Improving the Volumetric Capacity of Gallocyanine Flow Battery by Adding a Molecular Spectator

: Martínez-González, Eduardo; Peljo, Pekka

Publisher: American Chemical Society

: 2024

: ACS Applied Energy Materials

: 7

: 17

: 7169

: 7175

: 2574-0962

DOI: https://doi.org/10.1021/acsaem.4c00971

: https://doi.org/10.1021/acsaem.4c00971

: https://research.utu.fi/converis/portal/detail/Publication/457690789

Gallocyanine (GAL) was recently introduced as a promising aqueous-soluble electroactive molecule for preparing two-electron storage alkaline flow battery (FB) negolytes. The development of a cost-effective GAL FB electrolyte is limited by the unexpectedly low solubility of GAL. In this work, the compound 7-amino-4-hydroxy-2-naphthalenesulfonic acid was introduced as a molecular spectator to modulate the solubility of GAL in KOH; this formulation allowed the preparation of a negolyte with a theoretical volumetric capacity of 32.00 Ah L–1. The cycling stability of an improved GAL electrolyte was demonstrated by operating a FB cell outside of the glovebox (bubbling N2 in the tanks). The cell exhibited a Coulombic efficiency close to 98\% and began operating with 72.1\% of its theoretical capacity (16.06 Ah L–1), retaining 88\% of it after 110 cell cycles. This work demonstrates that significant improvement in electrolyte performance can be obtained with suitable additives and electrolyte engineering.

martínez-gonzález-peljo-2024-improving-the-volumetric-capacity-of-gallocyanine-flow-battery-by-adding-a-molecular.pdf

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The authors gratefully acknowledges the Academy ResearchFellow funding (Grant Nos. 315739, 343791, 320071 and343794) and BioFlow project (Grant No. 343493) fromAcademy of Finland, and European Research Council througha Starting grant (Agreement No. 950038).