Schematic diagram of the side-chain symmetry-breaking design strategy and the interactions between the molecule and the electrode.

Professor He Gang's research team at the Frontier Institute of Science and Technology, Xi'an Jiaotong University (XJTU), has proposed a side-chain symmetry-breaking strategy. They prepared a series of side-chain-asymmetrically modified naphthalenediimide (NDI) negative electrolyte materials using a one-pot method. Among them, diol-dex-NDI exhibits exceptional solubility, reaching as high as 1.82 M.

Density functional theory (DFT) calculations and molecular dynamics simulations reveal that this molecule preferentially adopts a dynamic anti-parallel π-π stacking mode, enhancing thermodynamic stability and effectively suppressing molecular aggregation.

In situ Raman spectroscopy analysis unveiled the dynamic evolution of the hydration shell during the electron transfer process, with calculations showing that the desolvation energy barrier of diol-dex-NDI is reduced by 35 percent compared to symmetric dex-NDI.

Furthermore, π-π and dipole interactions between the molecule and the electrode interface increase adsorption energy, thereby promoting electron transfer kinetics. Meanwhile, the molecular design strengthens the key C-N bond (with a significantly increased bond dissociation energy), improving resistance to electrochemical degradation.

Capitalizing on these advantages, a flow battery based on 1.0 M (2 M e^-) diol-dex-NDI/MiAcNH-TEMPO demonstrated no noticeable capacity decay after 620 cycles.

Starting from precise molecular design, this work regulates molecular π-π stacking behavior, water solubility, electrode reaction kinetics, and chemical stability using a side-chain symmetry-breaking strategy.

This research offers novel design concepts and experimental groundwork for creating high-concentration, durable aqueous organic redox flow batteries.

The findings were published as an inside front cover article in the internationally reputable journal Angewandte Chemie International Edition, titled Side-Chain Symmetry Breaking in Naphthalene Diimides Decouples High Concentration From Cycling Stability in Neutral Aqueous Organic Redox Flow Batteries.