Printed supercapacitor

A group of researchers led by George Gruner at the University of California, Los Angeles, has printed a supercapacitor for the first time by spraying carbon nanotubes onto a plastic film - two such films act as both the device's electrodes and charge collectors. Between the two films is placed a gel electrolyte made by mixing a water soluble synthetic polymer with phosphoric acid and water.

 

The printed supercapacitor follows on from Gruner's earlier work in 2007 where he produced printable batteries less than a millimeter thick by depositing a layer of nanotubes in the form of "nanotube ink" onto a surface. The layer acts as the charge collector, which removes current from the battery. A layer of nanotube ink is then mixed with manganese oxide powder and electrolytes, which carries charge within the cell, and is applied on top acting as the cathode. Finally, a piece of zinc foil is applied, which acts as the anode.

 

Capacitors and batteries both store electrical energy and are often used in tandem in electrical devices, batteries can store more energy but capacitors can discharge more rapidly. The printed supercapacitor has a power density of 70 kilowatts per kilogram to allow rapid charging and discharging but improvements in efficiency are still to be made and the team is working on increasing the power output. As both the printed supercapacitors and batteries can be made at room temperature it would be feasible for these to be mass produced according to Gruner.

 

Portable electronic devices are likely to ultimately carry both a battery and supercapacitor to provide the high energy storage and fast energy discharges that new electronics require, and printed supercapacitors would be extremely versatile.

 

 

For more read: Energy Harvesting and Storage for Electronic Devices 2009-2019