Direct writing of planar ultracapacitors by laser forward transfer processing

We employ a novel laser forward transfer process, Matrix Assisted Pulsed Laser Evaporation Direct Write (MAPLE-DW), in combination with ultraviolet laser micromachining, to fabricate mesoscale ultracapacitors and microbatteries under ambient temperature and atmospheric conditions. Our laser engineering approach enables the deposition of hydrous ruthenium oxide (RuOxHy or RuO2 . xH(2)O) films with the desired high surface area morphology, without compromising the electrochemical performance of this high specific capacitance material. We compare three different deposition formulations incorporating ethylene glycol, glycerol, or sulfuric acid. The best electrochemical performance is achieved using a mixture of sulfuric acid with RuO2 . 0.5 H2O 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.