Effect of Inorganic\nAdditive Strategy on the Stability\nof VO2+ in Vanadium Redox Flow Battery Electrolyte\nby Molecular Dynamics

Inorganic ions are considered to be effective additives\nto improve\nthe temperature stability of all-vanadium redox flow batteries. In\nthis study, molecular dynamics simulation has been performed to study\nthe solvation structure and dynamic properties of VO<sub>2</sub><sup>+</sup> in the positive electrolyte by\ndoping Na<sup>+</sup>, K<sup>+</sup>, and NH<sub>4</sub><sup>+</sup> in the presence of V<sub>2</sub>O<sub>5</sub> precipitation. The results show that VO<sub>2</sub><sup>+</sup> ions aggregate into chainlike\nclusters in the electrolyte due to the induction of SO<sub>4</sub><sup>2–</sup>. The additives,\nwhich are stable in the solvation layers of VO<sub>2</sub><sup>+</sup>, can work as protective shells\nto inhibit cluster growth. NH<sub>4</sub><sup>+</sup> is a superior dispersant compared with Na<sup>+</sup> and K<sup>+</sup> as it can stably exist in both the first\nsolvation layer and the second solvation layer of VO<sub>2</sub><sup>+</sup>. This work performed the molecular\ndynamics simulation of the electrolyte of vanadium redox flow batteries,\nand it gives some insights into the theoretical study of the modification\nof the cathode electrolyte.