Synergistic Effect of Hydrogen Bonding and π-π Stacking Enables Long Cycle Life in Organic Electrode Materials

Abstract

Small-molecule organic compounds have emerged as attractive candidates for energy storage in lithium-ion batteries due to their sustainability and modularity. To develop generalizable design principles for organic electrode materials (OEMs), we investigated the correlation between electrochemical performance and addition of functional groups that promote synergistic hydrogen bonding and π-π stacking using a series of quinone-fused aza-phenazines (QAPs) with different hydrogen bonding donor/acceptor arrays. The QAP containing the most hydrogen bonding groups (<b>3</b>) exhibits the best performance with discharge capacities of 145 mAh g<sup>-1</sup> at 2C with 82% capacity retention over 1000 cycles. The performance of <b>3</b> is attributed to the strategically incorporated -OH and -NH<sub>2</sub> groups, which facilitate strong intermolecular interactions and a tightly packed 2D structure. The intermolecular interaction strength was evaluated using variable temperature 1D <sup>1</sup>H NMR and 2D <sup>1</sup>H-<sup>1</sup>H NOESY, offering a new strategy to help understand and predict the performance of OEMs with hydrogen bonding motifs.

Diradicals or Zwitterions: The Chemical States of m -Benzoquinone and Structural Variation after Storage of Li Ions

“…The extensive diffusion of molecules in the solvents at higher temperature weakened the hydrogen bonds. 43,44 Such variation could also be supported by movements of the chemical shifts: the chemical shifts of H1A and H1B shifted to up-field;…”