Optimizing Zn-Mn Flow Batteries with Aminonaphthalene Sulfonic Acid via Hydrogen Bond Disruption and Interface

Irreversible MnO₂ dissolution into "dead MnO₂" limits capacity, efficiency, and cycle life in Mn²⁺/MnO₂-based flow batteries. This study introduces organic additives with sulfonic acid and amino groups into an MnSO₄ electrolyte to achieve a reversible Mn²⁺/MnO₂ process, with hydrogen bonding and electrode-electrolyte interface regulation playing critical roles. Specifically, 5-amino-2-naphthalenesulfonic acid adsorbs onto the electrode surface, enhancing hydrophilicity and ensuring uniform Mn²⁺ deposition, while coordinating with Mn²⁺ in solution to disrupt hydrogen bonds and refine solvation structure, thus optimizing both electrode interface and electrolyte dynamics. Consequently, the Zn-Mn flow battery sustains 200 cycles at 40 mA cm⁻² with an areal capacity of 15 mAh cm⁻², providing an innovative strategy for designing high-areal-capacity Mn-based flow batteries.