Organic Redox Flow Batteries: Simulation of Polymeric Membranes

Organic redox flow batteries (ORFBs) present a promising avenue for sustainable energy storage, offering higher charge density compared to traditional redox flow batteries. This emerging field requires extensive optimization efforts to improve performance. Our study utilizes classical molecular dynamics (MD) simulations, specifically with the non-polarizable OPLS-AA and CL&P force fields, to investigate the properties of potential ORFB candidates. We focus on the nanostructural, mechanical, and transport characteristics of membranes across various electrolyte solutions, as well as their interfacial interactions. Inspired by experimental fabrication methods, our approach begins with simulating PDADMA-TFSI in a DMF solution to achieve a relaxed polymer orientation. This simulation is followed by the evaporation of the solvent and a final energy relaxation of the remaining polymer within the simulation box. Next, we alter the fabrication parameters used for the membrane in an effort to improve ion selectivity and conductivity. The first step involves fine-tuning the simulation parameters to accurately reflect the density, dielectric coefficient, diffusivity, and nanoscale structural orientation of DMF molecules, which serve as the solvent in membrane preparation. The simulation results are consistent with existing literature, particularly with the partial charges proposed by Vallabh for DMF