JP3576358B2 - Polymer electrolyte battery - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polymer electrolyte secondary battery that is not only compact, lightweight and thin, but also has a high capacity.
[0002]
[Prior art]
For example, when making electronic devices such as mobile phones and portable notebook personal computers cordless, secondary batteries used as drive power sources must not only have high performance, small size, light weight and thinness, but also high capacity. ing. As such secondary batteries, lead-acid batteries, nickel-cadmium secondary batteries, nickel-metal hydride secondary batteries, and lithium-ion secondary batteries are generally used. There is interest in electrolyte batteries.
[0003]
In other words, the positive electrode layer, the polymer electrolyte layer, and the negative electrode layer are superimposed, the battery element is integrally formed into a sheet shape by heat and pressure bonding, and each electrode terminal is led out while being sealed in a liquid-tight manner with an exterior film. Are being developed (for example, US Pat. No. 5,296,318). Here, the positive electrode layer contains a carbonaceous material (for example, polyaniline or polyacene) or a metal oxide that absorbs and releases lithium ions, and the negative electrode layer contains lithium metal containing an active material capable of absorbing and releasing lithium ions. Carbonaceous and lithium alloy based. In addition, the positive electrode layer and the negative electrode layer appropriately contain an electrolyte-retaining polymer for imparting flexibility and the like, and have a current collector.
[0004]
FIG. 3A is a perspective view of a main part configuration of a conventional polymer electrolyte battery, and FIG. 3B is a cross-sectional view of a main part configuration of a conventional polymer electrolyte battery. In FIGS. 3 (a) and 3 (b), reference numeral 1 denotes a polymer-electrolyte system (for example, a polymer such as a hexafluoropropylene-vinylidene fluoride copolymer) and an ethylene carbonate solution such as a lithium salt, which function as a separator. , A nonaqueous electrolyte solution), 2 is formed by stacking a positive electrode layer containing an active material such as a metal oxide that occludes and releases lithium ions, a nonaqueous electrolyte solution, and an electrolyte-retaining polymer on a current collector. Positive electrode, 3 is a negative electrode formed by laminating a negative electrode layer containing an active material for absorbing and releasing lithium ions, a non-aqueous electrolyte and an electrolyte-retaining polymer on a current collector, and 4, 5 are back surfaces of the positive electrode 2 and the negative electrode 3 This is an exterior / sealing resin film (sheet) that covers and protects the side. In the drawing, 6a and 6b are lead terminals electrically connected to the current collectors of the positive electrode 2 and the negative electrode 3.
[0005]
[Problems to be solved by the invention]
However, the configuration of the polymer electrolyte battery has the following disadvantages. In other words, although high performance, small size, light weight, thinness, etc. can be achieved by using a sheet-shaped battery, there is a problem that a large battery capacity cannot be obtained in proportion to a planar size and shape.
[0006]
More specifically, the resin films (sheets) 4 and 5 for covering and sealing the rear and side surfaces of the positive electrode 2 and the negative electrode 3 and sealing them in a liquid-tight or air-tight manner generally have a peripheral portion. The heat welding / sealing area A is required, which reduces the effective functional area of the polymer electrolyte battery. For example, in the case of a thin polymer electrolyte battery having a size of 30 × 60 mm square, the heat-sealing / sealing area “a” of the peripheral portion is set to about 5 to 10 mm, and the area ratio of the heat-sealing / sealing area “a” As a result, the high capacity of the thin polymer electrolyte battery is impaired.
[0007]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a small, lightweight, thin, and high-capacity polymer electrolyte battery.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 provides a solid polymer electrolyte having an electrolyte retention function as a separator, a positive electrode containing an active material capable of inserting and extracting lithium ions, and a negative electrode containing an active material capable of inserting and extracting lithium ions. In a polymer electrolyte battery having a plate-shaped electrode element formed by laminating, and an exterior / sealing resin layer for covering and protecting the electrode element in a liquid-tight manner, the exterior / sealing resin layer is formed of a resin film piece. and sealing the folding type along a side edge portion of a pair of opposing the end face of the electrode elements to form a tubular body, sealed in a folding-type folding the opening end side of the cylindrical body, wherein A lead terminal electrically connected to each of the positive electrode and the negative electrode of the electrode element is led out to the outside from the other end of the opening, and the other end of the opening is folded and sealed in a folding type. Polymer characterized by the following: It is the solution electrolyte battery.
