One-step synthesis of branched sulfur/polypyrrole nanocomposite cathode for lithium rechargeable batteries

A nanostructured sulfur/polypyrrole binary composite was prepared by a simple one-step ballmilling without heat-treatment. High resolution transmission and scanning electronic microscopy showed the formation of a highly developed branched structure consisting of polypyrrole with uniform sulfur coating on its surface. Exclusion of heat-treatment in the composite preparation avoided the sulfur loss; the composite contained 65 wt% of sulfur. AC impedance spectroscopy data exhibited remarkable reduction in charge transfer resistance of the composite compared with pristine sulfur. This may be due to the high conductivity and large surface area of polypyrrole. This charge transfer enhancement led to the electrochemical performance improvement of the composite cathode, delivering first discharge capacity of 1320 mAh g(-1). (C) 2012 Elsevier B.V. All rights reserved.