Supercapacitor offers advances in solid state energy storage

The Rice team, which has reported its findings in the journal, Carbon, created the energy storage device by growing an array of 15 to 20nm bundles of single walled carbon nanotubes up to 50microns long. The array was then transferred to a copper electrode with thin layers of gold and titanium to aid adhesion and electrical stability. The nanotube bundles (the primary electrodes) were doped with sulfuric acid to enhance their conductive properties and were then covered with thin coats of aluminum oxide (the dielectric layer) and aluminium doped zinc oxide (the counterelectrode) through a process called atomic layer deposition (ALD). A top electrode of silver paint completed the circuit. "Essentially, you get this metal/insulator/metal structure," noted lab chemist Robert Hauge, who led the team. "No one's ever done this with such a high aspect ratio material and utilising a process like ALD." Hauge maintained that the new supercapacitor is stable and scaleable. "Potential uses span on chip nanocircuitry to entire power plants," he said. "Imagine an electric car body that is a battery, or a microrobot with an onboard, nontoxic power supply that can be injected for therapeutic purposes into a patient's bloodstream." According to Hauge, the supercapacitor holds a charge under high frequency cycling and can be naturally integrated into materials. He believes it would be ideal for use under the kind of extreme conditions experienced by desert based solar cells or in satellites, where weight is also a critical factor "The challenge for the future of energy systems is to integrate things more efficiently," the researcher concluded. "This solid state architecture is at the cutting edge."