JP2002075327A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery capable of stably maintaining battery performance for a long time, wherein a battery element is enclosed in a case, and air hardly intrudes into the case. SOLUTION: In this battery, a battery element is enclosed in a case formed by pasting case members, and thin piece-shaped positive electrode lead and negative lead 51 electrically connected to the battery element are extended to the outside of the case from the pasted surface of the case members 52A, 52B. The positive electrode lead and/or the negative electrode lead 51 have no burr-shaped acute angle part, on their cross section perpendicular to their extending direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery having a battery element sealed in a case, and more particularly to a battery having excellent sealing properties, which is suitable for a non-aqueous secondary battery such as a lithium secondary battery.

[0002]

2. Description of the Related Art A non-aqueous battery element is sealed in a case formed by bonding a case member, and a flaky positive electrode lead and a negative electrode lead electrically connected to the battery element are respectively bonded to the case member. A battery extending from the mating surface to the outside of the case is known. In such a battery, a flexible member such as a laminate film having a resin layer laminated on both surfaces of a metal layer is usually used as a case member. After enclosing the battery element in this case, the peripheral edges of the case member are heat-sealed with each other under reduced pressure. In this battery, the battery element is pressed by the atmospheric pressure via the case, and the battery performance is sufficiently exhibited.

The leads are generally made of metal, and the inner layer of the case member is often made of a resin such as polyolefin. Because of the low adhesion between the metal lead and the resin inner layer of the case member, it has been proposed to interpose a sealing material having excellent adhesion to a metal such as a modified polyolefin between them.

[0004]

In such a battery, it is very important to prevent intrusion of air from outside the case. That is, when air enters from the outside of the case, the pressure inside the case increases, so that the force for pressing the battery element is weakened. As a result, the battery performance tends to decrease. In addition, the penetration of moisture in the air may adversely affect non-aqueous battery elements.

However, in the conventional battery, the intrusion of air from the outside of the case is not sufficiently prevented, and the air invades with time and the battery performance tends to gradually decrease.

The present invention solves the above-mentioned conventional problems and is a battery having a battery element sealed in a case, in which air hardly enters the case, and as a result, the battery performance is improved for a long time. It is an object of the present invention to provide a battery that can be maintained stably over a long period of time.

[0007]

A battery according to the present invention is a battery having a battery element sealed in a case, the case comprising:
Peripheral portions of the case members arranged so as to sandwich the battery element are bonded to each other, and a flaky positive electrode lead and a negative electrode lead electrically connected to the battery element are respectively formed by the case members. In the battery extending from the bonding surface to the outside of the case, the positive electrode lead and / or the negative electrode lead has no burrs or burrs in the cross section in a direction perpendicular to the extending direction. I do.

The present inventors have studied the phenomenon of air intrusion into the battery and found that air intrusion from the outside of the case is often seen from the bonded portion of the case member from which the leads extend. That is, as shown in FIG. 14 (a), a conventional lead is formed by cutting a metal foil 41 into a flaky shape as shown in FIG. 14 (b). In the cross-section of each of 42A and 42B, burrs or burrs at the time of cutting are formed so as to rise from the main surface of the lead.
When the flaky lead 42 having such an acute angle portion is extended from the bonding surface of the laminate film as the case member, as shown in FIG.
Near the acute angle portion of the laminated film 44A or 44A
B cannot be brought into close contact, and a void (pinhole) 46 is formed even with the sealing material 45 interposed.
And, due to the existence of the gap 46, air easily enters the case.

On the other hand, the lead used in the present invention has a sharp edge such as burrs or burrs in a cross section perpendicular to the extending direction (hereinafter sometimes simply referred to as “cross section”). do not do. Therefore, the laminate film can be adhered to any part of the lead. In this case, the high sealing performance can be secured by interposing the sealing material between the lead and the film, and the intrusion of air from the bonding portion of the case member from which the lead extends can be reliably prevented. You.

In the present invention, the cross-sectional shape of the lead may be any shape as long as it does not have burrs or burrs.
For example, a lead having both ends curved as a whole,
In a cross section, a lead having a shape in which all corners of the corner are rounded, such as a lead having a curved corner, is exemplified.

