Tuning Electrode-Membrane Interface for Highly Efficient Polymer Electrolyte Membrane Fuel Cells

Abstract

Polymer electrolyte membrane fuel cells (PEMFCs) are typically comprised of porous electrodes with randomly distributed mixtures of Pt/C catalyst and ionomer formed during the ink deposition process. The randomness of catalyst particles, ionomer films, and voids, create a non-ideal disordered electrode structure with high tortuosity. These intrinsic characteristics of conventional electrodes create significant challenges during PEMFC operation. These challenges include: 1) low catalyst utilization; 2) high O2 transport resistance to catalyst through the ionomer and pores of carbon support; and 3) limited electronic/protonic conductivities. To improve the performance of the PEMFC electrode, we have previously shown that structured electrodes based on a patterned membrane surface can increase the interfacial area between the electrode and the membrane, enhancing mass transport at high current densities, and augmenting its ionic conductivity.[1][2] In this work, we will present further optimization of these type of structured electrodes using free-standing architectures, reduced ionomer content, and new catalyst deposition processes. More importantly, these newly tuned electrode structures can improve the performance of PEMFCs by maximizing three-phase boundaries and optimizing the electron, proton, gas, and water transport paths. Acknowledgement: We gratefully acknowledge support from the Laboratory Directed Research & Development Program at Los Alamos National Laboratory. Reference: [1] S. K. Babu, R. Mukundan, D. A. Cullen, and J. S. Spendelow, “Co-Axial Nafion Nanowire Electrode.” ECS, Oct. 15, 2019.[2] S. K. Babu, J. S. Spendelow, and R. L. Borup, “Meso-Structured Array Electrode for Polymer Electrolyte Fuel Cells.” ECS, Oct. 03, 2017.