JP3630510B2 - Conductive terminal and polymer sheet package battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conductive terminal installed on an electrode of a battery packaged with a polymer sheet packaging material, and a battery using the conductive terminal.
[0002]
[Prior art]
Currently, high energy density batteries have been developed as power sources for various portable devices such as personal computers, mobile phones, and video cameras. As this battery, a lithium ion secondary battery, a nickel metal hydride battery, a nickel cadmium battery, and the like that can be repeatedly charged and discharged are used. In particular, lithium ion secondary batteries are characterized by a high energy density, and since the batteries can be made smaller and lighter, active development is underway.
[0003]
Conventionally, a lithium ion secondary battery uses an electrolyte as an ion transfer medium between electrodes, and usually has a structure in which a laminate of electrodes and a porous separator is impregnated with an electrolyte. In such a battery using an electrolytic solution, a heavy metal material is used for the battery package in order to prevent liquid leakage.
On the other hand, a battery using a solid electrolyte as an ion transfer medium has substantially no liquid leakage compared to a battery using an ion transfer medium as a conventional electrolyte. Easiness of body formation, a high degree of freedom in battery configuration, simplification of package, and weight reduction are expected.
[0004]
A battery using a solid electrolyte is manufactured by processing a laminated body in which a sheet-like electrode and a solid electrolyte are laminated, or a laminated body in which a polymer solid electrolyte layer is applied and formed on the electrode surface and then processed into a predetermined shape. Can do. In addition, a method of forming each layer of electrode / polymer solid electrolyte / electrode by coating has also been proposed. Thus, it is expected that the manufacturing process is excellent in mass productivity because methods such as sheet lamination and coating can be adopted. In addition, since the liquid leakage that can occur in the conventional electrolyte-based battery does not occur substantially, the manufacturing process can be easily managed, and higher voltage is expected due to the serial connection lamination of the electrode / solid electrolyte / electrode laminate.
[0005]
The solid electrolyte battery is usually used by being packaged with a laminated polymer sheet in which a resin sheet and a metal sheet are laminated. In order to use this packaged battery, it is necessary to provide a current extraction terminal from the electrode inside the package to the outside of the package. Normally, the battery is configured with a structure in which the electrode terminal is sandwiched and fused by the sealing portion of the polymer sheet. Is done. However, this structure has a structure in which the electrode terminal portion protrudes from the package surface, which hinders downsizing of the battery. There has also been proposed a battery having a structure in which holes are provided in a part of the package and the current collector surface of the electrode stack is in close contact with the holes (US Pat. No. 5,478,668). However, batteries with these structures have problems such as leakage inside and outside the battery, disconnection of the electrode terminals during the process, poor conduction, and the like at the electrode terminal sealing portion of the package, thereby reducing the performance of the lithium secondary battery.
[0006]
Furthermore, when the battery is accidentally overcharged or when the electrode terminal is short-circuited in the charged state, heat may be generated inside the electrode and the safety of the battery may be impaired. In order to ensure safety in this case, a PTC element (Positive Temperature Coefficient element) is incorporated in the electrode terminal to give a function of preventing the conduction of the electrode at a high temperature. An attempt to use this PTC element also in a polymer package battery (US Pat. No. 5,478,668) has a problem of complicated connection processing to an electrode laminate.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a conductive terminal that is excellent in reliability, stability, and safety, and that enables downsizing of a battery, and a battery using the same.
[0008]
The inventors of the present invention have advanced the research of a solid battery packaging material and structure mainly using a solid electrolyte, and have completed the present invention.
That is, according to the present invention, in a battery in which an electrode laminate is packaged with a polymer sheet packaging material having an opening, the hole of the resin sheet having a hole in the central part from the inside is suddenly increased above a certain temperature. A conductive sheet filled with a mixture of conductive particles or conductive filler that increases electrical resistance and an insulating polymer , wherein the hole is smaller than the resin sheet and larger than the hole. It is fused or adhered with the resin sheet of the conductive terminal coated from both sides, and the conductive sheet constituting the conductive terminal is bonded to the electrode of the electrode laminate or the electrode current collector. The polymer sheet package battery is characterized.
[0009]
Hereinafter, the conductive terminal and battery of the present invention will be described.
The present invention relates to a conductive terminal that is installed in a battery electrode or an electrode current collector packaged with a polymer sheet packaging material to perform electron transfer to and from the outside of the package.
