Modeling of a Non-Aqueous Redox Flow Battery for Performance and Capacity Fade Analysis

This study presents a prototype non-aqueous redox flow battery that advances the capabilities of conventional systems by achieving a wide operational voltage range, high efficiency, and prolonged cycle life. Leveraging the redox pair 10-[2-(2-methoxy ethoxy)ethyl]-10H-phenothiazine and 2-ethylterephthalonitrile, the system delivers a discharge cell voltage ranging from approximately 2.25 V to 1.9 V. To address the economic challenges associated with non-aqueous redox flow batteries, this work explores a cost-efficient design using a symmetric cell architecture and a low-cost, porous separator. To evaluate the feasibility and scalability of this approach, a 2D time-transient reactive transport model is developed, integrating Nernst–Planck electroneutrality principles and porous electrode kinetics. The model is optimized and validated against experimental charge/discharge cycles, accurately predicting voltage behavior. Additionally, the study provides crucial insights into the crossover phenomenon, elucidating the transport dynamics and spatial distribution of active species within the cell. This comprehensive framework establishes a robust foundation for future efforts to scale and optimize non-aqueous redox flow batteries for large-scale energy storage applications, bringing them closer to commercial viability.