JP2001250515A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery where a bulk is small and strength and rigidity of side face are high. SOLUTION: A battery element 1 is laid between outer packaging materials 2, 3, and a peripheral part 2a, 3a thereof are jointed to form a jointing piece part 4A. This part 4A is folded back, and then jointed by an adhesive 5 on the side face of a covering part 4B covering the battery element 1 so as to form a battery.

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 suitable for a non-aqueous secondary battery such as a lithium secondary battery.

[0002]

2. Description of the Related Art As a thin battery, a thin battery in which a thin battery element (for example, a power generation element composed of a laminate of a positive electrode, a separator and a negative electrode) is covered with a laminate film is known as disclosed in Japanese Patent Application Laid-Open No. 8-83596. After the battery element is inserted into the laminate exterior material, the inside of the laminate exterior material is decompressed, and a pressing force in the stacking direction is applied to the battery element to increase the adhesion between the layers.

[0003]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 8-83596
In the battery disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, the joint pieces of the laminated films are extended outward from the encapsulation part enclosing the battery element, and only the joint pieces protrude. Batteries are bulky.

[0004] Furthermore, since the positive electrode and the negative electrode are exposed on the side surface of the stacked battery element, the rigidity of the side surface of the battery element is low. Therefore, when an external force is applied to the side surface (for example, when the battery element or the battery is dropped), the side surface may be deformed and the positive electrode and the negative electrode may be short-circuited. Also, even in the case of a wound type battery in which a battery element is wound, since a large amount of stress is applied to the side surface of the wound body of the battery element, when a shock is applied to the side surface of the battery element, the active material comes off. easy.

[0005] The present invention solves the various problems described above,
It is an object of the present invention to provide a battery having a small bulk and high strength and rigidity on a side surface.

[0006]

In the battery according to the present invention (claim 1), a battery element is interposed between two exterior materials, and the outer edges of the exterior materials are joined to each other to seal the battery element. In a battery, a battery having an enclosing portion enclosing the battery element and a joining piece portion formed by joining peripheral portions of the exterior material, at least a part of the joining piece portion is It is characterized by being bent along the envelope portion and being adhered to the envelope portion with an adhesive.

In the battery according to the present invention (claim 2), one package is folded into two pieces, the battery element is interposed between the two pieces, and the peripheral portions other than the folded sides of the two pieces are connected to each other. Is a battery in which the battery element is hermetically sealed and has a wrapped portion that wraps the battery element, and a joint piece that is formed by joining the peripheral edges of the exterior material. , At least a part of the joining piece is bent along the envelope,
Further, it is characterized by being adhered to the enclosing part by an adhesive.

[0008] In the battery according to the present invention (claims 1 and 2), at least a part of the joint piece is bent so as to be along the encased portion, and has a small bulk. In addition, since this bent joint piece is adhered to the encapsulating part with an adhesive,
High strength and rigidity on the side of the battery. Of course, it is also prevented by this adhesion that the bent joint piece part separates from the encased part.

In the battery of the present invention, the strength and rigidity of the side surface are high, so that even if an impact is applied to the side surface, the active material is prevented from peeling or short-circuiting.

In the present invention, the adhesive is preferably a hot melt adhesive which is easily cured and has a short curing time.

According to the present invention, when the concave portion for accommodating the battery element is formed in the exterior material in advance, the battery element can be accommodated more compactly and can be securely accommodated.

In the present invention, when the exterior material is constituted by a laminate of a synthetic resin layer and a metal layer, the size and weight of the battery can be reduced, and the effect of the present invention becomes more remarkable. in this case,
In order to increase the adhesive strength between the encapsulating part and the joining piece, it is preferable that both the joining surfaces of the joining piece and the enclosing body are made of the synthetic resin layer.

In the present invention, the joint piece may be bent only once at the base of the enclosing part, or may be bent a plurality of times. In the case of bending a plurality of times, it is preferable that the distal end edge of the joining piece is interposed between the joining piece and the envelope. With this configuration, the distal end edge of the joint piece is isolated from the outside air, and the intrusion of moisture, air, and the like from the distal end edge can be prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A battery according to an embodiment will be described below with reference to the drawings. FIG. 1A is a cross-sectional view of the battery according to the embodiment, and FIG. 1B is an enlarged cross-sectional view of a portion B in FIG. 1A. FIG. 4 is a perspective view showing an exterior material of the battery, and FIG. 9 is a perspective view showing the battery.

In this battery, the battery element 1 is wrapped with outer materials 2 and 3, the peripheral portions 2 a and 3 a of the outer materials 2 and 3 are joined, the joint piece 4 A is bent, and the adhesive 5 is used. The joining piece portion 4A is bonded to the side surface of the enclosing portion 4B. The joining piece 4A is a piece in which the peripheral edges 2a and 3a are joined. The enclosing portion 4B is a flat plate-shaped portion enclosing the battery element 1.

