As novel precursors in fabrication of carbon nanomaterials, ionic liquids have attracted much attention due to their remarkable properties, such as low toxicity, nonvolatility, processing flexibility, high stability and flexible designability. Even though the mechanism of carbonization, especially the formation of mesopores is not clear, ionic liquid-based carbon nanomaterials have been successfully applied in different fields, such as fuel cells, lithium ion batteries and supercapacitors. In this paper the advantages and structure requirements of ionic liquids as nitrogen-containing carbon precursors and the main factors about nitrogen content have been elaborated. The recent progress of ionic liquids in synthesizing nitrogen-containing carbon nanomaterials (including mesoporous carbon, carbon nanofibers and auxiliary carbon nanomaterials) has been presented. Furthermore template-free synthesis of nitrogen-containing mesoporous carbon by employing ionic liquids as precursors has been particularly introduced. The influence factors of the formation of mesopores, such as the cross linking, carbonization conditions, composition of precursors and pore defects, have been systematically discussed.

Contents
1 Introduction
2 The requirements of the structures of ionic liquids as precursors of nitrogen-containing carbon nanomaterials and the main factors of nitrogen content
2.1 The requirements of the structures of ionic liquids
2.2 The main factors of nitrogen content
3 The synthesis of nitrogen-containing carbon nanomaterials with different structures by ionic liquids as novel precursors
3.1 The synthesis of nitrogen-containing mesoporous carbon
3.2 The synthesis of nitrogen-containing carbon fibers
3.3 The synthesis of nitrogen-containing auxiliary carbon
4 Conclusion and outlook