TITLE Production technology development of the large-capacity capacitor applied CNT to an electrode
(Joint Program to Promote Technological Development with the Private Sectors)

ABSTRACT In this laboratory, we are developing technologies to produce large-capacity capacitors which are applied CNT (Carbon Nano Tubes) to the electrode. If these capacitors are spread, unused energy is utilized effectively. We are aiming to contribute to achieve the reduction of greenhouse gas by spreading these capacitors.

Result of 2006
1. Improvement of reliability of the CNT electrode

We repeated electric charge and discharge to the capacitor in 85 degrees Celsius and examined the characteristic change. We can estimate the durability of the capacitor constitution member by this characteristic change. We improved an electrode sheet based on analysis of a deterioration factor and realized improvement of reliability. We optimized the electrode, the electrolyte, the separator and evaluated the durability of the capacitor from an accelerated test for deterioration for three months. As a result, we found that it has 5 years durability in room temperature environment.

2. Trial manufacture and the evaluation of an extremely thin seat to collect electrons

We devised a resin composition based on an analysis result of an accelerated test for deterioration and developed a usable electrode sheet in a higher voltage condition.
In an electric conductivity, surface resistance became equal to aluminum foil.
The capacitor made of this material was able to make internal resistance extremely small.
In addition, this material has less reaction electric current than the last year seat, and the high-reliability of the electrode and the stabilization of the characteristic were realized.

3. The improvement design of a CNT capacitor for battery cars and improvement trial manufacture and evaluation

We studied methods to connect plural CNT capacitors to parallel while keeping the lowness of the internal resistance, and to mold resin and the CNT capacitors into a cell.
Through the study mentioned above, 50 thin CNT capacitor cells were experimentally produced for cars and were evaluated.
We put this CNT capacitor cell on a small battery car and examined its effect.
By this experiment we confirmed an effect of the CNT capacitor to assist the car in starting and accelerating and to regenerate electricity at the brakes.
The greatest point of the CNT capacitor is that an electric charge and discharge with more than 80% of the rating capacity are possible within one second. We confirmed this performance by an experiment in a small battery car, too.