As shown in FIG. 4, the exterior material 2 is flat. The exterior material 3 is a shallow, open box-like shape having a housing portion 3b formed of a rectangular box-shaped recess and a peripheral portion 3a projecting outward in a flange shape from four peripheral edges of the housing portion 3b.

The battery element 1 is accommodated in the housing 3b of the exterior material 3.
Is accommodated, and the exterior material 2 is covered thereon. The pair of leads 21 extending from the battery element 1 are drawn out through the mating surfaces of the peripheral portions 2a, 3a of the outer packaging materials 2, 3, respectively. Thereafter, the four peripheral edges 2a and 3a of the outer packaging materials 2 and 3 are hermetically joined to each other in a reduced pressure (preferably vacuum) atmosphere by a method such as thermocompression bonding or ultrasonic welding, and the battery element 1 is attached to the outer packaging materials 2 and 3. 3 is enclosed.

By joining the peripheral edges 2a and 3a together, a joining piece 4A is formed. This joining piece 4A
Project outward from the enclosing part 4B enclosing the battery element 1. Therefore, this joining piece 4A is enclosed
And adhere to the side surface of the enclosing part 4B with the adhesive 5.

FIG. 9 is a perspective view of the battery manufactured in such a manner, and a pair of leads 21 are drawn out from one side of the rectangular envelope.

In general, adhesives are classified into thermosetting resin adhesives, thermoplastic resin adhesives, rubber-based adhesives (elastomers), and composite adhesives based on their thermodynamic properties. The present invention is classified into adhesives, emulsion adhesives, pressure-sensitive adhesives, rewetting adhesives (water-soluble adhesives), polycondensation-type solventless adhesives, film adhesives, and hot melt adhesives. Then, any of them may be used.
However, in the present invention, a hot-melt adhesive is suitable as the adhesive because the curing time is short and the composition is easily cured even in an environment having a low dew point used in the production of a non-aqueous battery.

Examples of the hot-melt adhesive include polyvinyl acetate, polymethyl methacrylate, polystyrene, polyvinyl alcohol, polyvinyl butyral, methyl cyanoacrylate, polysulfone, polyimide, polybenzimidazole, nylon, polyparaphenyl oxide, Polycarbonate, polyacetal,
Preferred are polyethylene, polypropylene, other ethylene-vinyl acetate copolymers, butadiene, copolymerized plastic polymers (ABS, high impact polystyrene), and the like. In addition, terpene resins, alfalt, rosin and derivatives thereof, ethyl cellulose, petroleum resins, and the like can also be used.

In FIG. 4, 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. As a result, it is possible to reduce the length of the joint where moisture and air easily enter,
In addition, the production becomes easy.

In FIG. 1, the joint piece 4A is bent only once along its base, but in the present invention, as shown in FIG. 2, the joint piece 4A is bent once more on the way. Alternatively, the tip of the joining piece 4A may be interposed between the joining piece 4A and the side surface of the enclosing part 4B. As a result, intrusion of moisture and air from the joint piece can be more effectively prevented.

In FIGS. 4 and 5, the exterior material 3 having the accommodation portion 3b and the flat exterior material 2 are shown, but 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 bodies as in FIG. 4.

FIG. 3 is a cross-sectional view of a battery in which the battery element 1 is wrapped by using the exterior materials 6 and 7, and the peripheral portions 6a and 7a are shown.
The joining piece portion 4C formed by joining the two is bent at the base portion thereof, and is adhered to the side surface of the enclosing portion 4D enclosing the battery element 1 with the adhesive 5. In FIG. 3, the joining piece portion 4C is bent only at the base thereof.
May be bent twice.

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.

Also in this case, the leads 21 extending outward from the mating surface of the exterior material are extended outward from the side parallel to the central side 8a among the sides of the rectangular envelope. Although not shown, after that, the remaining one of the rectangular
In the parallel sides of the pair, a joint piece formed by joining the peripheral portions 8b is bent and adhered to the side surface of the enclosing portion with an adhesive.

In the above description, the joining piece and the envelope are uniformly adhered by the adhesive.
In the present invention, for example, an embodiment in which these are bonded using a double-sided tape is also included. At this time, as the adhesive used for the adhesive portion of the double-sided tape to be used, various types such as silicone, acrylic, and rubber can be used.

In the battery of the present invention thus configured, the joint piece is bent along the envelope,
Low bulk. Also, since the bent joint piece is adhered to the encapsulating part by an adhesive, the strength of the side surface of the battery,
High rigidity. Of course, it is also prevented by this adhesion that the bent joint piece part separates from the encased part. Also,
Since this battery has high strength and rigidity on the side surface, even if an impact is applied to the side surface, peeling of the active material is prevented.

