Investigation For Hydration Structure And Leakage Mechanism Of Vanadium Ions In Vanadium Redox Flow Battery

The energy crisis is hot issue in the world today.They are particularly serious in China,and environmental problems have arisen due to excessive coal mining and consumption.So researchers turned their attention to clean energy,such as wind,solar,geothermal energy and so on.But they cannot supply stable energy to human beings,so people use energy storage devices to convert them into chemical energy for our use,and all vanadium redox flow batteries are one of the most promising energy storage devices in 21 st century.It is not widely used in proton exchange membranes,and the experimental study of proton exchange membranes cannot overcome the interference of many factors.Therefore,we use single-wall functionalized carbon nanotubes by classical molecular dynamics simulation to simplify the ion channel of the proton exchange membrane.This way can investigate the ideal structure of the proton exchange membrane.First,we studied the hydration structure of vanadium ions in bulk solution and the transter of ion in the channel according to the size of ion.Since the previous simulation studies focused on the hydration structure of vanadium ion aqueous solution,we based on the all vanadium redox flow battery solution in the actual situation,the effects of sulfate and hydrated protons on the hydration structure of vanadium ions were studied.Finally,according to the hydration of vanadium ions,the recommended size of the proton exchange membrane channel size was in the range of 4.12~8.14?,which is beneficial to proton transfer and also hinders the leakage of vanadium ions.Subsequently,we investigated the effect of channel size and fluorine modification on vanadium leakage and proton transfer.The potential energy distribution of ions in the channel is calculated by the calculation method of adaptive biasing force.The leakage barrier of different vanadium ions and hydrated protons were analyzed.The optimal size of proton exchange membrane through proton hindrance vanadium is 10.8?.Moreover,according to the hydrated structure of vanadium ions in the channel,the mechanism of vanadium leakage is obtained as the size of the ion channel reduced.The effect of fluorine modification on vanadium ion transport was also investigated at the end of this section.Since some studies have pointed out that there is electric field in the ion channel of the proton exchange membrane of the actual vanadium redox flow battery.We first find that the hydrated structure of vanadium ion is weakened under the electric field,and the vanadium ion is not in the form of clusters in 1V/nm electric field.It is obviously detrimental to vanadium resistance.Hence,we investigated the effect of sulfonic acid group distribution on the ion channel in the ion channel at 1V/nm.Finally,it was found that the vanadium-resistance effect was the best when the sulfonic acid group distance was 8.44 ?,and the proton flux was also very well.