Boron-infused graphene helps quadruple performance of microsupercapacitor
The Rice lab of chemist James Tour uses commercial lasers to create thin, flexible supercapacitors by burning patterns into common polymers. The laser burns away everything but the carbon to a depth of 20 microns on the top layer, which becomes a foam-like matrix of interconnected graphene flakes.
By first infusing the polymer with boric acid, the researchers have boosted the performance of the supercapacitor and will allow the device to be suitable for wearable electronics.
The simple manufacturing process may also be suitable for making catalysts, field emission transistors and components for solar cells and lithium-ion batteries.
The research is detailed in the American Chemical Society journal ACS Nano.
In the earlier work, the team led by Rice graduate student Zhiwei Peng tried many polymers and discovered a commercial polyimide was the best for the process. For the new work, the lab dissolved boric acid into polyamic acid and condensed it into a boron-infused polyimide sheet, which was then exposed to the laser.
The two-step process produces microsupercapacitors with four times the ability to store an electrical charge and five to 10 times the energy density of the earlier, boron-free version. The new devices proved highly stable over 12,000 charge-discharge cycles, retaining 90 percent of their capacitance. In stress tests, they handled 8,000 bending cycles with no loss of performance, the researchers reported.
Tour said the technique lends itself to industrial-scale, roll-to-roll production of microsupercapacitors. “What we’ve done shows that huge modulations and enhancements can be made by adding other elements and performing other chemistries within the polymer film prior to exposure to the laser,” said Tour.
“Once the laser exposes it, those other elements perform new chemistries that really increase the supercapacitor’s performance. This is a step in making these even more amenable for industrial applications.”
Related articles and links:
https://pubs.acs.org/doi/abs/10.1021/acsnano.5b00436
https://naturalsciences.rice.edu
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