JPS6320371B2 - - 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. be.

Conventionally, as shown in FIG. 1, 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 thereof, as the current collector 2. The electric body is provided with a lead-out lead, and the electrode body is manufactured by molding and pressing together with a polarizable electrode mainly made of powdered activated carbon or by a rolling roller, and the current collector 2 is provided with a lead-out lead. It is being

For this reason, the connection between the current collector 2 and the 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 interposed therebetween, such as a general electrolytic capacitor. In an electrode body having a thickness of This may lead to the phenomenon of When a voltage is applied to such a capacitor, the leakage current level increases due to electrophoresis of carbon-charged fine particles detached from the electrode, which in turn causes dissolution of the polarizable electrode and current collector metal and precipitation on the counter electrode. Faraday current flows, leading to further increase in leakage current and, in extreme cases, cell destruction.

In order to solve the above-mentioned drawbacks, the present invention has been developed by winding a polarizable electrode with a separator made of a porous thermoplastic resin interposed therebetween, and then thermally welding the separator on the end face of the element to form a bag-shaped separator. It contains an electrode body inside.

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

FIG. 2 is a cross-sectional view of an embodiment of the electric double layer capacitor according to the present invention, in which 1 is a polarizable electrode layer, 2 is a current collector, and 4 is a thermoplastic material such as polypropylene, polyester, polyethylene, polyvinyl alcohol, vinyl chloride, etc. This is a separator made of porous resin.

The width of the separator 4 is determined by the diameter of the element after winding. Usually, the diameter of the wound element is R, and the width of the electrode body consisting of the polarizable electrode layer 1 and the current collector 2 is W. Then, W+√2・R/2×2
Any above is sufficient.

After winding an electrode body consisting of a polarizable electrode layer 1 and a current collector 2 via the above-mentioned separator 4, it is impregnated with an electrolyte, the separator 4 on the end surface is squeezed toward the winding core, and a method such as heat sealing is performed. heated with,
Welding and cooling are performed, and at this time the lead is 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 resin generally shrinks due to heat treatment, it tightens the connection surface between current collector 2 and polarizable electrode layer 1 and the entire wound element, and as a result, it is possible to reduce internal resistance. This improved the product's high-temperature load characteristics.

Figures 3 and 4 are ratings according to this example.
A high-temperature load characteristic diagram showing the loss value and leakage current change of a 1.5WV-20Farad product in an 80℃ atmosphere.
As is clear from the figure, the product of the present invention exhibits extremely stable characteristics compared to conventional products, the above-mentioned effects have been demonstrated, and it is extremely useful industrially.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a main part of a conventional electric double layer capacitor element, Fig. 2 is a 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 loss vs. time under high temperature load. The characteristic diagram, FIG. 4, is a leakage current-time characteristic diagram at high temperature load. 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, all the separators protruding from the end face of the wound element are collected through a separator made of thermoplastic porous resin. An electric double layer capacitor characterized by heat welding treatment.