[0009]
That is, the polymer electrolyte battery of the present invention is, for example, (1) a polymer-electrolyte system (for example, a polymer such as hexafluoropropylene-vinylidene fluoride copolymer and the like) capable of functioning as a separator having a thickness of about 90 μm. (2) a positive electrode layer containing an active material such as a metal oxide, a non-aqueous electrolyte, and an electrolyte-retaining polymer laminated on a current collector; A positive electrode having a thickness of about 150 μm; (3) a negative electrode having a thickness of about 130 μm formed by laminating a negative electrode layer containing an active material for absorbing and releasing lithium ions, a non-aqueous electrolyte and an electrolyte-retaining polymer on a current collector; {Circle around (4)} A port having a thickness of about 25 μm for liquid-tightly covering and protecting the outer surface (rear surface) and side surfaces of the positive electrode and the negative electrode which are superposed via the polymer electrolyte system. It is composed of an imide-based resin sealing layer.
[0010]
Although the basic configuration is the same as that of the conventional case, in the present invention, the resin layer for exterior and sealing is formed by folding at least at a pair of opposed side surfaces along the end surface of the electrode element. This is characterized in that the sealing region portion is reduced planarly, and the area occupied by the battery element portion is relatively increased planarly.
[0011]
Here, examples of the active material of the positive electrode include lithium manganese composite oxide, manganese dioxide, lithium-containing cobalt oxide, lithium-containing nickel cobalt oxide, lithium-containing amorphous vanadium pentoxide, chalcogen compound, and the like. Examples of the negative electrode active material include fired products of bisphenol resin, polyacrylonitrile, cellulose, and the like, and fired products of coke and pitch. These are natural or artificial graphite, carbon black, acetylene black, ketjen black, nickel powder, and the like. , Nickel powder or the like.
[0012]
Further, the electrolyte system may be used in a non-aqueous solvent such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate, for example, lithium perchlorate, lithium hexafluorophosphate, lithium borotetrafluoride, Examples thereof include those in which lithium arsenide hexafluoride, lithium trifluoromethanesulfonate, and the like are dissolved at about 0.2 to 2 mol / l. Examples of the current collector include aluminum foil, aluminum mesh, aluminum band metal, and aluminum punch metal. Examples of the current collector for the negative electrode include copper foil, copper mesh, and copper band metal. And copper punch metal.
[0013]
In the present invention, examples of the sealing resin layer that covers and protects the power generation element in a liquid-tight manner include a polyimide resin film, a polyester resin film, and an aramid resin film having a thickness of about 10 to 150 μm. Then, for example, the film cut into a square is formed into a tubular or bottomed tubular shape such as a rectangular, circular, or elliptical cross section by a welding / welding method using laser beam irradiation, and the power generating element is inserted into the tubular body. After positioning and mounting, the exterior end is sealed by folding the open end while leading out the electrode terminals and joining the folded portion with an adhesive or the like. The cylindrical body can be formed by folding a cut film.
[0014]
According to the first aspect of the present invention, the ratio of the joint portion of the exterior sealing occupying a plane can be reduced, and in the case of the same external dimensions, the proportion of the battery element region can be increased in a planar manner by the reduced joint portion. It is possible to increase the battery capacity at least by the planar enlarged area of the battery element area. That is, the polymer electrolyte battery can easily achieve not only high performance, small size, light weight and thinness but also high capacity.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment will be described below with reference to FIGS. 1 (a) and 1 (b) and FIGS. 2 (a) and 2 (b).
[0016]
FIG. 1A is a perspective view illustrating a schematic configuration of a polymer electrolyte battery according to a first embodiment, and FIG. 1B is a cross-sectional view taken along line BB of FIG. 1A. 1A and 1B, reference numeral 7 denotes a polymer electrolyte battery.
[0017]
Here, the polymer electrolyte battery 7 includes an electrolyte-holding polymer-electrolyte system 8 that functions as a separator, an active material such as a metal oxide that absorbs and releases lithium ions, a nonaqueous electrolyte, and an electrolyte-holding polymer. A positive electrode 9 formed by laminating a positive electrode layer on a current collector, and a negative electrode 10 formed by laminating a negative electrode layer containing an active material that occludes and releases lithium ions, a non-aqueous electrolyte solution, and an electrolyte-retaining polymer on a current collector. A battery element 7 'formed by lamination, and a resin layer (film or sheet) 11 for exterior and sealing for covering and protecting the front and back and side surfaces of the battery element 7'.
