Yuu Inatomi

Polymer-Bound Pyrene-4,5,9,10-Tetraone for Fast-Charge and -Discharge Lithium-Ion Batteries with High Capacity

Organic rechargeable batteries have received significant research interest from the viewpoints of structural diversity and sustainability of electrode materials. We designed core structures of organic cathode materials for lithium-ion (Li-ion) batteries based on density functional theory (DFT) calculations, which indicated that six-membered cyclic 1,2-diketones serve as excellent core structures because of the high redox energy change resulting from favorable coordination of the oxygen atoms to Li and the aromaticity of the reduced form. Here, we show that the Li-ion battery composed of pyrene-4,5,9,10-tetraone (PYT), which has two six-membered cyclic 1,2-diketone units, bound to polymethacrylate exhibits remarkable charge-discharge properties with a high specific capacity of 231 mAh/g, excellent rechargeability (83% of the capacity retained after 500 cycles), and charge-discharge ability (90% of the capacity at 30 C as compared to 1 C) in the LiNTf(2)/tetraglyme ionic-liquid system.

New tris- and pentakis-fused donors containing extended tetrathiafulvalenes: New positive electrode materials for rechargeable batteries

Summary Derivatives of tris-fused TTF extended with two ethanediylidenes (5), tris- and pentakis-fused TTFs extended with two thiophene-2,5-diylidenes (6–9) were successfully synthesized. Cyclic voltammograms of the tetrakis(n-hexylthio) derivative of 5 and 7 (5d, 7d) consisted of two pairs of two-electron redox waves and two pairs of one-electron redox waves. On the other hand, four pairs of two-electron redox waves and two pairs of one-electron redox waves were observed for the tetrakis(n-hexylthio) derivative of 9 (9d). Coin-type cells using the bis(ethylenedithio) derivatives of 5 (5b), 6 (6b) and the tetrakis(methylthio) derivatives of 5 (5c) and 8 (8c) as positive electrode materials showed initial discharge capacities of 157–190 mAh g−1 and initial energy densities of 535–680 mAh g−1. The discharge capacities after 40 cycles were 64–86% of the initial discharge capacities.