(Invited) Discovering Design Principles for Anion Exchange Membranes with High Hydroxide Conductivity: An Ab Initio Molecular Dynamics Study

Abstract

It is clear that in the identification and development of clean energy sources, a range of technologies will need to be leveraged. Electrochemical devices are an important part of this mix of technologies, and among these, fuel cells constitute some of the cleanest and most sustainable. However, several key hurdles to harnessing the potential of fuel cells (as well as various other electrochemical technologies) remain to be surmounted. We have mounted a Materials Genome Initiative inspired project that aims to address these challenges by designing, synthesizing, and testing new materials for use in alkaline fuel cells and to discover a set of rules for best practices in the development of future materials for fuel cell applications. In particular, the focus is on anion exchange membrane(AEM) fuel cells, which have advantages over other types of fuel cells in not requiring precious metals and being operable with a variety of fuels at low temperature. The overall strategy of the project employs density-functional theory based first-principles molecular dynamics calculations and dissipative-particle dynamics. In this talk, I will present results from first-principle molecular dynamics component of the proposal, which includes simulations of bulk solutions and idealized confined geometries, both containing cations of interest in the AEM design. Connections to the dissipative-particle dynamics will be made, and comparative results of water structure and distribution, solvation structures and their lifetimes, and hydroxide diffusion constants as functions of temperature, water content, cation spacing, and confinement parameters will be presented. Suggestions of design principles that lead to AEMs with high hydroxide conductivity will be made. Figure 1