Nano-carbon/sulfur composite cathode materials with carbon nanofiber as electrical conductor for advanced secondary lithium/sulfur cells

A carbon particle supported sulfur (C-S) composite cathode material was prepared by a chemical deposition method in an aqueous solution. The performance of the C-S cathode material with carbon particles (CP) and carbon nanofibers (CNFs) as electrical conductors and CMC + SBR as binder was evaluated in Li/S cells using cyclic voltammetry, constant current cycling, and electrochemical impedance spectroscopy. The C-S material and the electrodes were examined by scanning electron microscopy. It is found that the C-S cathode with CNFs shows improvement of not only discharge capacity but also cycling durability. It exhibits an initial discharge capacity of 1200 mAh g(-1), or 72% of theoretical, and retains 668 mAh g(-1), or 40% of the sulfur theoretical capacity after 50 cycles. The C-S electrode with CNFs has a three-dimensional network structure with regular pores, which can suppress the agglomeration of sulfur or lithium sulfide. Thus, the cell performance is improved. (C) 2012 Elsevier B.V. All rights reserved.