Ethynedithiol-based polyeneoligosulfides as active cathode materials for lithium-sulfur batteries

Ethynedithiol-based polyeneoligosulfides have been synthesized in 96% yield by the reaction of sodium acetylides (HC CNa, NaC CSNa) and elemental sulfur through the Na-C-sp bond in liquid ammonia with the following spontaneous polymerization of ethynedithiols (HSC CSH) formed by the hydrolysis. The polyeneoligosulfides synthesized are brown powders (up to 77% sulfur content, mp 128-184 degrees C), partially soluble in organic solvents. They are high-resistance semiconductors (10(-13) to 10(-14) S cm(-1)), possess paramagnetic (10(17) to 10(18) Spin g(-1)) and redox properties. The oligosulfides obtained, being redox systems capable of reversible redox processes, provide high values of discharge capacity (345-720 mA h g(-1)) of rechargeable lithium-sulfur batteries. (C) 2007 Wiley Periodicals, Inc.