[0018]
The exterior / seal resin layer 11 is protectively coated as follows. That is, a pair of opposite edge portions of a resin film piece cut into a square is overlapped 11a and welded by laser beam irradiation to form a cylindrical body 11 'having a rectangular cross section. Then, as shown in perspective in FIG. 2 (a), one open end side of the cylindrical body 11 'is folded, and as shown in side view on the surface (b), the tube is folded and welded by laser beam irradiation or the like. , Into a bottomed tubular body.
[0019]
Next, the battery element 7 'is inserted, positioned, and mounted in the bottomed cylindrical body, and lead-out terminals 12a, 12b electrically connected to the current collectors of the positive electrode 9 and the negative electrode 10 are led out. Then, after the other end of the opening of the bottomed cylindrical body is folded and folded, the folded portions are joined to each other by an adhesive or the like.
[0020]
A configuration in which the battery element 7 'is externally protected by a sealing resin layer 11, for example, in the case of a polymer electrolyte battery having an external size of 48 × 34 × 86 mm, as compared with a conventional configuration having the same external size (see FIG. 3). The battery capacity was improved by about 8%. That is, it was confirmed that not only high performance, small size, light weight, and thinning were performed, but also the polymer electrolyte battery functioned as a high capacity polymer electrolyte battery.
[0021]
In the above description, a configuration in which a resin film piece cut into a square is used as a material to form a tubular body 11 ′ having a rectangular cross section, and further a tubular body with a bottom to protect and cover the battery element 7 ′ has been described. It may be performed with a bottomed cylindrical body of a thin film formed by injection molding, etc., or it may be liquid-tightly protected / covered and sealed by folding / folding not only on a pair of opposing sides but also on the entire side. Similarly, the capacity can be increased.
[0022]
It should be noted that the present invention is not limited to the above examples, and various modifications can be made without departing from the spirit of the invention. That is, the constituent material, thickness and shape of the polymer electrolyte battery element, and the structure, material and shape of the resin layer for covering and protecting the battery element for exterior and sealing are not particularly limited.
[0023]
【The invention's effect】
According to the first aspect of the present invention, the space required for sealing and joining the resin film for exterior and sealing is reduced, so that downsizing can be easily achieved. Here, the improvement of the space efficiency of the sealing / joining portion of the resin film for the exterior / seal can be utilized as an area for the battery element, so that a polymer electrolyte battery having a large battery capacity can be provided with the same external dimensions. Is done. In other words, it is possible to provide a battery having characteristics required as a drive power source for cordless electronic devices, in other words, high performance, small size, light weight, thinness, and high capacity.
[Brief description of the drawings]
FIG. 1 shows a schematic configuration of a polymer electrolyte battery according to an example, in which (a) is a perspective view, and (b) is a cross-sectional view taken along line BB of (a).
FIG. 2A is an enlarged perspective view schematically showing a folded state of an open end of a cylindrical body forming a resin layer for exterior and sealing of a polymer electrolyte battery of an example, and FIG. 2B is a folded state. The side view which shows typically.
FIG. 3 shows a schematic configuration example of a conventional polymer electrolyte battery, wherein (a) is a perspective view, and (b) is a cross-sectional view taken along line AA of (a).
[Explanation of symbols]
1,8 ... Polymer-electrolyte system 2,9 ... Positive electrode 3,10 ... Negative electrode 4,5,11 ... Outer sealing resin layer (film, sheet)
6a, 6b, 12a, 12b Lead-out terminal 7 Polymer electrolyte battery 11a Lamination of film 11b Film cylindrical body

Claims (1)

A plate formed by stacking an electrolyte-retaining solid polymer electrolyte serving as a separator, a positive electrode containing an active material capable of absorbing and releasing lithium ions, and a negative electrode containing an active material capable of absorbing and releasing lithium ions. Electrode element, a polymer electrolyte battery having a resin layer for exterior and sealing to cover and protect the electrode element in a liquid-tight manner,
The outer seal resin layer along the side edge portions of a pair of opposed resin film piece on the end face of the electrode elements by sealing the folding-type to form a cylindrical body, the opening of the cylindrical body One end side is folded and sealed in a folding type, and lead terminals electrically connected to the positive electrode and the negative electrode of the electrode element are led out to the outside from the other end of the opening, and the other end of the opening is opened. Characterized in that the polymer electrolyte battery is constructed by folding and sealing in a folding type .

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