High Power Density Vanadium Flow Batteries with Laser-Cut Flow Field Patterns on Carbon Paper Electrodes
Although they provide higher power density, one drawback of carbon paper electrodes is that they have a lower porosity and reduced pore size, which can potential promote mass transport limitations. In a recent study, our group investigated the effects of macro-scale circular perforations on the power density and performance of the carbon paper electrodes to explore possible mitigation strategies for minimizing mass transport losses . We observed that laser-perforation of carbon paper electrodes improved the power density and performance of the VRFB cell up to 30 % when compared to raw (non-perforated) carbon paper, despite a loss in total surface area.
Motivated by the results of our previous work, in this study, we go beyond simple circular perforations and utilize laser manufacturing techniques to produce more complicated geometries and flow patterns on carbon paper electrodes to identify an optimum perforation geometry that would further minimize the transport losses and yield higher power density. Specifically, we study several common flow field patterns, varying the design and geometry of the transport channels. The effect of flow field pattern on the peak power density and limiting current is investigated with the goal of providing further understanding of the coupling between the surface area, performance and mass transport losses in VRFB electrodes.
 N. Trung, R. F. Savinell. J. Electrochem. Soc.19 (2010) 54-56.
 E. Agar, C. R. Dennison, K. W. Knehr, E. C. Kumbur, J. Power Sources. 225 (2013) 89-94.
 D. S. Aaron, Q. Lui, Z. Tang, G. M. Grim, A. B. Papandrew, A. Turhan, T. A. Zawodzinski, M. M. Mench, J. Power Sources. 206 (2012) 450-453.
 Q. H. Lui, G. M. Grim, A. B. Papandrew, A. Turhan, T. A. Zawodzinski, M. M. Mench. J. Electrochem. Soc. 159 (2012) 1246-1252.
 M. P. Manahan, Q. H. Lui, M. L. Gross, M. M. Mench, J. Power Sources. 222 (2013) 498-502.
 I. Mayrhuber, C. R. Dennison, V. Kalra, E. C. Kumbur, J. Power Sources. In press, DOI: 10.1016/j.jpowsour.2014.03.007.