Temperature-dependent study of AcFc-FeIII(acac)3 redox couple for non-aqueous redox flow battery

This article describes the temperature dependence electrochemical analysis of acetyl ferrocene (AcFc) and iron(III) acetylacetonate ([Fe(acac)3]) for non-aqueous redox flow batteries. An electrochemical cell consisting of AcFc and ([Fe(acac)3]) as catholyte and anolyte species, respectively, were constructed with a cell voltage of 1.41 V and Coulombic efficiencies >99% for up to 50 total cycles at 25o C (RT) and 0o C. Rotating ring disk electrode (RRDE) experiments suggest that diffusion coefficient decreases as the temperature decreases but overall storing capacity far better than aqueous redox flow battery (ARFBs). The electrochemical kinetic rate constant (k0) of AcFc was found larger than Fe(acac)3 but remains similar at both temperatures. NMR study shows no structural change in changing temperature and after battery experiments.