JP4590042B2 - Battery and manufacturing method thereof - Google Patents

Description

【００４５】
表１に見られるように、本実施例の電池１よりも比較例の方が残存容量及び回復容量で低い値を示す傾向があった。これは、比較例の電池では外部より侵入した空気中の水分によって電気分解反応が起こったためと思われる。また、比較例では、全ての電池についてアルミニウムの腐蝕が認められ、そのうち８個の電池については集電リード部分から、電解液の流出も認められたが、これらについても外部より侵入した空気に起因していると言える。
【００４６】
それに対して、本実施例の電池１では、電解液の流出もアルミニウムの腐蝕も認められなかった。以上より、本実施例によって製造された電池１は、従来の電池より気密性に優れていることが明らかとなった。
【００４７】
【発明の効果】
本発明によると、気密性の良い電池を効率的に製造することができる。
【００４８】
本発明の製造方法では、絶縁性及び液透過性をもつ防泡体を設置し、これを介して電解液を注入する。そのため、電解液は、防泡体に一度吸収されてから、発電要素の間隙に注入される。よって、電解液が正・負極などの発電要素に直接当たることがないので、跳ね返ることがない。また、空気を除去する際に、電解液中で気泡が破裂して飛沫が生じても、防泡体が蓋として機能し、飛散するのを抑える。さらに、集電リードが引き出された面とは反対側に固着し注液することにより、リードへ電解液が付着することも防止できる。したがって、本発明の製造方法によると、電池ケース内面の接着する部分に電解液の飛沫が付着することがなく、よって気密性の良い電池を得ることができる。
【００４９】
また、本発明によって製造された電池では、電解液がリチウム塩を含む非水電解液であっても、電池容量の低下、電解液の流出、及び金属の腐食を招くことはない。さらに、本発明の製造方法では、電解液の注入及び空気の除去の際にゆっくりと注意深くする必要もないので、効率よく製造することができる。また、集電リードが引き出された面とは反対側の発電要素に予め防泡体を固着させることにより、工程でのハンドリングや、電解液注入時のリードへの電解液の付着、空気の除去時の位置ずれを起こさないので、不良率を低減することが可能である。
【図面の簡単な説明】
【図１】本発明により製造された電池の平面図。
【図２】図１のＸ−Ｘ断面図。
【図３】本発明の製造方法を説明する図。
【符号の説明】
１ 電池
２ 電池ケース
３ リード端子
４ 発電要素
５ 防泡体
６ 開口部
２１ 表面保護層
２２ 金属バリア層
２３ 熱溶着層
３１ 金属導体
３２ 接着層
３３ バリア層[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a battery and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, electronic devices such as portable radio telephones, portable personal computers, and portable video cameras have been developed, and various electronic devices have been miniaturized to the extent that they can be carried. Accordingly, a battery having a high energy density and a light weight has been adopted as a built-in battery. A typical battery that satisfies such a requirement is an active material such as lithium metal or a lithium alloy, or a lithium ion host material (where the host material refers to a material that can occlude and release lithium ions). This is a nonaqueous electrolyte secondary battery in which a lithium intercalation compound occluded in a certain carbon is used as a negative electrode material, and an aprotic organic solvent in which a lithium salt such as LiClO ₄ or LiPF ₆ is dissolved is used as an electrolyte.
[0003]
This non-aqueous electrolyte secondary battery has a negative electrode plate in which the above negative electrode material is held by a negative electrode current collector as a support, and reversibly electrochemically reacts with lithium ions like a lithium cobalt composite oxide. A positive electrode plate that holds the positive electrode active material to be supported on a positive electrode current collector, and a separator that holds the electrolyte and is interposed between the negative electrode plate and the positive electrode plate to prevent a short circuit between the two electrodes. These are housed in a battery case made of a metal / resin laminate film so as to maintain airtightness.
