(Energy Technology Division Research Award) Multiphysics, Multiscale Modeling of Electrochemical Energy-Conversion Technologies

Abstract

As electrochemical technologies become increasingly important in our energy paradigm, there is a need to examine them holistically. For commercialization and optimization, one requires a detailed understanding of the underlying physics and phenomena. Furthermore, for such technologies to become practical, they need to operate at high current densities to minimize various cell costs. This operating space necessitates the need for efficient transport of reactants and removal of products from the reaction site, where it is increasingly recognized how critical this local environment and transport are to performance. Mathematical modeling is ideally suited to understand these various interactions and provide insights and optimization strategies. In this talk, various porous electrodes will be examined in terms of their intrinsic transport phenomena. Technologies to be discussed include proton-exchange-membrane fuel cells and electrolyzers and gas-diffusion electrodes for CO2 reduction.For PEMFCs, such mass transport is dominated by transport of oxygen molecules to the reaction site within the catalyst layer. For electrolysis applications, similar gas-diffusion-electrode (GDE) architectures are being investigated and the various tradeoffs endemic in such structures will be discussed such as reactant water transport. In this talk, we will explore the various tradeoffs endemic in GDE architectures for various electrochemical reactions including CO2 and CO reduction and O2 and H2 consumption and evolution. For all technologies, such tradeoffs are quantified through multiphysics modeling and key diagnostics of the cells including breakdowns of the various limiting phenomena at both the micro and macroscales, where the local conditions and environment around the reaction center impact reactivity in both transient and steady state conditions, enabling metastable states. It will be shown how transport phenomena dominate a lot of the performance and selectivity of the catalysts, which is critical to understand to improve overall performance. In addition, we will explore how different integration schemes can greatly impact overall response, which can overshadow any intrinsic changes due to different electrocatalyst materials, thereby providing different design rules. A key focus of this talk will be in exploring and describing the various transport and competing phenomena within the electrochemical cells and how to describe them physically and numerically