Optimization through response surface methodology of 3D printed membrane preparation conditions for use in vanadium redox flow battery: A vanadium/proton selectivity study

Abstract

AbstractSPEEK membrane applicable in Vanadium Redox Flow Battery (VRFB) have been 3D printed via Fused Deposition Modeling (FDM). Response Surface Methodology (RSM) has been used to optimize conditions for 3D printing membrane. Good membranes characteristics were obtained by manipulating three parameters, namely the printing temperature, the orientation of the printing layer and the sulfonation time. We evaluated the effects of these three variables on the permeability of membranes to protons and vanadium ions. Results have shown that sulfonation is the most significant variable influencing vanadium and proton permeability. The optimal printing conditions were found at 408°C temperature with a horizontal layer orientation, while the best sulfonation is obtained at 6 min. The optimal membrane has an ion exchange capacity of 0.86 mmolg−1, a water uptake ratio of 22%, a VO2+ permeability of 6.1 × 10−8 cm2 min−1, a H+ permeability of 7.0 × 10−6 cm2 min−1, excellent mechanical stability and better H+/VO2+ perm selectivity than conventional sulfonated polyether ether ketone (SPEEK), Fap450 and Nafion211 membranes. The above results show that the 3D‐SPEEK membrane has great advantages and broad prospects for VRFB applications.