Molecular Engineering of an Alkaline Naphthoquinone Flow Battery

Aqueous organic redox\nflow batteries (AORFBs) have recently gained\nsignificant attention as a potential candidate for grid-scale electrical\nenergy storage. Successful implementation of this technology will\nrequire redox-active organic molecules with many desired properties.\nHere we introduce a naphthoquinone dimer, bislawsone, as the redox-active\nmaterial in a negative potential electrolyte (negolyte) for an AORFB.\nThis dimerization strategy substantially improves the performance\nof the electrolyte versus that of the lawsone monomer in terms of\nsolubility, stability, reversible capacity, permeability, and cell\nvoltage. An AORFB pairing bislawsone with a ferri/ferrocyanide positive\nelectrolyte delivers an open-circuit voltage of 1.05 V and cycles\nat a current density of 300 mA/cm² with a negolyte concentration\nof 2 M electrons in alkaline solution. We determined the degradation\nmechanism for the naphthoquinone-based electrolyte using chemical\nanalysis and predicted theoretically electrolytes based on naphthoquinones\nthat will be even more stable.