Polymer-derived carbides and carbons with and without nitrogen-doping for electrochemical energy applications

Abstract

Porous carbon materials are widely used in electrochemical applications for intermediate energy storage or water desalination. This work aimed to synthesize nanoporous carbons with well-controlled properties (e.g., specific surface area, average pore size, chemical composition) to correlate them to the performance in electrochemical applications (e.g., supercapacitors, LiS batteries). Especially the surface chemistry of highly porous carbons with different oxygen and nitrogen groups influences the electrochemical behavior. The carbon materials were obtained from polymeric precursors, including phenolic resins and polysilsesquioxanes. A physical activation with CO 2 or NH 3 that additionally introduced nitrogen groups was applied to adjust the porosity of the phenolic resin-derived carbons. Thereby, it was possible to obtain materials with different properties from the same precursor. The polysilsesquioxanes were first pyrolyzed and then thermally treated with chlorine gas to produce carbide-derived carbons. The porosity was tuned by the composition of the precursor and the synthesis temperature. The intermediate product (silicon oxycarbide) is also an attractive electrode material for Li-ion batteries. It was shown that optimization of the carbon content resulted in extended cycling stability.