JP2000285907A - Battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve air-tightness by adhering a bubble-proof body to a power- generating element using an adhering means. SOLUTION: In this manufacturing method for this battery 1, a power- generating element 4 is fixed so that lead terminals 3 are firstly directed down, and a bubble-proof body 5 is placed at the top on the opposite side so as to cover the entire end and is fixed by an adhesive. As the bubble-proof body 5, a polyolefine-made net, a nonwoven fabric, or a felt foaming body can be used. In a subsequent process, if necessary, electrolyte is injected through the bubble-proof body 5, and therefore, the electrolyte does not bound against the power-generating element 4 and thus does not adhere near an opening in the inner surface of a battery case 2. Even if bubble breaks in the electrolyte when air is discharged, droplets do not disperse out of the powergenerating element 4 because the top of the power-generating element 4 is covered with the bubble- proof body 5. In addition, because the collecting lead side is sealed before injection of the electrolyte, the manufactured battery 1 has good air-tightness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery and a method for manufacturing the battery.

[0002]

2. Description of the Related Art In recent years, electronic devices such as a portable radio telephone, a portable personal computer, and a portable video camera have been developed, and various electronic devices have been reduced in size to be portable. Along with this, a battery having a high energy density and a light weight is also adopted as a built-in battery. A typical battery that satisfies such a requirement is an active material such as lithium metal or lithium alloy, or a host material containing lithium ions (here, a host material refers to a material that can occlude and release lithium ions). Lithium intercalation compound occluded in a certain carbon is used as a negative electrode material, and LiC
This is a non-aqueous electrolyte secondary battery using an aprotic organic solvent in which a lithium salt such as 10 ₄ or LiPF ₆ is dissolved as an electrolyte.

[0003] This nonaqueous electrolyte secondary battery has a negative electrode plate in which the above-mentioned negative electrode material is held by a negative electrode current collector as a support thereof, and a reversible electric charge with lithium ions such as a lithium-cobalt composite oxide. A positive electrode plate that holds a positive electrode active material that undergoes a chemical reaction on a positive electrode current collector that is a support thereof, and holds an electrolytic solution and intervenes between a negative electrode plate and a positive electrode plate to prevent a short circuit between both electrodes. And a separator which is housed in a battery case made of a metal / resin laminate film so as to maintain airtightness.

A battery including a sealed battery case and a positive / negative electrode and an electrolyte contained therein, including this non-aqueous electrolyte secondary battery, has conventionally been manufactured as follows. I have. First, the positive and negative electrodes to which the lead terminals are connected and the separator interposed therebetween are wrapped with a laminate film serving as a battery case so that only the lead terminals are exposed. Then, the periphery of the laminate film is bonded. However, some openings are provided. Next, an electrolyte is injected between the positive electrode and the negative electrode from the opening. Subsequently, after air in the battery case is removed from the opening by a vacuum pump, the opening is sealed by bonding.

[0005]

However, in the conventional method for manufacturing a battery, when the electrolyte is injected, the electrolyte hits the positive electrode and the negative electrode and rebounds, and when the air between the electrodes is removed, bubbles in the electrolyte are removed. Bursts. Therefore, the droplets of the electrolytic solution easily adhere to the inner surface of the battery case. Therefore, when the opening is subsequently sealed, the portion to be bonded is sealed with the electrolytic solution attached thereto, and as a result, the hermeticity is deteriorated although it is sealed. If the airtightness is poor, air may enter from the outside. If the airtightness is extremely poor, the electrolyte may flow out.

In particular, in the above-mentioned non-aqueous electrolyte secondary battery, if airtightness is poor, an electrolysis reaction occurs in the battery due to moisture contained in air, and the capacity of the battery is reduced. Also, when the electrolyte contains a lithium salt such as LiPF ₆ , this may react with water to generate a gas such as HF. When such a gas is generated, the electrolytic solution may be pushed out to the outside in accordance with the generation of the gas. Further, the gas permeates the resin of the metal / resin laminate film and corrodes the metal.

To solve these problems, it is conceivable to slowly and carefully inject the electrolyte and remove the air. Thereby, it is possible to suppress the splash of the electrolytic solution from adhering to the inner surface of the battery case as much as possible. However, there is a disadvantage that productivity is reduced because it takes time.

It is, therefore, an object of the present invention to provide a battery having good airtightness and a method for efficiently manufacturing such a battery.

