Energy-storage device could offer key to higher capacitance

Crucially, the researchers at Rice University say it is robust and can operate in extreme environments, and so could potentially be integrated into the manufacture of panels in items such as satellites and electric vehicles.

Standard capacitors that regulate flow or supply quick bursts of power can be discharged and recharged hundreds of thousands of times. Electric double-layer capacitors (EDLCs), generally known as supercapacitors, are hybrids that hold hundreds of times more energy than a standard capacitor, like a battery, while retaining their fast charge/discharge capabilities. 

But traditional EDLCs rely on liquid or gel-like electrolytes that can break down in very hot or cold conditions. In Rice’s supercapacitor, a solid, nanoscale coat of oxide dielectric material replaces electrolytes entirely. 

The key to high capacitance is giving electrons more surface area to inhabit, the researchers say. For this, the new device relies on numerous bundles of single-walled carbon nanotubes (SWNT) 15–20 in nanometre in diameter and up to 50 microns long, essentially grown as a carpet-like array.