Hierarchical porous nitrogen-rich carbon monoliths via ice-templating: high capacity and high-rate performance as lithium-ion battery anode materials

Abstract

Hierarchical porous nitrogen-rich carbon monoliths were prepared from a polyacrylonitrile (PAN) precursor by employing a novel & facile ice-templating, thermal annealing and pyrolysis technique. The achieved carbon monoliths were characterised by scanning electron microscopy (SEM), Hg-intrusion porosimetry, thermogravimetric analysis (TGA), N₂ gas-sorption, elemental analysis, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD) and Raman spectroscopy. Electrochemical evaluation of the carbon materials as anodes for the rechargeable lithium-ion battery revealed an impressive stable reversible capacity as high as 745 mA h g⁻¹ at a current density of 50 mA g⁻¹. Incorporation of melamine (for further N-doping) and graphene into the carbon monoliths was achieved easily, and found to significantly enhance high rate performance – with a reversible capacity of about 300 mA h g⁻¹ obtained at the ultra high current density of 10 A g⁻¹.