A 1.51 V pH neutral redox flow battery towards scalable energy storage†
Aqueous redox flow batteries using low-cost organic and inorganic active materials have received growing interest for sustainable energy storage. In this study, a low-cost, high redox potential (1.08 V vs. NHE) and high capacity ammonium bromide (NH4Br, 214.4 A h L−1) catholyte was coupled with an organic viologen anolyte to demonstrate 1.51 V high voltage (SPr)2V/Br− aqueous redox flow batteries under pH neutral conditions for the first time. Benefitting from the high water solubility of both the NH4Br catholyte and (SPr)2V anolyte, the newly designed (SPr)2V/Br− organic flow battery was operated at up to 1.5 M and an energy density of up to 30.4 W h L−1. Using multiwall carbon nanotubes as an electrochemical additive for the Br3−/Br− redox couple, the highly energy dense (SPr)2V/Br− flow battery manifested outstanding current performance, up to 78% energy efficiency at 40 mA cm−2 current density and 227 mW cm−2 power density, the highest power density known for pH neutral organic flow batteries.
- This article is part of the themed collection: 2019 Journal of Materials Chemistry A HOT Papers