(510c) Ultra-Low PGM and PGM-Free High-Performance Electrodes for Aemfcs
AIChE Annual Meeting
2018
2018 AIChE Annual Meeting
Engineering Sciences and Fundamentals
Electrochemical Advances to Enable Efficient Oxygen, Hydrogen and Water Reactions I
Wednesday, October 31, 2018 - 1:10pm to 1:30pm
Xiong Peng1, Travis J. Omasta1,2, Emanuele Magliocca1, and William E. Mustain1
- Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, USA.
- Department of Chemical & Biomolecular Engineering, University of Connecticut, Storrs, Connecticut 06269, USA
Anion exchange membrane fuel cells (AEMFCs) have received significant attention in recent years as a potentially lower cost electrochemical energy conversion device compared to proton exchange membrane fuel cells (PEMFCs) [1]. Several major advancements have been demonstrated in the past few years, which has now made it possible for AEMFCs to achieve peak power densities around 2 W cm-2 [2–4] and stability over 100’s[5] of ours of operation [4,6]. Though these are crucial steps towards the realization of commercially viable AEMFCs, there are more hurdles to overcome, specifically to bring down the cost below PEMFCs. A critical aspect of doing so is realizing AEMFCs with low/no precious metal catalysts without sacrificing performance or stability.
In this study, we take 3 approaches. First, we systematically optimize the composition of very low loading PGM-containing catalyst layers (~0.1 mgPGM/cm2) in order to optimize water management and avoid flooding events at high currents. These catalyst layers are analyzed through their electrochemical surface area, hydroxide transport resistance, as well as kinetic and mass transport reaction overpotentials. Operando and ex situ cell images are taken using 2D & 3D neutron imaging of the water content and X-ray tomography. Second, we created Pt-free (not PGM-free) catalyst layers in order to show that it is possible to achieve > 1 W cm-2 performance without any Pt in the cell – a first. Third, we created new Co@C cathode catalysts and are able to demonstrate that extremely low cost electrodes are possible that are able to support cell peak power densities > 1 W cm-2.
References
[1] J.R. Varcoe, P. Atanassov, D.R. Dekel, A.M. Herring, M.A. Hickner, P.A. Kohl, A.R. Kucernak, W.E. Mustain, K. Nijmeijer, K. Scott, T. Xu, L. Zhuang, "Anion-exchange membranes in electrochemical energy systems", Energy Environ. Sci. 7 (2014) 3135–3191.
[2] L. Wang, E. Magliocca, E.L. Cunningham, W.E. Mustain, S.D. Poynton, R. Escudero-Cid, M.M. Nasef, J. Ponce-González, R. Bance-Souahli, R.C.T. Slade, D.K. Whelligan, J.R. Varcoe, "An optimised synthesis of high performance radiation-grafted anion-exchange membranes", Green Chem. 19 (2017) 831–843.
[3] T.J. Omasta, L. Wang, X. Peng, C.A. Lewis, J.R. Varcoe, W.E. Mustain, "Importance of balancing membrane and electrode water in anion exchange membrane fuel cells", J. Power Sources. (2017).
[4] T.J. Omasta, A.M. Park, J.M. Lamanna, Y. Zhang, X. Peng, L. Wang, D.L. Jacobson, J.R. Varcoe, D.S. Hussey, B.S. Pivovar, W.E. Mustain, "Beyond Catalysis and Membranes: Visualizing and Solving the Challenge of Electrode Water Accumulation and Flooding in AEMFCs", Energy Env. Sci. Energy Environ. Sci. 0 (2018) 1–3.
[5] D.R. Dekel, "Review of cell performance in anion exchange membrane fuel cells", J. Power Sources. 375 (2018) 158–169.
[6] A.M. Park, Z.R. Owczarczyk, T.J. Omasta, Y.-N.A. C, G. Bender, K.C. Neyerlin, W.E. Mustain, B.S. Pivovar, Advances in Nrel’s Perfluorinated Anion Exchange Membrane (PFAEM): Chemistry, Cell Diagnostics, and Durability, in: ECS Fall Meet. Oral Present., 2017.