Unlocking Multielectron Transfer in a Quinone–Pyrazine Conjoined Redox Core for Capacity-Doubled and Ultrastable Aqueous Organic Redox Flow Batteries
Pengbo Zhang, Yongkang Chen, Yuzhu Liu, Jie Wei, Zuoao Wu, Binze Yang, Guochun Ding, Sheng Wen, Tengfei Dai, Zhihu You, Zuoxiu Tie, Yichao Yan, Zhong Jin
Abstract
Aqueous organic redox flow batteries (AORFBs) face energy density and stability challenges. We introduce DAPQ, an anthraquinone–phenazine fused molecule with a π-conjugated architecture enabling four-electron storage. The rigid fused-ring structure integrates four redox-active sites, enhancing aromaticity to resist degradation while achieving reversible multielectron transfer and superior volumetric capacity. The 0.6 M DAPQ-based AORFB delivers an exceptionally high energy density of 53.59 Wh L –1 (53.48 Ah L –1 ), and the 0.5 M DAPQ-based AORFB delivers a capacity retention of 99.86% over 2,300 cycles (1991 h), showing merely 0.0017% daily decay. Stable operation persists even at 50 °C, confirming conjugated rigidity’s critical role in redox core stabilization and longevity. Mechanistic studies reveal that extended π-conjugation and balanced charge distribution synergistically inhibit parasitic reactions. This conjugation-driven multielectron design establishes a paradigm for developing high-capacity, durable organic charge carriers, advancing scalable, safe, and sustainable grid-scale energy storage solutions.