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First-Principle Study of All-Vanadium Redox Flow Battery
All-vanadium redox flow batteries (VRFBs) are a promising solution for grid-scale electrochemical energy storage. The technology enables storage of multimegawatt-hours of electrical energy with the benefits of long cycling lifespan and scalable modular design. However, the widespread application of VRFBs is still hampered by relatively low energy and power density. Significant experimental efforts were previously directed at improving the energy characteristics of VRFBs. Nevertheless, atomistic mechanisms of electrochemical reactions in the electrolyte and at the electrolyte/electrode interfaces underlying the performance of VRFBs are still poorly understood. Therefore, there is a need to unveil the reaction mechanisms of vanadium redox transformations in VRFBs. The present theoretical investigation aims to complement the ongoing experimental studies through systematic ab initio molecular dynamics (AIMD) based simulations combined with static density functional theory (DFT) and Marcus electron-transfer theory calculations to explore chemical reaction dynamics relevant to VRFBs. The overarching goal of this research is to provide new fundamental atomistic insights into the complex vanadium chemistry and thus help enhance both the energy and power density of VRFBs. Our theoretical studies provide microscopic information into 1) the basic properties of aqueous vanadium ions (V2+, V3+, VO2+, and VO2+) including solvation dynamics, hydrolysis and diffusion, 2) the atomistic mechanisms of polymerization and internal self-discharge reactions between aqueous vanadium ions, and 3) the mechanisms and kinetics of the V2+/V3+ and VO2+/VO2+ redox transformations at the oxygen-functionalized graphite surfaces as exemplary carbon-based electrodes. Overall, not only our first principles based computational results help explain the apparent conflicts between different experimental studies of redox reaction kinetics, but also suggest efficient strategies to improve both the energy and power density of VRFBs.
Jiang, Zhen, "First-Principle Study of All-Vanadium Redox Flow Battery" (2019). ETD collection for University of Nebraska - Lincoln. AAI22588823.