Effect of Inorganic Additive Strategy on the Stability of VO2+ in Vanadium Redox Flow Battery Electrolyte by Molecular Dynamics

Inorganic ions are considered to be effective additives to improve the temperature stability of all-vanadium redox flow batteries. In this study, molecular dynamics simulation has been performed to study the solvation structure and dynamic properties of VO₂⁺ in the positive electrolyte by doping Na⁺, K⁺, and NH₄⁺ in the presence of V₂O₅ precipitation. The results show that VO₂⁺ ions aggregate into chainlike clusters in the electrolyte due to the induction of SO₄^2-. The additives, which are stable in the solvation layers of VO₂⁺, can work as protective shells to inhibit cluster growth. NH₄⁺ is a superior dispersant compared with Na⁺ and K⁺ as it can stably exist in both the first solvation layer and the second solvation layer of VO₂⁺. This work performed the molecular dynamics simulation of the electrolyte of vanadium redox flow batteries, and it gives some insights into the theoretical study of the modification of the cathode electrolyte.