Aniline-based polyorganodisulfide redox system of high energy for secondary lithium batteries

A novel redox system, poly(alpha,alpha'-dithio-3-amino-o-xylene) (PDTAn), has been presented as a cathode material for high-energy secondary lithium batteries. PDTAn, containing one six-member ring with S-S bond on the side chain of aniline, has been electrochemically polymerized and chemically polymerized with (NH4)(2)S2O8 from the monomer of DTAn (alpha,alpha'-dithio-3-amino-oxylene), respectively. It has been confirmed by IR and in situ Raman that the main chain of PDTAn is similar to that of polyaniline, and the S-S bond in the moiety of aniline is preserved after polymerization. This system has many advantages, such as high theoretical charge density (ca. 370 mAh/g), fast redox process and enhanced reversibility. The fast redox process and enhanced reversibility are due to the intramolecular cleavage and recombination of the S-S bond, and the intramolecular electrocatalytic effect of polyaniline chain. The charge-discharge tests of Li/PDTAn cell show an initial capacity of 225 mAh/g and the charge efficiency of more than 80% after the first cycle activation. (C) 2004 Elsevier B.V. All rights reserved.