JP2000149885A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a lowering of a yield rate and reliability in a manufacturing process caused by a crack in a metal layer and to eliminate a lowering of space efficiency, by providing a resin layer processed by a stretching method on the upper layer and the lower layer of the metal layer, in a laminated sheet equipped with the metal layer and the resin layer. SOLUTION: Aluminum foil in particular or its alloy foil can be used for a metal in a laminated sheet equipped with a metal layer and a resin layer, and titan foil can be also used. The aluminum laminated sheet forming a battery container has a PET layer 20 of 12 μm manufactured by a biaxial stretching method, an aluminum layer 21 of 9 μm, a PET layer 22 of 12 μm manufactured by the biaxial method, a PE layer 23 of 15 μm, and a denatured PE layer 24 in this order from the upper layer. In this case, the battery container is formed by fusing the natured PE layers each other. In addition, the resin sheet processed by the biaxial stretching method on the upper metal layer and the lower metal layer is laminated onto the metal layer by a dry laminating method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a 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.

This non-aqueous electrolyte secondary battery has a negative electrode plate in which the above-mentioned negative electrode material is held on a negative electrode current collector as a support, and a reversible electrochemical reaction with lithium ions such as a lithium-cobalt composite oxide. The positive electrode plate, which holds the positive electrode active material that reacts on the positive electrode current collector that is the support, from the separator that holds the electrolytic solution and intervenes between the negative electrode plate and the positive electrode plate to prevent a short circuit between the two electrodes Has become.

[0004] In the case of a non-cylindrical battery, the positive electrode plate and the negative electrode plate are each formed into a thin sheet or foil and formed into a spiral shape and a non-circular cross-section through a separator. Stop the outermost circumference with tape.
(See Fig. 2) And the completed electrode body is stainless steel,
It is housed in a battery container made of nickel-plated iron or metal such as aluminum, and after connecting the terminal lead and terminal connected to the electrode plate and injecting the electrolytic solution, it is sealed and fixed with a lid plate. The battery is assembled.

[0005]

However, as described above, battery containers include those made of stainless steel, nickel-plated iron, and those made of aluminum or an alloy thereof, which have high airtightness and high mechanical strength. Although it is excellent, it is a great constraint on further weight reduction of batteries, application of new materials for battery containers, and design. In order to solve the problem, there has been proposed a method in which an electrode body is housed in a battery container formed of an aluminum laminate sheet.
In this method, an electrode body and an electrolytic solution are housed in a battery container made of an aluminum laminate sheet, and the container is welded (for example, heat fusion, ultrasonic wave, etc.) with a terminal lead connected to an electrode plate of the electrode body interposed therebetween. Hermetically sealed, the battery is manufactured. However, in order to make the battery thinner and lighter, when the laminate is welded in a very tight state with the electrode body or the like housed or placed, the portion sealed by heat welding and the end on the electrode body side Cracks occur in the aluminum located at the edge,
The moisture permeability of the laminate sheet is reduced, and the life of the battery is shortened. Then, gas is generated by the decomposition of the water entering from that portion, and the battery swells. In addition, there is a possibility that the electrolyte solution may leak. Further, the manufactured battery is housed in a hard case provided with external device connection terminals and the like, for example, a plastic case. Also at this time, in order to make the battery thinner and lighter, the hard case itself has to be reduced accordingly. The laminated sheet battery accommodated in the hard case having such a small volume has an excessively bent welded portion and is accommodated. Therefore, the same problem as described above occurs due to the tension caused by the bending. Therefore, the present invention has been made in order to solve the above problems, the purpose of the present invention, by the occurrence of cracks in the metal layer of the laminate sheet,
It is an object of the present invention to provide a battery that does not cause a decrease in the yield, battery reliability, and space efficiency during the manufacturing process.