[0009]

The present invention comprises a power generating element,
In a battery provided with a battery case accommodating a power generation element and an electrolytic solution therein, and an anti-foaming body having insulation and liquid permeability, the anti-foaming body is fixed to the power generating element using fixing means. It is characterized by. Further, the foam body is fixed to the surface of the power generation element opposite to the surface from which the current collecting lead is drawn out, and the foam body is made of a polyolefin net, nonwoven fabric or felt foam. It is characterized by being.

The present invention also provides a battery case having a bag shape and an airtight structure, and an oval wound type power generating element whose winding center axis is perpendicular to the opening surface of the bag-shaped unit cell case. It is characterized in that it is housed, and that the material of the bag-shaped unit cell case is a metal laminated resin film.

Further, the present invention is characterized in that the electrolytic solution is injected through a foam preventer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment of the present invention is applied to a non-aqueous electrolyte secondary battery using an elliptical wound-type power generating element and an electrolyte of which is an organic solvent containing a lithium salt. This will be described with reference to FIG.

FIG. 1 is a plan view showing a battery manufactured by the manufacturing method of the present invention. In FIG. 1, 1 is a non-aqueous electrolyte secondary battery, 2 is a battery case, 3 is a lead terminal, 4 is a power generating element, and 5 is a foam preventive. In this non-aqueous electrolyte secondary battery 1, a power generation element 4 composed of a positive electrode plate, a negative electrode plate, and a separator is housed in a battery case 2 formed by heat welding a metal laminated resin film together with an electrolytic solution. The power generation element 4 is connected to the lead terminal 3 and is provided with an anti-foaming body 5 having insulation and liquid permeability.

FIG. 2 shows a cross section XX of the battery case 2.
As shown in a detailed cross section in FIG. 2, it is formed of a three-layer metal laminated resin film of a surface protective layer 21, a metal barrier layer 22, and a heat welding layer 23. As shown in FIG. 2, the lead terminal 3 is configured by bonding an adhesive layer 32 to a metal conductor 31 and providing an electrolyte barrier layer 33 outside the adhesive layer 32.

The battery 1 according to the present invention is manufactured by a method as shown in FIG. In FIG. 3, reference numerals 2 to 5 indicate the same components as in FIG. 1, and reference numeral 6 denotes an opening of the battery case 2.

First, the power generating element 4 is fixed so that the lead terminals 3 face downward (a), and an anti-foaming body 5 is installed at the upper end on the opposite side so as to cover the entire end, and is fixed with an adhesive ( b). Next, these were wrapped with a metal laminated resin film to be the battery case 2 so that only the lead terminals 3 were exposed, and the periphery of the metal laminated resin film was sealed by heat welding (c). However, the opening 6 was provided on the foam-proof body 5 side. Subsequently, the electrolyte was poured onto the foam preventive body 5 through the opening 6 (d). Then, after the electrolyte solution is absorbed by the foam preventive body 5, it permeates into the separator between the positive electrode plate and the negative electrode plate. Then, air in the battery case 2 was removed by a vacuum pump (e). Finally, the opening 6 was sealed by heat welding to obtain a battery (f).

The shape of the power generating element used in the present invention is not limited to an elliptical wound type in cross section, but may be a circular wound type, a non-circular wound type in cross section, or a flat plate-shaped electrode plate. A power generating element having any shape can be used, such as a stack type in which the sheet-shaped electrode plate is folded and a type in which the sheet-shaped electrode plate is folded and stacked through a separator.

In the case of an elliptical wound type power generating element, a sheet-like positive electrode plate and a negative electrode plate are wound around a winding central axis via a separator. Therefore, the elliptical wound-type power generating element has two side wall portions parallel to the winding center axis, a plane perpendicular to the winding center axis and a lead, and a lead perpendicular to the winding center axis. It has a flat surface.

When the shape of the power generating element is a stack type in which flat electrode plates are stacked via a separator or a type in which a sheet-shaped electrode plate is folded and stacked via a separator, the outer shape of the power generating element is a substantially rectangular parallelepiped. The lead terminals are taken out from one surface of the rectangular parallelepiped.

