Hydronium ions diffusion behavior in nafion membrane by mesoscopic simulation

Abstract

To study the mesoscopic transfer characteristics of water and hydronium ions in Nafion membrane of all vanadium flow battery, a mesoscopic model was developed in this paper. In this model, Nafion membrane, water, and hydronium ions were coarse-grained according to the Dissipative Particle Dynamics (DPD) method by Materials Studio software, and the three-dimensional topology of water channel is developed by the DPD theory as well. The impact of temperature, water content and hydronium ions content on diffusion coefficient was analyzed by the diffusion coefficient, and the radial distribution function and its influencing factor were also studied. The results show that, the adsorbed water on sulfonic acid group in the Nafion membrane forms the water channel for hydrated hydrogen ion transfer; more water and higher temperature respectively increase the transfer coefficient of hydrated hydrogen ion in the Nafion membrane by increasing water channel and speeding up movement of the hydrated hydrogen ion. This work is helpful to understand working principle of Nafion membrane and will promote the application of all vanadium flow battery.