Improving Supercapacitors by Adding Boron

[Guest_Jim_*]

For energy storage, most people think of batteries, but we may soon see some serious competition from supercapacitors. These energy storages systems are able to charge and discharge very quickly, can be flexible and cheap to make, and can even be safer to work with. Now researchers at Rice University have found a way to significantly increase the energy density of flexible microsupercapacitors made of graphene by adding boron to the mix.

Capacitors work by storing electrical charges on separated conductors, which allows them to charge up and release energy very rapidly. Supercapacitors bring with them higher energy capacities, similar to that of batteries, so one day they could see use in many applications where batteries now dominate. To create the microsupercapacitors they used, the Rice researchers used a laser to burn patterns into common polymers, resulting in the formation of a matrix of graphene flakes. From previous work they knew a commercial polyimide was the best choice, but this new study revealed that dissolving boric acid into polyamic acid, so that the polyimide sheet was boron infused, quadrupled the supercapacitor's storage capability.

With just a two-step process, the researchers are able to create microsupercapacitors with four times the storage ability and five to ten times the energy density of boron-free microsupercapacitors. Beyond that, the supercapacitors survived over 12,000 cycles while retaining 90% capacitance and after 8000 bending cycles, there was no performance loss. That flexibility could be an especially important aspect of this technique, by enabling industrial-scale roll-to-roll production.

Source: Rice University

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