[0004]
A battery including a sealed battery case, a positive / negative electrode, and an electrolyte contained therein, including the nonaqueous electrolyte secondary battery, has been conventionally manufactured as follows. 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. And the periphery of a laminate film is adhere | attached. However, a partial opening is provided. Next, an electrolytic solution is injected between the positive electrode and the negative electrode from the opening. Subsequently, after the air in the battery case is removed from the opening with a vacuum pump, the opening is bonded to seal it.
[0005]
[Problems to be solved by the invention]
However, in the conventional battery manufacturing method, when the electrolytic solution is injected, the electrolytic solution hits the positive and negative electrodes and rebounds, and when air between the electrodes is removed, bubbles in the electrolytic solution burst. Therefore, the splash of electrolyte solution tends to adhere to the inner surface of the battery case. Therefore, if the opening is sealed after that, the electrolyte is sealed while adhering to the part to be bonded, and as a result, the airtightness is deteriorated although it is sealed. When the airtightness is poor, air enters from the outside, and when it is extremely bad, the electrolyte may flow out to the outside.
[0006]
In particular, in the non-aqueous electrolyte secondary battery described above, if the airtightness is poor, an electrolysis reaction occurs in the battery due to moisture contained in the air, and the capacity of the battery is reduced. Also, if it contains a lithium salt of LiPF ₆ or the like in the electrolytic solution, and water which may be a gas such as HF and reactions occur. When such a gas is generated, the electrolytic solution may be pushed out to the outside. Further, the metal permeates the resin of the metal / resin laminate film, and the metal corrodes.
[0007]
As a means for solving 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 electrolyte solution adhering to the battery case inner surface as much as possible. However, since it takes time, there is a drawback that productivity is lowered.
[0008]
Therefore, an object of the present invention is to provide an airtight battery and a method for efficiently manufacturing such a battery.
[0009]
[Means for Solving the Problems]
According to the present invention, in a battery including a power generation element and a battery case that houses the power generation element and an electrolyte therein , an antifoaming body having insulating properties and liquid permeability is disposed at an end of the power generation element. It is characterized by. Further, the battery case has an opening, and the foam preventer is disposed between the battery case opening and the power generation element. In addition, the antifoaming body is arranged on the surface opposite to the surface from which the current collecting lead of the power generation element is drawn out. In addition, the antifoaming body is fixed to the power generating element using a fixing means, and the antifoaming body is a net, a nonwoven fabric or a felt foam made of polyolefin.
[0010]
In the present invention, the battery case has a bag shape and has an airtight structure, and the oval winding type power generation element is accommodated such that the winding center axis thereof is perpendicular to the opening surface of the bag type single battery case. characterized in that there further characterized in that the material of the bag-like unit cell case is a metal laminated resin film.
[0011]
Furthermore, the manufacturing method of the present invention is a method of manufacturing a battery in which an electrolyte is injected from the opening of a battery case having an opening and a power generation element is housed therein, and then the opening is sealed. A foam-proof body having permeability is disposed in a battery case and between the opening and the power generation element, and an electrolyte is injected through the foam-proof body. It is characterized in that the current collecting lead of the power generating element is arranged on the surface opposite to the surface from which the power collecting lead is drawn out, and the foam preventer is fixed to the power generating element using fixing means. Further, the battery case is made of a metal laminated resin film.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The case where an embodiment of the present invention is applied to a nonaqueous electrolyte secondary battery in which an oval winding type power generation element is used and an electrolytic solution is an organic solvent containing a lithium salt will be described with reference to the drawings.
[0013]
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 generation element, and 5 is a foam preventer. 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 thermally welding a metal laminate resin film together with an electrolytic solution. A lead terminal 3 is connected to the power generation element 4 and a foam preventer 5 having insulating properties and liquid permeability is provided.
[0014]
An XX cross section of the battery case 2 is shown in FIG. As shown in detail in FIG. 2, it is made of a metal laminate resin film having a three-layer structure 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 obtained by bonding an adhesive layer 32 to a metal conductor 31 and providing an electrolyte solution barrier layer 33 on the outside thereof.