The present invention is characterized in that the anti-foaming body is fixed to the surface of the power generating element opposite to the surface from which the current collecting lead is drawn out. Here, "the surface on the opposite side to the surface from which the current collecting lead of the power generation element is drawn out" means, in the case of an elliptical winding type power generation element, the lead is not taken out perpendicular to the winding center axis. In the case of a power generating element having a substantially rectangular parallelepiped outer shape in which flat electrode plates are stacked via a separator, it means a flat surface from which no lead is taken out, which is opposite to the plane from which the lead is taken out.

Further, in the present invention, a bag-shaped unit cell case having an airtight structure can be used, and a metal laminated resin film is preferably used as a material of the bag-shaped unit cell case.

In the present invention, when the elliptical wound type power generating element is stored in the bag-shaped unit cell case, the winding center axis of the elliptical wound type power generating element is set at the opening surface of the bag-shaped unit cell case. Preferably it is vertical. The vertical direction is
It does not only mean completely vertical, but also generally vertical.

Examples of the foam preventive include a net made of a polyolefin such as polypropylene and polyethylene;
There are nonwovens, felts or foams. As an adhesive,
Those conventionally used for adhesive tapes are preferable, and examples thereof include silicone-based, rubber-based, and acrylic-based adhesives. Examples of the battery case include a battery case made of a laminated film using at least one layer of metal. At this time, there is heat welding as a means for sealing the opening.

The electrolyte solvent used in the nonaqueous electrolyte secondary battery according to the present invention includes ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethyl Acetamide, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran,
A polar solvent such as 2-methyltetrahydrofuran, dioxolan, methyl acetate, or a mixture thereof may be used.

The lithium salt dissolved in the organic solvent includes LiPF6, LiClO4, LiBF4, LiAs
F6, LiCF3CO2, LiCF3SO3, LiN
(SO2CF3) 2, LiN (SO2CF2CF3)
2, LiN (COCF3) 2 and LiN (COCF2)
A salt such as CF3) 2 or a mixture thereof may be used.

The separator of the non-aqueous electrolyte secondary battery according to the present invention may be a material obtained by impregnating an electrolytic solution in a microporous insulating polyethylene film, a solid polymer electrolyte, or a solid polymer electrolyte. A gel electrolyte or the like may be used. Further, an insulating microporous film and a solid polymer electrolyte may be used in combination. Further, when a porous solid polymer electrolyte membrane is used as the solid polymer electrolyte, the electrolyte contained in the polymer and the electrolyte contained in the pores may be different.

Further, as a compound capable of inserting and extracting lithium as a cathode material, an inorganic compound is represented by a composition formula L
ixMO2 or LiyM2O4 (where M is a transition metal, 0 ≦ x ≦ 1, 0 ≦ y ≦ 2), a composite oxide, an oxide having tunnel-like vacancies, or a metal chalcogenide having a layered structure is used. be able to. Specific examples thereof include LiCoO2, LiNiO2, and LiMn2O.
4, Li2Mn2O4, MnO2, FeO2, V2O
5, V6O13, TiO2, TiS2 and the like.
Examples of the organic compound include a conductive polymer such as polyaniline. Further, the above-mentioned various active materials may be mixed and used regardless of an inorganic compound or an organic compound.

Further, as a compound as a negative electrode material, A
Alloys of lithium with l, Si, Pb, Sn, Zn, Cd, etc., transition metal oxides such as LiFe2O3, WO2, MoO2, carbonaceous materials such as graphite, carbon, Li5
Lithium nitride such as (Li3N) or metallic lithium foil, or a mixture thereof may be used.

[0029]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a plan view of a battery manufactured by the manufacturing method of this embodiment.

The positive electrode plate is a current collector in which a lithium-cobalt composite oxide is held as an active material. The current collector is an aluminum foil having a thickness of 20 μm. The positive electrode plate is
8 parts of polyvinylidene fluoride as a binder and 5 parts of acetylene black as a conductive agent were mixed together with 87 parts of an active material, and N-methylpyrrolidone was added as appropriate to prepare a paste. It was manufactured by applying and drying on both sides.

As the current collector of the negative electrode plate, a copper foil having a thickness of 14 μm was used. The negative electrode plate was prepared by mixing 92 parts of graphite (graphite) as a host substance and 8 parts of polyvinylidene fluoride as a binder on both sides of the current collector, and adding N-methylpyrrolidone as appropriate to prepare a paste. It was manufactured by coating and drying.

The separator is a polyethylene microporous membrane. The electrolyte was ethylene carbonate: diethyl carbonate = 1: 1 containing 1 mol / l of LiPF _6.
(Volume ratio).

