Nitrogen-doping effects on few-layer graphene as an anode material for lithium-ion batteries

Abstract

In this study, we propose two different nitrogen doping approaches, namely high temperature doping process (N-FLG-H) and high pressure doping processes (N-FLG-A), to investigate the electrochemical behavior of few-layer graphene (FLG) as anode materials for Li-ion batteries. The corresponding characterizations, such as phase structure, surface morphology, specific surface area, distribution of functional groups as well as electrochemical kinetics and cyclic performance of N-FLG-H and N-FLG-A are systematically demonstrated in terms of X-ray diffraction (XRD), scanning electronic microscopy (SEM), Raman microscopy, N2 adsorption/desorption isotherms, X-ray photoelectron spectroscopy (XPS) and galvanostatic charge/discharge measurements. XPS results show that nitrogen contents of N-FLG-H and N-FLG-A are 1.58% and 0.55%, respectively. The pyridinic N content in N-FLG-A was 34.21%, which was higher than that of N-FLG-H. The electrochemical results show that N-FLG-A exhibit higher reversible capacity and excellent rate capability than those of N-FLG-H. Even at 10 C current density, N-FLG-A electrode cell preserves a reversible capacity of 248 mAh g−1 and good cycle stability of remaining 493 mAh g−1 for 100 cycles without decay. The results indicated that the nitrogen doped process play a very important role on electrochemical performance of few layer graphene. The unique N doping process has a great potential for future applications to modify carbon-based anode materials for lithium-ion batteries.