Graphene-based supercapacitor to rival lithium-ion
A paper thin cell phone with a battery life to rival the biggest brick on the market today? New research from a US-China collaboration suggests that in this case the sci might soon be dropping the fi.
Commercial researchers in the US, working with academics in China, have built a graphene-based supercapacitor with an energy capacity comparable to that of a nickel metal hydride battery. The difference is in the speed of energy transfer: the graphene-based device can be charged or discharged in minutes or even seconds, according to Bor Jang of the US firm Nanotek Instruments.
"Our goal is to make a supercapacitor that stores as much energy as the best lithium-ion batteries (for the same weight) but which can still be recharged in less than two minutes," he said, in the announcement.
A supercapacitor is more properly known as an electric double layer capacitor. In 2007, the highest energy density in production was 30Wh/kg. This new graphene-based capacitor boasts an energy density of 85.6 Wh/kg at room temperature, and 136 Wh/kg at 80 degrees C.
From Physics World: The new device … has electrodes made of graphene mixed with 5wt per cent Super P (an acetylene black that acts as a conductive additive) and 10wt per cent PTFE binder. A sheet of carbon just one atom thick, graphene is a very good electrical conductor as well as being extremely strong and flexible.
The researchers coat the resulting slurry onto the surface of a current collector and assemble coin-sized capacitors in a glove box. The electrolyte-electrode interface is made of "Celguard-3501" and the electrolyte is a chemical called EMIMBF4.
Reports do not detail how long the device holds on to its charge.
The research is published here.