As described above, the battery of the present invention has a remarkable effect when the sealing material is interposed at least in a part between the lead and the case member. That is, the adhesive between the lead and the case member is improved by the sealing material,
Since the sealing material uniformly adheres to the periphery of the lead during sealing, it is possible to more reliably prevent the generation of voids.

In the present invention, the case member is preferably a laminate film in which a resin layer is laminated on both sides of a metal layer. Since such a laminated film has shape changeability, it is easy to change the shape of the battery in various ways, and also, by evacuating the inside of the case and sealing the peripheral edge of the case member. Thus, a pressing force can be applied to the battery element, and as a result, battery characteristics such as cycle characteristics can be improved. Moreover,
With such a laminated film, the case member can be made thinner and lighter, which is advantageous for miniaturizing the battery and improving the capacity per volume.

The lead is preferably made of a metal material such as a simple metal or an alloy, but a lead having no burrs or burrs in the cross-section is a strip-shaped material or a line having a substantially circular cross-section. By rolling the material,
Alternatively, after cutting the plate-shaped material, it can be easily manufactured by deburring or rolling the cut portion.

The battery of the present invention has a particularly remarkable effect when the battery element is sealed under reduced pressure in the case.

The battery of the present invention has a particularly remarkable effect particularly when a non-aqueous battery element is used as the battery element, for example, when applied to a lithium secondary battery.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A battery according to an embodiment will be described below with reference to the drawings.

First, the shape of the lead according to the present invention will be described with reference to FIGS. FIG. 15 is a cross-sectional view showing an extended portion of a lead from a case member of the battery according to the embodiment of the present invention (this figure corresponds to a cross section taken along line XV-XV in FIG. 4 described later). FIG. 16 is a schematic view showing an embodiment of a cross-sectional shape of a lead according to the present invention, and FIG. 17 is a cross-sectional view showing an example of a method for manufacturing a lead according to the present invention.

In the battery according to the present invention, the flaky positive electrode lead and the negative electrode lead are electrically connected to the battery element sealed in the case and extend from the bonding surface of the case member to the outside of the case. At least one of them, and preferably both of them, are shaped such that no burrs or burr-like acute portions are present in the cross section, as in the case of the lead 51 in FIG. With such a lead 51, the periphery thereof can be brought into close contact with the laminate films 52A and 52B as the case members. In particular, by interposing the sealing material 53, high sealing performance can be ensured, and intrusion of air from the portion where the laminated films 52A and 52B are bonded can be reliably prevented.

In the present invention, the cross section of the lead may be any shape as long as it does not have burrs or burrs.
As a specific cross-sectional shape, as shown in FIG. 16A, both ends 61A and 61B have leads 61 having a curved shape as a whole, or as shown in FIG.
62B, 62C and 62D are curved leads 62;
As shown in FIG. 16C, there are a lead 63 having four corners cut off, and a lead 64 having a convex lens shape as shown in FIG. 16D.

In the battery of the present invention, as shown in FIG. 15, a sealing material 53 is interposed at least in part, and preferably entirely, between the lead 51 and the laminate films 52A and 52B as a case member. Is preferred.
The sealing material 53 improves the adhesiveness between the lead 51 and the laminated films 52A and 52B, and also allows the sealing material 53 to adhere uniformly to the periphery of the lead 51 at the time of heat sealing. Generation can be more reliably prevented.

The leads 51 and the laminate film 52
As the sealing material 53 interposed between A, 52B and the like,
A modified polyolefin-based resin adhesive having excellent adhesion to the metal constituting the lead 51 is preferable.

In the present invention, the constituent material of the lead is preferably an annealed metal material having excellent strength and bending durability.

Examples of the type of metal material used for the lead include aluminum, copper, nickel, and SUS. In particular, in the case of a lithium secondary battery to be described later, a preferable material for the positive electrode lead is aluminum, and a preferable material for the negative electrode lead is copper.

The thickness of the lead (d in FIG. 17) is usually 1 μm.
m or more, preferably 10 μm or more, more preferably 20 μm or more.
μm or more, and most preferably 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, more preferably 10 μm or less.
0 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 advantages of using annealed metal for the leads are more pronounced as the thickness of the leads increases.

