Defects in carbon nanotubes could lead to improved charging for cell phones

WASHINGTON - Scientists have discovered that defects in carbon nanotubes could lead to supercapacitors that could possibly be used for improving charge and energy storage systems in portable electronic devices such as cell phones.

Mark Hoefer, a University of California San Diego (UCSD) materials science grad student, and mechanical engineering professor Prabhakar Bandaru, made the discovery.

Bandaru, along with graduate student Mark Hoefer, have found that artificially introduced defects in nanotubes can aid the development of supercapacitors.

“While batteries have large storage capacity, they take a long time to charge; while electrostatic capacitors can charge quickly but typically have limited capacity. However, supercapacitors/electrochemical capacitors incorporate the advantages of both,” Bandaru said.

Carbon nanotubes (CNTs) have been generally hailed as one of the wonder materials of the 21st century and have been widely recognized as ushering in the nanotechnology revolution.

However, defects are inevitable in such a practical structure, an aspect that was first investigated by UCSD engineering graduate student Jeff Nichols and then substantially extended by Hoefer in Bandaru’s lab.

“We first realized that defective CNTs could be used for energy storage when we were investigating their use as electrodes for chemical sensors,” Hoefer said.

“During our initial tests, we noticed that we were able to create charged defects that could be used to increase CNT charge storage capabilities,” he added.

Specifically, defects on nanotubes create additional charge sites enhancing the stored charge.

The researchers have also discovered methods which could increase or decrease the charge associated with the defects by bombarding the CNTs with argon or hydrogen.

Carbon nanotubes could serve as supercapacitor electrodes with enhanced charge and energy storage capacity.

“At the very outset, it is interesting that CNTs, which are nominally considered perfect, could be useful with so many incorporated defects,” said Bandaru.

According to the researchers, the energy density and power density obtained through their work could be practically higher than existing capacitor configurations which suffer from problems associated with poor reliability, cost, and poor electrical characteristics.

Bandaru and Hoefer hope that their research could have major implications in the area of energy storage, a pertinent topic of today.

“We hope that our research will spark future interest in utilizing CNTs as electrodes in charge storage devices with greater energy and power densities,” Hoefer said. (ANI)