Efficient AcFc‐[Fe^III(acac)₃] Redox Couple for Non‐aqueous Redox Flow Battery at Low Temperature

Abstract

The temperature dependency of the electrochemical analysis of acetyl ferrocene (AcFc) and iron(III) acetylacetonate ([Fe(acac) 3 ]) has been investigated for non-aqueous redox flow batteries (NARFBs). AcFc and [Fe(acac) 3 ] were utilized as catholyte and anolyte species, respectively, in an electrochemical cell with a cell voltage of 1.41 V and Coulombic efficiencies > 99% for up to 50 total cycles at room temperature (RT, 25 °C). Experiments with a rotating ring disk electrode (RRDE) indicate that the diffusion coefficient reduces with decreasing temperature from 25 °C to 0 °C, yet the overall storage capacity was higher than that of an aqueous redox flow battery (ARFBs). The electrochemical kinetic rate constant (k 0 ) of AcFc was found to be greater than that of [Fe(acac) 3 ]. However, the value of k 0 was not affected by the variable temperature. 1 H NMR investigations reveal that temperature change during battery trials did not occur in any structural modification. The obtained result demonstrates the suitability of this battery at low temperatures.

Phenyl Acrylate-Based Cross-Linked Anion Exchange Membranes for Non-aqueous Redox Flow Batteries

“…show1 H NMR and13 C NMR spectrum of FcNPF 6 and MV•2PF 6 which suggests that the electrolytes' synthesis was successful. The redox potential of electrolytes is shown in the cyclic voltammograms of Scheme 2, which is 0.32 V vs Fc +/0 for FcNPF 6 and −0.82 V vs Fc +/0 for MV•2PF 6 .…”

“…After synthesis, both anolyte and catholyte were characterized by a 500 MHz (Bruker) spectrometer. Characterization of the electrolytes was performed by both 1 H and 13 C NMR (acetonitrile-d 3 , Cambridge Isotope Laboratories).…”

“…The energy stored in RFBs is equal to the half-cell redox reaction Gibbs free-energy change, Δ G = − nF ( E c – E a ), where F is Faraday’s constant and n is the number of electrons transferred in that redox reaction. While strategies such as tuning the E c and E a redox potentials, by designing catholyte molecules with redox potentials more positive and anolyte molecules with redox potentials more negative, resulted in larger battery voltages. − In contrast to the aqueous (potential window ∼ 1.23 V) RFB (ARFB), a non-aqueous RFB (NARFB) system is attractive due to its wide operating voltage window (for example acetonitrile, MeCN, 5 V). − In addition to the major redox-active components (catholyte, anolyte) of RFBs, the ion-exchange membrane or separator also plays a crucial role in the RFB’s performance. Most of the commercially available separator membranes are designed for aqueous fuel cells and electrolyzers, so finding a suitable, robust membrane for organic solvents has not yet been achieved .…”

“…While strategies such as tuning the E c and E a redox potentials, by designing catholyte molecules with redox potentials more positive and anolyte molecules with redox potentials more negative, resulted in larger battery voltages. 10 − 13 In contrast to the aqueous (potential window ∼ 1.23 V) RFB (ARFB), a non-aqueous RFB (NARFB) system is attractive due to its wide operating voltage window (for example acetonitrile, MeCN, 5 V). 14 − 16 In addition to the major redox-active components (catholyte, anolyte) of RFBs, the ion-exchange membrane or separator also plays a crucial role in the RFB’s performance.…”

Doping in TiO2 to improve solar cell efficiency: A Comprehensive Review

“…Introduction: Generating energy from clean, renewable sources on a massive scale is crucial to meet future energy demand while mitigating the impacts of climate change. [1][2][3][4][5][6] Dyesensitized solar cells (DSSCs) and perovskite solar cells (PSCs) are indeed among the leading candidates in the field of renewable energy generation. DSSCs are a type of thin-film solar cell that uses a semiconductor material, typically titanium dioxide (TiO2), coated with a layer of organic dye.…”