The fast expansion in the use of mobile electronic equipment, as well as the increasing need for wireless sensor networks particularly raise the problem of microscale energy storage: How to power multiple systems without increasing connections or battery size? Rechargeable thin film batteries have been developed for this purpose since the 80’s. They have, however, a finite life-time and can be a major problem when it comes to applications where the source has to be embedded in permanent structures. Power densities of these storage devices are also quite low. Supercapacitors on the other hand, fill the gap between high power density capacitors and high energy density batteries. They have a long life cycle and are in this sense environmentally friendlier, since no replacement is needed during the lifetime of the system.

Microsupercapacitors integrated on silicon are being developed in the group ISGE through microtechnologies. Different processes such as inkjet or screen printing are used to deposit the active material constituted of nanoporous carbon onto current collectors. The active material is impregnated by a liquid organic electrolyte: a wafer-level hermetical encapsulation is therefore developed. Electrochemical characterizations are done with cyclic voltammograms and impedance spectroscopy.

With these microsupercapacitors, we are aiming to provide energy storage on chip, which can be realized in the same time as the electronic circuit and/or the sensor requiring power.