[0015]
The battery 1 according to the present invention is manufactured by a method as shown in FIG. In FIG. 3, symbols 2 to 5 are the same as those in FIG. 1, and 6 is an opening of the battery case 2.
[0016]
First, the power generation element 4 was fixed so that the lead terminal 3 faced downward (a), and the foam preventer 5 was installed at the upper end on the opposite side so as to cover the entire end and fixed with an adhesive (b). Next, these were wrapped with a metal laminate resin film to be the battery case 2 so that only the lead terminals 3 were exposed, and the periphery of the metal laminate resin film was sealed by thermal welding (c). However, an opening 6 was provided on the antifoam body 5 side. Subsequently, an electrolytic solution was poured onto the foam preventer 5 from the opening 6 (d). Then, after the electrolytic solution is absorbed by the antifoam body 5, it penetrates into the separator between the positive electrode plate and the negative electrode plate. And the air in the battery case 2 was removed by the vacuum pump (e). Finally, the opening 6 was sealed by heat welding to obtain a battery (f).
[0017]
The shape of the power generating element used in the present invention is not limited to the elliptical winding type in cross section, but the cross section is a circular winding type or non-circular winding type, or a plate type plate is laminated via a separator. A power generation element of any shape can be used, such as a stack mold that folds and a sheet-type electrode plate that is folded and stacked via a separator.
[0018]
In the case of an oval winding type power generation element, a sheet-like positive electrode plate and negative electrode plate are wound around a winding center axis via a separator. Therefore, the oval winding type power generation element has two side wall portions parallel to the winding center axis, a plane from which the lead is taken out perpendicular to the winding center axis, and a lead perpendicular to the winding center axis. Has a flat surface.
[0019]
In addition, when the shape of the power generation element is a stack type in which a flat plate plate is stacked via a separator or a type in which a sheet electrode plate is folded and stacked via a separator, the outer shape of the power generation element is a substantially rectangular parallelepiped. Lead terminals are taken out from one side.
[0020]
In the present invention, the foam preventer is fixed to a surface opposite to the surface from which the current collecting lead of the power generation element is drawn. Here, “the surface opposite to the surface from which the current collecting lead of the power generation element is drawn” means that in the case of an oval wound power generation element, the lead is perpendicular to the winding center axis and the lead is not taken out. In the case of a power generation element having a substantially rectangular parallelepiped outer shape in which flat plate plates are stacked via a separator, it means a plane in which a lead opposite to the plane from which the lead is taken out is not taken out.
[0021]
Further, in the present invention, a bag-shaped unit cell case having an airtight structure can be used, and it is preferable to use a metal laminated resin film as the material of the bag-shaped unit cell case.
[0022]
In the present invention, when the oval winding type power generation element is housed in the bag-shaped cell case, the oval winding type power generation element has its winding center axis perpendicular to the opening surface of the bag-shaped cell case. Preferably there is. Note that the vertical direction does not mean only complete vertical, but also generally means a vertical direction.
[0023]
Examples of the antifoaming body include nets, nonwoven fabrics, felts, and foams made of polyolefin such as polypropylene and polyethylene. As an adhesive, what was conventionally used for the adhesive tape is preferable, and there exist a silicone type, rubber type, and an acrylic adhesive. Examples of the battery case include a battery case made of a laminate film using at least one layer of metal. At this time, as a means for sealing the opening, there is thermal welding.
[0024]
Examples of the electrolyte solvent used in the nonaqueous electrolyte secondary battery according to the present invention include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide, 1 , 2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, methyl acetate and the like, or a mixture thereof may be used.
