By Josh Perry, Editor [email protected]
Researchers from Tohoku University in Sendai, Japan collaborated with supercapacitor manufacturer TOC Capacitor Co. to create a new material from graphene mesosponge, which contains nanoscale pores, that could be used to build supercapacitors with higher voltage and better stability than those built from conventional materials.
Developed GMS sheet and its supercapacitor connected to two LEDs. (Hirotomo Nishihara/Tohoku University)
The potential applications, according to a report from the university, include electric vehicles, which require a lot of energy and need to perform in harsh environments. Previous attempts to build supercapacitors were limited by the need to stack a large number of cells to achieve the necessary voltage, but this new material has a higher single-cell voltage and enables more compact devices.
“A key feature of the materials is that it is seamless - it contains a very small amount of carbon edges, the sites where corrosion reactions originate, and this makes it extremely stable,” the article explained.
Scientists used electron microscopy, X-ray diffraction, and vibrational spectroscopy techniques to test the new material and compared them with commercial graphene-based materials, like carbon nanotubes, to establish benchmarks.
“They showed that the material had excellent stability at high temperatures of 60°C and high voltage of 3.5 volts in a conventional organic electrolyte,” the article added. “Significantly, it showed ultra-high stability at 25°C and 4.4 volts - 2.7 times higher than conventional activated carbons and other graphene-based materials.”
The research was recently published in Energy and Environmental Science. The abstract said:
“The application of supercapacitors for objectives such as automobiles requires high voltage and high temperature operation, therefore development of new electrode materials that have sufficient stability under such harsh conditions is crucial.
“In this work, we report the development of seamless mesoporous carbon sheet consisting of continuous graphene walls, which exhibits extraordinarily high stability under high voltage and high temperature conditions. The sheet contains very few carbon edge sites (only 4% of the number present in conventional activated carbons) despite its high specific surface area (1500 m2 g−1), and it is possible to use it to assemble symmetric supercapacitors with excellent stability under 3.5 V@60 °C and 4.4 V@25 °C conditions, even using a conventional electrolyte (1 M Et3MeNBF4/propylene carbonate).
“Moreover, high-voltage operation at 4.4 V results in a 2.7 times higher energy density compared to that achieved using conventional activated carbons.”
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