Feb 29, 2008
Inventors roll out nanotube paper
Rolling a 1 cm diameter steel cylinder across an array of carbon nanotubes (CNTs) is a quick and easy way of preparing buckypaper – a film with excellent thermal and electrical properties. Developed by scientists at Tsinghua University, China, the method is being used to improve the performance of supercapacitors.
"From our comparison measurements, our buckypaper-based supercapacitors were at least twice as good as the commercially purchased carbon fiber-based capacitors," Changhong Liu of the Tsinghua-Foxconn Nanotechnology Research Center told nanotechweb.org. "High capacitance values can be obtained by using buckypaper as an electrode material because of its large surface area."
Thermal interfacing is another key area of interest for the team. "The material's high in-plane thermal conductivity means that it can be used to transmit heat from confined areas," said Liu. "For example, our tightly aligned buckypaper could be used to solve thermal management problems in microelectronic packaging."
The team's production method really is as simple as it sounds and has been described as "domino pushing". First, a microporous membrane is placed on top of the CNT array and then a steel cylinder is pushed slowly with a constant pressure over the covered sample. Next, the aligned buckypaper is peeled off the silicon substrate and finally removed from the microporous membrane by washing with ethanol.
Previously, buckypaper has been made by filtering a suspension of CNTs in a high magnetic field, but material properties can be variable due to problems with alignment and agglomeration.
Liu and his colleagues report that their dry in situ technique produces an incredibly flexible film and demonstrate the claim by folding their CNT material into an origami swan.
The researchers presented their results in Nanotechnology.
About the author
James Tyrrell is editor of nanotechweb.org.