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 specifi c surface areas as high as 2700 m 2 g −1 , coupled with ultrahigh microand mesopore volumes up to 2.6 cm 3 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 effi cient mass transfer and high capacities, the novel CDC shows outstanding performance as an electrode material in electrochemical double-layer capacitors (EDLCs) with specifi c capacities above 240 F g −1 when measured in a symmetrical two-electrode confi guration. 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 infi ltrated 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.

A sustainable synthesis procedure of a rational-designed silicon−carbon electrode for a high-performance rechargeable Li-based battery has been developed. It was realized by an economical approach using low-cost trichlorosilane as feedstock and without special equipment. The synthesis strategy includes polycondensation of trichlorosilane in the presence of a surfactant to selectively form spheric silicon@silica particles via a hydrogen silsesquioxane (HSQ) intermediate. After subsequent carbonization of a sucrose shell and etching the composite, we obtained an anode material based on silicon nanoparticles with 2−5-nm average diameter inside a porous carbon scaffold. The active material exhibits a high rate capability of 2000 mAh/g at a current rate of 0.5 A/g with exceptional cycle stability. After almost 1000 times of deep discharge galvanostatic cycling at 2.5 A/g current rate the capacity is still 60% of the initial 1200 mAh/g. The excellent electrochemical performance is attributed to an interaction of a stabilized solid electrolyte interface on extreme small silicon particles and a well-designed porous carbon cage which serves as efficient charge conductor.

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Ordered mesoporous carbide-derived carbon (OM-CDC) with a specific surface area as high as 2900 m(2) g(-1) was used as a model system in a supercapacitor setup based on an ionic liquid (IL; 1-ethyl-3-methylimidazolium tetrafluoroborate) electrolyte. Our study systematically investigates the effect of surface functional groups on IL-based carbon supercapacitors. Oxygen and chlorine functionalization was achieved by air oxidation and chlorine treatment, respectively, to introduce well-defined levels of polarity. The latter was analyzed by means of water physisorption isotherms at 298 K, and the functionalization level was quantified with X-ray photoelectron spectroscopy. While oxygen functionalization leads to a decreased capacitance at higher power densities, surface chlorination significantly improves the rate capability. A high specific capacitance of up to 203 F g(-1) was observed for a chlorinated OM-CDC sample with a drastically increased rate capability in a voltage range of ±3.4 V.