Analyzing The Micro Scale Details of Electrochemical Reactions in Vanadium Redox Flow Batteries through Computational Methods

Vanadium redox flow batteries (VRFBs) offer a compelling solution for large-scale electrochemical energy storage on the grid. This technology allows for the storage of multiple megawatt-hours of electrical energy while delivering advantages such as extended cycling lifespan and a scalable modular structure. However, the broad implementation of VRFBs encounters an obstacle in the form of their comparatively limited energy and power density. Extensive prior research efforts have been focused on enhancing the energy characteristics of VRFBs. Nonetheless, there remains a lack of comprehensive understanding regarding the atomic-level mechanisms governing the electrochemical reactions within the electrolyte and at the electrolyte/electrode interfaces, which significantly influence VRFB performance. The current theoretical investigation and ongoing experimental studies by simulations and electron transfer theory calculations need to uncover the underlying reaction mechanisms in VRFBs. Our theoretical investigations provide microscopic-level information on several crucial aspects, including the fundamental properties of aqueous redox couples (V²⁺/V³⁺, VO²⁺/VO₂⁺), the atomistic polymerization and internal self-discharge reactions, and the mechanisms and kinetics of redox couples on graphite surfaces as carbon-based electrodes. These computational findings not only provide explanations for the apparent discrepancies between various experimental studies on the kinetics of redox reactions but also suggest practical methods for increasing the energy and power density of VRFBs.