According to associate professor Mircea Dincă: “We’ve found an entirely new class of materials for supercapacitors. All double-layer supercapacitors today use carbon nanotubes, graphene, activated carbon, all shapes and forms, but nothing else besides carbon. So this is the first non carbon, electrical double-layer supercapacitor.”
The work is based on research into metal-organic frameworks (MOFs), extremely porous materials with sponge like structures. These materials have an extraordinarily large surface area for their size; an essential characteristic for supercapacitors. However, MOFs are not very conductive electrically – an essential property for a material used in a capacitor.
“One of our long-term goals was to make these materials electrically conductive,” said Dincă, even though this was thought to be difficult, if not impossible. However, the material conducts ions very well.
The devices produced by the team are said to match or exceed the performance of carbon based devices in such areas as their ability to withstand significant charge/discharge cycles. Tests showed they lost less than 10% of their performance after 10,000 cycles – comparable to the performance of commercial supercapacitors.
Because the characteristics of MOFs can be tuned by varying their chemical structure, the work might lead to variations that could outperform existing materials. “We have a new material to work with and we haven’t optimised it at all,” Dincă said. “It’s completely tunable and that’s what’s exciting.”