[0025]
Furthermore, as the lithium salt dissolved in an organic _{solvent, LiPF 6, LiClO 4, LiBF} 4, LiAsF 6, LiCF 3 CO 2, LiCF 3 SO 3, LiN (SO 2 CF 3) 2, LiN (SO 2 CF 2 CF ₃ ) ₂ , a salt such as LiN (COCF ₃ ) ₂ and LiN (COCF ₂ CF ₃ ) ₂ or a mixture thereof.
[0026]
In addition, as the separator of the nonaqueous electrolyte secondary battery according to the present invention, an insulating polyethylene microporous membrane impregnated with an electrolyte, a polymer solid electrolyte, or a polymer solid electrolyte containing an electrolyte A gel electrolyte or the like can also be used. Further, an insulating microporous membrane and a polymer solid electrolyte may be used in combination. Furthermore, when a porous polymer solid electrolyte membrane is used as the polymer solid electrolyte, the electrolyte solution contained in the polymer and the electrolyte solution contained in the pores may be different.
[0027]
Furthermore, as a compound capable of occluding and releasing lithium as a positive electrode material, an inorganic compound includes a composition formula Li _x MO ₂ or Li _y M ₂ O ₄ (where M is a transition metal, 0 ≦ x ≦ 1, 0 ≦ y A composite oxide, an oxide having tunnel-like vacancies, or a layered metal chalcogenide represented by ≦ 2) can be used. Specific examples thereof include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , Li ₂ Mn ₂ O ₄ , MnO ₂ , FeO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , and TiS ₂ . Examples of the organic compound include conductive polymers such as polyaniline. Furthermore, the above various active materials may be mixed and used regardless of whether they are inorganic compounds or organic compounds.
[0028]
Further, as a negative electrode material compound, Al, Si, Pb, Sn, Zn, Cd, etc. and lithium alloys, transition metal oxides such as LiFe ₂ O ₃ , WO ₂ , MoO ₂ , carbon such as graphite, carbon, etc. A material, lithium nitride such as Li ₅ (Li ₃ N) , or a metal lithium foil, or a mixture thereof may be used.
[0029]
【Example】
Embodiments of the present invention will be described with reference to the drawings.
[0030]
The top view of the battery manufactured by the manufacturing method of a present Example is shown in FIG.
[0031]
The positive electrode plate is obtained by holding a lithium cobalt composite oxide as an active material on a current collector. The current collector is an aluminum foil having a thickness of 20 μm. The positive electrode plate was prepared by mixing 8 parts of polyvinylidene fluoride as a binder and 5 parts of acetylene black as a conductive agent together with 87 parts of an active material, and appropriately adding N-methylpyrrolidone to prepare a paste. It was manufactured by applying and drying on both sides of the electrical material.
[0032]
The current collector for the negative electrode plate was a copper foil having a thickness of 14 μm. The negative electrode plate is prepared in a paste form by mixing 92 parts of graphite (graphite) as a host material and 8 parts of polyvinylidene fluoride as a binder on both sides of the current collector, and adding N-methylpyrrolidone as appropriate. It was manufactured by applying and drying the finished product.
[0033]
The separator is a polyethylene microporous membrane. The electrolytic solution is a mixed solution of ethylene carbonate: diethyl carbonate = 1: 1 (volume ratio) containing 1 mol / l of LiPF ₆ .
[0034]
The dimensions are as follows: the positive electrode plate is 180 μm thick and the width is 49 mm, the separator is 25 μm thick and the width is 53 mm, the negative electrode plate is 170 μm thick and the width is 51 mm. A power generation element is formed by winding an ellipse around it and making it a column.
[0035]
As shown in detail as a cross-sectional view in FIG. 2, the battery case 2 has a 12 μm PET layer 21 for surface protection as an outermost layer, and a 9 μm aluminum foil 22 is bonded as a barrier layer below with a urethane adhesive. is doing. Furthermore, it consists of a laminate film having a 100 μm acid-modified polyethylene layer 23 underneath as a heat-welded layer. Here, the acid-modified polyethylene layer, which is a heat-welded layer, has a softening point of 100 ° C.
