Researchers at the National Taiwan University of Science and Technology (Taipei, Taiwan) have developed techniques to prepare miniature planar CNT ultracapacitors via lift-off photolithography. They ensure electrical contact by gold-sputtering the CNT surface and inverting the patterned electrode.

In the study, the micro-ultracapacitor is inverted onto adhesive tape and can be transferred to any rigid or plastic substrate. One version of the wired micro-ultracapacitor features a drop of lithium gel electrolyte, which is capable of discharging 16.5 Wh kg–1 at a power of 50.0 kW kg–1 with a current density of 30 A g–1. The team also prepared an aqueous-electrolyte ultracapacitor that displays an energy density of 24.0 Wh kg–1 at a power density of 22.9 kW kg–1.

The interdigitated configuration adopted in these micro-ultracapacitors is particularly suited for flexible electronic applications.

Further details can be found in the journal Nanotechnology.