1 and 2, the conductive terminal of the present invention is a flat conductive terminal in which a conductive sheet and a resin sheet having a hole in the center are laminated, and the resin sheets are laminated. There is no conductive portion with a sufficient area from which current can be taken out. In the present invention, having a hole in the central portion means that when laminated, the conductive sheet has a structure in which a resin sheet is laminated on the periphery of the conductive sheet and has a sufficient area that allows current to be taken out to the outside. This means that there is a hole at a position where the conductive portion can be provided, and it does not necessarily mean that the hole is located in the center portion. The hole in the present invention only needs to be able to form a conductive portion having a sufficient area from which an electric current can be taken out, and the shape can take various shapes such as a circular shape, an elliptical shape, and a rectangular shape. Furthermore, the resin sheet laminated | stacked on the peripheral part of the electroconductive sheet which comprises an electroconductive terminal needs to be able to adhere or fuse | fuse with a polymer sheet package material. The resin sheet may be smaller than the conductive sheet as long as it can be joined to the polymer sheet package material, but is larger than the conductive sheet and laminated in a state of protruding from the periphery of the conductive sheet. It is preferable. The adhesive sheet or the adhesive sheet can be fused to bond the conductive terminal and the polymer sheet package material, so that leakage inside and outside can be prevented, and the electrode or electrode current collector in the polymer sheet package can be prevented. Conductive bonding between the body and the conductive terminal becomes possible, and current can be taken out of the package.
[0010]
As the shape of the conductive terminal of the present invention, various forms such as a disk shape, an elliptical plate shape, and a square plate shape are possible, and the conductive terminal is arranged on the upper surface, the lower surface portion, or the side surface portion of the battery package. The battery can be configured. Since the conductive terminal shape of the present invention is a flat shape , even if it is installed, the entire battery package is not bulky. Therefore, the volume energy density of the battery can be increased.
[0011]
The conductive terminal of the present invention is installed in such a manner that the conductive terminal is embedded in the opening provided in the package material in advance, and then the electrode laminate is put in the package material and sealed, and the electrode stack is provided in the package material provided with the opening. Any method of embedding a conductive terminal in an opening provided in advance after sealing the body is possible. Therefore, the resin sheet that can be fused or adhered to the conductive terminal needs to have a shape that can cover the opening of the package material.
[0012]
The conductive terminal of the present invention comprises a PTC element material of conductive particles or a conductive filler and an insulating polymer , whose electrical resistance increases rapidly at a certain temperature or higher and can interrupt conduction of the conductive terminal. By adopting a structure in which the mixture layers are laminated, it is possible to provide a current interrupting function at a high temperature of the conductive terminal. By cutting off the current at this high temperature, for example, abnormal operation such as overdischarge and external short circuit can be prevented, so that the safety of the battery can be improved. This PTC element material usually has a structure in which conductive particles or conductive fillers are dispersed with a resin binder, and is electrically conductive at high temperatures by utilizing the fact that the thermal expansion coefficient of the resin binder is larger than that of the conductive particles or conductive fillers . Operates by interrupting conduction between particles.
[0013]
As a method for producing a structure in which a mixture layer made of the PTC element material is laminated, a method of using a laminate of the mixture layer made of the PTC element material and a metal layer as a conductive sheet, a resin sheet on the resin sheet lamination side There is a method of laminating a mixture layer on a non-laminated conductive sheet.
As a specific example of the structure of the conductive terminal of the present invention, the laminated structure of the conductive sheet / donut type resin sheet shown in FIG. 1, the laminated structure of the metal layer / mixture layer (conductive sheet) / donut type resin sheet, FIG. And a laminated structure of conductive sheet / donut type resin sheet / mixture layer / conductive sheet shown in FIG. The thickness of the mixture layer laminated in the laminated structure shown in FIG. 2 is equal to or greater than the thickness of the donut-shaped resin sheet, preferably the same thickness. From the viewpoint of battery miniaturization, the conductive sheet and the resin sheet constituting the conductive terminal are preferably thin. In order to maintain the airtightness of the battery using this terminal, it is desirable that at least one of the conductive sheets in the above structure is a continuous body having no through hole.