[0036]
Further, as shown in FIG. 2, the lead terminal 3 has a 50 μm acid-modified PE layer 32 to be bonded to a metal adhered to a metal conductor 31 of 50 to 100 μm such as copper, aluminum, nickel, etc. A 70 μm Eval resin (Kuraray ethylene vinyl alcohol copolymer resin) layer 33 is provided as a barrier layer. When these are stacked 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.
[0037]
The antifoam body 5 is a long-fiber nonwoven fabric made of polypropylene (manufactured by Asahi Kasei). The thickness is 0.23 mm, the tear strength is 0.40 kg in both the longitudinal and lateral directions, and the basis weight is 22 g / m ² . The foam preventer 5 is fixed to the end of the electrode group 4 opposite to the lead terminal 3 with an adhesive so as to cover the entire end. The foam preventer 5 may be applied only to the end of the electrode group 4, but when fixed like the battery 1, even if the battery case 2 is not completely sealed, the electrolyte solution is externally applied. Can be prevented from leaking. Moreover, in this battery 1, the lead terminal 3 and the foam preventer 5 are provided on different sides with the electrode group 4 therebetween, but may be provided on the same side.
[0038]
The battery 1 was manufactured by a method as shown in FIG.
[0039]
First, the electrode group 4 was fixed so that the lead terminals 3 face downward (a), and a foam preventer 5 was installed at the upper end on the opposite side so as to cover the entire end and 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 thermal welding (c). However, an opening 6 was provided on the antifoam body 5 side. Subsequently, an electrolytic solution was poured onto the foam preventer 5 from the opening 6 (d). Then, after the electrolytic solution is absorbed by the antifoam body 5, it penetrates into the separator between the positive electrode plate and the negative electrode plate. And the air in the battery case 2 was removed by the vacuum pump (e). Finally, the opening 6 was sealed by thermal welding to obtain a battery 1 having a design capacity of 500 mAh (f).
[0040]
In this embodiment, since the electrolyte solution is injected through the antifoam body 5 when injected, the electrolyte solution does not hit the electrode group 4 and rebounds, and therefore adheres to the vicinity of the opening 6 on the inner surface of the battery case 2. Absent. Even if air bubbles are ruptured in the electrolytic solution when air is removed, the upper end of the electrode group 4 is covered with the antifoam body 5, so that splashes are not scattered outside the electrode group 4. Furthermore, since the current collecting lead side is sealed before injecting the electrolytic solution, the battery 1 manufactured according to this example is excellent in airtightness.
[0041]
The battery 1 according to the production method of this example was subjected to the following test.
[0042]
First, 10 cells of the battery 1 according to this example were prepared, and as a comparative example, a battery manufactured under the same conditions as in this example except that the electrolyte solution was injected from the current collecting lead side without using the antifoam body 5. 10 cells were also prepared. Next, after charging each battery at a constant current of 500 mA, charging at a constant voltage of 4.10 V (charging for a total of 3 hours), and discharging the battery to 2.75 V at a constant current of 500 mA (capacity before testing) It was measured. And 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. Furthermore, after each battery was recharged / redischarged under the same conditions as described above, the capacity (recovery capacity) was measured. Moreover, it was observed whether the aluminum of the laminate film was corroded and whether the electrolytic solution was not discharged to the outside.
[0043]
The results are shown in Table 1. In the table, * indicates a battery in which corrosion of aluminum was observed, and ** indicates a battery in which outflow of electrolyte was recognized in addition to corrosion of aluminum. Moreover, the remaining capacity and the recovery capacity are expressed as a percentage (%) with respect to the capacity before the test.
[0044]
[Table 1]

[0045]
As seen in Table 1, the comparative example tended to show lower values for the remaining capacity and the recovery capacity than the battery 1 of this example. This seems to be because in the battery of the comparative example, an electrolysis reaction occurred due to moisture in the air that entered from the outside. Further, in the comparative example, corrosion of aluminum was observed in all the batteries, and out of the eight batteries, outflow of the electrolyte solution was also recognized from the current collecting lead part. I can say that.
