Enhanced mass transport and water management of polymer electrolyte fuel cells via 3-D printed architectures

Abstract

H2–O2 polymer electrolyte fuel cells (PEFCs) represent one of the most promising next generation renewable energy conversion technologies. Two of the remaining unsolved key issues relate to inefficient mass transport and water management when working at high current densities. These problems arise from the structure of the existing flow fields and gas diffusion layers (GDLs), as well as the counter propagating flow directions of gas reactants and liquid products. To address these issues, we propose a novel design of an integrated flow field-gas diffusion layer (i-FF-GDL) generated by 3D printing of TiH2 followed by high temperature decomposition. In this new i-FF-GDL design, a porous Ti “bone” structure is used to drive water transport through capillary action, while regularly printed gaps transport gases. Benefiting from the separate gas and liquid flow channels, APEFCs using our i-FF-GDL design exhibit up to a 15% increase in peak power density (PPD) under H2-air (CO2 free) and H2–O2 conditions, when compared to traditional APEFCs. Operando electrochemical impedance spectroscopy (EIS) reveals that the enhanced performance arises largely from an increase in the mass transport. This work provides new insights and strategies for achieving high efficiency mass transport for fuel cells, water electrolyzers and related technologies.