JPS6322049B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric double layer capacitor, and its purpose is to surround a polarizable electrode with a separator to prevent an increase in leakage current due to charged carbon particles released from the electrode. It is in.

Conventionally, polarizable electrodes for this type of capacitor have been made of a metal plate, net, or expanded metal with a smooth surface, or a roughened surface of these metal plates as the current collector 2, as shown in Fig. 1, and powdered activated carbon. An electrode body is produced by molding and pressing together with a polarizable electrode mainly made of or using a rolling roller, and the current collector is provided with an extraction electrode.

For this reason, the connection between the current collector 2 and the electrode body polarizable electrode layer 1 cannot be said to be sufficiently strong, especially in the case of an element with a winding structure with a separator 3 in between, such as a general electrolytic capacitor, by 0.3 to 0.5 mm. In an electrode body having a thickness of This may lead to phenomena such as.

When voltage is applied to such a capacitor,
The level of leakage current increases due to electrophoresis of carbon-charged fine particles detached from the electrode, which in turn causes Faraday current to flow due to dissolution of the polarizable electrode and current collector metal and precipitation on the counter electrode, resulting in further leakage. This can lead to an increase in current and, in extreme cases, to cell destruction.

In order to solve the above-mentioned drawbacks, the present invention has provided that one polarizable electrode is housed in a bag-shaped separator by thermally welding both ends of a separator made of thermoplastic resin during winding.

Hereinafter, the electric double layer capacitor according to the present invention will be explained based on FIGS. 2 and 3.

Figure 2 is a cross-sectional view of an embodiment of an electric double layer capacitor, in which 1 is a polarizable electrode layer, 2 is a current collector, and 4 is made of a thermoplastic porous resin such as polypropylene, polyester, polyethylene, polyvinyl alcohol, vinyl chloride, etc. This is a separator. As shown in Fig. 3, the ends of the separator 4 are heated, welded, and cooled while being heated, welded, and cooled using a pressure roller 5 that can heat both end faces during winding. , which is impregnated with electrolyte. At this time, the lead-out lead is connected to the current collector by caulking or the like to form a polarizable electrode, and then led out from a part of the welded separator. Note that the separator 4 may be impregnated with the electrolyte in advance and then wound. As a result, the electrode body is surrounded by the separator 4, making it possible to prevent electrophoresis of carbon-charged fine particles and the like separated from the current collector 2 to the counter electrode. Furthermore, since thermoplastic resins generally shrink due to heat treatment, the connection surface between the current collector 2 and the polarizable electrode layer 1 and the entire wound element are tightened, and as a result, the separator is It is possible to seal the ends, improve productivity and reduce internal resistance, and is extremely effective industrially for improving the high temperature load characteristics of products.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part of a conventional electric double layer capacitor element, FIG. 2 is a cross-sectional view of a main part of an embodiment of an electric double layer capacitor element of the present invention, and FIG. 3 is a cross-sectional view of a main part of an electric double layer capacitor element according to the present invention. FIG. 3 is a sectional view of a main part of a capacitor element in the middle of winding. 1: polarizable electrode layer, 2: current collector, 4: separator made of thermoplastic porous resin.

Claims (1)

[Claims] 1. In a wound type electric double layer capacitor that applies an electric double layer formed at the interface between a polarizable electrode and an electrolyte, a thermoplastic porous resin is used as a pair of separators, and both ends of the separator are rolled while being heated and welded. An electric double layer capacitor characterized in that when the capacitor is turned, one polarizable electrode is housed in a bag-shaped separator.