In particular, as shown in FIG. 2, in a battery in which the tip of the joining piece is interposed between the joining piece 4A and the side surface of the enclosing portion 4B, the peripheral portion 2a is extended from the tip of the joining piece 4A. , 3a
Infiltration of moisture and the like into the bonding interface of the substrate is more reliably prevented.

The present invention is suitable as a thin-film battery, and particularly suitable for application to a non-aqueous battery such as a lithium secondary battery. A preferred configuration will be described.

This lithium secondary battery is, as shown in FIG.
It has a positive electrode 11, a negative electrode 12, and an electrolyte layer 13 interposed therebetween.

As shown in FIG. 11, the positive electrode 11 or the negative electrode 12 usually has a current collector 15 as a core material and the positive electrode active material 11a or the negative electrode active material 12a
Are laminated.

A metal foil such as aluminum, stainless steel or nickel can be used as a current collector for the positive electrode, and aluminum is particularly preferable. A metal foil such as copper, stainless steel or nickel can be used as a current collector for the negative electrode. Particularly, copper is preferred. The thickness of the current collector is preferably about 1 to 30 μm.

As the positive electrode active material, lithium ions are absorbed.
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 or 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 for binding 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. 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 vinyl,
Fluorinated resins such as polyvinylidene fluoride and polytetrafluoroethylene; CN group-containing polymers such as polyacrylonitrile and polyvinylidene cyanide; polyvinyl alcohol-based polymers such as polyvinyl acetate and polyvinyl alcohol; polyvinyl chloride and polyvinylidene chloride Halogen-containing polymers; conductive polymers 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 be used.

The amount of the binder is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight, based on 100 parts by weight of the active material. 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 optionally contain additives, such as conductive materials and reinforcing materials, exhibiting various functions, powders, and fillers.

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 are 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 on the current collector in a state where the active material is mixed with a binder and heated and 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 on the 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.

As shown in FIG. 10, the positive electrode 11 and the negative electrode 12
An electrolyte layer 13 is formed between them. Electrolyte layer 13
Usually includes 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 electrolyte, so that the advantage of using a case having a shape changeability such as a laminate film described later is maximized. You can make use 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 material which is stable as an electrolyte with respect to the positive electrode active material and the negative electrode active material and which can undergo lithium ion to undergo an electrochemical reaction 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 these, one or more solvents selected from cyclic carbonates such as ethylene carbonate and propylene carbonate, and non-cyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate are particularly preferred. 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.

As the polymer used for the gel electrolyte,
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-vinyl pyrrolidone, diethylene glycol di Acrylics obtained by polymerization of 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 Rimmer can also be preferably used.

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.

A battery element is obtained by laminating a positive electrode and a negative electrode via an electrolyte layer. The battery element may have a flat plate shape by laminating a positive electrode, a negative electrode, and an electrolyte layer in a thickness direction, or may have a substantially cylindrical shape or a flat cylindrical shape by laminating it after lamination.

For example, as shown in FIG.
The positive electrode composition is laminated on both surfaces of the positive electrode 11 to obtain a plate-shaped positive electrode 11.
The negative electrode material 12 is also formed in a plate shape by the same method, and the positive electrode 11 and the negative electrode 12 formed in the plate shape are, as shown in FIG.
The layers are alternately stacked via the electrolyte layer 13. FIG.
Can be stacked in the direction in which the positive electrode 11 side or the negative electrode 12 side is in contact with each other, such as the battery element shown in FIG. Such a configuration is particularly effective when a positive electrode or a negative electrode is formed on one surface of the current collector.

In both cases of FIGS. 10 and 13, the battery has a structure in which flat battery elements are stacked in the thickness direction.

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

As shown in FIGS. 10 to 14, the current collector 15 is usually provided with tabs 4a and 4b for lead connection. When the electrode is rectangular, a tab 4a projecting from the current collector 5 of the positive electrode 1 is usually formed near one side of one side of the electrode as shown in FIG. A tab 4b is formed near the side.

Laminating 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 usually have the configuration shown in FIG.
The positive and negative electrode lead connection terminals are formed by being joined in the thickness direction as shown in FIG. As a result, a large-capacity battery element 1 can be obtained.

As shown in FIG. 14, a lead 21 made of a flaky metal is connected to the tabs 4a and 4b. As a result, the lead 21 and the positive electrode 11 and the negative electrode 12 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, preferably for both 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 or 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 about 1 mm or more and 20 mm or less, particularly about 1 mm or more and 10 mm or less, and the length of the lead exposed to the outside is usually about 1 mm or more and 50 mm or less.

It is preferable that the exterior members 2, 3, 6, and 7 have shape variability. As a result, it is possible to easily change the shape of the battery 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.

