Synthesis and Properties of Fused Extended Tetrathiafulvalene Donors with Dithienylmethylene Spacer and Application to Organic Rechargeable Batteries

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 2Aahad 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 (2Beand 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 (2Bcor 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.Derivatives of a TTF-fused 1,3-dithiole[3]dendralene with two thiophene spacers (2) were synthesized. In cyclic voltammetry, six pairs of redox waves corresponding to the formation up to 27+were observed. The rechargeable batteries using 2as the positive electrode material exhibited the first discharge capacities of 133–138 mAh g−1.