Side‐Chain Symmetry Breaking in Naphthalene Diimides Decouples High Concentration From Cycling Stability in Neutral Aqueous Organic Redox Flow Batteries

Abstract

ABSTRACT Neutral aqueous organic redox flow batteries (AORFBs) offer a promising pathway for transitioning renewables from supplementary to primary energy sources. However, their advancement is constrained by the limited long‐term cycling stability and sluggish redox kinetics of materials under high‐concentration conditions. Although introducing hydrophilic groups can mitigate these issues, highly symmetric molecular architectures often impose performance penalties. In this study, a series of asymmetrically modified naphthalene diimide derivatives were synthesized via a one‐pot symmetry‐breaking strategy, which diol‐dex‐NDI achieves a high solubility of 1.82 M. Density functional theory and Molecular dynamics simulations reveal that diol‐dex‐NDI preferentially adopts a dynamic antiparallel π–π stacking mode, enhancing thermodynamic stability while effectively suppressing molecular aggregation. In situ Raman spectroscopy uncovers hydration shell dynamics during electron transfer, showing a 35% reduction in desolvation energy barrier compared to dex‐NDI. Furthermore, π–π and dipole interactions with the electrode enhance adsorption energy and accelerate electron transfer. This molecular design also strengthens the key C─N bond, as evidenced by increased bond dissociation energy, thereby intrinsically improving resistance to electrochemical degradation. Leveraging these advantages, 1.0 M (2 M e − ) diol‐dex‐NDI/MiAcNH‐TEMPO ‐based AORFB delivers stable performance over 620 cycles without notable capacity decay. This work highlights the potential of symmetry‐breaking molecular engineering for practical AORFB applications.