As the material of the exterior material, a metal such as aluminum or nickel-plated iron or copper, a synthetic resin, or the like can be used. Preferably, a laminated composite material in which a metal and a synthetic resin are laminated is used. Can be By using this 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. Further, since such a material itself has poor strength, the effect of the present invention is more remarkable.

FIG. 15 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, and for example, polyethylene, polypropylene, modified polyolefin, ionomer, ethylene-vinyl acetate copolymer and the like can be used.

As shown in FIG. 16, 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. A case is formed using these metals, synthetic resins or composite materials. 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. Also,
It can also 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.

When a battery is formed by using such an exterior material made of a composite material, it is preferable that the surface in contact with the adhesive 5 be a synthetic resin layer. By doing so, the adhesive strength between the adhesive and the exterior material can be increased. In addition, it adheres easily even in a dry room when a non-aqueous battery is manufactured.

[0081]

As described above, in the battery of the present invention, the joint piece is bent so as to be along the encased portion, and has a small bulk. In addition, since the bent joint piece is adhered to the enclosing part with an adhesive, the strength and rigidity of the side surface of the battery are high. Of course, it is also prevented by this adhesion that the bent joint piece part separates from the encased part. In addition, since the battery of the present invention has high strength and rigidity on the side surface, even when the side surface is impacted, peeling of the active material is prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a battery according to an embodiment.

FIG. 2 is a cross-sectional view of a battery according to another embodiment.

FIG. 3 is a cross-sectional view of a battery according to yet another embodiment.

FIG. 4 is a perspective view of exterior materials 2 and 3;

FIG. 5 is a perspective view showing another configuration example of the exterior materials 2 and 3;

FIG. 6 is a perspective view showing a configuration example of exterior materials 6 and 7;

FIG. 7 is a perspective view showing a configuration example of a packaging material 8;

8 is a plan view of a battery in the process of being manufactured using the exterior material of FIG. 7;

FIG. 9 is a perspective view of a battery according to the embodiment.

FIG. 10 is a schematic sectional view of a battery element.

FIG. 11 is a schematic sectional view of a positive electrode or a negative electrode.

FIG. 12 is a perspective view showing a configuration of a terminal portion of a battery element.

FIG. 13 is a cross-sectional view showing another configuration example of the battery element.

FIG. 14 is a longitudinal sectional view showing a relationship between tabs and leads of a plurality of battery elements.

FIGS. 15A and 15B are longitudinal sectional views each showing an example of a composite material constituting an exterior material.

FIG. 16 is a longitudinal sectional view showing another example of the composite material constituting the exterior material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery element 2, 3, 6, 7, 8 Exterior material 4a, 4b Tab 4A, 4C Joint part 4B, 4D Enclosure part 5 Adhesive 11 Positive electrode 11a Positive electrode active material 12 Negative electrode 12b Negative electrode active material 13 Non-fluid electrolyte layer 15 Current collector 21 Lead 40 Metal layer 41, 42 Synthetic resin layer 43 Adhesive layer

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Michiaki Kayano 3-10, Utsudori, Kurashiki-shi, Okayama Mitsubishi Chemical Corporation Mizushima Works F-term (reference) 5H011 AA01 CC02 CC06 CC10 DD03 DD06 DD13 DD14 5H029 AJ11 AK02 AK03 AK05 AK16 AL01 AL02 AL06 AL07 AL12 AM03 AM04 AM05 AM07 AM16 BJ04 BJ12 CJ02 CJ03 CJ05 DJ02 DJ03 DJ14 EJ01 EJ12 HJ12

Claims (7)

[Claims] 1. A battery element is interposed between two exterior materials,
A battery in which a battery element is hermetically sealed by joining peripheral parts of the exterior material, and a covering piece that encapsulates the battery element, and a joining piece formed by joining peripheral parts of the exterior material together A battery having at least a portion thereof, wherein at least a part of the joining piece is bent along the envelope, and is bonded to the envelope with an adhesive. 2. An outer package is folded back into two pieces, a battery element is interposed between these two pieces, and peripheral parts other than the folded sides of the two pieces are joined to seal the battery element. A battery comprising: an encapsulating portion enclosing the battery element; and a joining piece formed by joining peripheral edges of the exterior material, at least a part of the joining piece. Wherein the battery is bent along the envelope and is adhered to the envelope with an adhesive. 3. The battery element according to claim 1, wherein the adhesive comprises a hot-melt adhesive. 4. The battery according to claim 1, wherein a recess for accommodating the battery element is formed in the exterior material in advance. 5. The battery according to claim 1, wherein the exterior material comprises a laminate of a synthetic resin layer and a metal layer. 6. The battery element according to claim 5, wherein both the bonding surfaces of the joining piece and the encapsulating part are made of the synthetic resin layer. 7. The joining piece according to claim 1, wherein the joining piece is bent a plurality of times, and a leading edge of the joining piece is interposed between the joining piece and the envelope. A battery characterized in that: