Imide-Based Multielectron Anolytes as High-Performance Materials in Nonaqueous Redox Flow Batteries
journal contributionposted on 27.09.2021, 07:43 by Nicolas Daub, René A. J. Janssen, Koen H. Hendriks
Recent developments toward high-energy-density all-organic redox flow batteries suggest the advantageous use of molecules exhibiting multielectron redox events. Following this approach, organic anolytes are developed that feature multiple consecutive one-electron reductions. These anolytes are based on N-methylphthalimide, which exhibits a single reversible reduction at a low potential with good cycling stability. Derivatives with two or three imide groups were synthesized to enable multielectron reduction events. By incorporating suitably designed side chains, a volumetric capacity of 65 Ah/L is achieved in electrolyte solutions. Bulk-electrolysis experiments and UV–vis–NIR absorption spectroscopy revealed good cycling stability for the first and second reduction of monoamides and diimides, respectively, but a loss of stability for the third reduction of triimides. We identify N-2-pentyl-N′-2-(2-(2-methoxyethoxy)ethoxy)ethylaminepyromellitic diimide as a very promising multielectron anolyte with an excellent volumetric capacity and superior cycling and shelf-life stability compared to monoimides and triimides. The outstanding performance of this anolyte was demonstrated in proof-of-principle redox flow batteries that reach an energy density of 24.1 Wh/L.
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single reversible reductionlife stability comparedthree imide groupspromising multielectron anolyteexcellent volumetric capacitygood cycling stabilitybased multielectron anolytesvolumetric capacitysuperior cyclingthird reductionsecond reductionperformance materialspentyl -<outstanding performanceorganic anolytesn </low potentialelectron reductionselectrolyte solutionselectrolysis experimentsadvantageous use>- methylphthalimide>- 265 ah1 wh