Energy storage inspired by nature – ionic liquid iron–sulfur clusters as electrolytes for redox flow batteries

Abstract

A redox flow battery electrolyte with a high energy density based on redox-active ionic liquids with iron–sulfur-clusters was prepared and investigated.

Investigation of Cubic Fe4M4 Frameworks for Application in Nonaqueous Energy Storage

“…It is well‐established for biological systems that delocalization facilitates rapid electron‐transfer rates, owing to the minimal re‐organization energy upon oxidation or reduction . Electron‐transfer rate constants of this magnitude have likewise been observed for previously studied multimetallic NRFB charge carriers with delocalized electron density . Therefore, we expect that this principle is similarly operational here.…”

“…The stabilityo fF e 4 Mo 4 O 16 highlights ac riticala dvantage of multimetallic charge carriers for RFB application.W hereas molecular decomposition is commonf or charged solutions of metal coordination complexes [5] ando rganic radicals, [6] 12 O 40 ]a lso demonstrates multi-electron storagew ith no observed decomposition. [9d] In addition to these aqueous POM-based chargec arriers, we have reporteda system of stable nonaqueous POMs, the polyoxovanadium alkoxide clusters, which demonstratel ong-term, multi-electron storage.…”

“…[11] As eparate bio-inspired investigationd escribes the use of an iron-sulfur cluster, [Fe 4 S 4 (SR) 4 ] 2À ,a sa nN RFB charge carrier,f acilitating stable two-electron transfer at the negative electrode. [12] The observed physicochemical properties of these systemss uggests an avenuef or future development of NRFB charge carriers from polynuclear platforms.…”

“…In a recent study, a series of hexanuclear ruthenium(III) complexes demonstrated stable, two‐electron cycling in acetonitrile over nearly a 2.5 V window . A separate bio‐inspired investigation describes the use of an iron–sulfur cluster, [Fe 4 S 4 (SR) 4 ] 2− , as an NRFB charge carrier, facilitating stable two‐electron transfer at the negative electrode . The observed physicochemical properties of these systems suggests an avenue for future development of NRFB charge carriers from polynuclear platforms.…”

A Comparative Review of Metal‐Based Charge Carriers in Nonaqueous Flow Batteries

“…Modrzynski and Burger [64] drew inspiration from nature when they developed the cubic Fe 4 S 4 (Stfe) 4 ionic liquid negolyte, which has a maximum theoretical energy density of 87.7 Wh L À 1 and a redox potential of À 1.69 V. The complex was investigated up to 1 m at 50°C to decrease viscosity and achieved an energy density of 43.6 Wh L À 1 , although EE Table 2. Characteristics of macromolecular charge carriers.…”