ChemSusChem, 2014, 7, 563–569

Porous pyrolyzed polyacrylonitrile-sulfur@graphene nano-sheet (pPAN-S@GNS) composite materials are fabricated via a bottom-up strategy. Microspherical particles are formed by spray drying of a mixed aqueous colloid of PAN nanoparticles and graphene nanosheets, following a simple heating treatment with elemental sulfur. The pPAN-S primary nanoparticles are wrapped homogeneously and loosely within a three-dimensional network of GNS. The hierarchical pPAN-S@GNS composite shows a high reversible capacity of 1449.3 mAh g^–1 sulfur or 681.2 mAh g^–1composite in the second cycle; After 300 cycles at a 0.2 C charge/discharge rate the capacity retention is 88.8% of its initial reversible value. Additionally, the coulombic efficiency (CE) during cycling is near 100%, excepting the first cycle, where CE is 81.1%. A remarkable capacity, near 700 mAh g^–1sulfur, is obtained, even at a high discharge rate of 10 C. The superior performance of pPAN-S@GNS is ascribed to the spherical secondary GNS structure, which creates an electronically conductive 3-D framework and reinforces structural stability as well.

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http://onlinelibrary.wiley.com/doi/10.1002/cssc.201300742/full