Each of the dimensions is such that the thickness of the positive electrode plate is 180 μm.
m, width 49 mm, separator thickness 25 μm, width 53
mm, the negative electrode plate has a thickness of 170 μm and a width of 51 mm. .

The battery case 2 has a 12 μm PET layer 21 for surface protection on the outermost layer, and a 9 μm aluminum foil 22 as a barrier layer thereunder, as shown in detail in FIG. Adhesive. Further, it is made of a laminate film having a 100 μm acid-modified polyethylene layer 23 as a heat welding layer thereunder. Here, the acid-modified polyethylene layer serving as the heat welding layer had a softening point of 100 ° C.

Further, as shown in FIG.
Metal conductor 3 of １００100 μm copper, aluminum, nickel, etc.
1. 50 μm acid-modified PE layer 32 serving as an adhesive layer with metal
And a 70 μm Eval resin (Kuraray ethylene-vinyl alcohol copolymer resin) layer 33 is provided as an electrolyte barrier layer on the outside thereof. When these are overlapped and adhered as shown in the figure, good airtightness can be obtained. The lead terminal 3 is connected to the electrode plate inside the electrode group 4 and protrudes from the end of the electrode group 4 in the winding axis direction. In addition, aluminum was used for the positive electrode lead terminal material and nickel was used for the negative electrode lead terminal material.

The foam preventive body 5 is a long-fiber non-woven fabric (made by Asahi Kasei) made of polypropylene and has a thickness of 0.23 mm.
The tear strength is 0.40 kg in both the vertical and horizontal directions,
The basis weight is 22 g / m ² . The foam preventive body 5 is fixed to an end of the electrode group 4 opposite to the lead terminal 3 with an adhesive so as to cover the entire end. The anti-foaming body 5 may be merely applied to the end of the electrode group 4, but if the battery case 2 is fixed as in the case of the battery 1, even if the battery case 2 is not completely sealed, the electrolytic solution will Can be prevented from flowing out. Further, in the battery 1, the lead terminal 3 and the foam preventive body 5 are provided on different sides with the electrode group 4 interposed therebetween, but may be provided on the same side.

This battery 1 was manufactured by a method as shown in FIG.

First, the electrode group 4 was fixed so that the lead terminals 3 face down (a), and a foam-proof body 5 was installed at the upper end on the opposite side so as to cover the entire end, and was fixed with an adhesive ( b).
Next, these were wrapped with a laminate film to be the battery case 2 so that only the lead terminals 3 were exposed, and the periphery of the laminate film was sealed by heat welding (c). However, the opening 6 was provided on the foam-proof body 5 side. Subsequently, an electrolytic solution was poured from the opening 6 onto the foam preventive body 5 (d). Then
After the electrolytic solution is absorbed by the foam preventive body 5, the electrolytic solution permeates into the separator between the positive electrode plate and the negative electrode plate. Then, air in the battery case 2 was removed by a vacuum pump (e). Finally,
The opening 6 is sealed by heat welding to have a design capacity of 500 mAh.
Was obtained (f).

In this embodiment, since the electrolyte is injected through the foam preventive body 5 when the electrolyte is injected, the electrolyte does not hit the electrode group 4 and bounce off, so that the electrolyte adheres to the vicinity of the opening 6 on the inner surface of the battery case 2. Never do. Further, even if bubbles are ruptured in the electrolytic solution when removing air, the upper end of the electrode group 4 is covered with the foam preventive member 5, so that no splash is scattered outside the electrode group 4. Further, since the current collecting lead side is sealed before injecting the electrolytic solution, the battery 1 manufactured according to the present embodiment has excellent airtightness.

The battery 1 according to the manufacturing method of this example was subjected to the following tests.

First, 10 batteries 1 according to the present embodiment were prepared, and as a comparative example, the battery 1 was manufactured under the same conditions as in the present embodiment except that the electrolyte was injected from the current collecting lead side without using the foam preventive body 5. The prepared batteries were also prepared for 10 cells. Next, each battery was charged at a constant current of 500 mA, and then charged at a constant voltage of 4.10 V (3 hours in total), and 2.7 at a constant current of 500 mA.
The capacity of the battery when discharged to 5 V (capacity before the test) was measured. Then, after storing for 30 days under the conditions of 60 ° C. and 90% RH, the battery was discharged again under the same conditions and the capacity (remaining capacity) was measured. In addition, recharge each battery under the same conditions as above.
After the re-discharge, the capacity (recovery capacity) was measured. In addition, it was observed whether or not the aluminum of the laminate film was corroded, and whether or not the electrolytic solution flowed out.

