Redox flow batteries (RFBs), which combines the attributes of fuel cells and solid-state batteries, have been recognized as one of leading technologies for storing electricity that generated from solar and wind farms due to the striking advantages, including excellent scalability, high efficiency, long lifetime as well as high safety [1]. Despite the attractive merits, the widespread deployment of this type of technology was significantly limited by technical and economical issues, such as low power density, high capacity decay rate, low energy density and high capital cost [2]. To address these issues, electrode and membrane designs are of great importance. For instance, electrode design over porous structure and surface properties is critically important for improving the power density and lowering the capital cost. With regard to the electrode design and selection, several types of carbon-fiber based electrodes, such as graphite/carbon felt, carbon paper and carbon cloth, have been employed as the electrodes of RFBs and associated pretreatment procedures have also been investigated, demonstrating decent performance in different RFB systems [3]. However, comprehensive comparison studies on these porous electrodes in RFBs are scarce. In this presentation, we will offer a comprehensive comparison between the state of art RFB electrodes (carbon felt, carbon paper, carbon cloth) in terms of macro and micro porous structure, surface properties, transport properties (hydraulic permeability, mass transfer coefficients, MacMullin number) as well as electrochemical performance. Besides, the use of some novel electrodes, such as brush structured carbon materials, in RFBs will also be disclosed in the present work. With the present comprehensive comparison study, insights on future electrode design and engineering direction will be discussed at last.

[1] A.Z. Weber, M.M. Mench, J.P. Meyers, P.N. Ross, J.T. Gostick, Q. Liu, J.Appl.Electrochem. 41 (2011) 1137-1164.

[2] M.L. Perry, A.Z. Weber, J.Electrochem.Soc. 163 (2016) A5064-A5067.

[3] B.R. Chalamala, T. Soundappan, G.R. Fisher, M.R. Anstey, V.V. Viswanathan, M.L. Perry, Proc IEEE. 102 (2014) 976-999.