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Hierarchical carbide-derived carbon foams with advanced mesostructure as a versatile electrochemical energy-storage material

 
: Oschatz, M.; Borchardt, L.; Pinkert, K.; Thieme, S.; Lohe, M.R.; Hoffmann, C.; Benusch, M.; Wisser, F.M.; Ziegler, C.; Giebeler, L.; Rümmeli, M.H.; Eckert, J.; Eychmüller, A.; Kaskel, S.

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Advanced energy materials 4 (2014), Nr.2, Art. 1300645, 9 S.
ISSN: 1614-6840
ISSN: 1614-6832
Englisch
Zeitschriftenaufsatz
Fraunhofer IWS ()
carbide-derived carbons; electrochemical double-layer capacitors; lithium-sulfur batteries; mesocellular siliceous foams; nanocasting

Abstract
Highly porous carbide-derived carbon (CDC) mesofoams (DUT-70) are prepared by nanocasting of mesocellular silica foams with a polycarbosilane precursor. Ceramic conversion followed by silica removal and high-temperature chlorine treatment yields CDCs with a hierarchical micro-mesopore arrangement. This new type of polymer-based CDC is characterized by specific surface areas as high as 2700 m2 g-1, coupled with ultrahigh micro- and mesopore volumes up to 2.6 cm3 g-1. The relationship between synthesis conditions and the properties of the resulting carbon materials is described in detail, allowing precise control of the properties of DUT-70. Since the hierarchical pore system ensures both efficient mass transfer and high capacities, the novel CDC shows outstanding performance as an electrode material in electrochemical double-layer capacitors (EDLCs) with specific capacities above 240 F g-1 when measured in a symmetrical two-electrode configuration. Remarkable capacities of 175 F g-1 can be retained even at high current densities of 20 A g-1 as a result of the enhanced ion-transport pathways provided by the cellular mesostructure. Moreover, DUT-70 can be infiltrated with sulfur and host the active material in lithium-sulfur battery cathodes. Reversible capacities of 790 mAh g-1 are achieved at a current rate of C/10 after 100 cycles, which renders DUT-70 an ideal support material for electrochemical energy-storage applications.

: http://publica.fraunhofer.de/dokumente/N-261225.html