[0046]
On the other hand, in the battery 1 of this example, neither the outflow of the electrolytic solution nor the corrosion of aluminum was observed. From the above, it has been clarified that the battery 1 manufactured according to the present example is more airtight than the conventional battery.
[0047]
【The invention's effect】
According to the present invention, a battery with good airtightness can be efficiently manufactured.
[0048]
In the production method of the present invention, an antifoaming body having insulating properties and liquid permeability is installed, and an electrolytic solution is injected through this. Therefore, the electrolytic solution is once absorbed by the antifoam body and then injected into the gap between the power generation elements. Therefore, the electrolytic solution does not directly hit the power generation elements such as the positive electrode and the negative electrode, and therefore does not rebound. Moreover, when air is removed, even if bubbles burst in the electrolytic solution and splashes are generated, the antifoamer functions as a lid and suppresses scattering. Furthermore, by adhering and pouring the current collecting lead on the side opposite to the surface from which the current collecting lead is drawn, it is possible to prevent the electrolyte from adhering to the lead. Therefore, according to the manufacturing method of the present invention, the splash of the electrolytic solution does not adhere to the portion where the inner surface of the battery case adheres, and thus a battery with good airtightness can be obtained.
[0049]
In the battery manufactured according to the present invention, even when the electrolyte is a non-aqueous electrolyte containing a lithium salt, the battery capacity is not reduced, the electrolyte flows out, and the metal is not corroded. Furthermore, in the manufacturing method of the present invention, it is not necessary to be careful carefully when injecting the electrolyte and removing the air, so that the manufacturing can be performed efficiently. In addition, by attaching a foam-proof body to the power generation element on the opposite side of the surface from which the current collector lead is drawn out, handling in the process, adhesion of electrolyte to the lead during electrolyte injection, removal of air It is possible to reduce the defect rate because no positional displacement occurs.
[Brief description of the drawings]
FIG. 1 is a plan view of a battery manufactured according to the present invention.
FIG. 2 is a cross-sectional view taken along line XX in FIG.
FIG. 3 is a view for explaining a production method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Battery 2 Battery case 3 Lead terminal 4 Power generation element 5 Antifoam body 6 Opening part 21 Surface protective layer 22 Metal barrier layer 23 Thermal welding layer 31 Metal conductor 32 Adhesive layer 33 Barrier layer

Claims (9)

In a battery comprising a power generation element and a battery case that houses the power generation element and an electrolyte therein,
A battery, wherein an antifoaming body having insulating properties and liquid permeability is disposed at an end of the power generating element . The battery according to claim 1, wherein the battery case has an opening, and the anti-foaming body is disposed between the battery case opening and the power generation element. 3. The battery according to claim 1, wherein the foam preventer is disposed on a surface opposite to a surface from which a current collecting lead of the power generation element is drawn. The battery according to any one of claims 1 to 3, wherein the foam preventer is fixed to the power generation element using a fixing means. The battery according to any one of claims 1 to 4, wherein a material of the battery case is a metal laminated resin film. In the battery manufacturing method for sealing the opening after injecting an electrolyte from the opening of the battery case having an opening and the power generation element housed therein,
A method for manufacturing a battery, comprising: placing a foam preventive body having insulation and liquid permeability between a battery case and between the opening and the power generation element; and injecting an electrolyte through the foam preventive body. . The method of manufacturing a battery according to claim 6, wherein the foam preventer is disposed on a surface opposite to a surface from which the current collecting lead of the power generation element is drawn. The method for manufacturing a battery according to claim 6 or 7, wherein the foam preventer is fixed to the power generation element using a fixing means. The battery manufacturing method according to claim 6, wherein a material of the battery case is a metal laminated resin film.

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