New Paper in Materials Express

“Adsorption of proteins in channels of carbon nanotubes: Effect of surface chemistry,” featuring work by Vadym Mochalin, Maria Lukatskaya, and NMG alum Volker Presser, has been published in the March 2013 volume of Materials Express.

Activated graphene breaks record for low temperature storage of electrical energy

Many people can relate to the hardship of starting a vehicle during a bitter cold morning before work. It takes a huge amount of power relative to a warm sunny day for two reasons: the mechanical parts of an engine require more power to start moving when cold (motor oil becomes viscous, like honey), and the battery operates at a very low efficiency because the ions in electrolyte solution move much slower at freezing temperatures.

A collaboration between researchers at Drexel University in Philadelphia, The University of Texas at Austin, and Paul Sabatier University in Toulousse, France have recently engineered a supercapacitor system that can operate efficiently at very low temperatures – as low as -50 °C (-58 °F). Just published in the journal Nano Energy, their work involves a unique nanostructured carbon material deemed activated microwave exfoliated graphite oxide (“a-MEGO”), which was inspired by the recent interest in graphene. Graphene, which is an atomically thin layer of carbon, has many applications in energy storage and generation.

Transmission electron image of a-MEGO. Individual layers of carbon called graphene can be seen. Image taken by Dr. Eric Stach of Brookhaven National Lab
Transmission electron image of a-MEGO. Individual layers of carbon called graphene can be seen. Image taken by Dr. Eric Stach of Brookhaven National Lab

Combined with a-MEGO is an electrolyte called an ionic liquid. These are salts like sodium chloride, but are liquid at room temperature or below. The a-MEGO material has a high surface area, with about 2 grams having the surface area of a football field; as a result, a-MEGO is able to store a large amount of charge on its surface as a supercapacitor. The unique electrolyte, which is a mixture of ionic liquids, allows for operation at low temperature. Commercial supercapacitors, by comparison, use an electrolyte that will fail at temperatures below -25 °C (-13 °F). Finally, supercapacitors will last for more than 10 years and up to 1 million charge/discharge cycles, compared to batteries that will last a couple years for about 1 thousand cycles. Imagine never having to change your car battery!

This study reinforces the potential of graphene in energy storage applications, but also demonstrates that only the right combination of an electrode material and an electrolyte leads to truly outstanding performance. This opens the door to development of even better supercapacitors using safe and non-flammable ionic liquid electrolytes.

Citation: Lin, R.; Tsai, W.- Y.; Murali, S.; Zhang, L. L.; McDonough, J. K.; Ruoff, R. S.; Taberna, P.- L.; Gogotsi, Y.; and Simon, P. Outstanding Performance of Activated Graphene Based Supercapacitors in Ionic Liquid Electrolyte from -50 to 80°C. Nano Energy, 2013, doi 10.1016/j.nanoen.2012.11.006


Take Away

What? – Engineered a material / electrolyte supercapacitor system to store a large amount of energy at extremely low temperatures. Additionally, the system has a fast response rate and a high efficiency compared to batteries.

When? – First published online (Nano Energy).

Where? Collaboration between UTexas at Austin, Paul Sabatier University in Toulousse France, and Drexel University in Philadelphia.

Why? Present systems to power technology at very low temperatures, i.e. starting a vehicle in an Alaskan morning, require oversized batteries that have a very low efficiency and short lifetime. Our supercapacitor system delivers the most energy at a low temperature of -50 °C (-58 °F) and can operate for ~1 million charge / discharge cycles.

How? A unique carbon nanomaterial, activated microwave exfoliated graphite oxide (a-MEGO), was combined with a eutectic mixture of ionic liquids. The a-MEGO has a high surface area and allows for a large amount of charge to be stored capacitively on its surface, while the mixture of ionic liquids has a very low melting point and a wide voltage stability window.

Tunable Nanoporous Materials Research Featured in Live Science

Work by NMG alumni Volker Presser and Sun-Hwa Yeon is featured in Live Science: Nanoporous Carbon Materials Raise Chances of Surviving Sepsis. The researchers discuss their work on mesoporous carbons derived from silicon carbide-based ceramics for ultimate use in filtering cytokines from the blood to treat sepsis. The work was first published as the cover article in the November 2012 issue of Advanced Healthcare Materials.

CREDIT: Dr. V. Presser, INM Leibniz Institute for New Materials, and Uwe Bellhäuser
CREDIT: Dr. V. Presser, INM Leibniz Institute for New Materials, and Uwe Bellhäuser

First Paper of 2013 Published in Energy and Environmental Science

Min Hoen and NMG alum Volker Presser have published a paper in collaboration with the FIRST EFRC team at Oak Ridge National Laboratory. “In situ tracking of the nanoscale expansion of porous carbon electrodes” can be found in Energy and Environmental Science.

New Paper in J. Electrochemical Society

Resulting from the collaborative work between former visiting researcher Moritz Hantel, former Post Doctoral researcher Volker Presser, and Ph.D. student Jake McDonough, an article has been published entitled “In Situ Electrochemical Dilatometry of Onion-Like Carbon and Carbon Black” in the Journal of the Electrochemical Society.