[0006]

A battery according to a first aspect of the present invention is a battery in which a laminate sheet having a metal layer and a resin layer is stretched into an upper layer and a lower layer of a metal layer in a battery which is a component of a battery container. A battery comprising: A second invention is characterized in that the battery is a non-aqueous electrolyte secondary battery. By using a non-aqueous electrolyte secondary battery, a battery with extremely high capacity and high output can be provided. In the present invention, the metal of the laminate sheet including the metal layer and the resin layer is, in particular, an aluminum foil or an alloy foil thereof, and the others include a titanium foil. Also, the resin layer and the metal foil layer of the laminate sheet are not limited to one layer each,
Two or more layers may be used, and it is preferable that the thickness be thin in order to reduce the weight. However, needless to say, various thicknesses are possible in view of the function and characteristics of the battery. When the resin layer is a multilayer, each may be made of a different material, and the configuration is not limited to a resin layer, a metal layer, and a resin layer in that order. For example, a resin layer, a resin layer, a metal layer, a resin layer, and a resin layer, a metal layer, a resin layer, a metal layer, a resin layer, and the like are shown in this order. That is, in the laminate sheet according to the present invention, a resin layer, a metal layer,
It has a configuration of a resin layer, and means that the resin layers positioned above and below the metal layer have been subjected to stretching. However, even when the stretched resin layer, the ordinary resin layer, the metal layer, the ordinary resin layer, and the stretched resin layer are sequentially formed, when the ordinary resin layer is very thin, the present invention is substantially applied. Has the effect of Further, in the non-aqueous electrolyte secondary battery according to the present invention, as its configuration, a combination of a positive electrode, a negative electrode and a separator and a non-aqueous electrolyte, or a positive electrode, a negative electrode, an organic or inorganic solid electrolyte membrane as a separator, and It may be a combination with a non-aqueous electrolyte, or a combination with a positive electrode, a negative electrode, a separator, an organic or inorganic solid electrolyte, and a non-aqueous electrolyte, and is not particularly limited. Further, the separator means a known separator or an inorganic solid powder bound by an organic binder, and any known one can be used. It goes without saying that a known non-aqueous electrolyte can also be used. Further, an electrolyte membrane mainly composed of an organic material, an inorganic material, and a mixture thereof may be formed on the upper surface of the positive electrode mixture layer and / or the negative electrode mixture layer. The essential requirements for the electrolyte membrane are that it must be chemically and electrochemically stable in the battery and have high mechanical strength, and the electrolyte membrane is preferably made of a solid electrolyte. However, the electrolyte membrane does not need to consist entirely of a single component,
Also, it is not necessary that the whole be made of an electrolyte. For example, those in which the conductivity is improved by impregnating the solid electrolyte with an electrolytic solution, and those in which a known separator is impregnated with the electrolytic solution are also applicable. That is, the exchange of lithium ions at the interface between the electrolyte membrane and the electrode plate and in the electrolyte membrane is smoothly performed by the electrolyte. However, when the organic electrolyte is contained, the charging voltage cannot be increased beyond the decomposition voltage of the organic electrolyte, so that the range of selection of the active material to be used is limited. Therefore, more preferably, in order to improve the degree of freedom in material selection, an electrolyte membrane containing no organic electrolyte is preferred.

[0007] When organic solid materials such as polyethylene oxide, polyacrylonitrile, polyethylene glycol and modified products thereof are used as constituents of the solid electrolyte, they are lighter and more flexible than inorganic solid materials, and thus are wound. Sometimes hard to crack. On the other hand, when the component of the solid electrolyte is a lithium ion conductive inorganic solid material such as lithium lanthanum perovskite and lithium ion conductive glass, the solid electrolyte has heat resistance and thus has excellent reliability at high temperatures. In addition, when a mixture of an organic material and an inorganic material is used as a component of the electrolyte membrane, both of the advantages can be provided and the other can be compensated for. That is, even if the organic substance in the mixture is dissolved, the organic substance is retained by the inorganic substance and thus does not flow away. Even if the amount of the inorganic substance is large, the organic substance functions as a binder and does not break.
When the constituents of the electrolyte membrane are a mixture, if one component is an electrolyte, the other component is, for example, an inorganic material (inorganic filler) such as magnesium oxide, silicon oxide, or a calcium salt of silicon oxide, or a mixture of these inorganic materials. May be used as the non-electrolyte. The composition is, for example, 70 to 85% of an inorganic substance and 10 to 15% of an organic solid material.
% And others (such as a binder such as polyvinylidene fluoride). Further, an electrolyte salt or the like may or may not be used depending on the configuration.
In the present invention, the sheet includes a film.

