LiFePO4 nanoparticles encapsulated in graphene-containing carbon nanofibers for use as energy storage materials

LiFePO4/graphene/C composite nanofibers, in which LiFePO4 nanoparticles were encapsulated in graphene-containing carbon nanofiber matrix, were synthesized by using a combination of electrospinning and sol-gel techniques. Polyacrylonitrile (PAN) was used as the electrospinning media and the carbon source. Graphene was incorporated in order to increase the conductivity of the composite. PAN was dissolved in N,N-dimethylformamide (DMF). LiFePO4 precursor and graphene were dispersed in DMF separately and were mixed with PAN solution before electrospinning. Electrospun fibers were heat-treated to obtain LiFePO4/graphene/C composite nanofibers. The structure of LiFePO4/graphene/C composite nanofibers was determined by X-ray diffraction analysis. The surface morphology and microstructure of LiFePO4/graphene/C composite nanofibers were characterized using scanning electron microscopy and transmission electron microscopy. Electrochemical performance of LiFePO4/graphene/C composite nanofibers was evaluated in coin-type cells. Graphene flakes were found to be well-dispersed in the carbonaceous matrix and increased the electrochemical performance of the composite nanofibers. As a result, cells containing LiFePO4/graphene/C composite nanofiber cathodes showed good electrochemical performance, in terms of capacity, cycle life, and rate capability. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3690936]