A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Redox-Active Bisphosphonate-Based Viologens as Negolytes for Aqueous Organic Flow Batteries
Tekijät: Gonzalez, Gabriel; Nechaev, Anton A.; Peshkov, Vsevolod A.; Martínez-González, Eduardo; Belyaev, Andrey; Hamza, Andrea; Shahsavan, Mahsa; Pihko, Petri M.; Peljo, Pekka
Kustantaja: Wiley-VCH Verlag GmbH & Co. KGaA
Julkaisuvuosi: 2025
Journal: Chemistry - A European Journal
Artikkelin numero: e202404122
Vuosikerta: 31
Numero: 16
ISSN: 0947-6539
eISSN: 1521-3765
DOI: https://doi.org/10.1002/chem.202404122
Verkko-osoite: https://doi.org/10.1002/chem.202404122
Viologen derivatives feature two reversible one-electron redox processes and have been extensively utilized in aqueous organic flow batteries (AOFBs). However, the early variant, methyl viologen (MVi), exhibits low stability in aqueous electrolytes, restricting its practical implementation in AOFB technology. In this context, leveraging the tunability of organic molecules, various substituents have been incorporated into the viologen core to achieve better stability, lower redox potential, and improved solubility. In this work, we introduce bisphosphonate-substituted viologens (BBPE−Vi and MBPE−Vi) as candidates for AOFBs. The bulkiness and negative charges of the bisphosphonate groups enhance the solubility and the electrostatic repulsion among viologen molecules, minimizing the bimolecular side reactions that lead to degradation. Additionally, the electron-rich character of this new substituent in its deprotonated state significantly lowers the redox potential. As a result, the proposed viologen derivatives exhibit high solubility (1.45 M in water) and stability (capacity decay of 0.009 %/cycle or 0.229 %/day when tested at 0.5 M). These parameters are coupled with the lowest redox potentials exceeding all previously reported viologens utilized in AOFBs (−0.503 V and −0.550 V against SHE for MBPE−Vi and BBPE−Vi, respectively).
Julkaisussa olevat rahoitustiedot:
This project has received funding from the European Union's Horizon2020 Research and Innovation programme under grant agreement No 875565 (Project CompBat). Support from Research Council Finland (project 348328 \u2013 via European Union \u2013 NextGenerationEU instrument \u2013 to P.\u2005M.\u2005P.) and 346895 (to A.\u2005A.\u2005N.) is gratefully acknowledged. P.\u2005P. gratefully acknowledges the Academy Research Fellow funding (grant no. 315739, 343791, 320071 and 343794) and BioFlow project (grant no. 343493) from Research Council Finland, and European Research Council through a Starting grant (agreement no. 950038). We also thank Dr. Anniina Kiesil\u00E4 for assistance with mass spectrometry. We also acknowledge Ali Tuna and Jenni Jarju for the collaboration on NMR spectrometry studies, and Jenna Hannonen for the permeability measurements.