[0008]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of a non-aqueous electrolyte secondary battery according to the present invention. In the nonaqueous electrolyte secondary battery 1 according to the present embodiment, an electrode body 12 (not shown in FIG. 1) composed of a positive electrode plate, a negative electrode plate, and a separator serving as a separator is provided together with a nonaqueous electrolytic solution (not shown). It is stored in the battery container 6. Reference numeral 5 denotes a positive terminal lead, and 5 'denotes a negative terminal lead. Reference numeral 31 denotes a weld margin of the terminal lead-out portion, and reference numeral 30 denotes a weld margin on the opposite side of the weld margin 31 of the terminal lead-out portion. The battery container 6 has an aluminum laminate sheet as a constituent element. FIG. 3 is an explanatory cross-sectional view of the aluminum laminate sheet constituting the battery container 6. As shown in the figure, a PET layer (20) manufactured by a biaxial stretching method of 12 μm, an aluminum layer (21) of 9 μm, and a P layer manufactured by a biaxial stretching method of 12 μm from the upper layer.
An ET layer (22), a 15 μm PE (polyethylene) layer (23), and a 50 μm modified PE layer (24) are provided. Here, the PET layer (20), the PET layer (22),
The PE layer (23) and the modified PE layer (24) are resin layers,
The aluminum layer (21) is a metal layer. In this case, the modified PE layers (24) are welded to each other to form a battery container. The lamination of the metal layer and the resin sheet in which the upper layer and the lower layer of the metal layer are stretched is performed by a dry lamination method.

The positive electrode plate is a current collector in which a lithium-cobalt composite oxide is held as an active material. As the current collector, an aluminum foil having a thickness of 20 μm was used. 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, appropriately adding N-methylpyrrolidone to prepare a paste, and then collecting the paste. It was manufactured by applying and drying both sides of an electric conductor material.

As a current collector of the negative electrode plate, a copper foil having a thickness of 14 μm was used. The negative electrode plate is prepared by mixing 86 parts of graphite (graphite) as a host substance and 14 parts of polyvinylidene fluoride as a binder, and applying a paste prepared on both surfaces of the current collector, followed by drying. Made. The separator as a separator is a polyethylene microporous membrane.
The electrolytic solution is a mixed solution containing 1 mol / l of LiPF ₆ and ethylene carbonate: diethyl carbonate = 1: 1 (volume ratio). The dimensions are as follows: the positive electrode plate has a thickness of 180 μm, the width is 62 mm, and the separator has a thickness of 25 μm.
m, width 67 mm, negative plate thickness 170 μm, width 64 m
m. Next, a rectangular aluminum lead terminal was welded to each of the positive electrode plate and the negative electrode plate, and a welded portion was reinforced by bonding a polyimide resin tape with an electrolyte-resistant urethane-based adhesive. Next, a positive electrode, a separator,
The negative electrode and the separator were superimposed in this order, and were wound around the rectangular core of polyethylene so that the long side was parallel to the winding axis of the electrode body to form an electrode body having a non-circular cross section. Then, the end portion of the electrode is affixed to a side wall portion of the electrode body parallel to the winding axis by applying a length corresponding to the electrode width (length of the electrode body parallel to the winding axis) with a winding tape made of polyimide. The main body was stopped and fixed. (See FIG. 2) Next, the electrode body 12 was placed on an aluminum laminate sheet, and the worship portion was heat-sealed so as to surround the electrode body 12.
(The welded portion is the weld margin 32.) Then, the laminate sheet on which the lead terminal was not formed was thermally fused. Next, each electrode and the separator are sufficiently wetted with the electrolytic solution,
An amount of free electrolyte solution outside the electrode group was injected under vacuum. Next, heat-fusion was similarly performed on the winding shaft surface side on which the lead terminals were provided. Therefore, only three locations are welded. As described above, the design capacity is 800 mAh, the length is 80 mm, the width is 35 mm, and the thickness is 4 m.
m batteries (A) according to the present invention were produced. Also,
With the same configuration and procedure, ten batteries (B), (C), and (D) of the present invention having a design capacity of 800 mAh, a length of 80 mm, a width of 35 mm, and a thickness of 4 mm were produced. However, the difference is that the structure of the aluminum laminate sheet which is a component of the battery container 6 is as follows. The structure of the aluminum laminate sheet of the battery (B) is, in order from the upper layer, a PET layer manufactured by a biaxial stretching method of 12 μm, an aluminum layer of 9 μm, a PP layer (drawn polypropylene) manufactured by a stretching method of 15 μm, and a 50 μm It is a modified PP layer. In this case, the modified PP layers are welded to each other to form a battery container. The structure of the aluminum laminate sheet of the battery (C) is, in order from the upper layer, a PET layer manufactured by a biaxial stretching method of 12 μm, an aluminum layer of 9 μm, a nylon layer (drawn nylon) manufactured by a stretching method of 12 μm, 50
It is a modified PE layer of μm. The structure of the aluminum laminate sheet of the battery (D) is as follows: a nylon layer (stretched nylon) manufactured by a stretching method of 12 μm from the upper layer;
m aluminum layer, PP layer (stretched polypropylene) manufactured by a stretching method of 12 μm, modified PE of 50 μm
Layers. The design capacity is 800 mAh, the length is 80 mm, and the width is 3 according to the same configuration and procedure as the battery (A).
Ten comparative batteries (E) having a size of 5 mm and a thickness of 4 mm were produced. However, the difference is that the structure of the aluminum laminate sheet which is a component of the battery container 6 is as follows. The structure of the aluminum laminated sheet of the battery (E) is a PET layer manufactured by a biaxial stretching method of 12 μm in order from the upper layer,
An aluminum layer of 9 μm and a modified PE layer of 70 μm were formed.