Table 1 shows the results. In the table, * indicates that the battery was found to be corroded by aluminum, and ** indicates that the battery was found to have leaked out of the electrolyte in addition to the corrosion of aluminum. The values of the remaining capacity and the recovery capacity are shown as percentages (%) with respect to the capacity before the test.

[0044]

[Table 1]

As can be seen from Table 1, the battery 1 of this example
The comparative example tended to show lower values in the remaining capacity and the recovery capacity than in the comparative example. This is presumably because in the battery of the comparative example, the electrolysis reaction occurred due to moisture in the air that entered from the outside. In the comparative example, corrosion of aluminum was observed in all the batteries, and out of the eight batteries, outflow of the electrolyte from the current collecting lead was also observed. It can be said that.

On the other hand, in the battery 1 of this example, neither outflow of the electrolytic solution nor corrosion of the aluminum was observed.
From the above, it was clarified that the battery 1 manufactured according to the present example is more airtight than the conventional battery.

[0047]

According to the present invention, a battery having good airtightness can be efficiently manufactured.

In the manufacturing method of the present invention, an insulating and liquid-permeable foam preventer is provided, and an electrolytic solution is injected through the foamer. Therefore, the electrolyte is once absorbed by the foam preventive body and then injected into the gap between the power generating elements. Therefore, since the electrolyte does not directly hit the power generating elements such as the positive and negative electrodes, it does not bounce. In addition, when air is removed, even if air bubbles rupture in the electrolytic solution to cause splashing, the foam preventer functions as a lid and suppresses scattering. Furthermore, by fixing and injecting liquid on the side opposite to the surface from which the current collecting lead was drawn out,
Adhesion of the electrolyte to the leads can also be prevented. Therefore, according to the manufacturing method of the present invention, a droplet of the electrolytic solution does not adhere to a portion where the inner surface of the battery case adheres, and thus a battery having good airtightness can be obtained.

In the battery manufactured according to the present invention, even if the electrolyte is a non-aqueous electrolyte containing a lithium salt,
It does not cause a decrease in battery capacity, outflow of electrolyte, or corrosion of metal. Furthermore, according to the manufacturing method of the present invention, since it is not necessary to slowly and carefully perform the injection of the electrolytic solution and the removal of the air, the manufacturing can be performed efficiently. In addition, by attaching an anti-foaming body to the power generating element on the opposite side of the surface from which the current collecting lead was drawn out, handling in the process, adhesion of the electrolytic solution to the lead when the electrolytic solution was injected, and removal of air Since no positional displacement occurs at the time, the defect rate can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a battery manufactured according to the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a diagram illustrating a manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery 2 Battery case 3 Lead terminal 4 Power generation element 5 Foam preventive body 6 Opening 21 Surface protection layer 22 Metal barrier layer 23 Heat welding layer 31 Metal conductor 32 Adhesive layer 33 Barrier layer

Continued on the front page F term (reference) 5H011 AA09 CC02 CC06 CC10 5H023 AA03 BB00 CC27 5H029 AJ14 AK03 AL06 AL12 AM03 AM07 BJ02 BJ14 CJ13 DJ13 DJ15 EJ01 EJ12

Claims (6)

[Claims] 1. A battery comprising: a power generating element; a battery case for housing the power generating element and an electrolytic solution therein; and a foam preventive having insulation and liquid permeability, wherein the foam preventive uses a fixing means. And a battery fixed to the power generating element. 2. The battery according to claim 1, wherein the anti-foaming body is fixed to a surface of the power generating element opposite to a surface from which the current collecting lead is drawn. 3. The battery according to claim 1, wherein the foam preventer is a net, a nonwoven fabric, or a felt foam made of polyolefin. 4. The battery case has a bag shape and has an airtight structure, and an oval wound type power generating element is housed such that its winding center axis is perpendicular to the opening surface of the bag-shaped unit cell case. The non-aqueous electrolyte secondary battery according to claim 1, wherein: 5. The non-aqueous electrolyte battery according to claim 1, wherein the material of the bag-shaped unit cell case is a metal laminated resin film. 6. The method for producing a battery according to claim 1, wherein the electrolyte is injected through a foam preventer.