Pyrolyzed polyaniline and graphene nano sheet composite with improved rate and cycle performance for lithium storage

Abstract

Pyrolyzed poly-aniline graphene nano sheets (PAGNS) composite was investigated serving as a novel anode material for lithium storage. The composite material with carbon coating and nitrogen doping on graphene were synthesized by heat treatment of polyaniline and graphite oxide precursors under an Ar/H2 atmosphere at 850°C. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy techniques were employed to characterize the PAGNS composites with various contents of carbon and nitrogen doping on graphene in comparison with pristine graphene nanosheets (GNS). The PAGNS composites show defects resulting from nitrogen doping in graphene lattice, and carbon is coated on graphene surface causing vertical alignment of nanosheets which leads to improved electronic conductivity. Electrochemical tests show that the PAGNS composites exhibit enhanced rate performance and cycle capability. The PAGNS is also examined at a 1.6Ag−1 high rate and at 55°C high temperature, and the material demonstrates 282mAhg−1 capacity after 500 cycles, which is superior over that of GNS. The enhanced Li-ion storage properties could be attributed to the synergetic effect of carbon-coating and nitrogen-doping in graphene nanosheets.