(190a) Molecular Dynamics Study of the Effect of Si/Al Ratio on Ion Transport through MFI Zeolite Membranes in Redox Flow Batteries

Redox flow batteries (RFB’s) have generated considerable interest in recent years due to their low environmental footprint, safety, and adjustable capacity. RFB’s are an attractive solution to address peak-smoothing problems with renewables such as wind and solar energy. Currently polymeric ion-exchange membranes are used in RFB’s which, because of several shortcomings related to efficiency, are limiting their commercial development. These membranes have stability and selectivity issues which decrease both their lifetime and efficiency. To overcome these shortcomings, zeolite membranes show promise as an alternative material and their potential for success has been shown both computationally and experimentally. Previously, it was shown that MFI zeolites possess the correct pore size to prevent the leakage of the reactive ions in vanadium-RFB’s while still allowing for the transport of water and protons. This study aims on further examining how changes made to the zeolite, namely aluminum substitutions, can further facilitate these transport processes. This is done by investigating two key characteristics: membrane loading and intramembrane diffusion. Combination of these two parameters allows for prediction of the overall ion permeability. The goal is to determine the optimum Si/Al ratio for high proton permeability while maintaining is selectivity to undesirable ions.