Unravelling the effect of benzoquinone intercalators on the aqueous zinc-ion storage performance toward a vanadium pentoxide cathode

Abstract

Intercalating vanadium pentoxide (V₂O₅) with organic molecules has emerged as an efficient approach for boosting the performance of aqueous zinc-ion batteries (ZIBs). However, the effect of molecular properties on the related electrochemical energy storage is rarely explored. Herein, we systematically compared the performance of three benzoquinone-intercalated V₂O₅ electrodes which can be easily synthesized through a one-step hydrothermal reaction. The V₂O₅ intercalated by tetrabromo-benzoquinone (denoted as V₂O₅-BQ4Br) shows an outstanding capacity of 477 mA h g⁻¹ at 0.3 A g⁻¹ and better cycle performance (93.7%/75.1% capacity retention after 100/5000 cycles at 0.5/3 A g⁻¹) than that of V₂O₅ treated with benzoquinone (V₂O₅-BQ) and tetrafluoro-benzoquinone (V₂O₅-BQ4F). DFT calculations reveal lower binding energy, faster Zn²⁺ migration and faster internal charge transfer for V₂O₅-BQ4Br. Furthermore, ex situ characterizations confirms that the energy storage process includes the Zn²⁺ intercalation, quinone carbonyl conversion and V valence transition with high reversibility. The comparative investigation of benzoquinone intercalators can guide the development of organic molecules intercalating two-dimensional oxides for robust ZIB applications.