3D Printed Carbon Aerogels for Polymer-Electrolyte Fuel Cells

Abstract

Carbon aerogels (CA) are known for ultra-low density, very high surface area, fine porous structure, and excellent electrical conductivity. Recent advances in high resolution 3D printing at LLNL enable the manufacturing of complex CA structures which have been demonstrated for electrolysis, flow battery, and supercapacitor applications. Polymer-electrolyte fuel cells (PEFC) may be an excellent candidate for these materials/methods as designers seek to optimize membrane-electrode assemblies to achieve higher power densities. A major challenge to PEFC design is two-phase flow due to water production which causes pore flooding and leads to cell instability. To mitigate these effects, groups have investigated the creation of liquid specific pathways in the porous layers to alleviate liquid buildup and enhance gas diffusion. Methods employed include the addition of small holes to the gas-diffusion layer (GDL) for liquid drainage as well as porosity gradients to exploit capillary effects. While some progress has been made, traditionally manufactured GDLs, which consist of randomly distributed carbon fibers, are limiting. 3D printed CAs are a promising solution as complex macroporous electrode structures can be manufactured out of microporous filaments with a high level of control. Additionally, the process may allow for the consolidation of multiple layers (MPL, GDL, & flow channels) into a single printed architecture. In this work various CA lattice structures were printed using a direct ink write (DIW) method and breakthrough pressures were measured to demonstrate the ability to tune the liquid pathways to achieve specific pressure thresholds. A discussion of the prospects for printed CA electrodes in PEFC will focus on material properties, synthesis techniques, and current challenges.*anthony.santamaria@wne.edu