The structural and morphological evolution of carbon sphere electrodes, prepared by autogenic reactions, has been monitored by various techniques.  In-situ X-ray diffraction was used to track the real-time thermal dissociation of polyethylene in an enclosed vessel to 700 �C and the nucleation of carbon spheres (CS) on cooling to room temperature.  Further heating of the spheres to 2400 �C (CS-2400) and 2800 �C (CS-2800) in an inert atmosphere increases their long-range order and graphitic character, as confirmed by X-ray diffraction, Raman spectroscopy, pair-distribution-function analysis  of neutron scattering data, and aberration-corrected electron microscopy.  High-resolution transmission electron microscopy of CS-2800 reveals that the inner structure of the heated spheres is composed of graphitic sheets, aligned perpendicular to curved graphene 'domes' at the surface. Molecular dynamics simulations of CS at the nanoscale suggest that several types of defects in the structure provide multi-dimensional diffusion pathways with access to favorably aligned graphite blocks for reversible lithium diffusion. A steady capacity of 250 mAh/g with >99% cycling efficiency has been achieved from these carbon electrodes.

Structural and morphological evolution of carbon sphere electrodes prepared by autogenic reactions

245th National Meeting (2013)

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