(General Student Poster Award Winner, 3rd Place) Biomimetic Auxiliary Channels for Enhanced PEM Fuel Cell Performance

The bipolar plate of polymer electrolyte membrane (PEM) fuel cells is responsible for reactant delivery, liquid product water removal, and mechanical stability of PEM fuel cell stacks. Bipolar plates account for 70-90% of the weight and volume and 18-28% of the production costof stacks [1]. Improving the function of the flow fields embedded in the bipolar plates can significantly impact the energy density of PEM fuel cells by improving liquid water management and reactant distribution. Researchers have modified conventional flow fields by adding baffles or partially narrowed channels as semi-obstructive structures in the channels, exploiting Forchheimer’s intertial effect to locally increase gas velocity, thereby increasing oxygen diffusion and water removal in the GDL [2,3]. However, adding obstructions such as baffles or narrowed channels inherently increases the overall pressure drop across the flow fields, thus increasing the power required to supply reactant gases. In other attempts, biomimetic channel architectures have been shown to enhance preferential water flow; however, these designs have not been tailored to control water accumulation for improved reactant distribution [4,5]. Therefore, there is still a need to investigate flow field land-channel architectures that both enhanced inertial gas diffusion to the catalyst layer reaction sites and efficiently remove excess liquid water. In this work, PEM fuel cell flow fields were laser-cut to enhance the liquid water removal and reactant distribution in the under-land region of the GDL. Operando synchrotron X-ray radiography revealed reduced GDL water accumulation when using our novel flow fields. The reduced mass transport overpotential and corresponding power density increase were attributed to enhanced liquid water removal and reactant distribution due to the flow field design. Ultimately, this work can be used to further optimize the design of bipolar plates for more efficient stacks and accelerate the commercialization of PEM fuel cells. References: Y. Wang, D. F. Ruiz Diaz, K. S. Chen, Z. Wang, and X. C. Adroher, Materials Today, 32, 178–203 (2020). H. Guo, H. Chen, F. Ye, and C. F. Ma, Int J Energy Res, 43, 2737–2755 (2019). H. Chen, H. Guo, F. Ye, and C. F. Ma, Int J Hydrogen Energy, 46, 2990–3007 (2021). N. Guo, M. C. Leu, and U. O. Koylu, Int J Hydrogen Energy, 39, 21185–21195 (2014). S. Feng et al., Science, 373, 1344–1348 (2021).