Synthesis and properties of novel phenylethynyl-containing organodisulfide as cathode material for secondary lithium batteries

摘要

A novel phenylethynyl-containing conjugative organodisulfide compound 9-trimethylsilane ethynyl-5,8-dihydro-lH,4H-2,3,6,7-tetrathia-anthracene (TMSEDTTA) was synthesized by a facile preparation method, characterized by elemental analysis, Fourier transform infrared spectroscopy (FT-IR), Raman spectrum, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA), and was tested as cathode active material in rechargeable lithium batteries. The electrochemical properties of S-S bonds redox behavior in the organodisulfides were investigated in 1.0 M LiClO_4/EC/DMC (1:1, v/v) solution. The system has many advantages, such as high theoretical charge density (ca. 365 mAh g~(-1)), fast redox process and enhanced reversibility. The fast redox process and enhanced reversibility are due to the intramolecular cleavage-recombination of the S-S bond, and the intramolecular electrocatalytic effect of phenylethynyl chain. The cyclic voltammogram of TMSEDTTA shows multiple redox peaks. The separation of the anodic and cathodic peak potentials for disulfide bond in TMSEDTTA is 0.4 V. The charge-discharge tests show an initial capacity of 330 mAh g~(-1) and the coulomb efficiency of more than 80 % after the electrochemical activation.