Carbon-Based Supercapacitors Produced by Activation of Graphene

1. Yanwu Zhu¹, 
2. Shanthi Murali¹, 
3. Meryl D. Stoller¹, 
4. K. J. Ganesh¹, 
5. Weiwei Cai¹ , 
6. Paulo J. Ferreira¹, 
7. Adam Pirkle²,
8. Robert M. Wallace² , 
9. Katie A. Cychosz³, 
10. Matthias Thommes³, 
11. Dong Su⁴, 
12. Eric A. Stach⁴, and 
13. Rodney S. Ruoff¹,*#

1. 
   

Science DOI: 10.1126/science.1200770

• Received for publication 22 November 2010.
• Accepted for publication 2 May 2011.

Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high surface area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a BET surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low O and H content. This sp²-bonded carbon has a continuous three-dimensional network of highly curved, atom thick walls that form primarily 0.6- to 5-nm-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.