Simulation and Analysis of Electrochemical Systems

Abstract

Porous electrodes are essential components in redox flow batteries, a promising technology for long duration, grid-scale energy storage, which will be a vital part of the clean energy transition. Carbon capture and storage (CCS) can mitigate and eventually reverse global warming. In this thesis I present four works, in which a porous electrode and a CCS system are each subject to one simulation and one analysis. First, I show a 3D digital twin for porous electrodes that uses direct numerical solution of the governing Navier-Stokes and Nernst-Plank equations for incompressible flow and electrochemical mass transport with Butler-Volmer reaction kinetics. Our performant, open source code handles systems approaching a billion cells at 1.25 μm resolution on a single workstation, and will scale well on modern scientific supercomputers. This work also includes a novel reformulation of the steady state concentration problem, and introduces a figure of merit, the mass-transport limiting utilization of an electrode Umt. Second, I simulate the steady state concentrations in an electrochemical acid-base generator that was experimentally characterized by my collaborators and is suitable for CCS. Third, I solve for the equilibrium concentrations in another experimental CCS system, in which aqueous quinones capture CO₂ via both pH-swing and nucleophilicity swing mechanisms. Finally, I perform an elaborate nonlinear iterative calibration to measure the state of charge of an operating porous electrode given experimental image intensity and electrochemical data obtained by fluorescence microscopy.