The width of the lead (w in FIG. 17) is usually 1
The length of the lead exposed to the outside is usually about 1 mm to 50 mm.

As shown in FIG. 17, a lead made of a metal or alloy having no sharp edges such as burrs and burrs in the cross section is formed by rolling a linear material 70 having a substantially circular cross section as shown in FIG. By doing so, it is preferable to manufacture the lead 71 according to the present invention. Also, FIG.
After cutting the plate-shaped material 80 as described above, the ends 81A and 81B of the cut pieces 81 generated by the cutting in FIG. 18B are deburred or rolled to form leads 82 of a similar shape. Is also preferred.

Next, the configuration of the battery of the present invention using the lead having such a sectional shape will be described with reference to FIGS.

FIG. 1 is an exploded perspective view of a battery according to an embodiment, FIG. 2 is a sectional view of a main part of the battery, FIG. 3 is a schematic perspective view of a battery element, and FIG. 4 is a perspective view of the battery. .

In this battery, the battery element 1 is housed in the concave portion (housing portion 3b) of the case member 3, then the case member 2 is put on the case member 3, and the peripheral portions 2a, 2a, 3a.

As shown in FIG. 1, the case member 2 is flat. The case member 3 is a housing portion 3b formed of a rectangular box-shaped recess.
It has a shallow open box shape having a peripheral portion 3a which protrudes outward in a flange shape from four peripheral edges of the housing portion 3b.

As shown in FIG. 3, the battery element 1 is formed by stacking a plurality of unit battery elements. From each unit battery element,
Tab 4a or 4b is pulled out. The tabs 4a from the positive electrode are bundled (that is, overlapped with each other), and the positive electrode lead 21 is joined to form a positive electrode terminal portion. The tabs 4b from the negative electrode are also bundled together, and the negative electrode lead 21 is joined to form a negative electrode terminal. The leads 21 correspond to the leads 51 and 6 shown in FIGS.
1, 62, 63, 64, 71, or 82.

The battery element 1 is accommodated in the housing 3b of the case member 3.
Is accommodated, and the case member 2 is covered.

A pair of leads 21 extending from the battery element 1
Are peripheral edges 2a, 1a of one side of the case members 2, 3, respectively.
It is drawn out through the mating surfaces of the 3a. Thereafter, the case member 2 is placed under a reduced pressure (preferably vacuum) atmosphere.
The four peripheral edges 2a, 3a of 3 are hermetically joined to each other by a method such as thermocompression bonding or ultrasonic welding, and the battery element 1 is sealed in the case members 2, 3. By sealing under reduced pressure, a pressing force can be applied to the battery, and as a result, good battery characteristics can be obtained. In addition, since the intrusion of air from the outside becomes a more direct problem, the effects of adopting the configuration of the present invention are remarkable.
By joining each other, the joint pieces 4A, 4F, 4
G is formed. The joining pieces 4A, 4F, 4G project outward from the enclosing part 4B enclosing the battery element 1. Therefore, among the joining pieces 4A, 4F, 4G, 4A, 4G are bent along the enclosing part 4B and fastened to the side surface of the enclosing part 4B by an adhesive or an adhesive tape (not shown). Can be

In FIG. 1, the case members 2 and 3 are separate bodies, but the case members 2 and 3 may be integrally formed as shown in FIG. In FIG. 5, one side of the case member 3 and one side of the case member 2 are connected, and the case member 2 has a lid shape that is connected to the case member 3 so as to be bent. A concave portion of the housing portion 3b is formed from one side where the case members 2 and 3 are continuous, and the one side has the same configuration as the joining piece portion except that the joining piece portion is not formed.

FIGS. 1 and 5 show the case member 3 having the housing portion 3b and the flat case member 2, but in the present invention, as shown in FIG. ,
The battery element 1 may be covered by the case members 6 and 7 having the peripheral portions 6a and 7a projecting from the four peripheral edges of the housing portions 6b and 7b. In FIG. 6, the case members 6, 7
Are integrated as a series, but these may be separate as in FIG.

