded perspective view of a battery according to an embodiment, and FIG. 2B is a cross-sectional view of a main part of the battery.

FIG. 3 is a perspective view showing a battery element of the battery according to the embodiment.

FIG. 4 is a perspective view of the battery according to the embodiment.

FIG. 5 is a perspective view of a battery according to another embodiment in the process of being manufactured.

FIG. 6 is a perspective view of a battery according to still another embodiment in the process of being manufactured.

FIG. 7 is a perspective view of a battery according to still another embodiment in the process of being manufactured.

8 is a plan view of the battery of FIG. 7 in the process of being manufactured.

FIG. 9 is a schematic sectional view of a unit battery element.

FIG. 10 is a schematic sectional view of a positive electrode or a negative electrode.

FIG. 11 is a schematic sectional view of a battery element.

FIGS. 12A and 12B are longitudinal sectional views each showing an example of a composite material constituting an exterior material.

FIG. 13 is a longitudinal sectional view showing another example of the composite material constituting the exterior material.

FIG. 14 is a schematic cross-sectional view of the vicinity of a battery lead according to a conventional example.

FIG. 15 is a schematic cross-sectional view showing the vicinity of a lead of a battery according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery element 2, 3, 6, 7, 8 Exterior material 4a, 4b Tab 4A, 4F Joint piece 4B, 4G Enclosure piece 5 Insulating material 11 Positive electrode 11a Positive electrode active material 12 Negative electrode 12b Negative electrode active material 13 Non-fluidity Electrolyte layer 15a Positive electrode current collector 15b Negative electrode current collector 18 Concave portion 19 Notch 20 Insulating film 21 Lead 22 Positive electrode current collector 23 Positive electrode active material 24 Spacer (electrolyte layer) 25 Negative electrode active material 26 Negative electrode collector 40 Metal layer 41, 42 synthetic resin layer 43 adhesive layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H011 AA09 CC10 DD13 DD21 EE04 FF02 GG09 HH02 HH13 5H022 AA09 BB03 BB12 BB19 CC02 CC08 CC12 CC13 CC15 CC24 EE06 5H028 AA01 BB01 CC02 CC07 CC08

Claims (4)

[Claims] 1. A battery in which a battery element is wrapped with two or two pieces of exterior material made of a laminated composite material in which a metal layer and a synthetic resin layer are laminated, wherein a lead connected to the battery element is provided. In a battery that is drawn out from between two or two pieces of the exterior material, an insulating film is provided on the lead to separate the lead from a metal layer exposed on an end face of the exterior material, and a bent portion of the lead or A battery, wherein a concave portion or a cut is provided in the insulating film at a portion to be bent. 2. The battery according to claim 1, wherein the insulating film is present from the bonding surface of the two or two pieces of the exterior material to the outside. 3. The battery element according to claim 1, wherein the insulating film is a synthetic resin film. 4. The battery according to claim 1, wherein the recess or the cut is provided along an outer edge of the exterior material.