Hierarchically Interconnected N-Doped Carbon Aerogels Derived from Cellulose Nanofibrils as High Performance and Stable Electrodes for Supercapacitors

Abstract

Nitrogen (N) is an important heteroatom that improves the capacitance of carbon materials used in supercapacitors. Here, N-doped carbon aerogels are prepared using cellulose nanofibril aerogels as the carbon source and template. Two types of N-doped carbon aerogels are prepared by N-doping at two stages of the carbon aerogel preparation process: N-doping before and after carbonization. Irrespective of the type of the process, the N-doped carbon materials maintain their interconnected hierarchical porous architectures and large specific surface areas. However, the amounts of N incorporated and the specific capacitance are highly dependent on the N-doping process. Compared with the carbon aerogel precursor, the N-doped carbon aerogels exhibit a larger volume, improved wettability, and excellent conductivity. In particular, the as-obtained N-doped carbon aerogel exhibits a high specific capacitance (152% higher than carbon aerogel) and good cycling stability (∼94.5% capacitance retention after 10 000 cycles) as consequences of its mesoporosity and the positive effect of the incorporated N. Given their excellent electrochemical performance coupled with their simple and environmentally friendly synthesis method, N-doped carbon aerogels have strong application potential in supercapacitors.