Parametric Study of a Bio-Inspired Non-Aqueous Redox Flow Battery Model

Abstract

The future of sustainable energy will consist of renewable energy integration with the critical enabler energy storage technologies, such as batteries. Specifically, redox flow batteries represent one type of grid-scale energy storage devices with long life spans of at least 10 years and capabilities like peak shaving and load leveling. As more experimentalists are investigating the novel nonaqueous redox flow batteries (NRFBs) to achieve higher energy densities, there is a lack of mathematical models for NRFBs to understand the rate-limiting factors of the battery system. This paper is one of the first modeling efforts to understand key characteristics of NRFB system and operation with experimental validation. The model presented by this paper concludes that the bio-inspired nonaqueous solution (tetrabutylammonium vanadium(v) hydroxyiminodiacetate T B A V B H and bis-tetrabutylammonium vanadium(iv) bis-hydroxyiminodiacetate T B A 2 V B H diluted in acetonitrile) is a promising half–cell electrolyte. One key advantage for this half–cell electrolyte is its generally facile reaction kinetics and insignificant activation losses. The real limiting factors for the flow battery system are ohmic losses and mass transport losses with high sensitivities. Mass transport losses can be controlled by increasing concentrations of active species and staying within an SOC region of 10% to 90%. Ohmic losses can be reduced by enhancing the ionic conductivity of the membrane.