Vanadium - Transforming Possibilities

Modelling of redox flow battery electrode processes at a range of length scales: a review

Abstract:

In this article, the different approaches reported in the literature for modelling electrode processes in redox flow batteries (RFBs) are reviewed. Models for RFBs vary widely in terms of computational complexity, research scalability and accuracy of predictions. Development of models of RFBs have been quite slow in the past but in recent years researchers have reported on a range of modelling approaches for the optimization of RFB systems. Flow and transport processes, and their influence on the electron transfer kinetics, play an important role in the performance of RFBs. Macro-scale modelling, typically based on a continuum approach for the porous electrode modeling, have been used to investigate current distribution, to optimize cell design and to support techno-economic analyses. Microscale models have also been developed to investigate the transport properties within porous electrode materials. These microscale models exploit experimental tomographic techniques for characterization of the three-dimensional structures of different electrode materials. New insights into the effect of the electrode structure on transport processes are being provided from these new approaches. Modelling the flow, transport, electrical and electrochemical processes within the electrode structure is a developing area of research, and there are significant variations in the requirements of models for different redox systems, in particular for multiphase chemistries (gas-liquid, solid-liquid etc.) and for aqueous and nonaqueous solvents. Further development is essential to better understand the kinetic and mass transport phenomena in the porous electrodes, and multiscale approaches are also needed to enable optimization across the relevent length scales.