[0014]
Examples of the conductive sheet used for the conductive terminal of the present invention include a metal sheet such as a stainless sheet, a carbon sheet, a dispersion in which conductive particles are mixed and dispersed in a resin or ceramic, a conductive polymer sheet, and the mixture layer and metal. Examples include a laminate of layers.
The material of the resin sheet needs to be able to be fused or adhered to the package material. Specific examples include polyethylene, polypropylene, ionomer resin, ethylene / vinyl alcohol copolymer, nylon, aromatic polyamide, aromatic polyester, polyphenylene oxide, polyoxymethylene, polycarbonate and other thermoplastic resins, styrene / butadiene copolymer, etc. And a thermoplastic resin or thermosetting resin having an adhesive portion such as an adhesive such as latex and epoxy. Further, a sheet laminated with these resins, for example, polyethylene / polyethylene terephthalate / polyethylene can be used. In this case, the resin sheet to be laminated is naturally not limited to the above resin.
[0015]
As a method for producing the conductive terminal of the present invention, for example, a method of laminating a resin sheet on a conductive sheet, a method of applying a resin layer to a part of the conductive sheet, and a method of applying and forming a conductive sheet on a resin sheet Can be mentioned.
Moreover, in the package battery using the conductive terminal of the present invention, the battery is operated by conductively bonding the conductive terminal and the electrode or the electrode current collector. As this bonding method, direct contact is made by crimping, adhesion, or caulking. Examples thereof include welding methods such as methods, conductive adhesives, spot welding, and ultrasonic welding. In order to improve the direct contact conduction, it is possible to provide an uneven shape on a part of the electrode laminate or the conductive terminal.
[0016]
In the polymer sheet package battery of the present invention, since the conductive terminals are embedded in the package material, a high energy density battery can be produced without being bulky. Further, the battery of the present invention can be used as a single cell or a multiple cell pack battery. Furthermore, the conductive terminal of the present invention is easy to manufacture and rich in mass productivity, and can be applied to various battery forms. The battery of the present invention is particularly suitable for a lithium ion battery, but is not limited to this, and can be applied to various batteries such as a lead battery, an alkaline battery, and a nickel metal hydride battery.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to examples.
[0018]
[ Reference Example 1 ]
A stainless steel sheet disc (thickness 10 μm) punched to a diameter of 19 mm and a polyethylene / polyethylene terephthalate / polyethylene laminate sheet disc (thickness 50 μm) cut to an outer diameter of 30 mm and an inner diameter of 15 mm are laminated to coincide with each other. A hot roll press (temperature 130 ° C.) was performed while sandwiched between fluoroethylene sheets (thickness 50 μm), and after cooling, a polyethylene laminate sheet / stainless steel laminate was taken out of the polytetrafluoroethylene sheet. This laminate is the conductive terminal shown in FIG.
[0019]
After the polyethylene / aluminum / polyethylene terephthalate laminated sheet is processed into a bag shape (100 mm x 105 mm, heat sealing with 4 mm width on 2 sides, 1 side folded back, 1 side open), this bag-shaped center Was punched out with a diameter of 20 mm, and a hole was formed as an opening (two holes were made in the package). After arranging two conductive terminals in the hole of the package, the conductive terminals are subjected to hot roll pressing with a polytetrafluoroethylene sheet (width 92 mm, length 150 mm) sandwiched between the conductive terminals inside the package. Was embedded in a package bag. LiCoO ₂ sheet (width 90 mm, polyvinylidene fluoride as binder, film thickness 110 μm single-sided coating, aluminum current collector), needle coke sheet (width 90 mm, binder as styrene-butadiene latex, film thickness 125 μm single-sided coating, copper current collector) Were used for the positive electrode and the negative electrode, respectively, to prepare an electrode laminate in which a polyvinylidene fluoride-hexafluoropropylene copolymer foam sheet was laminated with a solid electrolyte (width 92 mm) impregnated with an electrolyte solution. The laminate sheet was bent four times every 100 mm and processed into a structure having an aluminum current collector on the upper surface of the folded laminate and a copper current collector on the lower surface. After inserting this folded laminate into the polymer package bag, the insertion port was heat-sealed with a width of 3 mm to produce a battery package. As a result of charging / discharging by connecting the conductive terminals on the upper and lower surfaces of the battery to the charger / discharger, the initial discharge capacity is 1.1 Ah, the average voltage is 3.6 V (3.96 Wh), and repeated charging / discharging is possible. Met.
