Synthesis of nitrogen-doped ordered mesoporous carbon with enhanced lithium storage performance from natural kaolin clay

Abstract

N-doped ordered mesoporous carbon (N-OMC) samples with different N contents were synthesized by infiltrating molten melamine (the N source) into the framework of mesoporous silica–sucrose. The framework was prepared using an ordered mesoporous silica hard template derived from natural kaolin clay, subsequent carbonization in an inert gas atmosphere, and etching of the silica template. In this simple methodology, N-heteroatoms were incorporated into the C framework during the carbonization. The N-doping content of the prepared N-OMC was conveniently tuned by modifying the melamine/sucrose ratio. After the N-doping, the synthesized N-OMC exhibited remarkable Li storage properties; further, it demonstrated an initial discharge capacity of 1887 mA h g−1 at a current density of 0.1 A g−1. After 100 discharge–charge cycles, the electrode retained a reversible capacity of 648.7 mA h g−1, which is significantly higher than the theoretical capacity of the commercial graphite anode. The enhanced electrochemical performance of the N-OMC was attributed to the large number of defects introduced by N-doping as well as the abundant micropores and mesopores, which provided additional Li storage sites. The N-OMC anode material, which was synthesized by the hard template method using natural kaolin clay as the raw material, exhibited remarkable electrochemical properties including a long life cycle and superior rate of performance. Thus, this study demonstrates that natural kaolin clay exhibits considerable potential for application in Li-ion batteries.