Switchable Design of Redox-Enhanced Nonaromatic Quinones Enabled by Conjugation Recovery.

Abstract

An innovative switchable design strategy for modulating the electronic structures of quinones is proposed herein, leading to remarkably enhanced intrinsic redox potentials by restoring conjugated but nonaromatic backbone architectures. Computational validation of two fundamental hypotheses confirms the recovery of backbone conjugation and optimal utilization of the inductive effect in switched quinones, which affords significantly improved redox chemistry and overall performance compared to reference quinones. Geometric and electronic analyses provide strong evidence for the restored backbone conjugation and nonaromaticity in the switched quinones, while highlighting the reinforcement of the inductive effect and suppression of the resonance effect. This strategic approach facilitates the development of an exceptional quinone, viz. 2,6-naphthoquinone, with outstanding performance parameters (338.9 mAh g-1 and 912.9 mWh g-1). Furthermore, 2,6-anthraquinone with superior cyclic stability, demonstrates comparable performance (257.4 mAh g-1 and 702.8 mWh g-1). These findings offer valuable insights into the design of organic cathode materials with favorable redox chemistry in secondary batteries.