Building Bridges: Unifying Design and Development Aspects for Advancing Non-Aqueous Redox-Flow Batteries

Abstract

Renewable energy sources have been a topic of ever-increasing interest, not least due to escalating environmental changes. The significant rise of research into energy harvesting and storage over the years has yielded a plethora of approaches and methodologies, and associated reviews of individual aspects thereof. Here, we aim at highlighting a rather new avenue within the field of batteries, the (noaqueous) all-organic redox-flow battery, albeit seeking to provide a comprehensive and wide-ranging overview of the subject matter that covers all associated aspects. This way, subject matter on a historical perspective, general types of redox-flow cells, electrolyte design and function, flow kinetics, and cell design are housed within one work, providing perspective on the all-organic redox-flow battery in a broader sense.

A Digital Blueprint for 3D‐Printing Lab Scale Aqueous and Organic Redox‐Flow Batteries

“…When transferring the electrolyte from standard three electrode setup towards static RFB setup a current density increase can be observed, as well as an overall stretching, as described elsewhere (Figure 4 right) [38] . The current response of Fc in‐flow increases with increasing scan rate as expected.…”

“…Note that in the region of mass transport limitation, current noise due to slightly varying convective mass transport from RAS to the three‐dimensionally distributed electrode surface (graphite block and carbon felt) causes also variation in current response. These local RAS refreshing differences become more intense at higher electrochemical conversion rates, which can be seen in the increasing noise with increasing scan rate [38] . The impedance spectroscopy exhibits a low impedance (Figure 6), congruent with the multimeter reading of under 10 Ω (as explained in Figure 4).…”

“…When transferring the electrolyte from standard three electrode setup towards static RFB setup a current density increase can be observed, as well as an overall stretching, as described elsewhere (Figure 4 right). [38] The current response of Fc in-flow increases with increasing scan rate as expected. When further applying volume flow (Figures 5 and S9), the peak current increases as expected with higher flow rates, as the rate of refreshing goes up.…”

“…These local RAS refreshing differences become more intense at higher electrochemical conversion rates, which can be seen in the increasing noise with increasing scan rate. [38] The impedance spectroscopy exhibits a low impedance (Figure 6), congruent with the multimeter reading of under 10 Ω (as explained in Figure 4). Higher flow rates result in a reduction of the mass transport resistance since the diffusion fraction of the material transport is reduced by increased convection.…”

“… Cyclic voltammogram of organic electrolyte (10 mM Fc and FcBF 4 , 0.1 M TBABF 4 , acetonitrile,) in flow RFB setup at different scan rates. The noise of the CV signal is caused by the additional, turbulentconvective mass transport during cycling [38] …”