Batteries to get boost from nanotechnology
Mobile devices in the future may get extra battery power thanks to nanotechnology. Researchers from the Massachusetts Institute of Technology (MIT) have come up with a way of storing extra charge in ‘ultracapacitors’.
The team led by Riccardo Signorelli, Joel Schindall and John Kassakian have developed a new type of double layer capacitor that can store charge way beyond the limits of normal capacitors. They say that their new design is 1,000 times the power density of conventional batteries and 10,000 times that of the much touted fuel cells.
Capacitors have been a way of storing charge for electrical devices for many years. Typically, a capacitor consists of two plates. As a current is applied to the circuit, a negative charge will build up on one plate and a positive charge on the other. The amount of charge that can be held on a plate depends on its size. Over the years engineers have come up with ways of folding the plate to increase its surface area without necessarily increasing the space the device takes up.
The MIT has increased the surface area of a plate by covering the capacitor with ‘carbon nanotubes’ (CNTs) arranged in a vertical matrix. The team claim to have grown CNTs with diameters of between 0.7 and 2nm and lengths up to tens of microns long. As a result, the team say they have created a device which has packed 10 million such tubes only a few nanometres long in each square millimetre of the capacitor, dramatically increasing the surface area and its ability to hold a charge.
The devices are robust too with the team claiming that a CNT based capacity has a lifetime of 300,000 cycles.
It is estimated that commercial products containing capacitors based on CNT technology are between three and five years away.