Direct writing of planar ultracapacitors by laser forward transfer processing

Abstract

We employ a novel laser forward transfer process, Matrix Assisted Pulsed Laser Evaporation Direct Write, in combination with UV laser micromachining, to fabricate mesoscale ultracapacitors and micro batteries under ambient temperature and atmospheric conditions. Our laser engineering approach enables the deposition of hydrous ruthenium oxide films with the desired high surface area morphology, without compromising the electrochemical performance of this high specific capacitance material. We compare three different desorption formulations incorporating ethylene glycol, glycerol, or sulfuric acid. The best electrochemical performance is achieved using a mixture of sulfuric acid with RuO<SUB>2</SUB> 0.5 H<SUB>2</SUB>O electrode material. Our ultracapacitors exhibit the expected linear discharge behavior under a constant current drain, and the electrochemical properties of these cells scale proportionately when combined in parallel and series.