In the present invention, as shown in FIG. 7, one flat sheet-like case member 8 is folded in two along the central side 8a to form two pieces, a first piece 8A and a second piece 8B. The battery element 1 is formed between the first piece 8A and the second piece 8B.
As shown in FIG. 8, the battery element 1 may be sealed by joining the peripheral portions 8b of the first piece 8A and the second piece 8B as shown in FIG.

Also in this case, the battery element 1 is sealed by overlapping the first piece 8A and the second piece 8B of the case member 8.

In this embodiment, the bent joint piece is fixed along with the enclosing part with an adhesive or an adhesive tape, so that 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.

The battery of the present invention also has a structure as shown in FIG.
One long sheet-like exterior member 9 is wrapped around the battery element with the lead 21 pulled out, and the both ends 9A and 9B of the exterior member 9 are overlapped and folded. 9C may be fixed with an adhesive or an adhesive tape.

In any of the batteries, since the cross-sectional shape of the lead 21 is such that no burrs or burrs are present in the cross-section as described above, the periphery of the lead 21 is preferably provided via a sealing material. Since it can be covered with a member with good adhesiveness, it is possible to prevent the formation of voids and obtain extremely high sealing performance, and it is possible to reliably prevent air from entering the case.

It is preferable that the case members 2, 3, 6, 7, and 8 have shape variability. As a result, it is possible to easily change the shape of the battery in various ways. Further, after the inside of the case member is evacuated, by sealing the peripheral portion of the case member, 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 a material for the case member, a metal material such as iron or copper, a synthetic resin, or the like can be used. Preferably, a laminated composite film (laminated film) in which a metal and a synthetic resin are laminated is used. Can be By using this laminate film, the case member can be made thinner and lighter, and the capacity of the whole battery can be improved.

FIG. 12 shows a laminate film.
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 by using a metal foil, a metal deposition film, a metal sputter or the like.

The synthetic resin layer 41 is used for protecting the case member, preventing invasion by the electrolyte, preventing contact between the metal layer and the battery element, or protecting 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 film 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 laminate film 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 bond 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 laminate film. A case is formed using these metals, synthetic resins or laminated films as case members. 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 case member, drawing can be performed.

The battery element of the present invention can be 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. The present invention is particularly suitable for application to a non-aqueous battery such as a lithium secondary battery. Therefore, a preferred configuration when the above 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. The unit battery element includes a positive electrode current collector 22, a positive electrode active material layer 23, a spacer (electrolyte layer) 24, a negative electrode active material layer 25, and a negative electrode current collector 26.
Are laminated.

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 layer, a spacer and a negative electrode active material layer are stacked 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 layer 11a or a negative electrode active material layer 12a on both sides of the current collector 15a or the negative electrode current collector 15b as a core material. As shown in FIG. 11, a unit battery element may be formed by alternately stacking via a spacer (electrolyte layer) 13. 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) is a unit cell element. Is equivalent to

As the positive electrode current collectors 15a and 22, metal foils such as aluminum, stainless steel, and nickel can be used. Aluminum is particularly preferable, and the negative electrode current collectors 15b and 26 can be used.
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.

As the positive electrode active material, an inorganic compound or an organic compound can be used as long as it can occlude and release lithium ions. As the inorganic compound, a transition metal oxide, a composite oxide of lithium and a transition metal, a transition metal sulfide, specifically, a transition metal oxide such as MnO, V ₂ O ₅ , TiO ₂ , lithium nickelate, cobalt Examples thereof include composite oxides of lithium and a transition metal such as lithium oxide and lithium manganate, and transition metal sulfides 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. The positive electrode active material may be used by mixing these inorganic compounds and organic compounds. Particularly 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 may be appropriately selected depending on 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, carbonaceous materials such as graphite and coke are usually mentioned. 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 blending amount of the binder with respect 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, as necessary.

The conductive material is not particularly limited as long as it is capable of imparting 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 can 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 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 material for the electrolyte layer 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 kinds of electrolytes such as an electrolyte having fluidity and a non-flowable electrolyte such as a gel electrolyte or 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. 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 material which is stable as an electrolyte with respect to the positive electrode active material and the negative electrode active material, and which can perform a lithium ion to perform 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 electrolytic 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 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 usually have 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.

