Synthesis and Properties of Fused Extended Tetrathiafulvalene Donors with Dithienylmethylene Spacer and Application to Organic Rechargeable Batteries
Tomokazu Yamauchi, Takashi Kubo, Atsushi Fujioka, Aya Yoshimura, Takashi Shirahata, Hisakazu Miyamoto, Masaru Yao, Yohji Misaki
Abstract
Abstract Several derivatives of 1,3-dithiole[3]dendralene derivatives with two thiophene spacers (2) were synthesized. The results of an X-ray structure analysis of an analog without fused TTF units and a DFT calculation of the unsubstituted-2 (2Aa) suggested that 2Aa had a structure significantly distorted between the central 1,3-dithiole (DT) ring and one of the thiophene rings. Cyclic voltammograms of tetrakis(n-hexylsulfanyl) derivatives (2Be and 2Ce) consisted of one pair of two-electron redox waves and five pairs of one-electron redox waves in correspondence with the presence of seven redox-active DT rings. The tetrakis(methylsulfanyl) or bis(ethylenedithio) derivative (2Bc or 2Bd) worked as a positive electrode material for lithium-ion batteries, and the 2Bc/Li and 2Bd/Li cells exhibited the first discharge capacities of 133–138 mAh g−1.