[Tests and Results] Using a laminate sheet (width 20 mm × length 50 mm), which is a component of the battery container 6 using these batteries A to E, the middle of the length direction was bent to 180 degrees. A series of operations of returning to the original state after bending (this operation is defined as one time), bending and returning to the original state were repeated, and the number of times when cracks occurred in aluminum as the metal layer was investigated. Table 1 shows the results.

[0012]

[Table 1]

Table 1 shows that the laminate sheet of the comparative battery (E) had cracks at the first bending. On the other hand, a battery (A) having a stretched resin layer as an upper layer and a lower layer of aluminum as a metal layer,
It was shown that the laminate sheets (B), (C), and (D) were much less likely to crack than the laminate sheet of Comparative Battery (E). Next, the battery (A)
To (E), using 10 pieces each, 800 mAh,
The battery was charged at a constant current and a constant voltage under the conditions of 4.1 V and 3 hours, and was brought into a fully charged state. Then, the welding margin portion 30 was bent in the terminal direction to be folded in two. 60 ° C, 90% R
It was left for 30 days in an environment of H. Then, the presence or absence of corrosion (visual) of the bent portion of aluminum, the swelling in the thickness direction of the battery, and the presence or absence of liquid leakage were confirmed. Table 2 shows the results.

[0014]

[Table 2]

Table 2 shows that the battery of the present invention did not corrode or leak the aluminum metal layer and hardly swelled as compared with the battery of the comparative example. Needless to say, the stretched resin sheet is not limited to the one used in the embodiment.

[0016]

According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery using a battery container made of a laminated sheet of metal and resin, which eliminates the yield during the manufacturing process and is easy to assemble. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a nonaqueous electrolyte secondary battery according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of an electrode body of the nonaqueous electrolyte secondary battery according to one embodiment.

FIG. 3 is an explanatory sectional view of an aluminum laminate sheet constituting the battery container according to one embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-aqueous electrolyte secondary battery 5 Positive electrode lead terminal 5 'Negative electrode lead terminal 6 Battery container 10 Fixing means 12 Electrode body 20 PET layer 22 PET layer 23 PE layer 24 Modified PE layer 21 Aluminum layer

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 4F100 AB01A AB10A AK01B AK01C AK42B AK42C BA03 BA06 BA10B BA10C BA13 EJ37B EJ37C EJ38B EJ38C GB41 JL02 5H011 AA03 AA09 CC10 DD13 EE04 FF04 GG09 H03 AM03 AJ03A03 AM07 AM16 BJ02 BJ14 CJ03 DJ02 EJ01 EJ11

Claims (2)

[Claims] 1. A battery in which a laminate sheet having a metal layer and a resin layer is a constituent element of a battery container, comprising a stretched resin layer as an upper layer and a lower layer of the metal layer. 2. The battery according to claim 1, wherein the battery is a non-aqueous electrolyte secondary battery.