Engineering Lung-Inspired Flow Field Geometries for Redox Flow Batteries with Stereolithography 3D Printing

Redox flow batteries are a promising electrochemical technology for low-cost, scalable and long-duration energy storage, but their energy market penetration is hampered by elevated costs 1,2 . One effective strategy is to increase the overall efficiency of the electrochemical stack. At the core of the electrochemical cells, the design of the flow fields—which distribute the electrolyte through the porous electrodes—determines, in combination with the electrode microstructure, the performance of the system 3 . To date, current designs are inspired on fuel cell technologies but have not been engineered for redox flow cells where single-phase reactive flows are sustained 4 . In this work, we tailor lung-inspired flow field geometries for carbon paper electrodes using stereolithography 3D printing 5,6 . We propose two new lung-inspired geometries—with two and three channel levels—and compare them to a baseline interdigitated flow field. A two-step process based on stereolithography 3D printing followed by the application of a conductive coating is used to manufacture these complex flow field geometries. We employ a suite of electrochemical (i.e., polarization and electrochemical impedance spectroscopy) and fluid dynamic (pressure drop measurement) techniques together with numerical modelling to elucidate flow architecture-performance relationships. We find that lung-inspired structural patterns homogenize the electrolyte distribution into the electrode, accessing a larger electrode reaction area. These fractal geometries can outperform traditional interdigitated flow fields, providing a more favourable balance between low pressure drop and high electrochemical performance ( Figure 1 ). In this talk, I aim to leverage lung-inspired flow field geometries as a promising prospect for engineering advanced flow cell architectures for emerging electrochemical devices. References 1 E. Sánchez-Díez, J. Power Sources , 2021, 23 . 2 L. F. Arenas, C. Ponce de León and F. C. Walsh, J. Energy Storage , 2017, 11 , 119–153. 3 R. M. Darling and M. L. Perry, J. Electrochem. Soc. , 2014, 161 , A1381–A1387. 4 C. R. Dennison, E. Agar, B. Akuzum and E. C. Kumbur, J. Electrochem. Soc. , 2016, 163 , A5163–A5169. 5 J. Marschewski, L. Brenner, N. Ebejer, P. Ruch, B. Michel and D. Poulikakos, Energy Env. Sci , 2017, 10 , 780–787. 6 M. P. Browne, E. Redondo and M. Pumera, Chem. Rev. , 2020, 120 , 2783–2810. Figure 1