It is effective to stack a plurality of battery elements in order to increase the capacity of the battery. At this time, however, each of the tabs 4a and 4b from each of the battery elements is usually in the thickness direction. The positive electrode and the negative electrode are connected to form a terminal portion. 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 is electrically connected to the positive and negative electrodes of the battery element. Connection between tabs 4a, 4b and tab 4
The connection between the leads a and 4b and the lead 21 can be performed by resistance welding such as spot welding, ultrasonic welding or laser welding.

[0085]

As described above, according to the present invention, there is provided a battery in which battery elements are sealed under reduced pressure in a case. Almost no air enters the case and the battery performance is stable for a long time. A battery is provided that can be maintained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a battery according to an embodiment.

FIG. 2 is a cross-sectional view of a main part of the battery according to the embodiment.

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 perspective view showing a preferred example of a unit battery element of a lithium secondary 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 a case member.

FIG. 13 is a longitudinal sectional view showing another example of the composite material forming the case member.

FIG. 14 is a cross-sectional view showing a conventional method for manufacturing a lead and an extension of the lead from a case member of a battery.

FIG. 15 is a cross-sectional view showing an extension of a lead from a case member of the battery according to the present invention.

FIG. 16 is a schematic view showing an embodiment of a cross-sectional shape of a lead according to the present invention.

FIG. 17 is a cross-sectional view illustrating an example of a method for manufacturing a lead according to the present invention.

FIG. 18 is a cross-sectional view showing another example of the method for manufacturing a lead according to the present invention.

FIG. 19 is a perspective view of a battery according to an embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Battery element 2, 3, 6, 7, 8 Case member 4a, 4b Tab 4A, 4F Joint piece part 4B, 4G Enclosure piece part 11 Positive electrode 11a Positive electrode active material 12 Negative electrode 12b Negative electrode active material 13 Non-fluid electrolyte layer 15a Positive electrode collector 15b Negative electrode collector 21, 51, 61, 62, 63, 64, 71, 82 Lead 22 Positive electrode 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 52A, 52B Laminate film 53 Sealing material

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 5H011 AA10 AA17 CC02 CC06 CC10 DD13 EE04 FF02 GG08 HH02 JJ12 JJ25 JJ27 5H022 AA09 BB01 BB02 CC01 EE01 EE03 EE04 5H029 AJ15 AK02 AK03 AK05 AM11 AL04 BJ04 BJ12 CJ03 CJ04 CJ06 CJ28 DJ02 DJ03 DJ05 EJ01 EJ12 HJ12

Claims (10)

[Claims] 1. A battery in which a battery element is enclosed in a case, wherein the case is formed by bonding peripheral parts of a case member arranged so as to sandwich the battery element, In a battery, a flaky positive electrode lead and a negative electrode lead, which are electrically connected to each other, extend out of the case from the bonding surface of the case members, wherein the positive electrode lead and / or the negative electrode lead A battery characterized in that no burrs or burrs are present in a cross section in a direction orthogonal to the direction. 2. The device according to claim 1, wherein the positive electrode lead and / or the negative electrode lead have rounded corners at corners in a cross section in a direction orthogonal to the extending direction. battery. 3. The battery according to claim 1, wherein a sealing material is interposed at least in a portion between the positive electrode lead and / or the negative electrode lead and the case member. 4. The battery according to claim 1, wherein the case member is made of a laminated film in which a resin layer is laminated on both surfaces of a metal layer. 5. The battery according to claim 1, wherein the positive electrode lead and / or the negative electrode lead are formed by rolling a material having a substantially circular cross section. 6. The positive electrode lead and / or the negative electrode lead according to any one of claims 1 to 4, wherein after cutting the plate material, the cut portion is deburred or rolled. A battery comprising: 7. The battery according to claim 1, wherein the positive electrode lead and / or the negative electrode lead are made of a metal material. 8. The battery according to claim 1, wherein the battery element is sealed under reduced pressure in a case. 9. The battery according to claim 1, wherein the battery element is a non-aqueous battery element. 10. The battery according to claim 9, wherein the battery element is a lithium secondary battery.