Engineering Heterogeneous Interfaces in the Proton Exchange Membrane Fuel Cell Catalyst Layer

Speaker: Prof. Steven C. DeCaluwe, Colorado School of Mines
Date: Feb 5, 2021; Time: 2:30pm Location: WebEx

Webex Link:  https://s.uconn.edu/meseminar

Abstract: Proton exchange membrane fuel cells (PEMFCs) provide clean and efficient conversion of chemical energy into electrical energy, and fuel cell electric vehicles offer attractive range, weight, and refueling times when compared to similar technologies. However, challenges in infrastructure, performance, durability, and cost hinder wide-spread adoption. PEMFC cost, performance, and durability are closely tied to the Pt catalyst in PEMFC electrodes. Efforts to lower the Pt loading or replace the catalyst altogether show poor performance or low durability. This difficulty highlights the challenges related to optimizing processes in the PEMFC catalyst layer (CL), a heterogeneous region made up of carbon, catalyst, gas, and ion-conducting polymer electrolyte phases where key limiting phenomena occur in PEMFCs.
In this presentation we cover the challenges and progress in developing structure-property-function relationships for the Nafion polymer phase in the PEMFC cathode catalyst layer. Work is presented in terms of developing a modeling tool for predicting and optimizing PEMFC performance based on CL design parameters (e.g., microstructure, nanostructure, and catalyst loading). To understand the influence of CL Nafion on PEMFC performance, Nafion properties as a function of film thickness, thermochemical conditions, and polymer structure at solid support interphases must be better understood. We use neutron reflectometry, combined with complementary thin-film techniques, to develop quantitative structure-property relationships for thin-film Nafion, for deploying in our model framework. Insights include an evaluation of modeling approaches for the PEMFC CL microstructure, quantifying Nafion water uptake and conductivity for varying thicknesses and solid substrates, and non-intuitive design principles for PEMFC CL performance. We conclude by highlighting remaining knowledge gaps and next steps for improved understanding and control in PEMFC catalyst layers.

Biographical Sketch: Steven C. DeCaluwe is an Associate Professor of Mechanical Engineering at the Colorado School of Mines in Golden, CO. He received his BS in mathematics and elementary education from Vanderbilt University (2000). After teaching elementary school for three years, he earned a PhD in mechanical engineering from the University of Maryland (2009) before serving as a postdoctoral fellow at the NIST Center for Neutron Research (2009–2012). He has been at the Colorado School of Mines Department of Mechanical Engineering, where he leads the CORES Research Group (cores-research.mines.edu). His research employs operando diagnostics and numerical simulation to bridge atomistic and continuum-scale understanding of electrochemical energy devices, with a focus on processes occurring at material interfaces and in reacting flows. Applications include lithium-ion batteries, beyond lithium-ion batteries (Li-O2 and Li-S), and proton exchange membrane fuel cells.