[0020]
[ Example 1 ]
Using the same stainless steel sheet disc and polyethylene laminate sheet disc as used in Reference Example 1 , a PTC sheet (diameter: 10 mm, thickness: about 100 μm) is placed in the center of the polyethylene laminate sheet disc, Stainless steel sheet discs were laminated to form a stainless steel / polyethylene-PTC element / stainless steel sheet, and heated roll press in the same manner as in Reference Example 1 to produce a laminate. This laminate was used as a conductive terminal (FIG. 2).
[0021]
After arranging conductive terminals in the two holes of the polyethylene / aluminum / polyethylene terephthalate laminated sheet perforated bag used in Reference Example 1 , a polytetrafluoroethylene sheet (width 92 mm, length 150 mm) was sandwiched inside the package. In this state, the conductive terminals were embedded in the package bag by hot roll pressing. The electrode laminate sheet used in Reference Example 1 was bent four times every 100 mm, and processed into a structure having an aluminum current collector on the upper surface of the folded laminate and a copper current collector on the lower surface. After inserting this folded laminate into the polymer package bag, the insertion port was heat-sealed with a width of 3 mm to produce a battery package. As a result of charging / discharging by connecting the conductive terminals on the upper and lower surfaces of the battery to the charger / discharger, the initial discharge capacity is 1.12 Ah, the average voltage is 3.6 V (4.0 Wh), and repeated charging / discharging is possible. Met. As a result of measuring the battery resistance while heating the battery externally, it was found that the resistance increased rapidly at 110 ° C., and the PTC element was operating.
[0022]
[ Reference Example 2 ]
A stainless sheet (thickness 10 μm) was punched out to produce a disk having a diameter of 20 mm, and a styrene-butadiene latex was applied to the circumference 5 mm width and dried. Using this disk as a conductive terminal (FIG. 1), it was processed into a polyethylene / aluminum / polyethylene terephthalate laminated sheet bag shape as in Reference Example 1 (100 mm × 120 mm, two sides of four sides were heat sealed with a width of 3 mm, one side was The sheet was folded back and one side was opened, and the center was punched out with a diameter of 10 mm to provide a hole as an opening (two holes were formed in the package). After placing two conductive terminals in the hole of the package, hot roll pressing with a polytetrafluoroethylene sheet (width 92 mm, length 150 mm) sandwiched inside the package embeds the conductive terminals in the package bag I let you. The electrode laminate sheet used in Reference Example 1 was bent four times every 100 mm, and processed into a structure having an aluminum current collector on the upper surface of the folded laminate and a copper current collector on the lower surface. After inserting this folded laminate into the polymer package bag, the insertion port was heat-sealed with a width of 3 mm to produce a battery package. As a result of charging / discharging by connecting the conductive terminals on the upper and lower surfaces of the battery to the charger / discharger, the initial discharge capacity is 1.12 Ah, the average voltage is 3.6 V (4.0 Wh), and repeated charging / discharging is possible. Met.
[0023]
【The invention's effect】
In the polymer sheet package battery of the present invention, since the conductive terminals are embedded in the package material, a high energy density battery can be produced without being bulky.
[Brief description of the drawings]
1 is a longitudinal sectional view showing an example of a conductive terminal used in Reference Example 1. FIG.
FIG. 2 is a longitudinal sectional view showing an example of a conductive terminal used in the present invention.
FIG. 3 is a partial longitudinal sectional view showing a mounting portion of a polymer package battery to which a conductive terminal of the present invention is mounted.
[Explanation of symbols]
1. 1. Conductive sheet 2. Resin sheet 3. PTC sheet 4. Polymer packaging material 5. Electrode or electrode current collector Aperture

Claims (1)

In a battery in which an electrode laminate is packaged with a polymer sheet packaging material having an opening ,
The opening is from the inside ,
The holes of the resin sheet having a hole in its central portion, is abruptly electrical resistance increases at a constant temperature or higher, are filled with a mixture of conductive particles or conductive filler and the insulating polymer, and pores are The resin sheet of the conductive terminal that is covered from both sides with the conductive sheet having an area smaller than the resin sheet and larger than the area of the hole ,
And polymer sheet package batteries, characterized in that said conductive sheet constituting the conductive terminals are bonded to the electrode or electrode current collector of the electrode stack.

Images