Abstract: The present invention relates to a redox flow battery comprising: a positive compartment containing a positive electrode in contact with a first aqueous-based electrolyte solution comprising a positive electrolyte dissolved in a first aqueous-based solvent; and a negative compartment containing a negative electrode in contact with a second aqueous-based electrolyte solution comprising a negative electrolyte being an organic redox-active molecule dissolved in a second aqueous-based solvent wherein at least one of the first and second aqueous-based electrolytes is based on an ammonium-based salt, wherein the organic redox-active molecule is a naphthalene diimide, abbreviated NDI, or a modified NDI.