205: Stinkfruit supercapacitors


Graphene supercapacitors are expensive to make. About half the materials cost comes from the use of activated carbon to coat the electrodes. Supercapacitor-grade activated carbon can cost $15 per kilogram.


Using inexpensive biochar to coat electrodes and a new method to create the porous surface needed to capture electricity may reduce the cost of supercapacitors. Activating the biochar using plasma processing takes only five minutes with no external heating or chemicals needed.

Vincent Gomes, a chemical engineer at the University of Sydney, and his team, including Labna Shabnam have found a solution to convert the inedible parts of the world’s largest and smelliest fruits, Durian and Jackfruit (Artocarpus heterophyllus) into carbon aerogels – porous super-light solids – with “exceptional” natural energy storage properties.

These fruits were used to produce carbon aerogel electrodes incorporating stable scaffolding of base material and natural nitrogen doping. They heated, freeze-dried and then baked the inedible spongey core of each fruit in an oven at temperatures of more than 1,500°C (2732°F).

The black, highly porous, ultralight structures they were left with could then be fashioned into electrodes of a low-cost supercapacitor.

Until now, 70% of jackfruit or durian has been thrown away – but can now be recycled.

Discover Solution 206: Kayaks from recycled plastics.

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